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.     

Contamination of the Chalk Aquifer by Chlorinated Solvents: A Case Study of the Luton and Dunstable Area

A detailed investigation of contamination by chlorinated solvents of the Chalk Aquifer underlying the towns of Luton and Dunstable was undertaken to assess the extent, causes and mechanisms of pollution. The research programme incorporated land-use surveys, regional groundwater surveys, monitoring of groundwater abstraction points and aquifer profiling by means of the drilling of observation boreholes, the analysis of the recovered core material and the depth sampling of these and other boreholes.
Low-level solvent contamination of the Chalk Aquifer was found to be widespread with 'hotspots'of higher concentrations. At the drilling sites, both the saturated and unsaturated zones were contaminated with solvents, although free product was not observed. The presence of an additional contaminant, oil, at some sites was noted to influence the distribution of solvents within the aquifer.
Clean-up of the aquifer is not a practical option, and treatment of the groundwater at the abstraction points has been adopted.     

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.     

The Development of a Control Policy for Fish Farming

The polluting effects of fish farming have been well-documented, but the scale of the problem and the difficulty in effectively controlling the industry are less well known. In approximately twenty years, production by this industry in Scotland has increased by two orders of magnitude and it has been estimated that the population equivalent of fish farming effluents is as high as 1.5 million.
The development of a pollution control policy for both land-based and floating-cage farms is described. The role of other controlling agencies is discussed and legislative weaknesses are identified. In addition, the industry's reaction to pollution control is highlighted.
Polluting discharges are not controlled only through the issuing of consents, but effective monitoring is also required. Resource constraints resulted in a policy which includes the requirement of certain fish farmers to self-monitor their activities.     

Sensory Pollution and Microbial Contamination of Ventilation Filters

Abstract The sensory pollution load and microbial contamination of glass-fibre filters at high and low relative humidity were investigated in an experimental set-up in the laboratory. Dust and particles from the outdoor air were collected in two EU7 glass-fibre filters for a pre-conditioning period of 16–18 weeks during which there was a constant airflow with a velocity of 1.9 m/s through the filters. One of the filters was exposed to outdoor air of approximately 40% relative humidity and 10°C, the other to outdoor air of approximately 80% relative humidity and 5°C. The dust in ventilation filters can constitute a serious pollution source in the indoor environment, causing deterioration in the quality of the supply air even before it enters the ventilated spaces. The sensory pollution load from the used filters after the continuous operating time of 16–18 weeks was significantly higher than the sensory pollution load from new filters but the sensory load at 40% and 80% relative humidity did not differ. The microbial contamination of the supply air downstream of the filters, which on average had been exposed to outdoor air of 40% and 80% relative humidity, was negligible.     

Contamination by organochlorine pesticides in the aquifer of the Ring of Cenotes in Yucatán,México

Banned or restricted organochlorine pesticides in many countries worldwide are still in use in developing countries for agricultural and livestock activities, as well as for vector control in public health campaigns. The present study was conducted to map estimated concentrations of organochlorine pesticides in a karstic region in the Yucatan Peninsula, Mexico, known as ‘Ring of Cenotes’. Water samples from 20 sinkholes (‘cenotes’) were collected during the dry and rainy seasons in 2010–11, analysed by gas chromatography and maps of pesticide concentrations were produced using geographical information system. Results show the presence of banned pesticides, all of them exceeding the limits stated by the Mexican Official Norm. The number and concentration of pesticides during the dry season were qualitatively and quantitatively higher than in the rainy season. The spatial distribution of pesticide concentrations shows that causes of pesticide pollution in the aquifer of the Ring of Cenotes are multifactorial.     

The Impact of Intensive Dairy Farming Activities on River Quality: The Eastern Cleddau Catchment Study

Pollution from farm wastes has been one of the principal causes of deterioration in river quality in recent years. However, little is understood of how, and which, farming activities affect the chemical and biological quality of rivers. To address this problem, a field study has been initiated in the Eastern Cleddau catchment, West Wales, to investigate relationships between land use, farm waste management practices and river quality.
Water quality of small tributaries in this area is poor, and intensive chemical monitoring has shown that discharges from farmyards are a major source of pollution. Rainfall has been shown to exacerbate this effect either through field runoff or wastes washing directly from the farmyards. The status of benthic macroinvertebrate communities in these tributaries is poor and, typically, only a few pollution-tolerant species are present.
Small tributaries from farms appear to affect both the water chemistry and biology of larger watercourses, although this effect may be quite localized.
Future research will look at ways to reduce the impact of farm wastes on river quality. This will provide the basis for producing recommendations and guidelines for catchment management aimed at minimizing pollution of rivers from farming practices.     

Desorption kinetics of trichloroethylene and perchloroethylene from aged dense nonaqueous phase liquid-contaminated soil

Batch experiments were conducted to investigate the desorption kinetics of a contaminated soil collected from a field site at Hill Air Force Base (AFB), Utah. The site has been contaminated with many dense nonaqueous phase liquids (DNAPLs), primarily trichloroethylene (TCE) and perchloroethylene (PCE), for more than 60 years. Similar desorptive behaviour of both TCE and PCE was observed: a stage of fast release of the contaminant at the start followed by a very slow stage. Moreover, it is suggested that not all the contaminant in the solid phase may be released to the aqueous phase, apparently due to the age factor. Local variations were observed in the effective diffusivity and other sorption-related parameters across the site due to aquifer heterogeneity. Experimental results were then simulated using a numerical code based on the intraparticle diffusion model. Good agreement was found between both results.     

Lead removal from groundwater by granular mixtures of pumice,perlite and lime using permeable reactive barriers

Permeable Reactive Barrier (PRB) is an in situ technology for remediation of contaminated groundwater. This article presents results of studies on three granular mixtures were used for remediation of lead (Pb²⁺) contaminated groundwater using PRBs. The mixtures were composed of pumice, perlite and lime in different proportions. Several column experiments were conducted for evaluation of performance of the mixtures for lead removal. The experiments were carried out for over 50 days to evaluate the long‐term performance of the PRBs. It was found out that pumice‐perlite mixture with a weight proportion of 1 : 1 and pumice‐lime‐perlite mixture with a weight proportion of 2 : 2 : 1 can be used as effective reactive media for lead removal. The removal efficiency of the proposed mixtures was 99.9%. The permeability of the reactive media was relatively constant over 53 days continuous experiments and the results demonstrated that the mentioned mixtures have acceptable performance to maintain hydraulic conductivity of PRBs.     

Screening of organic matter in leachates from sanitary landfills using gas chromatography combined with mass spectrometry

Sanitary landfills are potential groundwater pollution sources, normally producing leachate with very high content of organic matter. Leachates from five Danish sanitary landfills were sampled in order to investigate the composition of the organic matter. The samples were extracted using dichloromethane followed by sodium hydroxide solution, in this way dividing the sample into one phase containing the basic and neutral compounds and one containing the acidic compounds. One of the leachates was extracted using pentane, for analysis of volatile compounds. The three extracts were analysed using gas chromatography combined with mass spectrometry. Several compounds were identified, including chlorinated pesticides (2 of the 5 leachates), aromatic carboxylic acids and alkylbenzenes. Benzene, toluene and trichloroethylene were found in the leachate analysed for volatile compounds. Some of the compounds identified in this work have been reported in the literature to give rise to severe groundwater problems.     

环境岩土工程研究综述

地下水土环境污染评估、控制及修复已成为我国环保领域的重大需求。利用岩土工程的手段来解决水土环境污染问题是最为经济、最符合国情的途径之一,也是环境岩土工程工作者的优势所在。结合我国水土环境污染控制方面重大需求及现阶段我国迫需解决的环境岩土工程问题来阐述环境岩土工程研究及工程实践进展,主要包括城市固体废弃物可持续填埋处置,废弃泥的工程特性、工程处置及资源化利用,土体和地下水污染评价与防治和土工合成材料在环境岩土工程中应用。     

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.     

Origin,properties and disposal problems of chromium ore residue

Chromium mining operations were conducted in the United States during the first fifty years of this century. During this period, large amounts of chromium waste were produced and used as fill in some areas. Over a period of time, toxic chromium compounds leach out of the ore residue. This poses a severe threat. Structural distress, ground and surface water pollution and parking lot deterioration have been reported in the areas where chromium residue was used as fill. Information regarding chromium residue disposal is rather limited and not readily available. The purpose of this paper is to address this problem and to discuss the production and properties of chromium, and the available technologies for the control and treatment of chromium residue.     

嘉陵江重庆段雨季悬浮颗粒相PAHs的污染分布及来源解析

利用GC-MS研究了嘉陵江重庆段雨季13个悬浮颗粒相样品中的多环芳烃(PAHs)含量,同时应用比值法及主成因子分析/多元线性回归法(PCA-MLR)对PAHs进行来源解析。结果表明,16种PAHs总的浓度范围为447.47~1 344.92 ng/g,平均浓度值为927.48 ng/g,且在空间分布上呈现出“升高-降低-升高-降低”的趋势;PAHs的组成以4环PAHs为主,占PAHs总量的41.87%。汽油和柴油等化石燃料燃烧的交通源是嘉陵江重庆段雨季悬浮颗粒相PAHs的主要污染来源,其贡献率分别为 37.97%和 29.97%。通过效应区间中值(ERM)和效应区间低值(ERL)对悬浮颗粒相PAHs的生态风险进行了评价,结果表明,Acy、Ace、Fl和DahA具有一定的生态风险,其余12种PAHs都不超标,嘉陵江重庆段雨季悬浮颗粒相PAHs的生态风险比较小。     

Evaluating Natural Attenuation of Groundwater Pollution from a Coal-Carbonisation Plant: Developing a Local-Scale Model using MODFLOW, MODTMR and MT3D

The effluent from a former coal-carbonisation plant in Nottinghamshire has contaminated the underlying aquifer with ammonium and organic compounds. In terms of flow and contamination, the site has experienced a complex history. MODFLOW has been used to unravel the past flow directions and to provide a basis for solute transport and biodegradation modelling. The modelling has shown that a fine grid is required to represent local flows to prevent incorrect site interpretations. A telescopic mesh technique was essential for this study to enable the site features to be adequately represented while including the regional hydrogeological influences. The influence of grid size to numerical dispersion was investigated for the MT3D computer program. The 'method of characteristics'and 'hybrid method of characteristics'modules of MT3D were found to be relatively free from numerical dispersion for all the grid sizes investigated. However, the 'modified method of characteristics'suffered extensively, and a linear relationship between grid size and numerical dispersion was demonstrated for this complex model.