Mudflats play a vital role in maintaining the dynamic balance between sea and land.To understand the characteristics,sources,and pollution risks of six heavy metals(As,Cd,Cr,Cu,Hg,and Pb)in the coastal mudflats on the...Mudflats play a vital role in maintaining the dynamic balance between sea and land.To understand the characteristics,sources,and pollution risks of six heavy metals(As,Cd,Cr,Cu,Hg,and Pb)in the coastal mudflats on the Leizhou Peninsula,257 surface sediment samples were studied using mathematical statistics,correlation analysis,and factor analysis.The results show that the overall concentrations of these heavy metals are low although there are several high abnormal points in the local areas.The strong correlation between these heavy metals indicates that the sources of some of the metals are similar,yet their elemental combinations in different cities(counties)varied.According to the calculated enrichment factor(EF),anthropogenic activity-induced heavy metals were determined in order of decreasing influence:As,Cd,Pb,Cr,Cu,and Hg.The low EF values of Hg indicate that it does not present as a contaminant in the study area,while low values of Cr and Cu from the Lianjiang City suggest that these two metals were also attributed to natural sources.The presence of As,Cd,Cr,Cu,and Pb from the remaining cities(counties)should be influenced by anthropogenic activities.The overall potential ecological risk index indicates that the ecological risks posed by the six analyzed heavy metals to the Leizhou Peninsula mudflats,in order of decreasing risk,are Cd,As,Hg,Pb,Cu,and Cr.It is noteworthy that only Cd in Lianjiang City demonstrated substantial ecological risk.Other examined heavy metals in other cities of the study area showed slight ecological risk.展开更多
In this paper diatomite samples taken from the Leizhou Peninsula have beenstudied by chemical analysis, DTA, TG, XRD, IR, SEM and X-ray Energy Spectroscopy.The study shows that the diatomaceous genera and species and ...In this paper diatomite samples taken from the Leizhou Peninsula have beenstudied by chemical analysis, DTA, TG, XRD, IR, SEM and X-ray Energy Spectroscopy.The study shows that the diatomaceous genera and species and their organic contents arevariable with buried depth, from Melosira to Stephanodiscus and then to Cyclotella.Various impurities in the samples, such as quartz, kaolinite and montmorillonite indicatedifferent sedimentary environments. When heated, the diatom would change in shape dueto the phase transformation in which amorphous silica crystallized from disordered opal toordered cristobalite. The temperatures of phase transformation are different for variousdiatorns due to the presence of different impurities and constituents of diatomaceousgenera and species.展开更多
Leizhou Peninsula, located at southern end of mailand China, has 9 284.3 ha mangrove distributed more than 100 sites along its inlets and open coastlines.This paper presents the surveys on mangrove area in Leizhou Pen...Leizhou Peninsula, located at southern end of mailand China, has 9 284.3 ha mangrove distributed more than 100 sites along its inlets and open coastlines.This paper presents the surveys on mangrove area in Leizhou Peninsula during 2000 and 2008, especially the survey in the eight major mangrove areas in 2002.The flora recorded in mangrove systems includes 69 large algea species, 13 native true mangrove species, nine native semi-mangrove species, and another seven intoduced true mangrove species with Sonneratia apetala as the quickest growing exotic mangrove species dominatant in the mangrove plantations, and more than 100 land flora species, consisting of 17 main mangrove associations.The plant biodiversity habitats remained mainly small patches and diverse, and were becoming worse under the intensive disturbance of human acitivities and coastal pollutions, which decreased the value of mangrove coasts as the important sites for flying-by migrating birds in Leizhou Peninsula.The effective mangrove conservation measures should be implemented.展开更多
The Yingfengling section composed of red soil and volcanic rocks can be distinguished into 8 stratigraphic units and 4 red soil-volcanic rock cycles. 64 paleomagnetic-orientated samples were collected from the bottom ...The Yingfengling section composed of red soil and volcanic rocks can be distinguished into 8 stratigraphic units and 4 red soil-volcanic rock cycles. 64 paleomagnetic-orientated samples were collected from the bottom to the top of the section. Natural remanent magnetization and magnetic susceptibility were firstly measured. All the samples were stepwisely treated with thermal or/and alternating fields. Four clear polarity segments were recorded in the section. Compared with the geo-magnetic polarity scale, the section was formed since the late Olduvai subchron, about 1.37 Ma.B.P.展开更多
As the second common type of volcanic vent on Earth, maar-diatreme volcanoes and their post-eruptive lacustrine sediments are a main focus of volcanology, palaeolimnology, palaeoclimatology and palaeontology. A number...As the second common type of volcanic vent on Earth, maar-diatreme volcanoes and their post-eruptive lacustrine sediments are a main focus of volcanology, palaeolimnology, palaeoclimatology and palaeontology. A number of maar-type volcanoes have been found in Leizhou Peninsula, South China, but little is known about their eruption processes and detailed stratigraphy of the post-eruptive sediments. We present a combined geophysical and geological analysis to study the eruptive history and post-eruptive sediment stratigraphy of a large maar, the elliptical(1.8 × 3.0 km^(2)) Jiudouyang(JDY) maar. The lacustrine stratigraphy revealed by drilling cores shows that the JDY maar lake has three major stages of evolution:(i) deep-lake sedimentary environment characterized by high autochthonous diatom productivity;(ii) shallow lake to swamp with very low water levels, characterized by a high total organic carbon(TOC) and abundant wood fragments;and,(iii) intermittent shallow lake and alluvial deposits composed of clay minerals and sand. The electrical resistivity tomography(ERT) values and lithological features are highly consistent, which clearly reveal the presence of ca. 50 m thick lacustrine sediments, directly underlain by a ca. 70 m thick basaltic lava rather than diatreme breccia in the crater. This infill sequence implies an alternation of eruption style from phreatomagmatic to Strombolian and/or lava flow, due to high magma flux and ascent rate of the Hainan Plume during the middle Pleistocene. The ERT data also reveal the initial phreatomagmatic crater floor at ca. 120 m depth. The initial crater had a large diameter/depth ratio(ca. 17), with an elongated shape(major axis to minor axis = 0.6), implying possible lateral vent migration during the eruption. A significant erosion under tropical weathering condition during the last few hundred thousand years, accounted for the large size of the maar crater. The study provides insights into the eruptive history and post-eruptive evolution of a large maar, as well as the spatial distribution of the lacustrine sediments.展开更多
Based on first-hand materials obtained from field investigations in Malaysia, the results show that: firstly, there are 17 initials in the Leizhou dialect of Malaysia, including the implosives initial and the [f] init...Based on first-hand materials obtained from field investigations in Malaysia, the results show that: firstly, there are 17 initials in the Leizhou dialect of Malaysia, including the implosives initial and the [f] initial. The pronunciation of Leizhou dialect in China is already rare, some of which are retained in the Leizhou dialect of Malaysia. Its initial consonant is borrowed from local Hua Yu or other Chinese dialects. Secondly, the Leizhou dialect of Malaysia has 46 finals. The pronunciation and timbre of some of its vowels are similar to the Yue dialect of Malaysia [ɐ] main vowel. Thirdly, there are 8 monosyllabic tones in the Leizhou dialect of Malaysia. The pronunciation and tone of some of its characters are similar to the Xia Yin entering tone of Yue dialect of Malaysia.展开更多
The garnet megacrysts from Yingfengling basalts are characterlzed by high FeO (】20%), CaO (7.02% -8.16%) and low MgO (5.88%-10.87%). Significant composition variations are observed in these megacrysts, of which Ni, V...The garnet megacrysts from Yingfengling basalts are characterlzed by high FeO (】20%), CaO (7.02% -8.16%) and low MgO (5.88%-10.87%). Significant composition variations are observed in these megacrysts, of which Ni, V, Sc, Co, and HREE are positively correlated with their Mg# and Zr, Hf, Ga, Y, Sr, Nb, Zn and LREE-MREE are negatively correlated with Mg#. Megacryst parent magma is a highly evolved residual melt with strongl depletion in Ti, Sr, Hf, Nb and HREE. This parental magma was generated by more than 60% of crystallization fractionation of clinopyroxene, garnet, plagioclase and ilmenite from quartz tholeiitic magma. It has not erupted to the surface, but stayed at the upper mantle and formed the megacrystic cumulate. Megacrysts and their host basalt are in disequilibrium.展开更多
orientated samples were collected from Drilling Core ZK1 in southern Leizhou Peninsula for the study of Quaternary paleomagnetic strato\|chronology. The polarity measurement results indicate that the core recorded pal...orientated samples were collected from Drilling Core ZK1 in southern Leizhou Peninsula for the study of Quaternary paleomagnetic strato\|chronology. The polarity measurement results indicate that the core recorded paleomagnetic information in three main parts: the upper one of the core, from the ground surface to the depth of 39 m, is normally magnetized in polarity, the middle one, from 39m to 210m in depth, mainly shows reversed polarity and the lower one recorded normal polarity again. They correspond to the Brunhes normal chron, the Matuyama reversed chron and the Guass normal chron in the geomagnetic polarity time scale, respectively. The age of the core could be over 3.4 Ma. Meanwhile, the magnetic susceptibility was measured and its result is significant for stratigraphic division and paleoclimatic research.展开更多
雷州半岛地处热带北缘,受东亚季风影响强烈。以取自雷州半岛北部下录地区的埋藏泥炭沉积作为研究材料,测试分析了该岩心的汞浓度及其分布情况,将测试结果与其他气候环境代用指标如孢粉、炭屑、烧失量(LOI)以及有机碳同位素(δ^(13)C_(or...雷州半岛地处热带北缘,受东亚季风影响强烈。以取自雷州半岛北部下录地区的埋藏泥炭沉积作为研究材料,测试分析了该岩心的汞浓度及其分布情况,将测试结果与其他气候环境代用指标如孢粉、炭屑、烧失量(LOI)以及有机碳同位素(δ^(13)C_(org))等进行对比分析,讨论自MIS(Marine Isotope Stages)-3晚期(约40 cal ka B.P.)至全新世早期(约6.9 cal ka B.P.)区域气候与环境变化影响下的汞沉积过程及可能的影响机制。结果显示:近4万年以来,沉积物的汞浓度与乔木类孢粉浓度的变化较吻合,两者之间显示出较高的相关性,揭示了晚更新世晚期以来,森林群落作为重要的地表汞库,在地区汞沉积过程中起到固定、储存和传输作用。此外,汞浓度与岩心中炭屑沉积通量(指示了区域性野火发生状况)的变化存在相反趋势,反映了区域性野火活动对地表植被以及土壤有机质的焚毁破坏,造成地表汞向大气的释放,不利于汞在地表和沉积物中的沉积与保存。对比不同区域的汞沉积记录发现,晚更新世晚期以来,下录泥炭汞浓度记录与全球其他地区汞记录、粉尘记录等具有较高的相似度,特别是MIS-2时期均存在明显峰值,反映了全球气候变化影响下,大气粉尘沉降对地表汞的输送和沉积具有较大贡献。展开更多
基金The Guangdong,Guizhou,Hunan and Jiangxi 1:250000 Land Quality Geochemical Survey under contract No.DD20160327-04the National Natural Science Foundation of China under contract No.U1911202+1 种基金the Guangdong Basic and Applied Basic Research Foundation under contract No.2021A1515011547the Guangzhou Basic and Applied Basic Research Foundation under contract No.202102020465.
文摘Mudflats play a vital role in maintaining the dynamic balance between sea and land.To understand the characteristics,sources,and pollution risks of six heavy metals(As,Cd,Cr,Cu,Hg,and Pb)in the coastal mudflats on the Leizhou Peninsula,257 surface sediment samples were studied using mathematical statistics,correlation analysis,and factor analysis.The results show that the overall concentrations of these heavy metals are low although there are several high abnormal points in the local areas.The strong correlation between these heavy metals indicates that the sources of some of the metals are similar,yet their elemental combinations in different cities(counties)varied.According to the calculated enrichment factor(EF),anthropogenic activity-induced heavy metals were determined in order of decreasing influence:As,Cd,Pb,Cr,Cu,and Hg.The low EF values of Hg indicate that it does not present as a contaminant in the study area,while low values of Cr and Cu from the Lianjiang City suggest that these two metals were also attributed to natural sources.The presence of As,Cd,Cr,Cu,and Pb from the remaining cities(counties)should be influenced by anthropogenic activities.The overall potential ecological risk index indicates that the ecological risks posed by the six analyzed heavy metals to the Leizhou Peninsula mudflats,in order of decreasing risk,are Cd,As,Hg,Pb,Cu,and Cr.It is noteworthy that only Cd in Lianjiang City demonstrated substantial ecological risk.Other examined heavy metals in other cities of the study area showed slight ecological risk.
文摘In this paper diatomite samples taken from the Leizhou Peninsula have beenstudied by chemical analysis, DTA, TG, XRD, IR, SEM and X-ray Energy Spectroscopy.The study shows that the diatomaceous genera and species and their organic contents arevariable with buried depth, from Melosira to Stephanodiscus and then to Cyclotella.Various impurities in the samples, such as quartz, kaolinite and montmorillonite indicatedifferent sedimentary environments. When heated, the diatom would change in shape dueto the phase transformation in which amorphous silica crystallized from disordered opal toordered cristobalite. The temperatures of phase transformation are different for variousdiatorns due to the presence of different impurities and constituents of diatomaceousgenera and species.
基金supported by GDOU: 0717112GDSTC: 2008A0303007NSFC: 20376086/ B060407.
文摘Leizhou Peninsula, located at southern end of mailand China, has 9 284.3 ha mangrove distributed more than 100 sites along its inlets and open coastlines.This paper presents the surveys on mangrove area in Leizhou Peninsula during 2000 and 2008, especially the survey in the eight major mangrove areas in 2002.The flora recorded in mangrove systems includes 69 large algea species, 13 native true mangrove species, nine native semi-mangrove species, and another seven intoduced true mangrove species with Sonneratia apetala as the quickest growing exotic mangrove species dominatant in the mangrove plantations, and more than 100 land flora species, consisting of 17 main mangrove associations.The plant biodiversity habitats remained mainly small patches and diverse, and were becoming worse under the intensive disturbance of human acitivities and coastal pollutions, which decreased the value of mangrove coasts as the important sites for flying-by migrating birds in Leizhou Peninsula.The effective mangrove conservation measures should be implemented.
文摘The Yingfengling section composed of red soil and volcanic rocks can be distinguished into 8 stratigraphic units and 4 red soil-volcanic rock cycles. 64 paleomagnetic-orientated samples were collected from the bottom to the top of the section. Natural remanent magnetization and magnetic susceptibility were firstly measured. All the samples were stepwisely treated with thermal or/and alternating fields. Four clear polarity segments were recorded in the section. Compared with the geo-magnetic polarity scale, the section was formed since the late Olduvai subchron, about 1.37 Ma.B.P.
基金This work was supported by the National Key R&D Program of China(Grant No.2016 YFA0600500)the National Natural Science Foundation of China(Grant Nos.41472143 and 41661144003)the Guangdong Province Introduction of Innovative R&D Team of Geological Processes and Natural Disasters around the South China Sea(Grant No.2016ZT06N331)。
文摘As the second common type of volcanic vent on Earth, maar-diatreme volcanoes and their post-eruptive lacustrine sediments are a main focus of volcanology, palaeolimnology, palaeoclimatology and palaeontology. A number of maar-type volcanoes have been found in Leizhou Peninsula, South China, but little is known about their eruption processes and detailed stratigraphy of the post-eruptive sediments. We present a combined geophysical and geological analysis to study the eruptive history and post-eruptive sediment stratigraphy of a large maar, the elliptical(1.8 × 3.0 km^(2)) Jiudouyang(JDY) maar. The lacustrine stratigraphy revealed by drilling cores shows that the JDY maar lake has three major stages of evolution:(i) deep-lake sedimentary environment characterized by high autochthonous diatom productivity;(ii) shallow lake to swamp with very low water levels, characterized by a high total organic carbon(TOC) and abundant wood fragments;and,(iii) intermittent shallow lake and alluvial deposits composed of clay minerals and sand. The electrical resistivity tomography(ERT) values and lithological features are highly consistent, which clearly reveal the presence of ca. 50 m thick lacustrine sediments, directly underlain by a ca. 70 m thick basaltic lava rather than diatreme breccia in the crater. This infill sequence implies an alternation of eruption style from phreatomagmatic to Strombolian and/or lava flow, due to high magma flux and ascent rate of the Hainan Plume during the middle Pleistocene. The ERT data also reveal the initial phreatomagmatic crater floor at ca. 120 m depth. The initial crater had a large diameter/depth ratio(ca. 17), with an elongated shape(major axis to minor axis = 0.6), implying possible lateral vent migration during the eruption. A significant erosion under tropical weathering condition during the last few hundred thousand years, accounted for the large size of the maar crater. The study provides insights into the eruptive history and post-eruptive evolution of a large maar, as well as the spatial distribution of the lacustrine sediments.
文摘Based on first-hand materials obtained from field investigations in Malaysia, the results show that: firstly, there are 17 initials in the Leizhou dialect of Malaysia, including the implosives initial and the [f] initial. The pronunciation of Leizhou dialect in China is already rare, some of which are retained in the Leizhou dialect of Malaysia. Its initial consonant is borrowed from local Hua Yu or other Chinese dialects. Secondly, the Leizhou dialect of Malaysia has 46 finals. The pronunciation and timbre of some of its vowels are similar to the Yue dialect of Malaysia [ɐ] main vowel. Thirdly, there are 8 monosyllabic tones in the Leizhou dialect of Malaysia. The pronunciation and tone of some of its characters are similar to the Xia Yin entering tone of Yue dialect of Malaysia.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 49773191) an AusAID Australia-China Institutional Links Program and the State Key Basic Research Program (Grant No. 1999043202)
文摘The garnet megacrysts from Yingfengling basalts are characterlzed by high FeO (】20%), CaO (7.02% -8.16%) and low MgO (5.88%-10.87%). Significant composition variations are observed in these megacrysts, of which Ni, V, Sc, Co, and HREE are positively correlated with their Mg# and Zr, Hf, Ga, Y, Sr, Nb, Zn and LREE-MREE are negatively correlated with Mg#. Megacryst parent magma is a highly evolved residual melt with strongl depletion in Ti, Sr, Hf, Nb and HREE. This parental magma was generated by more than 60% of crystallization fractionation of clinopyroxene, garnet, plagioclase and ilmenite from quartz tholeiitic magma. It has not erupted to the surface, but stayed at the upper mantle and formed the megacrystic cumulate. Megacrysts and their host basalt are in disequilibrium.
文摘orientated samples were collected from Drilling Core ZK1 in southern Leizhou Peninsula for the study of Quaternary paleomagnetic strato\|chronology. The polarity measurement results indicate that the core recorded paleomagnetic information in three main parts: the upper one of the core, from the ground surface to the depth of 39 m, is normally magnetized in polarity, the middle one, from 39m to 210m in depth, mainly shows reversed polarity and the lower one recorded normal polarity again. They correspond to the Brunhes normal chron, the Matuyama reversed chron and the Guass normal chron in the geomagnetic polarity time scale, respectively. The age of the core could be over 3.4 Ma. Meanwhile, the magnetic susceptibility was measured and its result is significant for stratigraphic division and paleoclimatic research.
文摘雷州半岛地处热带北缘,受东亚季风影响强烈。以取自雷州半岛北部下录地区的埋藏泥炭沉积作为研究材料,测试分析了该岩心的汞浓度及其分布情况,将测试结果与其他气候环境代用指标如孢粉、炭屑、烧失量(LOI)以及有机碳同位素(δ^(13)C_(org))等进行对比分析,讨论自MIS(Marine Isotope Stages)-3晚期(约40 cal ka B.P.)至全新世早期(约6.9 cal ka B.P.)区域气候与环境变化影响下的汞沉积过程及可能的影响机制。结果显示:近4万年以来,沉积物的汞浓度与乔木类孢粉浓度的变化较吻合,两者之间显示出较高的相关性,揭示了晚更新世晚期以来,森林群落作为重要的地表汞库,在地区汞沉积过程中起到固定、储存和传输作用。此外,汞浓度与岩心中炭屑沉积通量(指示了区域性野火发生状况)的变化存在相反趋势,反映了区域性野火活动对地表植被以及土壤有机质的焚毁破坏,造成地表汞向大气的释放,不利于汞在地表和沉积物中的沉积与保存。对比不同区域的汞沉积记录发现,晚更新世晚期以来,下录泥炭汞浓度记录与全球其他地区汞记录、粉尘记录等具有较高的相似度,特别是MIS-2时期均存在明显峰值,反映了全球气候变化影响下,大气粉尘沉降对地表汞的输送和沉积具有较大贡献。
