Groundwater NO3 and F Contamination Processes in Pushkar Valley, Rajasthan as Reflected from 18O Isotopic Signature and 3H Recharge Studies

Agricultural activity in the Pushkar Valley, Rajasthan is constrained due to limited availability of good quality water. In this context, occurrence of nitrate and fluoride in the groundwater was investigated and reported. Integration of stable isotope (18O) data with recharge characteristics (based on 3H-tracer studies) helps in clearly characterizing the processes controlling contamination by point and non-point sources. High nitrate and fluoride groundwaters are associated with high 18O waters. This indicates that significant quantities of evaporated (isotopically enriched) surface run-off water and rain water infiltrate along with nitrate and fluoride salts in the soil. The applicability of this approach under different hydrometeorological conditions is also confirmed.     

THE EFFECTS OF MINE ACID ON THE POND RIVER WATERSHED IN WESTERN KENTUCKY1

ABSTRACT: H₂SO₄ (sulfuric acid) is formed by a chemical process that occurs in unreclaimed coal mines. The highly toxic acid then flows into the lower swamp areas where it causes considerable damage to the ecosystem. The major effect of the acid is the mass destruction of thousands of trees and various other phreatophytic plants. The contamination is so serious that most of the wildlife has migrated out of the affected area of the swamp in order to survive. Certain geological features such as coal bearing monadanocks make the area somewhat sensitive to mining activities and related geologic hazards. New methods of mine acid abatement make the concept of mass reclamation more realistic than at any time in the past. The constant annihilation of swamp life and processes emphasizes the urgent need for reclamation of the swamp.     

RESEARCH INTO THE EFFECTS OF ARTIFICIAL GROUNDWATER RECHARGE,LEA VALLEY,LONDON ENGLAND1

ABSTRACT: Large-scale groundwater abstraction from the Cretaceous Chalk/Lower Tertiary Basal Sands aquifer system of the London Basin in the last 150 years has developed storage of more than 1000 Mm³. Limited operational recharge was undertaken in the 1950's encouraging further detailed study of the wider possibilities. Following a comprehensive hydrogeological reappraisal, an economic and engineering study and pilot-scale experiments, the Lea Valley has been shown to have the greatest potential for recharge. Artificial recharge into the Chalk at a rate of 9000 m³/d appears possible, through acidised 900 mm diameter boreholes. An understanding of the degree of interconnection between the Chalk and Basal Sands and of the causes of changes in quality of recharged water during storage was shown to be of particular importance to the successful operation of any recharge scheme using this system. A two-layer numerical groundwater model of the 800 km² area and a surface/groundwater simulation model have been used to assist with the design of the 84,000 m³/d prototype scheme, and will also help in assessing its efficiency. The models will ultimately be used to manage the operation of the first stage development, now coming into use.     

RETENTION BASIN FAILURES IN CARBONATE TERRANES1

ABSTRACT Sinkholes and subsidence in areas subject to dewatering of carbonate formations have been documented in several geologic and hydrologic investigations. Excessive ground-water pumpage has been cited as a causative factor in areas of increased sinkhole activity. Subsurface erosion of unconsolidated materials underlain by carbonate rocks is one cause of the collapses. Infiltrating water from retention basins may cause subsurface erosion and eventual failure by collapse of the structure. The resulting ground-water contamination would be great as the pollutants spread throughout the solution-cavity system.     

Analysis of Sediment Retention in Western Riverine Wetlands: The Yampa River Watershed,Colorado, USA

We quantified annual sediment deposition, bank erosion, and sediment budgets in nine riverine wetlands that represented a watershed continuum for 1 year in the unregulated Yampa River drainage basin in Colorado. One site was studied for 2 years to compare responses to peak flow variability. Annual mean sediment deposition ranged from 0.01 kg/m² along a first-order subalpine stream to 21.8 kg/m² at a sixth-order alluvial forest. Annual mean riverbank erosion ranged from 3 kg/m-of-bank at the first-order site to 1000 kg/m at the 6^th-order site. Total sediment budgets were nearly balanced at six sites, while net export from bank erosion occurred at three sites. Both total sediment deposition (R² = 0.86, p < 0.01) and bank erosion (R² = 0.77, p < 0.01) were strongly related to bankfull height, and channel sinuosity and valley confinement helped to explain additional variability among sites. The texture and organic fraction of eroded and deposited sediment were relatively similar in most sites and varied among sites by watershed position. Our results indicate that bank erosion generally balances sediment deposition in riverine wetlands, and we found no distinct zones of sediment retention versus export on a watershed continuum. Zones of apparent disequilibrium can occur in unregulated rivers due to factors such as incised channels, beaver activity, and cattle grazing. A primary function of many western riverine wetlands is sediment exchange, not retention, which may operate by transforming materials and compounds in temporary sediment pools on floodplains. These results are considered in the context of the Hydrogeomorphic approach being implemented by the U.S. government for wetland resource management.     

渗滤液回灌在实际应用中应注意的问题

本文介绍了垃圾填埋场渗滤液回灌的机理、优缺点,“干填埋”与“湿填埋”之间的区别。渗滤液回灌可增加填埋废物的含水率,加快垃圾的降解速率,减少渗滤液的处理时间,提高填埋气中甲烷的含量,加速填埋场稳定化进程。鉴于以上这些优点,渗滤液回灌作为一种渗滤液处理方式将会有极大的应用前景。但在实际应用中回灌的渗滤液容易泄漏而导致地下水污染,这是影响渗滤液回灌广泛应用的主要原因。为了避免使地下水受污染,本文总结和分析了渗滤液回灌在实际应用中应注意的问题。     

室内环境中化学污染物质测定法研究

室内环境中化学污染物质的测定是研究和解决室内环境问题的基础。本文以甲醛和挥发性有机化合物两种室内环境中的主要化学污染物质为例,介绍了目前世界各国采用的各种测定法及其动向,并探讨了测定时期、测定时间、采样点布置等有关问题,提出了一些看法供参考。     

Assessing potential bioavailability of metals in sediments: A proposed approach

Due to anthropogenic inputs, elevated concentrations of metals frequently occur in aquatic sediments. In order to make defensible estimates of the potential risk of metals in sediments and/or develop sediment quality criteria for metals, it is essential to identify that fraction of the total metal in the sediments that is bioavailable. Studies with a variety of benthic invertebrates indicate that interstitial (pore) water concentrations of metals correspond very well with the bioavailability of metals in test sediments. Many factors may influence pore water concentrations of metals; however, in anaerobic sediments a key phase controlling partitioning of several cationic metals (cadmium, nickel, lead, zinc, copper) into pore water is acid volatile sulfide (AVS). In this paper, we present an overview of the technical basis for predicting bioavailability of cationic metals to benthic organisms based on pore water metal concentrations and metal-AVS relationships. Included are discussions of the advantages and limitations of metal bioavailability predictions based on these parameters, relative both to site-specific assessments and the development of sediment quality criteria.     

天然放射性物质及环境问题

天然放射性物质（ｎａｔｕｒａｌｌｙｏｃｃｕｒｒｉｎｇｒａｄｉｏａｃｔｉｖｅｍａｔｅｒｉａｌｓ，简称ＮＯＲＭ）广泛存在于地层中，当石油或天然气从地下开采出来时，痕量的天然放射性核素如镭、氧等也随之采出，并分别集中于管道及设备的垢层或天然气加工装置的内壁薄膜上。文章在对外文资料调研的基础上，将ＮＯＲＭ的有关知识、存在场所、对人体潜在的危害途径及有关辐射防护方法进行了介绍。     

In situ bioremediation of an underground diesel fuel spill: A case history

In the winter months of 1983, approximately 1000 gallons of diesel fuel had flowed along an asphalt parking lot of a commercial establishment towards a surface drain near an open creek. Investigations led to the discovery of an underground storage tank leaking diesel fuel. Exploratory borings showed that contamination was near the surface horizon and the capillary zone of the water table. Hydrocarbon quantities ranged up to 1500 mg/kg of soil. The plume continued to move in an eastward direction toward the surface water of the creek. A laboratory study indicated relatively high numbers of hydrocarbon-oxidizing organisms relative to glucose-utilizing microorganisms in the unsaturated vadose zone. Bioreclamation was initiated in April 1984 by injecting nutrients (nitrogen and phosphorus) and hydrogen peroxide and terminated in October 1984 upon no detection (<1 mg/kg) of hydrocarbons. A verification boring within the vicinity of the contaminated plume confirmed that residual contamination had attained background levels. The monitoring program was terminated in January 1987.