Trace Metals in Upland Headwater Lakes in Ireland

Trace elements (n = 23) in Irish headwater lakes (n = 126) were investigated to determine their ambient concentrations, fractionation (total, dissolved, and non-labile), and geochemical controls. Lakes were generally located in remote upland, acid-sensitive regions along the coastal margins of the country. Total trace metal concentrations were low, within the range of natural pristine surface waters; however, some lakes (~20 %) had inorganic labile aluminum and manganese at levels potentially harmful to aquatic organisms. Redundancy analysis indicated that geochemical weathering was the dominant controlling factor for total metals, compared with acidity for dissolved metals. In addition, many metals were positively correlated with dissolved organic carbon indicating their affinity (or complexation) with humic substances (e.g., aluminum, iron, mercury, lead). However, a number of trace metals (e.g., aluminum, mercury, zinc) were correlated with anthropogenic acidic deposition (i.e., non-marine sulfate), suggesting atmospheric sources or elevated leaching owing to acidic deposition. As transboundary air pollution continues to decline, significant changes in the cycling of trace metals is anticipated.     

Mechanism of NO reduction with non-thermal plasma

Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2/O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in SelfConsistent Field(SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction.     

无定河流域地表水地下水的水化学特征及控制因素

以无定河流域为研究区,分析地下水和地表水水化学特征,讨论溶质来源及其控制因素,为水质管理提供参考依据.考虑季节效应,在枯水期和汛期分别进行水样采集,综合运用图解法、相关性分析和正向推演模型分析水化学时空演化特征,探讨水化学形成机制并定量不同来源对溶质的贡献率.结果表明,无定河流域水体整体呈弱碱性,主要的阴、阳离子分别为...     

电化学强化脱氮中反硝化菌对活性炭纤维电极电化学反应影响初步研究

研究固定反硝化菌活性炭纤维电极的阴极极化行为及其硝酸盐氮脱除率,考察了活性炭纤维电极电化学强化脱氮系统中生物过程对电化学过程的影响。实验表明,反硝化过程影响电极电化学反应,参数表观交换电流密度可用来表征体系反硝化菌的反硝化能力,新定义了生物效益量,其变化率与硝酸盐氮脱除率相关性良好。     

Real-time wet scavenging of major chemical constituents of aerosols and role of rain intensity in Indian region

Real-time simultaneous studies on chemical characteristics of rainwater and PM₁₀ aerosols were carried out to understand the scavenging of major chemical components in Indian region. The concentrations of Ca²⁺, NH₄⁺, SO₄²⁻ and NO₃⁻ were observed to be lower in the aerosol samples collected during rain as compared to before and after rain events. The most significant reduction was noticed for Ca²⁺ (74%) during rain which showed highest scavenging ratio (SR) and indicated that below-cloud scavenging is an effective removal process for Ca²⁺ in Indian region. Among non-sea salt components, Ca²⁺ had highest SR at Hyderabad indicating typical characteristics of crustal influence as abundance of calcium carbonate in soil dust has been reported in India. However, the levels of these major chemical components gradually got build-up in due course of time. After rain events, the levels of SO₄²⁻ aerosols were noticed to be substantially higher (more than double) within 24 h. In general, scavenging ratios for all components (except Ca²⁺, NH₄⁺ and K⁺) were higher over BOB as compared to Hyderabad. The maximum fall in aerosol levels (BR minus AR) was observed during continuous and low intensity rain events that did not allow building up of aerosol concentrations.     

我国环境化学研究的进展

本文综合介绍了二十年来我国环境化学研究的发展概况。在环境分析化学方面包括了环境分析监测方法、标准参考物质、环境分析方法、形态分析、采样技术与分析测试仪器化等方面。环境污染化学包括了有关大气、水体和土壤环境中化学问题的研究，着重对大气污染物表征、迁移和转化、化学模式和重金属、有机物的水环境化学、水环境中金属烷基化以及土壤中农药等环境化学研究。有关污染生态效应中的化学集中介绍了硒与地方病环境因素关系有     

土壤环境污染化学与化学修复研究最新进展

概述了不同历史时期重点涉及的土壤污染物以及近年来出现的4大类新型污染物,论述了土壤环境中化学污染物的动态与归趋以及相关科学问题及今后的研究重点,介绍了在评价土壤环境中污染物(特别是有机污染物)生物有效性的方法体系方面取得的重要进展,分析了污染土壤化学修复各种方法的化学原理以及为降低成本而实施的工艺强化和技术创新方面的最新突破.     

Investigation into atmospheric deposition through precipitation studies at New Delhi (India)

Rain water samples were collected during the monsoon of 1994, using automatic wet-only and manual bulk collectors at a height of 30 m above the ground at the National Physical Laboratory, New Delhi. The average pH of the rain water was 5.7 and its chemical composition was dominated by NH₄ and SO₄. The free acidity of the rain water was found to be due to S04 rather than N03 and it was mainly neutralized by NH₄ and Ca. Calculation of sea salt fraction and enrichment factor revealed that this site is free for marine influence. On an average the bulk samples had 13% higher concentration than that of wet-only samples which may be due to the deposition of soil-derived particles during the 24 h period of exposure. The higher neutralization factors of Ca and Mg in bulk samples and highest dry deposition rates for Ca in comparison to other components, indicated the positive interference of dust particles in neutralization.     

陆上物质的远距离输送对西太平洋热带海域降水化学组成的影响

１９８８年９－１０月在西太平洋热带海域收集了４６个雨水样品和３８８份雨水样品和３８８份雨滴谱。分析结果表明，３个ｐＨ值范围下的平均两滴谱的分布基本上满足指数递减律。在风系作用下，远距离输送来的陆上物质对该海域雨水的平均ｐＨ值为５．７３，而“陆地性”降雨的平均ｐＨ值只有４．８０。ｐＨ５．７３可认为是ＴＷＰＡ上未受陆地源直接影响的天然降雨的平均ｐＨ值。最后还给出了观测期间该海域非海化学组分的湿沉降通量     

水溶性农药流失的影响因素及污染防治

根据实际室和田间试验结果，分析了水溶性农药稻田流失的影响因素，提出了对水稻生长前期的农药渗滤量、降雨径流量和排水流失量的估算。结果表明，仅渗滤与排水两项流失，占农药用量的１７．２８％～５９．３１％，调查表明，环境水体已受杀虫单的污染，最后提出了防治水溶性农药稻田流失的节水灌溉，控制排水等措施。