The production of toxic sulfides is a common environmental problem in mariculture.Therefore,the effective inhibition of sulfidogens is the key to prevent sulfides production.In this study,the possibility and mechanism...The production of toxic sulfides is a common environmental problem in mariculture.Therefore,the effective inhibition of sulfidogens is the key to prevent sulfides production.In this study,the possibility and mechanism of nitrate(NO_(3)^(−))inhibiting the activity of the sulfate-reducing microbiota(SRM)from mariculture sediments was investigated.The results showed that 1,3,and 5 mmol L^(−1)NO_(3)^(−)continuously inhibited sulfide production for 1-3 d.As NO_(3)^(−) dosage increased to 7 mmol L^(−1),the duration of inhibition increased to 6 days.Denitrifying product NO_(2)^(−)heavily inhibited the activity of dissimilar sulfate reductase gene(dsrB)by 3 orders,which was the main reason that the sulfate-reducing activity was inhibited.The SRM structure changed significantly with the dosage of NO_(3)^(−),while the abundance of sulfidogens Desulfovibrio species increased due to their capability of detoxifying nitrite through nitrite reductase.Hence,sulfidogens Desulfovibrio species are more adaptable to a high nitrate/nitrite environment,and the traditional control strategies by dosing nitrate/nitrite should be paid more attention to.The findings will serve as helpful guidelines for sulfate-reducing microbiota in the habitat of mariculture to reduce their generation of poisonous sulfide.展开更多
Different from rivers in humid areas,the variability of riverine CO_(2) system in arid areas is heavily impacted by anthropogenic disturbance with the increasing urbanization and water withdrawals.In this study,the wa...Different from rivers in humid areas,the variability of riverine CO_(2) system in arid areas is heavily impacted by anthropogenic disturbance with the increasing urbanization and water withdrawals.In this study,the water chemistry and the controls of carbonate system in an urbanized river(the Fenhe River)on the semi-arid Loess Plateau were analyzed.The water chemistry of the river water showed that the high dissolved inorganic carbon(DIC)concentration(about 37 mg L^(-1))in the upstream with a karst land type was mainly sourced from carbonate weathering involved by H_(2)CO_(3) and H_(2)SO_(4),resulting in an oversaturated partial pressure of CO_(2)(pCO_(2))(about 800μatm).In comparison,damming resulted in the widespread appearance of non-free flowing river segments,and aquatic photosynthesis dominated the DIC and pCO_(2) spatiality demonstrated by the enriched stable isotope of DIC(δ^(13)CDIC).Especially in the mid-downstream flowing through major cities in warm and low-runoff August,some river segments even acted as an atmospheric CO_(2) sink.The noteworthy is wastewater input leading to a sudden increase in DIC(>55 mg L^(-1))and pCO_(2)(>4500μatm)in the downstream of Taiyuan City,and in cold November the increased DIC even extended to the outlet of the river.Our results highlight the effects of aquatic production induced by damming and urban sewage input on riverine CO_(2) system in semi-arid areas,and reducing sewage discharge may mitigate CO_(2) emission from the rivers.展开更多
The effects of phenanthrene(Phe)on the denitrification activity and denitrifying genes(narG,nirS and nosZ)were evaluated by dose-response experiments in sediments of Dagu River Estuary(DRE)and Jiaozhou Bay(JZB).The re...The effects of phenanthrene(Phe)on the denitrification activity and denitrifying genes(narG,nirS and nosZ)were evaluated by dose-response experiments in sediments of Dagu River Estuary(DRE)and Jiaozhou Bay(JZB).The results showed that potential denitrification activity(PDA),N2O,NO3−and NO2−reduction rates of both areas were inhibited with an increase of Phe concentrations.The PDA,N2O,NO3−and NO2−reduction rates of both areas was highest and lowest in the control(DRE:0.453,0.427,7.439 and 3.222mgNkg−1 h−1,JZB:0.592,0.555,8.470 and 3.793mgNkg−1 h−1)and highest Phe amended treatments(DRE:0.069,0.001,4.486,and 1.563 mgNkg−1 h−1;JZB:0.114,0.024,5.527 and 2.200 mgNkg−1 h−1).The inhibition rate of PDA was highest,follow by NO2−reduction and then NO3−reduction.Moreover,with the increasing of Phe concentrations,total bacteria count and the abundance of denitrifying genes were decreased.And N2O accumulation was promoted with the addition of Phe for both areas.Based on the comparison of EC50 values,denitrifiers harboring three genes were more sensitive to Phe than PDA,and denitrifiers harboring nirS gene were more sensitive,followed by nosZ gene,and then narG gene.Furthermore,according to correlation analysis,the relative abundance of denitrifying genes was much more positively correlated with PDA,NO3−and NO2−reduction than total bacteria count.In addition,the denitrification activity and total bacteria count in JZB were more inhibited than that of DRE.This study is useful for understanding the impact of Phe pollution on denitrification in estuary and marine sediments,with profound implications for the management of aquatic ecosystems regarding eutrophication(N-removal)and greenhouse effect.展开更多
Nonylphenol（NP） and bisphenol A（BPA） are endocrine disruptors causing harmful effects including feminization and carcinogenesis to various organisms,and consequently,their contamination in natural environment has ...Nonylphenol（NP） and bisphenol A（BPA） are endocrine disruptors causing harmful effects including feminization and carcinogenesis to various organisms,and consequently,their contamination in natural environment has received wide concerns.This study reports the distribution characteristics of NP and BPA in surface sediments and their deposition history based on a dated sediment core in the Changjiang River（Yangtze River） Estuary and its adjacent East China Sea.The contents of NP and BPA in surface sediments ranged from 1.56-35.8 and 0.72-13.2 ng/g（dry mass）,respectively,with high values recorded in the two mud zones,the Changjiang River Estuarine Mud Zone and the Zhejiang Coastal Mud Zone.High values in the Zhejiang Coastal Mud Zone suggest the possibility of long distance transport of both contaminants through the Changjiang riverine plume.The contents were not correlated with the distance from the pollution source,indicating other factors including particle deposition rate and sediment grain size obviously affecting the distribution pattern.NP was also detected in a sediment core at layers deposited from the year of 1971 to 2001 with contents of up to 20.9 ng/g（dry mass）.The deposition fluxes of NP varied from 0.68 to 17.9 ng/（cm^2 · a） with peaks and valleys reflecting the traces of economic development history in China during the previous three decades.BPA was detected at sediment layers deposited from 1973 to 2001 with contents of up to 3.66 ng/g.The fluxes of BPA varied from 0.62 to 3.13 ng/（cm^2 · a） showing a similar pattern as NP.The contents of NP and BPA also indicated potential risks on benthic organisms in the study area.展开更多
Riverine carbon input is closely related to the inshore aquatic environment, the marine carbon pool and climate change. Samples were synchronously obtained from 16 rivers discharging into the Bohai Sea （China） in 1-...Riverine carbon input is closely related to the inshore aquatic environment, the marine carbon pool and climate change. Samples were synchronously obtained from 16 rivers discharging into the Bohai Sea （China） in 1-5 July 2005. The dissolved organic carbon （DOC） concentrations of the 16 rivers were mainly controlled by anthropogenic activities. The particulate organic carbon （POC） of the Haihe, Luanhe, Ziyaxinhe, Chaobaixinhe, Xiaoqinghe, Xiaolinghe, Duliujianhe, Jiyunhe, and Majiahe Rivers mainly originated from pollutants discharged by human, while that of the Huanghe River （Yellow River）, Daliaohe, Shuangtaizihe, Tuhaihe, Dalinghe, Daqinghe, and Liuguhe Rivers were generated mainly by soil erosion. Higher dissolved inorganic carbon （DIC） concentrations in the 16 rivers were detected, which were influenced by the large amounts of carbonate and industrial pollution. The estimated DOC, POC and DIC fluxes from the 16 rivers discharging into the Bohai Sea in summer, 2005 were 0.91×10^5, 1.23×10^5 and 6.31×10^5t, respectively.展开更多
Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod...Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod Schmackeria poplesia, rotifer Brachionus plicatilis and anostraca crustacean Artemia sp. were analyzed for fatty acid contents, and were used as live food for cul- turing larval Japanese flounder, Paralichthys olivaceus. The total content of three types of HUFAs （DHA, EPA and ARA） in S. po- plesia was significantly higher than that in the other two live foods （P〈O.O1）. Three live organisms were used for raising larvae and juveniles of Paralichthys olivaceus respectively for 15 and 10 d. Then the growth, survival and fatty acid composition of the larvae and juveniles were investigated. The results showed that the larvae and juveniles fed with copepods （S. poplesia） had significantly higher growth rate than those fed with the other two organisms （P〈0.01）. The survival of the flounder larvae fed with copepods was significantly higher than that of the others （P〈0.01）, and the survival of the juvenile fish fed with copepods was higher than that fed with Artemia （P〈0.05）. The contents of three types of HUFAs （DHA, EPA and ARA） and the ratio of DHA/EPA in larval and juve- nile flounder P. olivaceus were analyzed. The results showed that the contents of DHA, EPA and ARA in the larvae and juveniles fed with S. poplesia were higher than those fed with a mixed diet orArtemia only, and the ratio of EPA/ARA in larvae and juveniles of P. olivaceus fed with S. poplesia was lower than that in the case of feeding with a mixed diet or Artemia only. The present data showed that copepod is the best choice for feeding the larvae and juveniles of fish considering its effects on the survival, growth and nutrition composition of the fish.展开更多
It is well known that acid-volatile sulfide (AVS) plays an important role in influencing the toxicity of divalent cationic metals within anoxic sediments. In studying sediment core samples collected from tidal flats w...It is well known that acid-volatile sulfide (AVS) plays an important role in influencing the toxicity of divalent cationic metals within anoxic sediments. In studying sediment core samples collected from tidal flats within the Jiaozhou Bay, China, we found that the AVS concentration gradually increases with depth and decreases from high tidal flat to low tidal flat areas. We evaluated the chemical activity and bioavailability of heavy metals in the tidal flat based on the molar ratio of simultaneously ex- tracted metals (SEM) and AVS. The value of SEM/AVS is generally less than 1 in this area except for the surface layer, which suggests that the heavy metals only have chemical activity in the surface layer. SEM is most highly concentrated at the boundary of the redox layer. SEM have similar depth distributions throughout the tidal flat. The aeration of low tidal flat sediment indicates that SEM gradually move to deeper sites via interstitial water.展开更多
Chlorella pyrenoidosa(Chlorophyceae)is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effe...Chlorella pyrenoidosa(Chlorophyceae)is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effects of high temperature on photosynthesis and photoprotection can help optimize the productivity ofC.pyrenoidosa cultures.In this study,we investigated effect of high temperature(35,38,or 41℃)on the balance between photosynthetic light absorption and energy utilization of C.pyrenoidosa.In contrast to 30℃,higher temperature of 35 or 38℃did not inhibit the growth of C.pyrenoidosa.Treatment in 35℃maintained the balance.Moreover,the PSI acceptor side in 38℃was over-reduced and PSII reaction centers were over-excited under strong light,which destroyed the balance and generated active oxygen species(AOS).However,the activated antioxidant enzymes might remove completely the over-production of AOS,thereby protect C.pyrenoidosa cells from photodamage.It shows that this C.pyrenoidosa strain could tolerate as high as 38℃.Furthermore,treatment in 41℃resulted in more lack of the balance than that in 38℃.However,the activities of antioxidant enzymes stopped increasing in 41℃,and were not strong enough to remove the excess AOS.Therefore,treatment in 41℃could decrease the growth ofC.pyrenoidosa.In addition,strong and longtime light exposure would cause serious photodamage to C.pyrenoidosa cells.展开更多
The process of habitat degradation varies in habitat type and driving force which shows certain spatial and temporal heterogeneity on regional scales. In the present study, a new diagnostic model for enclosed bay habi...The process of habitat degradation varies in habitat type and driving force which shows certain spatial and temporal heterogeneity on regional scales. In the present study, a new diagnostic model for enclosed bay habitat degradation was established, with which the spatial and temporal variation patterns of habitat degradation during 1991–2012 in Sansha Bay, Fujian, China was investigated. The results show that anthropogenic disturbance is the major controlling factor for the habitat degradation in large temporal heterogeneity in the bay. On the other hand, the habitat degradation experienced signifi cant spatial variations among six sub-bays. Under the joint action of temporal and spatial heterogeneity, the degradation trend in growing scale shows a more signifi cant correlation with the distribution of local leading industries along shorelines. Therefore, we quantifi ed the main characters of habitat degradation in Sansha Bay, and have understood the relationship between the status of habitats spatio-temporal variation value and the main controlling factor leading to the changes. However, a defi ciency of this research is the lack of or inaccessible to the detailed data, which shall be better solved in the future study for accessing more data from more sources.展开更多
This study was conducted to evaluate the impact of hazy and foggy weather on the bacterial communities in bioaerosols, for which samples were collected from the Qingdao coastal region on sunny, foggy, and hazy days in...This study was conducted to evaluate the impact of hazy and foggy weather on the bacterial communities in bioaerosols, for which samples were collected from the Qingdao coastal region on sunny, foggy, and hazy days in January and March 2013. Bacterial community compositions were determined using polymerase chain reaction denaturing gradient gel electrophoresis(PCR-DGGE). The bacterial community diversity was found to be high on foggy and hazy days, and the dominant species differed during hazy weather. The Shannon-Wiener index revealed that the bacterial community diversity of coarse particles was higher than that of fine particles in the bioaerosols. The bacterial community diversity of fine particles significantly correlated with relative humidity(RH; r^2 = 0.986). The cluster analysis results indicated that the bacterial communities on sunny days differed from those on hazy and foggy days. Compared with sunny days, the bacterial communities in the fine particles during hazy weather exhibited greater changes than those in the coarse particles. Most of the sequenced bacteria were found to be closely affiliated with uncultured bacteria. During hazy weather, members of the classes Bacilli and Gammaproteobacteria(Pseudomonas and Acinetobacter) were dominant. The DGGE analysis revealed that Proteobacteria and Firmicutes were the predominant phyla, and their relative percentages to all the measured species changed significantly on hazy days, particularly in the fine particles. Haze and fog had a significant impact on the bacterial communities in bioaerosols, and the bacterial community diversity varied on different hazy days.展开更多
In order to examine the seasonal and spatial distributions of benthic animals in the intertidal mudflat of the southern Yellow River Delta,field investigations were carried out in 2007 and 2008 and multiple methods we...In order to examine the seasonal and spatial distributions of benthic animals in the intertidal mudflat of the southern Yellow River Delta,field investigations were carried out in 2007 and 2008 and multiple methods were applied.Results showed that,the biomass of macro benthos ranged at 0.75-1151.00 g wet m^(-2) and averaged at 156.31 g wet m^(-2),in which Mactra veneriformis accounted for 75.6%-93.4% of the total macro benthic biomass.More than 90% of macro benthos inhabited in the middle and low tide lines,and higher biomass occurred in early summer and lower in winter.Statistical analysis showed that:1)M.veneriformis growth was primarily favored at higher temperature and lower salinity;2)after long time interaction,benthic bivalve grazers led to patching distributions of Chlorophyll a(Chl a);3)macro benthic biomass positively related with Chl a when the concentration of Chl a was low,but they were negatively related when Chl a concentration was high;and 4)furthermore,the biomass of benthic bivalves peaked in the sediment with median grain size about 0.55 mm,but decreased gradually in coarse or fine sediments.The secondary productivity ranged at 0.37-283.68 g m^(-2)yr^(-1) and averaged at 47.88 g m^(-2) yr^(-1),in which 69.7% was contributed by M.veneriformis It was estimated that primary production was transformed to secondary production at a rate of 6.87%approximately,which implies that there is a local sustainability of high bivalve production.展开更多
Unbalanced inputs and outputs of material are the root cause of habitat degradation in Sansha Bay,Fujian Province,China. However,the cumulative pollution varies in different geographic locations and natural conditions...Unbalanced inputs and outputs of material are the root cause of habitat degradation in Sansha Bay,Fujian Province,China. However,the cumulative pollution varies in different geographic locations and natural conditions in the enclosed bay. In this study,hydrodynamic conditions,sediment characteristics,and aquaculture methods were recognized as the underlying causes of spatial heterogeneity in the distribution of nitrogen and phosphorous pollutants,the two major controlling factors of habitat degradation in the bay area. In order to achieve the goal of balancing nutrient inputs and outputs in Sansha Bay,we developed a feasible and practical zone restoration strategy for reasonable adjustment and arrangement of aquaculture species and production scale in accordance with varying hydrodynamic conditions and sediment characteristics in six sub-bay areas(sub-systems). The proposed zone restoration strategy lays a solid foundation for habitat restoration and management in Sansha Bay.展开更多
Presently, research is lacking regarding the diagnosis and evaluation of habitat degradation in enclosed bay systems. We established a diagnostic model for enclosed bay habitat degradation(EBHD model) using a multi-ap...Presently, research is lacking regarding the diagnosis and evaluation of habitat degradation in enclosed bay systems. We established a diagnostic model for enclosed bay habitat degradation(EBHD model) using a multi-approach integrated diagnostic method in consideration of driving force-pressurestate-infl uence-response. The model optimizes the indicator standardization with annual average change rate of habitat degradation as the basic element, to refl ect accurately the impact of the change and speed of degradation on the diagnostic results, to quantify reasonably the contribution of individual diagnostic indicator to habitat degradation, and to solve the issue regarding the infl uence of subjective factors on the evaluation results during indicator scoring. We then applied the EBHD model for the Sansha Bay in Fujian Province, China, evaluated comprehensively the situation of habitat degradation in the bay, and screened out the major controlling factors in the study area. Results show that the diagnostic results are consistent in overall with the real situation of the study area. Therefore, the EBHD model is advantageous in terms of objectivity and accuracy, making a breakthrough in diagnosis and evaluation for habitat degradation in enclosed bay systems.展开更多
From 28 March to 17 April, 2018, different forms of mercury(Hg) in the Yellow Sea and Bohai Sea were measured to study the influencing factors on the distribution and transformation of Hg in spring using a shared crui...From 28 March to 17 April, 2018, different forms of mercury(Hg) in the Yellow Sea and Bohai Sea were measured to study the influencing factors on the distribution and transformation of Hg in spring using a shared cruise. The mean concentration of dissolved gaseous mercury(DGM) in the surface water of the Yellow and Bohai Seas was(44.3 ± 43.9) pg/L, which was close to that in mid-latitude oceans and deep seas. The ratio of DGM to THg(total mercury) was lower than in the oceans and in the Yellow and Bohai Seas in summer or fall. DGM concentrations in surface water were highest in the central part of the South Yellow Sea and were higher than those in the Bohai Sea, and their spatial distributions were consistent with RHg(reactive mercury). DGM and RHg correlated positively with water temperature in surface seawater(r = 0.506, P < 0.01;r = 0.278, P < 0.05). The concentrations of both DGM and RHg in surface water were controlled by solar radiation and water temperature. Foggy weather did not benefit the production of DGM and RHg. DGM in the bottom seawater was mainly affected by Dissolved Oxygen and water temperature(r =-0.366, P < 0.01;r = 0.331, P < 0.01), produced mainly by anaerobic reactions of the bottom seawater and sediment microorganisms. The bottom DGM concentrations in the Yellow and Bohai Seas were the highest, and DGM produced in bottom seawater and sediment plays a more important role than the surface water in spring. The concentrations of DGM and RHg in the surface and bottom water in the South Yellow Sea were all higher than those in the middle layer. Vertical variations in the North Yellow Sea and the Bohai Sea were small. The production and distribution of DGM and RHg were influenced by differences of latitude and by the Yellow Sea warm current in spring.展开更多
This study determined growth and lipid accumulation in Nannochloropsis sp. MASCC 11 cultivated at different pH, temperatures, and CO2 concentrations in 10-day period. The suitability for biodiesel production was also ...This study determined growth and lipid accumulation in Nannochloropsis sp. MASCC 11 cultivated at different pH, temperatures, and CO2 concentrations in 10-day period. The suitability for biodiesel production was also evaluated based on the fatty acid profiles of microalgae lipid. Nannochloropsis sp. MASCC 11 showed an excellent tolerance to acidic pH(as low as 4.0), high temperatures(at least 40℃), and high CO2 concentrations(5%-15%), which are major stressed conditions in flue gas. The highest algal biomass was acquired at pH of 9.0(0.44 g L^-1), a temperature of 35℃(0.63 g L^-1), and a CO2 concentration of 5%(2.27 g L^-1). Maximum lipid production was obtained at p H of 6.0(108.2 mg L^-1), a temperature of 35℃(134.6 mg L^-1), and a CO2 concentration of 5%(782.7 mg L^-1). Synthesis of polyunsaturated fatty acids(PUFAs) in biomass was stimulated under high CO_2 concentrations, remaining above 80% of total fatty acids, mainly composed of C16:3, C18:2, and C18:3. This led to the algae-based biodiesel having a lower oxidation stability, better cold flow properties, and other parameters such as its kinematic viscosity, cetane number, and specific gravity complied with ASTM or EN 14214 biodiesel specifications. Therefore, the improvement of oxidative stability needs to be considered before Nannochloropsis sp. MASCC 11 lipid can be used for biodiesel production, even if this species can grow well under stressful conditions.展开更多
High salt and low temperature are the bottlenecks for the remove of oil contaminants by enriched crude-oil degrading microbiota in Liaohe Estuarine Wetland(LEW),China.To improve the performance of crude-oil removal,mi...High salt and low temperature are the bottlenecks for the remove of oil contaminants by enriched crude-oil degrading microbiota in Liaohe Estuarine Wetland(LEW),China.To improve the performance of crude-oil removal,microbiota was further immobilized by two methods,i.e.,sodium alginate(SA),and polyvinyl alcohol and sodium alginate(PVA+SA).Results showed that the crude oil was effectively removed by the enrichment with an average degrading ratio of 19.42-31.45 mg(L d)^(−1).The optimal inoculum size for the n-alkanes removal was 10%and 99.89%.Some members of genera Acinetobacter,Actinophytocola,Aquabac-terium,Dysgonomonas,Frigidibacter,Sphingobium,Serpens,and Pseudomonas dominated in crude-oil degrading microflora.Though the removal efficiency was lower than free bacteria when the temperature was 15℃,SA and PVA+SA immobilization im-proved the resistance to salinity.The composite crude-oil degrading microbiota in this study demonstrated a perspective potential for crude oil removal from surface water under high salinity and low temperature conditions.展开更多
In June 2003 and 2006 concentrations of nutrient were determined in the Changjiang Estuary. The data indicated that phosphate and nitrate did not behave conservatively in the estuary, but silicate behaved conservative...In June 2003 and 2006 concentrations of nutrient were determined in the Changjiang Estuary. The data indicated that phosphate and nitrate did not behave conservatively in the estuary, but silicate behaved conservatively. An important mobilization of phosphate and nitrate was observed from the river up to halfway in the estuary. Both input flux （from river to estuary） and output flux （from estuary to coastal zone） of phosphate, silicate and nitrate were calculated from statistical interpretations of the salinity profiles. There was a large discrepancy between input and output fluxes of phosphate and nitrate. The river fluxes of silicate, phosphate and nitrate （fr） are augmented 5.3%, 28.9% and 36.6% in June 2003 and 1.0%, 62.5%, 31.7% in June 2006 by internal inputs （fi）.The phosphate and nitrate fluxes are enhanced through the estuarine process, while silicate flux is unaltered. The authors present some long-term data for nutrient concentrations and the ratios of silicon to nitrogen to phosphorus in the Changjiang Estuary. Silicate level falled in the last two decades, while concentration of nitrate increased. Phosphate concentration had no significant change.展开更多
The spatial distribution of ammonia-oxidizing Betaproteobacteria （βAOB） was investigated by FISH （fluorescence in situ hybridization） and DGGE （denaturing gradient get electrophoresis） techniques in the sedimen...The spatial distribution of ammonia-oxidizing Betaproteobacteria （βAOB） was investigated by FISH （fluorescence in situ hybridization） and DGGE （denaturing gradient get electrophoresis） techniques in the sediment off the Changjiang River Estuary. Sediment samples were collected from eight stations in June before the formation of hypoxia zone in 2006. The abundance of βAOB ranged from 1.87× 10^5 to 3.53×10^5 cells/g of sediment. βAOB abundance did not present a negative correlation with salinity, whereas salinity was implicated as the primary factor affecting nitrification rates. The DGGE profiles of PCR-amplified amoA gene fragments revealed that the βAOB community structure of sample S2 separated from other samples at the level of 40% similarity. The variations in composition ofβAOB were significantly correlated with the salinity, temperature, absorption ability of sediments and TOC. The statistical analysis indicates that theβAOB abundance was a main factor to influence nitrification rates with an influence ratio of 87.7% at the level of 40% biodiversity similarity. Considering the good correlation between βAOB abundance and nitrification estimates, the abundance and diversity of βAOB community could be expected as an indirect index of nitrification activity at the study sea area in summer.展开更多
Based on the characteristic of ‘one river one oasis’ in the arid areas, the Yerqiang River Basin, which is the largest irrigated area of Xinjiang, is taken as an example in this paper, and the regional water circula...Based on the characteristic of ‘one river one oasis’ in the arid areas, the Yerqiang River Basin, which is the largest irrigated area of Xinjiang, is taken as an example in this paper, and the regional water circulation pattern is investigated through the analysis of 60 groups of isotope data in the basin. From the phreatic evaporation data analysis of different soils, we study the law of phreatic evaporation, complete the research of the main consumption path of the groundwater, and improve the assessment precision of water resources. The transformation mount of regional water resources are predicted by calculation, which provides a scientific basis for water resources assessment and allocation in arid regions, and offers a new method for the study of regional water circulation patterns.展开更多
基金supported by the National Natural Science Foundation of China(No.41977315)the Fundamental Research Funds for the Central Universities of China(No.201964004).
文摘The production of toxic sulfides is a common environmental problem in mariculture.Therefore,the effective inhibition of sulfidogens is the key to prevent sulfides production.In this study,the possibility and mechanism of nitrate(NO_(3)^(−))inhibiting the activity of the sulfate-reducing microbiota(SRM)from mariculture sediments was investigated.The results showed that 1,3,and 5 mmol L^(−1)NO_(3)^(−)continuously inhibited sulfide production for 1-3 d.As NO_(3)^(−) dosage increased to 7 mmol L^(−1),the duration of inhibition increased to 6 days.Denitrifying product NO_(2)^(−)heavily inhibited the activity of dissimilar sulfate reductase gene(dsrB)by 3 orders,which was the main reason that the sulfate-reducing activity was inhibited.The SRM structure changed significantly with the dosage of NO_(3)^(−),while the abundance of sulfidogens Desulfovibrio species increased due to their capability of detoxifying nitrite through nitrite reductase.Hence,sulfidogens Desulfovibrio species are more adaptable to a high nitrate/nitrite environment,and the traditional control strategies by dosing nitrate/nitrite should be paid more attention to.The findings will serve as helpful guidelines for sulfate-reducing microbiota in the habitat of mariculture to reduce their generation of poisonous sulfide.
基金supported by the National Natural Science Foundation of China (NSFC) (No.41376123)the Youth Project of Shanxi Basic Research (Nos.20210302124317,201901D211383)+1 种基金the Research and Promotion Project of Water Conservancy Science and Technology in Shanxi Province (No.2023GM41)the Science and Technology Innovation Fund of Shanxi Agricultural University (No.2018YJ21)。
文摘Different from rivers in humid areas,the variability of riverine CO_(2) system in arid areas is heavily impacted by anthropogenic disturbance with the increasing urbanization and water withdrawals.In this study,the water chemistry and the controls of carbonate system in an urbanized river(the Fenhe River)on the semi-arid Loess Plateau were analyzed.The water chemistry of the river water showed that the high dissolved inorganic carbon(DIC)concentration(about 37 mg L^(-1))in the upstream with a karst land type was mainly sourced from carbonate weathering involved by H_(2)CO_(3) and H_(2)SO_(4),resulting in an oversaturated partial pressure of CO_(2)(pCO_(2))(about 800μatm).In comparison,damming resulted in the widespread appearance of non-free flowing river segments,and aquatic photosynthesis dominated the DIC and pCO_(2) spatiality demonstrated by the enriched stable isotope of DIC(δ^(13)CDIC).Especially in the mid-downstream flowing through major cities in warm and low-runoff August,some river segments even acted as an atmospheric CO_(2) sink.The noteworthy is wastewater input leading to a sudden increase in DIC(>55 mg L^(-1))and pCO_(2)(>4500μatm)in the downstream of Taiyuan City,and in cold November the increased DIC even extended to the outlet of the river.Our results highlight the effects of aquatic production induced by damming and urban sewage input on riverine CO_(2) system in semi-arid areas,and reducing sewage discharge may mitigate CO_(2) emission from the rivers.
基金supported by the National Major Project of Water Pollution Control and Management Technology in China (No. 2013ZX07202-007)
文摘The effects of phenanthrene(Phe)on the denitrification activity and denitrifying genes(narG,nirS and nosZ)were evaluated by dose-response experiments in sediments of Dagu River Estuary(DRE)and Jiaozhou Bay(JZB).The results showed that potential denitrification activity(PDA),N2O,NO3−and NO2−reduction rates of both areas were inhibited with an increase of Phe concentrations.The PDA,N2O,NO3−and NO2−reduction rates of both areas was highest and lowest in the control(DRE:0.453,0.427,7.439 and 3.222mgNkg−1 h−1,JZB:0.592,0.555,8.470 and 3.793mgNkg−1 h−1)and highest Phe amended treatments(DRE:0.069,0.001,4.486,and 1.563 mgNkg−1 h−1;JZB:0.114,0.024,5.527 and 2.200 mgNkg−1 h−1).The inhibition rate of PDA was highest,follow by NO2−reduction and then NO3−reduction.Moreover,with the increasing of Phe concentrations,total bacteria count and the abundance of denitrifying genes were decreased.And N2O accumulation was promoted with the addition of Phe for both areas.Based on the comparison of EC50 values,denitrifiers harboring three genes were more sensitive to Phe than PDA,and denitrifiers harboring nirS gene were more sensitive,followed by nosZ gene,and then narG gene.Furthermore,according to correlation analysis,the relative abundance of denitrifying genes was much more positively correlated with PDA,NO3−and NO2−reduction than total bacteria count.In addition,the denitrification activity and total bacteria count in JZB were more inhibited than that of DRE.This study is useful for understanding the impact of Phe pollution on denitrification in estuary and marine sediments,with profound implications for the management of aquatic ecosystems regarding eutrophication(N-removal)and greenhouse effect.
基金The National Natural Science Foundation of China under contract No. 40676067the National Basic Research Program of China (973) under contract No. 2005CB422304
文摘Nonylphenol（NP） and bisphenol A（BPA） are endocrine disruptors causing harmful effects including feminization and carcinogenesis to various organisms,and consequently,their contamination in natural environment has received wide concerns.This study reports the distribution characteristics of NP and BPA in surface sediments and their deposition history based on a dated sediment core in the Changjiang River（Yangtze River） Estuary and its adjacent East China Sea.The contents of NP and BPA in surface sediments ranged from 1.56-35.8 and 0.72-13.2 ng/g（dry mass）,respectively,with high values recorded in the two mud zones,the Changjiang River Estuarine Mud Zone and the Zhejiang Coastal Mud Zone.High values in the Zhejiang Coastal Mud Zone suggest the possibility of long distance transport of both contaminants through the Changjiang riverine plume.The contents were not correlated with the distance from the pollution source,indicating other factors including particle deposition rate and sediment grain size obviously affecting the distribution pattern.NP was also detected in a sediment core at layers deposited from the year of 1971 to 2001 with contents of up to 20.9 ng/g（dry mass）.The deposition fluxes of NP varied from 0.68 to 17.9 ng/（cm^2 · a） with peaks and valleys reflecting the traces of economic development history in China during the previous three decades.BPA was detected at sediment layers deposited from 1973 to 2001 with contents of up to 3.66 ng/g.The fluxes of BPA varied from 0.62 to 3.13 ng/（cm^2 · a） showing a similar pattern as NP.The contents of NP and BPA also indicated potential risks on benthic organisms in the study area.
基金The National Natural Science Foundation of China under contract Nos 40476063 and 40940019
文摘Riverine carbon input is closely related to the inshore aquatic environment, the marine carbon pool and climate change. Samples were synchronously obtained from 16 rivers discharging into the Bohai Sea （China） in 1-5 July 2005. The dissolved organic carbon （DOC） concentrations of the 16 rivers were mainly controlled by anthropogenic activities. The particulate organic carbon （POC） of the Haihe, Luanhe, Ziyaxinhe, Chaobaixinhe, Xiaoqinghe, Xiaolinghe, Duliujianhe, Jiyunhe, and Majiahe Rivers mainly originated from pollutants discharged by human, while that of the Huanghe River （Yellow River）, Daliaohe, Shuangtaizihe, Tuhaihe, Dalinghe, Daqinghe, and Liuguhe Rivers were generated mainly by soil erosion. Higher dissolved inorganic carbon （DIC） concentrations in the 16 rivers were detected, which were influenced by the large amounts of carbonate and industrial pollution. The estimated DOC, POC and DIC fluxes from the 16 rivers discharging into the Bohai Sea in summer, 2005 were 0.91×10^5, 1.23×10^5 and 6.31×10^5t, respectively.
基金supported by the National High-Tech Research and Development Program of China (863 Program, Nos. 2002AA629100 and 2004AA626100
文摘Zooplankton constitutes a major part of the diet for fish larvae in the marine food web, and it is generally believed that copepods can meet the nutritional requirements of fish larvae. In this study, calanoid copepod Schmackeria poplesia, rotifer Brachionus plicatilis and anostraca crustacean Artemia sp. were analyzed for fatty acid contents, and were used as live food for cul- turing larval Japanese flounder, Paralichthys olivaceus. The total content of three types of HUFAs （DHA, EPA and ARA） in S. po- plesia was significantly higher than that in the other two live foods （P〈O.O1）. Three live organisms were used for raising larvae and juveniles of Paralichthys olivaceus respectively for 15 and 10 d. Then the growth, survival and fatty acid composition of the larvae and juveniles were investigated. The results showed that the larvae and juveniles fed with copepods （S. poplesia） had significantly higher growth rate than those fed with the other two organisms （P〈0.01）. The survival of the flounder larvae fed with copepods was significantly higher than that of the others （P〈0.01）, and the survival of the juvenile fish fed with copepods was higher than that fed with Artemia （P〈0.05）. The contents of three types of HUFAs （DHA, EPA and ARA） and the ratio of DHA/EPA in larval and juve- nile flounder P. olivaceus were analyzed. The results showed that the contents of DHA, EPA and ARA in the larvae and juveniles fed with S. poplesia were higher than those fed with a mixed diet orArtemia only, and the ratio of EPA/ARA in larvae and juveniles of P. olivaceus fed with S. poplesia was lower than that in the case of feeding with a mixed diet or Artemia only. The present data showed that copepod is the best choice for feeding the larvae and juveniles of fish considering its effects on the survival, growth and nutrition composition of the fish.
基金This work is supported by the National Natural Science Foundation of China(40476063).
文摘It is well known that acid-volatile sulfide (AVS) plays an important role in influencing the toxicity of divalent cationic metals within anoxic sediments. In studying sediment core samples collected from tidal flats within the Jiaozhou Bay, China, we found that the AVS concentration gradually increases with depth and decreases from high tidal flat to low tidal flat areas. We evaluated the chemical activity and bioavailability of heavy metals in the tidal flat based on the molar ratio of simultaneously ex- tracted metals (SEM) and AVS. The value of SEM/AVS is generally less than 1 in this area except for the surface layer, which suggests that the heavy metals only have chemical activity in the surface layer. SEM is most highly concentrated at the boundary of the redox layer. SEM have similar depth distributions throughout the tidal flat. The aeration of low tidal flat sediment indicates that SEM gradually move to deeper sites via interstitial water.
基金Supported by the Shandong Provincial Natural Science Foundation,China(No.ZR2017QC008)
文摘Chlorella pyrenoidosa(Chlorophyceae)is widely cultured for production of health food and animal feed.In outdoors,mass cultivation of C.pyrenoidosa often suffers from high temperature.A better understanding of the effects of high temperature on photosynthesis and photoprotection can help optimize the productivity ofC.pyrenoidosa cultures.In this study,we investigated effect of high temperature(35,38,or 41℃)on the balance between photosynthetic light absorption and energy utilization of C.pyrenoidosa.In contrast to 30℃,higher temperature of 35 or 38℃did not inhibit the growth of C.pyrenoidosa.Treatment in 35℃maintained the balance.Moreover,the PSI acceptor side in 38℃was over-reduced and PSII reaction centers were over-excited under strong light,which destroyed the balance and generated active oxygen species(AOS).However,the activated antioxidant enzymes might remove completely the over-production of AOS,thereby protect C.pyrenoidosa cells from photodamage.It shows that this C.pyrenoidosa strain could tolerate as high as 38℃.Furthermore,treatment in 41℃resulted in more lack of the balance than that in 38℃.However,the activities of antioxidant enzymes stopped increasing in 41℃,and were not strong enough to remove the excess AOS.Therefore,treatment in 41℃could decrease the growth ofC.pyrenoidosa.In addition,strong and longtime light exposure would cause serious photodamage to C.pyrenoidosa cells.
基金Supported by the Public Science and Technology Research Funds Projects of Ocean(No.201205009)
文摘The process of habitat degradation varies in habitat type and driving force which shows certain spatial and temporal heterogeneity on regional scales. In the present study, a new diagnostic model for enclosed bay habitat degradation was established, with which the spatial and temporal variation patterns of habitat degradation during 1991–2012 in Sansha Bay, Fujian, China was investigated. The results show that anthropogenic disturbance is the major controlling factor for the habitat degradation in large temporal heterogeneity in the bay. On the other hand, the habitat degradation experienced signifi cant spatial variations among six sub-bays. Under the joint action of temporal and spatial heterogeneity, the degradation trend in growing scale shows a more signifi cant correlation with the distribution of local leading industries along shorelines. Therefore, we quantifi ed the main characters of habitat degradation in Sansha Bay, and have understood the relationship between the status of habitats spatio-temporal variation value and the main controlling factor leading to the changes. However, a defi ciency of this research is the lack of or inaccessible to the detailed data, which shall be better solved in the future study for accessing more data from more sources.
基金supported by the National Natural Science Foundation of China (No. 41775148)the Program for New Century Excellent Talents in University (No. NCET-13-0531)the Fundamental Research Funds for the Central Universities (No. 201762006)
文摘This study was conducted to evaluate the impact of hazy and foggy weather on the bacterial communities in bioaerosols, for which samples were collected from the Qingdao coastal region on sunny, foggy, and hazy days in January and March 2013. Bacterial community compositions were determined using polymerase chain reaction denaturing gradient gel electrophoresis(PCR-DGGE). The bacterial community diversity was found to be high on foggy and hazy days, and the dominant species differed during hazy weather. The Shannon-Wiener index revealed that the bacterial community diversity of coarse particles was higher than that of fine particles in the bioaerosols. The bacterial community diversity of fine particles significantly correlated with relative humidity(RH; r^2 = 0.986). The cluster analysis results indicated that the bacterial communities on sunny days differed from those on hazy and foggy days. Compared with sunny days, the bacterial communities in the fine particles during hazy weather exhibited greater changes than those in the coarse particles. Most of the sequenced bacteria were found to be closely affiliated with uncultured bacteria. During hazy weather, members of the classes Bacilli and Gammaproteobacteria(Pseudomonas and Acinetobacter) were dominant. The DGGE analysis revealed that Proteobacteria and Firmicutes were the predominant phyla, and their relative percentages to all the measured species changed significantly on hazy days, particularly in the fine particles. Haze and fog had a significant impact on the bacterial communities in bioaerosols, and the bacterial community diversity varied on different hazy days.
基金supported by the National Natural Science Foundation of China(No.41176064)NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406403)
文摘In order to examine the seasonal and spatial distributions of benthic animals in the intertidal mudflat of the southern Yellow River Delta,field investigations were carried out in 2007 and 2008 and multiple methods were applied.Results showed that,the biomass of macro benthos ranged at 0.75-1151.00 g wet m^(-2) and averaged at 156.31 g wet m^(-2),in which Mactra veneriformis accounted for 75.6%-93.4% of the total macro benthic biomass.More than 90% of macro benthos inhabited in the middle and low tide lines,and higher biomass occurred in early summer and lower in winter.Statistical analysis showed that:1)M.veneriformis growth was primarily favored at higher temperature and lower salinity;2)after long time interaction,benthic bivalve grazers led to patching distributions of Chlorophyll a(Chl a);3)macro benthic biomass positively related with Chl a when the concentration of Chl a was low,but they were negatively related when Chl a concentration was high;and 4)furthermore,the biomass of benthic bivalves peaked in the sediment with median grain size about 0.55 mm,but decreased gradually in coarse or fine sediments.The secondary productivity ranged at 0.37-283.68 g m^(-2)yr^(-1) and averaged at 47.88 g m^(-2) yr^(-1),in which 69.7% was contributed by M.veneriformis It was estimated that primary production was transformed to secondary production at a rate of 6.87%approximately,which implies that there is a local sustainability of high bivalve production.
基金Supported by the Projects of Public Science and Technology Research Funds of Ocean Sector of China(No.201205009)the National Natural Science Foundation of China(No.41201569)
文摘Unbalanced inputs and outputs of material are the root cause of habitat degradation in Sansha Bay,Fujian Province,China. However,the cumulative pollution varies in different geographic locations and natural conditions in the enclosed bay. In this study,hydrodynamic conditions,sediment characteristics,and aquaculture methods were recognized as the underlying causes of spatial heterogeneity in the distribution of nitrogen and phosphorous pollutants,the two major controlling factors of habitat degradation in the bay area. In order to achieve the goal of balancing nutrient inputs and outputs in Sansha Bay,we developed a feasible and practical zone restoration strategy for reasonable adjustment and arrangement of aquaculture species and production scale in accordance with varying hydrodynamic conditions and sediment characteristics in six sub-bay areas(sub-systems). The proposed zone restoration strategy lays a solid foundation for habitat restoration and management in Sansha Bay.
基金Supported by the Projects of Public Science and Technology Research Funds of Ocean Sector of China(No.201205009)the National Natural Science Foundation of China(No.41201569)
文摘Presently, research is lacking regarding the diagnosis and evaluation of habitat degradation in enclosed bay systems. We established a diagnostic model for enclosed bay habitat degradation(EBHD model) using a multi-approach integrated diagnostic method in consideration of driving force-pressurestate-infl uence-response. The model optimizes the indicator standardization with annual average change rate of habitat degradation as the basic element, to refl ect accurately the impact of the change and speed of degradation on the diagnostic results, to quantify reasonably the contribution of individual diagnostic indicator to habitat degradation, and to solve the issue regarding the infl uence of subjective factors on the evaluation results during indicator scoring. We then applied the EBHD model for the Sansha Bay in Fujian Province, China, evaluated comprehensively the situation of habitat degradation in the bay, and screened out the major controlling factors in the study area. Results show that the diagnostic results are consistent in overall with the real situation of the study area. Therefore, the EBHD model is advantageous in terms of objectivity and accuracy, making a breakthrough in diagnosis and evaluation for habitat degradation in enclosed bay systems.
基金Under the auspices of the National Natural Science Foundation of China(No.41506128)Shandong Natural Science Foundation(No.ZR2018MD004)。
文摘From 28 March to 17 April, 2018, different forms of mercury(Hg) in the Yellow Sea and Bohai Sea were measured to study the influencing factors on the distribution and transformation of Hg in spring using a shared cruise. The mean concentration of dissolved gaseous mercury(DGM) in the surface water of the Yellow and Bohai Seas was(44.3 ± 43.9) pg/L, which was close to that in mid-latitude oceans and deep seas. The ratio of DGM to THg(total mercury) was lower than in the oceans and in the Yellow and Bohai Seas in summer or fall. DGM concentrations in surface water were highest in the central part of the South Yellow Sea and were higher than those in the Bohai Sea, and their spatial distributions were consistent with RHg(reactive mercury). DGM and RHg correlated positively with water temperature in surface seawater(r = 0.506, P < 0.01;r = 0.278, P < 0.05). The concentrations of both DGM and RHg in surface water were controlled by solar radiation and water temperature. Foggy weather did not benefit the production of DGM and RHg. DGM in the bottom seawater was mainly affected by Dissolved Oxygen and water temperature(r =-0.366, P < 0.01;r = 0.331, P < 0.01), produced mainly by anaerobic reactions of the bottom seawater and sediment microorganisms. The bottom DGM concentrations in the Yellow and Bohai Seas were the highest, and DGM produced in bottom seawater and sediment plays a more important role than the surface water in spring. The concentrations of DGM and RHg in the surface and bottom water in the South Yellow Sea were all higher than those in the middle layer. Vertical variations in the North Yellow Sea and the Bohai Sea were small. The production and distribution of DGM and RHg were influenced by differences of latitude and by the Yellow Sea warm current in spring.
基金supported by the National Key Technology R&D Programme (No. 2011BAD14B04)。
文摘This study determined growth and lipid accumulation in Nannochloropsis sp. MASCC 11 cultivated at different pH, temperatures, and CO2 concentrations in 10-day period. The suitability for biodiesel production was also evaluated based on the fatty acid profiles of microalgae lipid. Nannochloropsis sp. MASCC 11 showed an excellent tolerance to acidic pH(as low as 4.0), high temperatures(at least 40℃), and high CO2 concentrations(5%-15%), which are major stressed conditions in flue gas. The highest algal biomass was acquired at pH of 9.0(0.44 g L^-1), a temperature of 35℃(0.63 g L^-1), and a CO2 concentration of 5%(2.27 g L^-1). Maximum lipid production was obtained at p H of 6.0(108.2 mg L^-1), a temperature of 35℃(134.6 mg L^-1), and a CO2 concentration of 5%(782.7 mg L^-1). Synthesis of polyunsaturated fatty acids(PUFAs) in biomass was stimulated under high CO_2 concentrations, remaining above 80% of total fatty acids, mainly composed of C16:3, C18:2, and C18:3. This led to the algae-based biodiesel having a lower oxidation stability, better cold flow properties, and other parameters such as its kinematic viscosity, cetane number, and specific gravity complied with ASTM or EN 14214 biodiesel specifications. Therefore, the improvement of oxidative stability needs to be considered before Nannochloropsis sp. MASCC 11 lipid can be used for biodiesel production, even if this species can grow well under stressful conditions.
基金supported by the National Key R&D Program of China(No.2018YFD0900805)the Start up Foundation for Introducing Talent of Nanjing Univer-sity of Information Science and Technology。
文摘High salt and low temperature are the bottlenecks for the remove of oil contaminants by enriched crude-oil degrading microbiota in Liaohe Estuarine Wetland(LEW),China.To improve the performance of crude-oil removal,microbiota was further immobilized by two methods,i.e.,sodium alginate(SA),and polyvinyl alcohol and sodium alginate(PVA+SA).Results showed that the crude oil was effectively removed by the enrichment with an average degrading ratio of 19.42-31.45 mg(L d)^(−1).The optimal inoculum size for the n-alkanes removal was 10%and 99.89%.Some members of genera Acinetobacter,Actinophytocola,Aquabac-terium,Dysgonomonas,Frigidibacter,Sphingobium,Serpens,and Pseudomonas dominated in crude-oil degrading microflora.Though the removal efficiency was lower than free bacteria when the temperature was 15℃,SA and PVA+SA immobilization im-proved the resistance to salinity.The composite crude-oil degrading microbiota in this study demonstrated a perspective potential for crude oil removal from surface water under high salinity and low temperature conditions.
基金The National Natural Science Foundation of China (NSFC) under contract No. 30490232Chinese "973" Projectunder contract Nos 2002CB412405 and 2005CB422305
文摘In June 2003 and 2006 concentrations of nutrient were determined in the Changjiang Estuary. The data indicated that phosphate and nitrate did not behave conservatively in the estuary, but silicate behaved conservatively. An important mobilization of phosphate and nitrate was observed from the river up to halfway in the estuary. Both input flux （from river to estuary） and output flux （from estuary to coastal zone） of phosphate, silicate and nitrate were calculated from statistical interpretations of the salinity profiles. There was a large discrepancy between input and output fluxes of phosphate and nitrate. The river fluxes of silicate, phosphate and nitrate （fr） are augmented 5.3%, 28.9% and 36.6% in June 2003 and 1.0%, 62.5%, 31.7% in June 2006 by internal inputs （fi）.The phosphate and nitrate fluxes are enhanced through the estuarine process, while silicate flux is unaltered. The authors present some long-term data for nutrient concentrations and the ratios of silicon to nitrogen to phosphorus in the Changjiang Estuary. Silicate level falled in the last two decades, while concentration of nitrate increased. Phosphate concentration had no significant change.
基金The National Fundamental Project of China under grant No.2006CB400602
文摘The spatial distribution of ammonia-oxidizing Betaproteobacteria （βAOB） was investigated by FISH （fluorescence in situ hybridization） and DGGE （denaturing gradient get electrophoresis） techniques in the sediment off the Changjiang River Estuary. Sediment samples were collected from eight stations in June before the formation of hypoxia zone in 2006. The abundance of βAOB ranged from 1.87× 10^5 to 3.53×10^5 cells/g of sediment. βAOB abundance did not present a negative correlation with salinity, whereas salinity was implicated as the primary factor affecting nitrification rates. The DGGE profiles of PCR-amplified amoA gene fragments revealed that the βAOB community structure of sample S2 separated from other samples at the level of 40% similarity. The variations in composition ofβAOB were significantly correlated with the salinity, temperature, absorption ability of sediments and TOC. The statistical analysis indicates that theβAOB abundance was a main factor to influence nitrification rates with an influence ratio of 87.7% at the level of 40% biodiversity similarity. Considering the good correlation between βAOB abundance and nitrification estimates, the abundance and diversity of βAOB community could be expected as an indirect index of nitrification activity at the study sea area in summer.
文摘Based on the characteristic of ‘one river one oasis’ in the arid areas, the Yerqiang River Basin, which is the largest irrigated area of Xinjiang, is taken as an example in this paper, and the regional water circulation pattern is investigated through the analysis of 60 groups of isotope data in the basin. From the phreatic evaporation data analysis of different soils, we study the law of phreatic evaporation, complete the research of the main consumption path of the groundwater, and improve the assessment precision of water resources. The transformation mount of regional water resources are predicted by calculation, which provides a scientific basis for water resources assessment and allocation in arid regions, and offers a new method for the study of regional water circulation patterns.
