Combined with the practical experience of wastewater treatment plant, the chemical coagulants have inhibition effects on microorganism activity, with the influence degree of PAC (polyaluminium chloride) > AlCl3>...Combined with the practical experience of wastewater treatment plant, the chemical coagulants have inhibition effects on microorganism activity, with the influence degree of PAC (polyaluminium chloride) > AlCl3> Fe2(SO4)3. In synchronization dephosphorization, the inhibition rates of PAC in 10 ppm and 20 ppm are 11.9% and 33% respectively;while the inhibition rates of AlCl3 and Fe2(SO4)3 in 20 ppm are 15.8% and 8.5% respectively, compared with 9.6% and 5.4% in 10 ppm. Backwash wastewater from sand filter after adding coagulants has no direct inhibition effect on microorganism, but it results in inorganic components increase in active sludge. By taking North STP as an example, the VSS/SS ratio reduced from 0.65 after coagulants application to 0.54.展开更多
Aims Plant community assembly in wetlands usually changes with eleva-tion gradients,which may be due to the direct effect of flooding and indirect effects such as changes in soil properties and competition.However,the...Aims Plant community assembly in wetlands usually changes with eleva-tion gradients,which may be due to the direct effect of flooding and indirect effects such as changes in soil properties and competition.However,the respective importance of each factor remains to be investigated.Methods We investigated patterns of plant diversity,community biomass and soil properties along an elevation gradient of a lakeshore meadow at Poyang Lake,China.Important Findings(i)With increasing elevation,species richness and Simpson diver-sity index decreased.Both aboveground biomass(AGB)and below-ground biomass(BGB)increased with elevation,however,the BGB/AGB ratio also increased,which suggests a significant effect of belowground competition.(ii)Soil N content and soil N:P ratio increased,whereas soil pH decreased with elevation.Other soil properties showed no significant response.(iii)Structural equa-tion modeling showed that variation of plant diversity was mainly explained by BGB.Thus,intensified belowground competition seems to be the primary mechanism causing lower plant diversity at higher elevations.(iv)These findings were further supported by the observed greater response ratio of N and P storage in plant commu-nities than the response ratio of soil N and P content to elevation,suggesting that soil nutrient limitation and belowground nutrient competition increased with elevation.Our study has important implications to wetland management and biodiversity conserva-tion under environmental change(e.g.changes in flooding regimes,eutrophication).展开更多
文摘Combined with the practical experience of wastewater treatment plant, the chemical coagulants have inhibition effects on microorganism activity, with the influence degree of PAC (polyaluminium chloride) > AlCl3> Fe2(SO4)3. In synchronization dephosphorization, the inhibition rates of PAC in 10 ppm and 20 ppm are 11.9% and 33% respectively;while the inhibition rates of AlCl3 and Fe2(SO4)3 in 20 ppm are 15.8% and 8.5% respectively, compared with 9.6% and 5.4% in 10 ppm. Backwash wastewater from sand filter after adding coagulants has no direct inhibition effect on microorganism, but it results in inorganic components increase in active sludge. By taking North STP as an example, the VSS/SS ratio reduced from 0.65 after coagulants application to 0.54.
基金This work was supported by National Natural Science Foundation of China(31600369,31260107)China Postdoctoral Science Foundation(2016M590315)+2 种基金Key Laboratory of Poyang Lake Environment and Resource Utilization,Ministry of Education(PYH2015-09)Key Laboratory of Watershed Ecology and Geographical Environment Monitoring,NASG(WE2015009)Guangxi Key Laboratory of Water Engineering Materials and Structures,Guangxi institute of Water Resources Research(GXHRI-WEMS-2018-4).
文摘Aims Plant community assembly in wetlands usually changes with eleva-tion gradients,which may be due to the direct effect of flooding and indirect effects such as changes in soil properties and competition.However,the respective importance of each factor remains to be investigated.Methods We investigated patterns of plant diversity,community biomass and soil properties along an elevation gradient of a lakeshore meadow at Poyang Lake,China.Important Findings(i)With increasing elevation,species richness and Simpson diver-sity index decreased.Both aboveground biomass(AGB)and below-ground biomass(BGB)increased with elevation,however,the BGB/AGB ratio also increased,which suggests a significant effect of belowground competition.(ii)Soil N content and soil N:P ratio increased,whereas soil pH decreased with elevation.Other soil properties showed no significant response.(iii)Structural equa-tion modeling showed that variation of plant diversity was mainly explained by BGB.Thus,intensified belowground competition seems to be the primary mechanism causing lower plant diversity at higher elevations.(iv)These findings were further supported by the observed greater response ratio of N and P storage in plant commu-nities than the response ratio of soil N and P content to elevation,suggesting that soil nutrient limitation and belowground nutrient competition increased with elevation.Our study has important implications to wetland management and biodiversity conserva-tion under environmental change(e.g.changes in flooding regimes,eutrophication).
