Mechanisms of Groundwater Pollution by Pesticides

An increasing number of pesticide compounds are being detected in groundwater supplies worldwide. There has, nevertheless, been little research into the mechanisms by which such pollution occurs and the routes via which pesticides move from the land surface into aquifers. In view of the potential time-lag in the response of groundwater systems to pollution inputs, such knowledge is essential if the current situation is to be appraised adequately and if any necessary controls on pesticide use are to be introduced.
From basic data on the physicochemical properties of pesticide compounds and on groundwater flow and pollutant transport in the principal British aquifers, some useful observations can be made about the relative significance of different mechanisms of potential groundwater pollution. These mechanisms and their implications for field research on pesticide pollution of groundwater are discussed. This problem is compared and contrasted to that of nitrate pollution from agricultural land-use practices.     

Nitrogen leaching in a typical agricultural extensively cropped catchment,China: experiments and modelling

Protecting water resources from nitrogen (N) contamination is an important public-health concern and a major national environmental issue in China. Loss of N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing N pollution in aquatic environments. The study area selected is in a typical agricultural extensively cropped land, Fuxianhu Lake catchment in Yunnan Province, China. Three sets of soil columns laboratory experiments were conducted to investigate the migration dynamics and leaching loss of N under different artificial rainfall intensities. One groundwater observation well in agricultural extensively cropped land was built to investigate the groundwater pollution caused by agriculture N loss. Based on the laboratory experiment and field monitoring results, the migration dynamics of ammonia-nitrogen (NH₄-N) and nitrate-nitrogen (NO₃-N) were analysed in detail. The LEACHMN model was used to test against the laboratory and field data to evaluate the drainage water and N leaching loss from the soil. The results indicate that the LEACHMN model is useful to carry out a numerical simulation of the water and N transport both in a laboratory experiment and in field monitoring. The findings of this paper help to demonstrate the distribution and migration of N in agricultural lands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities. The work presented in this paper is also believed to be useful in formulating management strategies for an extensively cropped catchment to reduce diffusive pollution from agricultural activities.     

Environmental degradation related to mining,urbanization and pollutant sources: Poços de Caldas,Brazil

The paper considers the environmental problems associated with development within a volcanic depression at Poços de Caldas, Brazil, which was undertaken without appropriate investigation and planning. Engineering geological mapping was carried out to characterize the area and identify the main environmental problems. The results allowed the division of the region into geological and geotechnical zones. Decommissioned and abandoned mines, agricultural uses, point and non-point pollutant sources and urban land use were identified as the main causes of erosion, siltation, soil and surface water pollution and changes in geomorphology, infiltration rates, groundwater recharge conditions, groundwater pollution, runoff and channel density.     

Natural denitrification in the Kakamigahara groundwater basin,Gifu prefecture,central Japan

Although nitrate is recognized as the most common groundwater contaminant due to growing anthropogenic sources, such as agriculture in particular, its adverse effects on human and animal health are debatable. The current issue, however, is to control and reduce nitrate contamination with regards to the long residence time of groundwater within aquifers. Denitrification has recently been recognized for its ability to reduce high nitrate concentrations in groundwater. The Kakamigahara groundwater basin, Gifu prefecture, Japan, witnessed rising levels of nitrate (>12 mg/l NO(3)-N) originating from agricultural sources. Chemical analyses for the determination of major constituents of groundwater and delta(15)N of residual nitrate were performed on representative groundwater samples in order to fulfill two main objectives. One is to investigate the current situation of nitrate groundwater pollution. The second objective is to determine whether the denitrification is a potential natural mechanism, which eliminates nitrate pollution in the Kakamigahara aquifer. Agricultural nitrate contamination of groundwater was obvious from characteristically high concentrations of Ca(2+), Mg(2+), NO(3)(-) and SO(4)(2-). High nitrate concentrations were found on the eastern side of the basin in association with vegetable cultivation fields, and decreased gradually towards the west of the basin along the direction of groundwater flow. The decrease of nitrate concentration was conveniently coupled with increase of HCO(3)(-) (the heterotrophic denitrification product), pH and delta(15)N of residual nitrate (due to isotopic fractionation) from east to west. Therefore, denitrification in situ is continuously removing nitrate from the Kakamigahara groundwater system.     

Identifying Land Contaminated by Chlorinated Hydrocarbon Solvents

This paper provides a method of identifying land contaminated with chlorinated hydrocarbon solvents by sampling and analysing soil gas. Relationships are presented which enable levels of soil gas contamination to be related to levels of soil and groundwater pollution. Two case studies are presented. Soil gas surveying of an industrial site with severe groundwater pollution demonstrated that standards for contaminated land are insufficient to protect groundwater. Solvent levels in groundwater were one to two orders of magnitude higher than UK permitted concentrations in drinking water, whereas soil contamination values did not reach polluted levels. Surveying of a site occupied by a disused fire station showed significant differences in patterns of soil gas and groundwater pollution. This is explained by direct pollution of groundwater though the well at the site and/or possible flow of polluted groundwater to the site from adjacent areas.     

石家庄市地下水氮污染检测分析

石家庄市地下水的污染问题制约着该地区的经济发展,而地下水的氮污染和硬度升高是石家庄市地下水环境污染的主要问题。氮在地下水中的主要存在形式是NH3、NO2-和NO3-。根据数据采集与实验分析,得出市区的氮污染现状及污染趋势,为该地区地下水保护提供了依据。     

Water quality in Scotland: the view of the regulator

Water quality in Scotland has progressively improved over the past 50 years as the environmental damage, which resulted from the industrial revolution, has been addressed. This paper provides an overview of current water quality in rivers, lochs, estuaries and coastal waters and describes the limited information available on groundwater. The main factors affecting water quality are reviewed, with sewage, diffuse agricultural pollution, acidification and urban drainage identified as the most important. Trends in pollution pressure and levels of investment in pollution control have been used to predict the condition of Scotland's surface water over the next 10 years. Major improvements are expected. However, progress will be slowed by the increased relative importance of diffuse sources of pollution, which are less amenable to legislative controls. Future changes in environmental monitoring are also expected to move the emphasis away from point source pollution. The current freshwater classification schemes are based upon a relatively narrow measure of water quality and are expected to expand to include a wider range of ecological parameters. This will result in an increase in the waters defined as impacted as the effects of other environmental pressures are taken into account. Finally the implications of these changes for the future management of the aquatic environment are assessed.     

The Protection of Urban Groundwater from Pollution

The serious pollution of groundwater under cities is demonstrated with data from Coventry (UK), Madras (India) and Birmingham (UK). Microbiological organisms, nitrates, and organic chemicals are common, but many other pollutants are also found. The main sources are industry and inadequate sewerage. The provision of sewerage must remain a priority, on health grounds, for cities in the developing world. Virtually all industrial sites pollute the soil and groundwater through careless handling of chemicals. Industrial sites should be treated like landfills: contained and carefully monitored. If industrialists had to use groundwater from below their own sites, they would suffer the consequences of any pollution. This would also clean up the aquifer by pumping out polluted water.     

Sources of nitrates in groundwater of the coastal plain of Israel Evolution of ideas

A critical review of the studies conducted on the problem of nitrate pollution of the Coastal Plain aquifer of Israel is presented. The quantitative nitrogen balance of the aquifer is analyzed based on the reconstructed average nitrate trends in groundwater. This balance indicates that most of the nitrates found today in the aquifer reached the water table in the period 1930–1960. We suggest that the mineralization of the organic matter in the soil and unsaturated zone was the main source of nitrate pollution. The steep rise in the average nitrate concentration of groundwater over the last 50 years was the inevitable result of the agricultural development of the area. If no large transient nitrate reservoir exists in the unsaturated and water table zones, it is expected that the average nitrate content of groundwater will decrease with time.     

Delineating cost‐effective wellhead protection zones in a rural area in Greece

The aim of this study is the protection of groundwater resources from nitrate pollution by regulating land use and by establishing guidelines for agricultural activities within specific wellhead protection areas. Wellhead protection zones are specifically designed in four wells in the municipality of Nea Moudania, an area of intensive agricultural activities in northern Greece. Recent water samples from these wells indicate high levels of nitrates concentrations. Wellhead protection areas are delineated through a geographic information systems (GIS) analysis in order to determine the boundaries of protection zones, as well as to identify the land use patterns and the specific crop types around the contaminated wells. Different land use management techniques for groundwater protection zoning are also examined with respect to their implementation cost. The purpose of this analysis is to identify the least expensive management strategy for wellhead protection. The results show that land use changes are always more expensive than implementing agro‐environmental measures.     

Optimising water and phosphorus management in the urban environmental sanitation system of Hanoi, Vietnam

Many areas in the world face clean water scarcity problems and phosphorus reserves are likely to be depleted in the near future. Still, a large amount of clean water is used to transport excreta through sewer systems. Most of the wastewater generated worldwide is discharged untreated into aquatic systems and leads to water pollution and loss of valuable nutrients. In Hanoi, Vietnam's capital city, high population and economic growth as well as industrialisation have led to a decrease in groundwater level and to serious river and lake pollution. A probabilistic model, simulating the impact of measures on groundwater abstraction and nutrient recovery, was used to determine the impact of policy changes in Hanoi. The results obtained reveal that harmonising environmental sanitation and agricultural systems with one another will considerably increase nutrient recovery for food production, lower expenditure for artificial fertilisers and reduce the nutrient load into the environment. The model can be applied in urban areas of developing countries to assist in the design of environmental sanitation concepts.     

运用调查监测数据对北京农业面源污染现状分析与评价

农业面源污染已成为三大环境污染之一,严重制约了农业和社会的可持续发展。本文对几种不同地质类别区域的地下水农田灌溉水质和农用地土壤环境质量污染特征因子开展监测,对调查所得地下水及土壤监测数据进行分析评价。     

Persistency of organic contaminants in groundwater,lessons from soil pollution incidents in the Netherlands

Based on an inventory of the presence of halogenated substances in raw water of 232 groundwater pumping stations and on the study of a number of soil pollution incidents in The Netherlands a compilation of more than 100 organic substances identified in contaminated groundwater is discussed. Subsequently the reason why a number of these substances are very persistent under the circumstances prevailing in the soil is analysed. Water solubility is shown to be a major parameter determining the occurrence in groundwater of frequently used chemicals and controlling to a large extend the persistence in groundwater of non-degradable organic chemicals. A list of 12 pollutants, mainly hydrocarbons and chlorinated hydrocarbons, which are of a major concern due to their widespread use, transportability and persistence observed in groundwater in The Netherlands.     

太原市盆地区浅层地下水脆弱性评价

本文从影响地下水脆弱性的因素出发,结合国内外已有的地下水脆弱性影响因素、评价指标和评价标准,根据研究区的具体实际情况和可获得资料,选取影响地下水脆弱性的地下水埋深、含水层净补给量、含水层介质、土壤包气带、地形、包气带介质和水力传导系数7个参数作为评价因子,建立太原市盆地区浅层地下水脆弱性评价DRASTIC指标体系和评价标准。依据标准对其所含的7个参数进行评分,并具体阐述了评分中所应注意的问题,在获得了DRASTIC模型的7个指标在研究区的评分图之后,利用GIS平台空间分析技术将7张评分图叠加,同时对7个指标按照各自的权重取其加权和,这样便得到了太原市盆地区浅层地下水脆弱性分区图,结果表明汾河沿岸和吴家堡工业区地下水脆弱性指数较高,在盆地两侧的黄土台塬区,地下水脆弱性评分为低或极低,评价模型能合理的反映太原市盆地区浅层地下水脆弱性的高低。研究结果可以为太原市土地利用规划、地下水水资源保护规划、地下水水质监测等提供参考,也可以提高公众关于地下水污染的风险意识。     

The spatial distribution of polluted groundwater from rural centres in a recharge area in the Netherlands — The Veluwe

A topographically elevated area of ice-pushed ridges was selected for a study on groundwater chemical composition in relation to the potential pollution sources.A groundwater sampling technique using small ceramic cups was adapted for this study. This technique allows detailed sampling in depth for each borehole, even in areas with deep groundwater levels.Results of the chemical analyses show great variations in vertical distribution of the ion-concentrations in groundwater. These variations reflect the differences in land use and are also shown to be a function of the groundwater flow patterns.     

洞庭湖浅层地下水环境背景值的研究

依据洞庭湖区浅层地下水1720个水质检测数据,运用格拉布斯(Grubbs)准则和拉依达准则剔除异常数据,再运用数理统计方法和SPSS软件确定概率分布类型和不同类型的地下水的环境背景值,为该地区地下水污染评价和治理修复提供了重要的地球化学依据。     

蜀山背斜—双庙地垒岩溶地下水资源量的数值模拟

蜀山背斜—双庙地垒岩溶地下水是近年来鲁西南地区勘探开发的一项重要水资源,对鲁西南地区工农业的发展具有重要意义。为此,本文对蜀山背斜—双庙地垒岩溶地下水资源进行了深入研究,并对邵庄、东刘庄、双庙3个拟建水源地在不同开采方案下的允许开采量及其水位进行了预报,为合理开发和利用该地下水资源提供了科学依据。     

Analysis of vulnerability factors that control nitrate occurrence in natural springs (Osona Region, NE Spain)

Nitrate pollution is one of the main concerns of groundwater management in most of the world's agricultural areas. In the Osona region of NE Spain, high concentrations of nitrates have been reported in wells. This study uses the occurrence of this pollutant in natural springs as an indicator of the sub-surface dynamics of the water cycle and shows how groundwater quality is affected by crop fertilization, as an approach to determine the aquifer vulnerability.Nitrate concentration and other hydrochemical parameters based on a biannual database are reported for approximately 80 springs for the period 2004-2009. The background concentration of nitrate is first determined to distinguish polluted areas from natural nitrate occurrence. A statistical treatment using logistic regression and ANOVA is then performed to identify the significance of the effect of vulnerability factors such as the geological setting of the springs, land use in recharge areas, sampling periods, and chemical parameters like pH and EC, on groundwater nitrate pollution.The results of the analysis identify a threshold value of 7-8 mg NO₃⁻/L for nitrate pollution in this area. Logistic regression and ANOVA results show that an increase in EC or a decrease in pH values is linked to the possibility of higher nitrate concentrations in springs. These analyses also show that nitrate pollution is more dependent on land use than the geological setting of springs or sampling periods. Indeed, the specific geological and soil features of the uppermost layers in their recharge areas do not contribute to the buffering of nitrate impacts on aquifers as measured in natural springs. Land use, and particularly fertilization practices, are major factors in groundwater vulnerability.     

Controlling Diffuse Pollution of Groundwater from Agriculture and Industry

The greatest threat of contamination to groundwater resources is posed by pollutants from diffuse sources, yet legislation in the UK has until recently been focused on point sources. The problem of widespread pollution from industrial sources is described and compared with that from agriculture. The legislative controls available under the Water Resources Act 1991 are outlined, and the approach adopted by the National Rivers Authority in its Groundwater Protection Policy is discussed with respect to the concept of groundwater vulnerability.