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.     

Aniline degradation by electrocatalytic oxidation

The degradation of aniline solution in alkaline medium of pH 11.0 by electrocatalytic oxidation has been studied using an electrochemical reactor containing a SnO₂–Sb₂O₃–PtO anode and a Ti cathode, both of 54 cm² area. Hydroxyl radicals (HO^√) are produced at the anode, being tested with the trace catcher salicylic acid and phenol by spectrophotometery and high performance liquid chromatography. Intermediates dianiline, 4-anilino phenol and azobenzol were detected by gas chromatography–mass spectrometry. The existence of HO^√ produced in the aniline degradation was assayed with scavenger tertiary butanol. The results showed that electrocatalytic oxidation is an effective process for the degradation of aniline. A general reaction pathway that accounts for aniline degradation to CO₂ involving those intermediates is proposed.     

浅层地下水矿化度测定方法的探讨

矿化度是地下水化学成分测定的重要指标 ,在环境监测中 ,用重量法测定矿化度是目前普遍采用的方法。其缺点主要是费时、繁琐、耗电。本研究通过测定洛阳市地下水的电导率 ,分析对比电导率与矿化度的关联 ,并进一步用回归方程确定电导率与矿化度之间的数量关系 ,探索出用电导率法间接测定地下水矿化度 ,具有快速、经济、准确的优点     

负载型纳米TiO2光催化剂的制备及其光催化活性

采用悬浮聚合法制备粉煤灰-聚苯乙烯微珠载体,通过矿化接枝技术将水热法制备的纳米TiO2负载在粉煤灰-聚苯乙烯微珠载体上,制成负载型纳米TiO2光催化剂。用x射线衍射仪、扫描电子显微镜对负载型纳米TiO2光催化剂进行了表征;通过光催化降解甲醛实验评价了负载型纳米TiO2光催化剂的活性。实验结果表明,纳米TiO2在载体上分散良好,平均粒径为36．4nm;该催化剂活性较高,明显优于粉体纳米TiO2光催化剂,重复使用10次左右,该催化剂的活性无明显下降。     

聚乙烯醇生化矿化度及自然降解的研究

通过对聚乙烯醇(PVA)生化矿化度、PVA在目然水域及土壤中的自净能力以及PVA降解过程中结构变化的研究,探讨PVA的可生化性及降解进程中物质的转化规律.PVA的生化矿化度高达50-70％,表明PVA在微生物作用下可以高度降解.由自净能力和结构变化过程的研究表明,PVA首先由大分子转变为小分子,经相应时间后向无机物转化,说明PVA在自然水域和土壤中有较好的自净作用。     

第三产业环境行为信息公开指标体系研究

随着第三产业的快速发展 ,其带来的环境污染也日趋严重 ,这给我国环境管理工作提出了新的挑战。本文探讨了一项新的环境管理手段———环境信息公开制度在第三产业环境管理中的应用 ,并就这项手段的指标体系做了初步的研究     

Degradation of ethylenethiourea pesticide metabolite from water by photocatalytic processes

In this study, photocatalytic (photo-Fenton and H₂O₂/UV) and dark Fenton processes were used to remove ethylenethiourea (ETU) from water. The experiments were conducted in a photo-reactor with an 80 W mercury vapor lamp. The mineralization of ETU was determined by total organic carbon analysis, and ETU degradation was qualitatively monitored by the reduction of UV absorbance at 232 nm. A higher mineralization efficiency was obtained by using the photo-peroxidation process (UV/H₂O₂). Approximately 77% of ETU was mineralized within 120 min of the reaction using [H₂O₂]₀ = 400 mg L^?1. The photo-Fenton process mineralized 70% of the ETU with [H₂O₂]₀ = 800 mg L^?1 and [Fe²⁺] = 400 mg L^?1, and there is evidence that hydrogen peroxide was the limiting reagent in the reaction because it was rapidly consumed. Moreover, increasing the concentration of H₂O₂ from 800 mg L^?1 to 1200 mg L^?1 did not enhance the degradation of ETU. Kinetics studies revealed that the pseudo-second-order model best fit the experimental conditions. The k values for the UV/H₂O₂ and photo-Fenton processes were determined to be 6.2 × 10^?4 mg L^?1 min^?1 and 7.7 × 10^?4 mg L^?1 min^?1, respectively. The mineralization of ETU in the absence of hydrogen peroxide has led to the conclusion that ETU transformation products are susceptible to photolysis by UV light. These are promising results for further research. The processes that were investigated can be used to remove pesticide metabolites from drinking water sources and wastewater in developing countries.     

The degradation of anilazine and dihydroxy‐anilazine at various soil depths of an orthic luvisol

Abstract

In conformity with Guideline 4.1 of the Federal German Biological Agency, degradation experiments with the fungicide active ingredient [benzene ring‐U‐¹⁴C]anilazine and its major metabolite [triazine ring‐U‐¹⁴C]dihydroxy‐anilazine were carried out in an orthic luvisol. Mineralization of the benzene ring carbon of anilazine amounted to less than 2 % in 110 days and that of the triazine ring carbon of dihydroxy‐anilazine to less than 8 %. Increasing the incubation temperature from 22 °C to 30 °C and adding organic substance influenced the mineralization slightly. In soils which received two or three applications in succeeding years with subsequent ageing in the open‐air lysimeter no stimulation of the mineralization was observed. Extractions after incubation showed that only 10.2 to 18.6 % of the ¹⁴C‐activity applied with anilazine was extractable with acetone/CaCl₂. The major proportion was bound in the fractions of the soil organic matter, namely 45.0 to 59.6 % of the radiocarbon applied was accounted for by the humin fraction, 12.0 to 27.4 % by the fulvic acids, and 9.4 to 15.0 % by the humic acids. In the case of dihydroxy‐anilazine, 28.9 to 89.7 % of the applied ¹⁴C‐activity was extractable with acetone/CaCl₂. Of tJhe radiocarbon bound in the soil, the greatest proportion, i.e. 18.5 to 35.5 % of the radiocarbon applied, was accounted for by the fulvic acids.     

Carbofuran degradation in soil profiles

Abstract

Two soils, Puyallup fine sandy loam from Puyallup, WA, and Ellzey fine sand from Hastings, FL, each with a prior history of carbofiiran exposure but with different pedological and climatological characteristics, were found to exhibit enhanced degradation toward carbofiiran in surface and subsurface soil layers. The treated Puyallup and Ellzey soils exhibited higher mineralization rates for both the carbonyl and the aromatic ring of carbofiiran when compared to untreated soils. Disappearance rates of [¹⁴C‐URL (uniformly ring labeled)] carbofiiran in the treated Ellzey soil was faster than in untreated soil, and also faster in surface soil than in subsurface soil. Initial degradation patterns in the treated Ellzey soil were also different from those in the untreated soil. The treated Ellzey soil degraded carbofuran mainly through biological hydrolysis, while untreated soil degraded carbofuran through both oxidative and hydrolytic processes.     

Quantification of centimeter-scale spatial variation in PAH, glucose and benzoic acid mineralization and soil organic matter in road-side soil

The aim of the study was to determine centimeter-scale spatial variation in mineralization potential in diffusely polluted soil. To this end we employed a 96-well microplate method to measure the mineralization of ¹⁴C-labeled organic compounds in deep-well microplates and thereby compile mineralization curves for 348 soil samples of 0.2-cm³. Centimeter-scale spatial variation in organic matter and the mineralization of glucose, benzoic acid, and PAHs (phenanthrene and pyrene) was determined for urban road-side soil sampled as arrays (7 × 11 cm) of 96 subsamples. The spatial variation in mineralization was visualized by means of 2-D contour maps and quantified by means of semivariograms. The geostatistical analysis showed that the easily degradable compounds (glucose and benzoic acid) exhibited little spatial variation in mineralization potential, whereas the mineralization was highly heterogeneous for the PAH compounds that require specialized degraders. The spatial heterogeneity should be taken into account when estimating natural attenuation rates.