Although pesticide regulatory tools are mainly based on individual substances, aquatic ecosystems are usually exposed to multiple pesticides from their use on the variety of crops within the catchment of a river. This...Although pesticide regulatory tools are mainly based on individual substances, aquatic ecosystems are usually exposed to multiple pesticides from their use on the variety of crops within the catchment of a river. This study estimated the impact of measured pesticide mixtures in surface waters from 2002 and 2008 within three important Portuguese river basins（＇Mondego＇, ＇Sado＇ and ＇Tejo＇） on primary producers, arthropods and fish by toxic pressure calculation. Species sensitivity distributions（SSDs）, in combination with mixture toxicity models, were applied. Considering the differences in the responses of the taxonomic groups as well as in the pesticide exposures that these organisms experience, variable acute multi-substance potentially affected fractions（ms PAFs） were obtained. The median msP AF for primary producers and arthropods in surface waters of all river basins exceeded 5%, the cut-off value used in the prospective SSD approach for deriving individual environmental quality standards. A ranking procedure identified various photosystem II inhibiting herbicides, with oxadiazon having the relatively largest toxic effects on primary producers, while the organophosphorus insecticides, chlorfenvinphos and chlorpyrifos, and the organochloride endosulfan had the largest effects on arthropods and fish, respectively. These results ensure compliance with European legislation with regard to ecological risk assessment and management of pesticides in surface waters.展开更多
Metal contamination of soils may pose long-term risks to ecosystem health if not proper-ly managed.Future projection of contamination trends,coupled with ecological assessment,is needed to assess such risks.This can b...Metal contamination of soils may pose long-term risks to ecosystem health if not proper-ly managed.Future projection of contamination trends,coupled with ecological assessment,is needed to assess such risks.This can be achieved by coupling dynamic models of soil metal accumulation and loss with risk assessment on the basis of projected metal levels.In this study,we modeled the long-term dy-namics of Cu,Zn,and Cd in agricultural topsoils of a northern Chinese catchment(Guanting reservoir)and related projected metal levels to 2060 to ecological risk.Past metal dynamics were simulated using historical metal inputs from atmospheric deposition,irrigation,fertilizers,and animal manures.Model-ing future dynamics was done using scenarios of projected metal input rates.Ecological risk assessment was done using the Potentially Affected Fraction(PAF)approach to estimate the combined toxic pressure due to the three metals.Modeled labile soil metals agreed well with measurements from monitoring in 2009 following adjustment of the porewater dissolved organic concentration.Metals were predicted to be largely retained in the topsoil.Projections were sensitive to changes in imposed soil pH,organic mat-ter,and porewater dissolved organic carbon.Modeling suggests that decreases in input rates to between 5%and 7.5%of 2009 levels are required to prevent further accumulation.Computed PAFs suggest zinc makes the greatest contribution to ecological risk.Under the most conservative estimate of PAF,the threshold of potential ecological risk was reached before 2060 in two of the three future input scenarios.展开更多
文摘Although pesticide regulatory tools are mainly based on individual substances, aquatic ecosystems are usually exposed to multiple pesticides from their use on the variety of crops within the catchment of a river. This study estimated the impact of measured pesticide mixtures in surface waters from 2002 and 2008 within three important Portuguese river basins（＇Mondego＇, ＇Sado＇ and ＇Tejo＇） on primary producers, arthropods and fish by toxic pressure calculation. Species sensitivity distributions（SSDs）, in combination with mixture toxicity models, were applied. Considering the differences in the responses of the taxonomic groups as well as in the pesticide exposures that these organisms experience, variable acute multi-substance potentially affected fractions（ms PAFs） were obtained. The median msP AF for primary producers and arthropods in surface waters of all river basins exceeded 5%, the cut-off value used in the prospective SSD approach for deriving individual environmental quality standards. A ranking procedure identified various photosystem II inhibiting herbicides, with oxadiazon having the relatively largest toxic effects on primary producers, while the organophosphorus insecticides, chlorfenvinphos and chlorpyrifos, and the organochloride endosulfan had the largest effects on arthropods and fish, respectively. These results ensure compliance with European legislation with regard to ecological risk assessment and management of pesticides in surface waters.
基金supported by the International Scientific Cooperation Program with Grant No.2012DFA91150the National Natural Science Foundation of China under Grant No.414201040045,No.41371488the Key Project of the Chinese Academy of Sciences under Grant No.KZZD-EW-TZ-12,the UK Natural Environment Research Council.
文摘Metal contamination of soils may pose long-term risks to ecosystem health if not proper-ly managed.Future projection of contamination trends,coupled with ecological assessment,is needed to assess such risks.This can be achieved by coupling dynamic models of soil metal accumulation and loss with risk assessment on the basis of projected metal levels.In this study,we modeled the long-term dy-namics of Cu,Zn,and Cd in agricultural topsoils of a northern Chinese catchment(Guanting reservoir)and related projected metal levels to 2060 to ecological risk.Past metal dynamics were simulated using historical metal inputs from atmospheric deposition,irrigation,fertilizers,and animal manures.Model-ing future dynamics was done using scenarios of projected metal input rates.Ecological risk assessment was done using the Potentially Affected Fraction(PAF)approach to estimate the combined toxic pressure due to the three metals.Modeled labile soil metals agreed well with measurements from monitoring in 2009 following adjustment of the porewater dissolved organic concentration.Metals were predicted to be largely retained in the topsoil.Projections were sensitive to changes in imposed soil pH,organic mat-ter,and porewater dissolved organic carbon.Modeling suggests that decreases in input rates to between 5%and 7.5%of 2009 levels are required to prevent further accumulation.Computed PAFs suggest zinc makes the greatest contribution to ecological risk.Under the most conservative estimate of PAF,the threshold of potential ecological risk was reached before 2060 in two of the three future input scenarios.
