Counting of visitors in the Meijendel dunes, The Netherlands

Accurate and sufficiently detailed information about recreation-related use of dune areas is necessary for their management. Long-term monitoring can provide this information. This paper presents the visitor counting programme used in the Meijendel dune area since 1992. The data collected during the first ten years are used to evaluate the method. The combination of mechanical vehicle counts and additional visual counts proved to be reliable and produced an accurate data set. Costs could be reduced through eventually reducing the number of counting locations and limiting the number of visual counts.     

铁(III)-丙酮酸盐配合物光解引发水中铬(Ⅵ)还原

初步研究了含有Fe(III)及丙酮酸盐的溶液在高压汞灯照射下对铬(VI)的光还原反应.考察了溶液pH值、Fe(III)浓度、丙酮酸钠浓度、Cr(VI)浓度对反应的影响.分析了光还原反应的动力学及反应机制.结果表明:铁丙酮酸盐体系能光还原Cr(VI);最佳pH为3.0;Cr(VI)光还原的初始速率随着加入的铁(III)、丙酮酸盐、Cr(VI)初始浓度的增加而增加;实验条件下的表观动力学方程为:-dCCr(VI)/dt=0.021[Cr(VI)]0.39[Fe(III)]1.05[CH3COCOONa]0.39;Fe(III)-丙酮酸盐配合物光解产生的Fe(II)是Cr(VI)的主要还原剂.     

长江镇江段COD排放量控制的环境效益分析

在镇江金东造纸工程环境影响评价中，提出了长江镇江段全江段ＣＯＤ排放量控制方案，通过模式进行分段定量计算，分析了工程实施所造成的环境损失和实施区域排放量控制所产生的环境效益。结果表明，拟用控制方案环境效益显著，其实施将明显改善内江江段和畅洲江段南汊的水环境质量；金东造纸工程选址合理，充分利用了大港江段水环境容量大的优势，其实施所造成的环境损失较小。考虑到污染负荷削减的环境效益，对我国实施污染物排放总量控制提出了４条建议。     

Fe~（2＋）和Mn~（2＋）对水稻锌吸收与运转的影响

水培试验结果表明，Ｆｅ（２＋）、Ｍｎ（２＋）对水稻锌的吸收和运转有明显的影响．高浓度Ｆｅ（２＋）或Ｍｎ（２＋）（５μｇ／ｇ）显著降低水稻吸锌量、抑制锌由根向茎、叶的运转．稻株生物量与叶片Ｆｅ／Ｚｎ比值或Ｍｎ／Ｚｎ比值有明显的负相关关系，在叶片Ｆｅ／Ｚｎ＞８或Ｍｎ／Ｚｎ＞２６时，水稻生物量明显降低．造成水稻缺锌的主要原因是土壤有效锌含量低，而高浓度Ｆｅ（２＋）和Ｍｎ（２＋）是诱发和加重水稻缺锌的重要条件．因此在生产上应重视改善缺锌低洼稻田的排水通气状况．     

广东山地土壤粘粒矿物

本文研究了广东山地土壤的粘粒矿物组成、粘粒阳离子交换量和游离氧化铁等化学性质。结果表明,随着海拔的逐渐升高,高岭石含量渐减,2:1型矿物渐增;而三水铝石和1.4nm矿物含量以山体中部为最高。粘粒阳离子交换量的高低与2:1型粘土矿物含量的多少相吻合。粘粒的游离氧化铁含量,每个山体均是山地黄壤高于山地红壤和山地赤红壤。     

水处理氧化还原过程的电动化学特性

以流动电流为参数,研究了水处理条件下氧化还原过程的电动化学特性.考察了水中KMnO_4及其与Mn~(2+),Fe~(2+)之间氧化还原作用的流动电流(SC)规律,探讨了氧化还原的初始条件、水处理环境、原水水质、氧化剂与还原剂的投加方式等对流动电流的影响.结果表明,水中约0.5mg·l~(-1)的KMnO_4可产生SC的峰值,而且当它与Mn~(2+)和Fe~(2+)经不同条件进行氧化还原作用时,可通过SC值的变化表现出更为明显的电动化学特性.     

焦炭和废铁屑微电解预处理垃圾渗滤液的研究

研究表明,废铁屑和焦炭微电解是预处理垃圾渗滤液的一种有效方法,可去除垃圾渗滤液COD、色度和腐殖酸等污染物质,改善其可生化性、降低负荷,为后续生化处理创造良好的条件.通过静态正交实验确定废铁屑和焦炭最佳投加体积比为1∶3;最佳反应pH值为4;动态实验中,反应时间为1 h时,COD和色度去除率分别高达68%和91%;BOD/COD从0.3提高到0.5左右.     

选择性催化还原NO反应的研究进展

本文介绍了近年来选择性催化还原ＮＯ反应的研究进展状况，并对目前研究中存在的问题及今后研究的方向提出一些看法。     

The Role of a Salt Marsh Plant on Trace Metal Bioavailability in Sediments. Estimation By Different Chemical Approaches * (7 pp)

Goal, Scope and Background The presence or absence of vegetation can condition sediment characteristics. The main aim of this work was to investigate the influence of the sea rush Juncus maritimus on metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) availability to organisms living on or in estuarine sediments, from Douro River (NW Portugal), by comparing the characteristics and chemical behaviour of rhizosediments (collected within the plant assemblage) and those of sediment (collected around the plant). In order to evaluate whether and how sediment characteristics condition the role of plants on metal availability, sandy and muddy sediments colonised by J. maritimus were studied in parallel. Methods Metal availability was estimated by enzymatic digestion with pepsin (ED), which may provide an estimate of metal availability to organisms living at estuarine sediments. Nevertheless, since no consensus exists yet on the most suitable methodologies to estimate metal bioavailability in sediments, two more conventional approaches, BCR sequential extraction (SE) and AVS/SEM model, were also used, in parallel, and the information these approaches provided was compared with that provided by ED. Total-recoverable metal contents were determined by atomic absorption spectrophotometry after sediment digestion using a high-pressure microwave system. Results and Discussion Plants could concentrate metals around its roots and rhizomes. In addition, they were capable of oxidizing (release of oxygen by the roots) the anaerobic medium surrounding their roots in muddy sediment (reducing AVS). As sulphide oxidation renders metals (Cd, Cu, Ni, Pb and Zn) into more soluble forms, according to the AVS/SEM model, metals from muddy sites would be more available in rhizosediment than in sediment. The SE approach led to a similar conclusion. Nevertheless, the results provided by ED pointed at opposite conclusion, particularly for Cd and Zn, indicating less availability at rhizosediments than in the surrounding sediment. ED results were interpreted as a consequence of an enrichment of the rhizosediment in organic ligands exuded by the roots or liberated by dead plants. The effect of complexation of metals by organic compounds, which ED could not decompose/dissolve, seemed to overcome that caused by sediment oxidation. In general, a comparison of the information about metal availability by ED, SE, AVS/SEM, showed that it did not always match and in few cases it was even contradictory. Conclusion and Outlook Therefore, a thorough evaluation of the metal availability in sediments requires a combination of different chemical approaches, so as to take into consideration differences in ways of organism exposure (interstitial water and/or ingestion of sediment particles). - * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August to 1 September 2004, Bordeaux, France.     

对淮安市盐化工循环经济发展的探析

主要对江苏淮安盐化工循环经济发展的现状，发展的必要性、可行性及可操作性进行了分析研究，并对加快淮安盐化工循环经济发展提出了几点建议。