Predicting the aquatic risk of realistic pesticide mixtures to species assemblages in Portuguese river basins

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.     

Pesticides in the groundwater of a spring draining a sandy aquifer: temporal variability of concentrations and fluxes

A 250 ha agricultural catchment has been characterized with respect to its hydrogeology and groundwater contamination by pesticides from October 1999 to August 2004. Five years after the ending of atrazine (At) application, used since the sixties, At and deethylatrazine (DEA) are still systematically quantified at the outlet of the watershed with concentrations from 0.07 to 0.43 microg l(-1) for At, and between 0.14 and 1.16 microg l(-1) for DEA. Isoproturon and chlortoluron are detected in only one (0.3 microg l(-1)) and two (0.7 and 2.0 microg l(-1)) of the 124 semi-monthly samples, respectively. DEA concentrations can be very different between two samples with a 15-day time step. The annual mean exported fluxes of cumulated At and DEA are stable, which indicates a long time transfer in the unsaturated or saturated zone with a progressive leaching of the stock of At and DEA probably accumulated in the soil and the vadose zone. These fluxes, between 0.90% and 2.82% of the annual mean dose of At applied before 1999, similar to those calculated in several studies at the bottom of the root zone, could be explained by low adsorption and degradation properties of At and DEA in the unsaturated and saturated zone.     

Improving pesticide regulation in the third world: The role of an independent hazard auditor

Central to the environmental and health hazards created by the expanding use of pesticides in developing countries is the weakness of national regulatory agencies. This article reviews current international efforts aimed at supporting these institutions and describes the contribution that an external “hazard auditor” might make in assessing the pesticide industry's adherence to accepted standards of health and environmental protection. An independent evaluation of this kind may prove attractive to all parties in the long-standing confrontation over the control of pesticide technology: the industry, public interest groups, developing and developed countries, and international agencies. The article outlines one approach to operationalizing the concept and examines initial responses to the proposal. An earlier version of this paper was presented at the International Commission on Occupational Health/International Development Research Centre Symposium on the Impact of Pesticide Use on Health in Developing Countries, 17–21 September 1990, Ottawa, Canada.     

中国杀虫剂类持久性有机污染物的生命周期管理

中国已签署《关于持久性有机污染物的斯德哥尔摩公约》。面对目前杀虫剂类持久性有机污染物 (POPs)的生产、使用和环境污染现状 ,中国履约形势十分严峻。笔者探讨了生命周期管理的概念 ;分析了污染历史、现状和原因 ;提出了杀虫剂类POPs在生产、运输、销售、使用、库存和废弃处置等阶段的生命周期管理建议 ;指出相关法律、法规和制度的建立和执行应体现源头控制、优先控制和生命周期管理的思想。     

Effect and Control of Pollution in Catchment Area of Lake Sapanca, Turkey

/ Land-based point and diffuse pollution sources in the catchment area of Lake Sapanca, Turkey, were investigated. The present and future distribution of pollution loads were evaluated in terms of nitrogen, phosphorus, biochemical oxygen demand, and pesticides. A methodology for the estimation of pollution loads was presented; most of which were based on "unit loads." Presently domestic and industrial point sources dominate over diffuse sources including fertilizers and pesticides from agricultural use, nutrient loads from forests and meadows, urban runoff, and leachates from unregulated dumps of solid wastes. For the future, the aim of the control action is to maintain the sustainability of the water quality of the lake, at least at the second class of European Community standards. Within this framework; urgent/short-term and medium/long-term control actions will be exercised. In the urgent/short-term stage, simpler and natural ways of treatment will be employed. In the medium/long-term stage an integrated collection and treatment system will be put on operation. After completion of a proposed collection system and treatment plants to handle point sources, the control of diffuse sources will be more significant. Control of diffuse sources for the abatement of further deterioration of water quality then becomes the key issue to be emphasized in the Lake Sapanca catchment area. Diffuse sources control will be achieved by dividing the catchment area into three major protection zones. Use of pesticides and fertilizers on agricultural land and all other activities within these protection zones will be accomplished according to control plans, which will be supervised by an institution established to be responsible of all the activities within the basin.KEY WORDS: Diffuse sources; Land-based pollution; Nutrients; Pesticides; Point sources; Protection zones     

A comparison of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) for monitoring chlorinated trace organic contaminants in Hong Kong coastal waters

A comparison of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) was carried out at five sites, representing a gradient of contaminant concentrations, in Hong Kong coastal waters. Mussels, originally collected from a “clean” location, were deployed along with SPMDs at each site for 30 days. Analyses for chlorinated pesticides and polychlorinated biphenyls (PCBs) indicated that SPMDs have potential as monitoring tools, and to some extent can overcome the problems associated with mussels, such as natural variability, differing age, sex, and physical condition. However, in most cases, SPMDs failed to rank the sites in the same order as mussels in terms of contaminant concentrations. Nonetheless, in localities where mussels cannot survive – as shown at Kwun Tong in the present experiment – SPMDs may be valuable in providing an indication of potentially bio-available lipophilic pollutants.     

钦州湾沉积物有机氯农药赋存特征与生态风险

利用GC-ECD测定了钦州湾沉积物中17种有机氯农药的含量,并对其组分分布和来源进行了分析。结果表明,样品中有机氯农药的总量为1.50～129ng/g,滴滴涕(DDTs)浓度为0.59～126ng/g,六六六(HCHs)的浓度为nd～2.65ng/g。有机氯农药的分布特征为茅尾海>钦州外湾,茅尾海东岸>西岸。组分分布特征分析显示,DDTs主要来自于历史积累,林丹在某些采样区域内有近期输入。与国内外不同地区沉积物中有机氯农药残留相比,钦州湾沉积物中有机氯农药污染处于低到中等水平。以沉积物生态风险评估值为基准的分析表明,研究区内DDT含量存在较大的生态风险。     

Molten hydroxide for detoxification of chlorine-containing waste: Unraveling chlorine retention efficiency and chlorine salt enrichment

Hazardous waste dechlorination reduces the potential of creating dioxins during the incineration process. To investigate the salt effect on waste dechlorination, molten hydroxides with a low melting temperature were utilized for the pre-dechlorination and decomposition of chlorine-containing organic wastes(COWs) including trichlorobenzene(TCB),perchloroethylene, hexachlorobenzene and chlordane. The results showed that a eutectic mixture of caustic sodium and potassium hydroxides(41 wt.% NaOH and 59 wt.% KOH) led to a low melting point below 300°C and a relatively high chlorine retention efficiency(CRE) with TCB as a representative COWs. The amounts of hydroxides, reaction time, and temperature all had notable influence on CRE. When the mass ratio of hydroxides to TCB reached 30:1,approximately 98.1% of the TCB was destroyed within 2.5 hr at 300°C with CRE of 71.6%.According to the residue analysis, the shapes of reaction residues were irregular with particles becoming swollen and porous. The benzene ring and C–Cl bonds disappeared, while carboxyl groups formed in the residues. The stripped chlorine was retained and condensed to form chloride salts, and the relative abundance of the chloride ions associated with the mass of TCB in residues increased from 0 to 75.0% within the 2.5 hr reaction time. The observed concentration of dioxins in residues was 5.6 ngTEQ/kg. A reaction pathway and possible additional reactions that occur in this dechlorination system were proposed. Oxidizing agents may attack TCB and facilitate hydrogenation/dechlorination reactions, making this process a promising and environmentally friendly approach for chlorine-containing organic waste treatment.     

Sorption of hydrophobic pesticides on a Mediterranean soil affected by wastewater, dissolved organic matter and salts

Irrigation with treated wastewaters as an alternative in countries with severe water shortage may influence the sorption of pesticides and their environmental effects, as wastewater contains higher concentrations of suspended and dissolved organic matter and inorganic compounds than freshwater. We have examined the sorption behaviour of three highly hydrophobic pesticides (the herbicide pendimethalin and the insecticides α-cypermethrin and deltamethrin) on a Mediterranean agricultural soil using the batch equilibration method. We considered wastewater, extracts from urban sewage sludge with different dissolved organic carbon contents, and inorganic salt solutions, using Milli Q water as a control. All pesticides were strongly retained by soil although some sorption occurred on the walls of the laboratory containers, especially when wastewater and inorganic salt solutions were used. The calculation of distribution constants by measuring pesticide concentrations in soil and solution indicated that pendimethalin sorption was not affected whereas α-cypermethrin and deltamethrin retention were significantly enhanced (ca. 5 and 2 times, respectively) when wastewater or salt solutions were employed. We therefore conclude that the increased sorption of the two pesticides caused by wastewater cannot be only the result of its dissolved organic carbon content, but also of the simultaneous presence of inorganic salts in the solution.     

浅谈农药生态毒性试验的设计思路及评价方法

从试验周期、剂量和控制水平三方面探讨了农药生态毒性试验的设计思路以及试验结果与安全性评价的衔接．按照试验持续的时间，农药生态毒性试验可分为急性和慢性二种类型．由于实际当中农药的急性和慢性毒害往往同时存在，相应地，急性和慢性毒性试验亦需要同时进行．农药生态毒性试验在选择剂量时可以考虑，也可以不考虑田间污染水平．两种设计的评价方法也不相同．室内试验、半田间试验和田间试验构成农药生态毒性试验的三个阶段．