关于长江产业带建设总体布局的初步思考

重点开发长江是90年代中国经济重大战略布署。将长江产业带建设成具有强大经济实力的国家一级经济轴线,宜采用分层次推进与中心辐射相结合的发展战略,以浦东开发和三峡建设为契机,加强基础产业,发展新兴产业和第三产业,优化产业结构,以能源和交通建设先行,改善基础设施。同时,要协调产业带建设与浦东开发、三峡工程建设的关系。     

核算间接冷却水污染当量数的研讨

针对间接冷却水的特点和核算其污染当量数过程中存在的问题，阐述了间接冷却水的界定，水源水的采样监测技术，本底值的扣除以及超标排放的判别等环节的技术要求和注意事项，并就与之密切相关的几个问题展开了讨论,为核算间接冷却水当量数提供了一定的参考依据，建议增加水湿排放指标，以切实控制间接冷却水造成的主要污染－热污染。     

ARSENIC CONSUMPTION AND HEALTH RISK PERCEPTIONS IN A RURAL WESTERN U.S. AREA1

ABSTRACT: Churchill County, Nevada, has approximately 23,000 residents, among whom an estimated 13,500 relied on private wells for water supply in 2002. This study examined exposure to arsenic in water supplies among residents with private domestic wells and factors related to householder choice to consume tap water. It compared opinions and concerns about water quality with consumption habits and observed concentrations from tap water samples. The results from 351 households indicated that a majority (75 percent) of respondents consumed tap water and that a minority (38 percent) applied treatment. Approximately 66 percent of those who consumed tap water were exposed to concentrations of arsenic that exceeded 10 ppb. Water consumption was related to application of treatment. Among 98 respondents who were not at all concerned about the health effects of aqueous arsenic, 59 (60 percent) reported consuming tap water with concentrations of arsenic exceeding 10 ppb. Conversely, among 86 respondents who were highly concerned about arsenic, 33 (37 percent) consumed tap water with concentrations of arsenic exceeding 10 ppb. Results from a national sampling effort showed that 620 of 5,304 private wells sampled (11.7 percent) had arsenic concentrations above 10 ppb. The paradox of awareness of arsenic in water supplies coupled with consumption of aqueous arsenic in concentrations greater than 10 ppb may be common in other parts of the nation. Enhanced educational efforts, especially related to tap water sampling and explanations of efficacy of available treatment, may be useful means of reducing exposure through private water supplies.     

Heavy metal contamination in the vicinity of an industrial area near Bucharest

BACKGROUND, AIMS AND SCOPE: Chromium enters into the aquatic environment as a result of effluent discharge from steel works, electroplating, leather tanning industries and chemical industries. As the Cr(VI) is very harmful to living organisms, it should be quickly removed from the environment when it happens to be contaminated. Therefore, the aim of this laboratory research was to develop a rapid, simple and adaptable solvent extraction system to quantitatively remove Cr(VI) from polluted waters. METHODS: Aqueous salt-solutions containing Cr(VI) as CrO4(2-) at ppm level (4-6 ppm) were prepared. Equal volumes (5 ml) of aqueous and organic (2-PrOH) phases were mixed in a 10 ml centrifuge tube for 15 min, centrifuged and separated. Concentrations of Cr(VI), in both the aqueous and organic phases, were determined by atomic absorption spectrometry. The effects of salt and acid concentrations, and phase-contact time on the extraction of Cr(VI) were investigated. In addition, the extraction of Cr(VI) was assessed in the presence of tetramethylammonium chloride (TMAC) in 2-PrOH phase. Effects of some other metals, (Cd(II), Co(II), Cu(II), Ni(II) and Zn(II)), on the extraction of Cr(VI) were also investigated. RESULTS AND DISCUSSION: The Cr(VI) at ppm level was extracted quantitatively by salting-out the homogeneous system of water and 2-propanol(2-PrOH) using chloride salts, namely CaCl2 or NaCl, under acidic chloride media. The extracted chemical species of Cr(VI) was confirmed to be the CrO3Cl-. The ion-pair complex extracted into the organic phase was rationalized as the solvated ion-pair complex of [2-PrOH2+, CrO3Cl-]. The complex was no longer stable. It implied the reaction between extracted species. Studies revealed that salts and acid directly participated in the formation of the above complex. Use of extracting agents (TMAC) didn't show any significant effect on the extraction of Cr(VI) under high salting-out conditions. There is no significant interference effect on the extraction of Cr(VI) by the presence of other metals. The Cr(VI) in the organic phase was back-extracted using an aqueous ammonia solution (1.6 mol dm(-3)) containing 3 mol dm(-3) NaCl. The extraction mechanism of Cr(VI) is also discussed. CONCLUSIONS: Salting-out of homogeneous mixed solvent of 2-propanol can be employed to extract Cr(VI) quantitatively, as an ion-pair of [2-PrOH2+ * CrO3Cl-] solvated by 2-PrOH molecules. Then, the complex becomes 'solvent-like' and is readily separated into the organic phase. The increase of Cl- ion concentration in the aqueous phase favors the extraction. The 2-PrOH, salts and acid play important roles in the extraction process. There is no need to use an extracting agent at a high salting-out condition. RECOMMENDATIONS AND PERSPECTIVES: Chromium(VI) must be quickly removed before it enters into the natural cycle. As the 2-PrOH is water-miscible in any proportion, ion-pairing between 2-PrOH2+ and CrO3Cl- becomes very fast. As a result, Cr(VI) can easily be extracted. Therefore, the method is recommended as a simple, rapid and adaptable method to quickly separate Cr(VI) from aqueous samples.     

COMPARISON OF STOCHASTIC AND DETERMINISTIC DYNAMIC PROGRAMMING FOR RESERVOIR OPERATING RULE GENERATION1

ABSTRACT: Two dynamic programming models — one deterministic and one stochastic — that may be used to generate reservoir operating rules are compared. The deterministic model (DPR) consists of an algorithm that cycles through three components: a dynamic program, a regression analysis, and a simulation. In this model, the correlation between the general operating rules, defined by the regression analysis and evaluated in the simulation, and the optimal deterministic operation defined by the dynamic program is increased through an iterative process. The stochastic dynamic program (SDP) describes streamflows with a discrete lag-one Markov process. To test the usefulness of both models in generating reservoir operating rules, real-time reservoir operation simulation models are constructed for three hydrologically different sites. The rules generated by DPR and SDP are then applied in the operation simulation model and their performance is evaluated. For the test cases, the DPR generated rules are more effective in the operation of medium to very large reservoirs and the SDP generated rules are more effective for the operation of small reservoirs.     

EFFECTS OF ADJACENT AGRICULTURAL ACTIVITIES AND WATERSHED CHARACTERISTICS ON STREAM MACROINVERTEBRATE COMMUNITIES1

Benthic macroinvertebrate communities in streams adjacent to cornfields, streams where cows had unrestricted access, and reference locations without agriculture were compared to examine the effects of local land use and land use/land cover in the watershed. At each local site, macroinvertebrates and a variety of habitat parameters were measured upstream, adjacent, downstream, and farther downstream of the local land use. A geographic information system (GIS) was used to calculate drainage basin area, land use/land cover percentages in each basin, and the distance from sample sites to the stream source. Three‐way analysis of covariance (ANCOVA) tests with date, site type, and sampling location as main effects were used to explore differences in macroinvertebrate metrics using median substrate size, percent hay/pasture area, and stream depth as covariates. The covariates significantly improved model fit and showed that multiple contributing factors influence community composition. Local impacts were greatest at sites where cows had access, probably because of sedimentation and embeddedness in the substrate. Differences between the upstream and the adjacent and downstream locations were not as great as expected, perhaps because upstream recolonization was reduced by agricultural impacts or because of differences in the intensity or proximity of agriculture to riparian areas in the watershed. The results underscore the importance of both local and watershed factors in controlling stream community composition.     

水雾荷电净化空气飘尘与细菌的研究

研究一种高压静电水雾场产生的荷电净化空气中飘尘与细菌的方法。实验结果表明:在静电电压15kV、通风量540m~3/h的工况下,实验装置的一次性除尘效率高于80%、除菌效率达到88%以上;实验装置可以连续运行,能耗低、出风无二次污染。     

黄河流域水资源价值的计算与分析

利用经济杠杆的调节作用促使水资源的高效利用，是缓和水资源供需矛盾的有效措施之一。本文以水资源价值理论为基础，从黄河全流域水资源优化配置角度出发，以利用水资源获得最大经济效益为目标，测算了黄河水资源的理论价值，为制定黄河水资源费的征收标准提供科学的理论依据。     

三峡库区几种林下苔藓的保水功能

通过对三峡库区三种森林类型(松栎混交林、栓皮栎纯林、马尾松纯林)林下苔藓储量调查分析及其持水特性试验，得到不同森林类型林下苔藓储量、最大持水量、吸水速率等水文特征参数。结果表明，马尾松纯林林下苔藓储量最大(12．93t／hm^2)，松栎混交林和栓皮栎纯林林下苔藓储量相同(9．47t／hm^2)。松栎混交林林下苔藓最大持水量为5．36mm，栓皮栎纯林为5．73mm，马尾松纯林为6．26mm。研究结果还表明，三峡库区林下苔藓持水量随时间变化过程与森林类型无关。在只有苔藓覆盖情况下，不同森林类型林内不产生水分下渗和地表径流时的最大降雨量和最大降雨雨强分别为：松栎混交林林地5．36mm，5．820mm／h；马尾松纯林林地6．26mm，7．420mm／h；栓皮栎纯林林地5．73mm，6．060mm／h。     

脆弱生态环境耦合下的贫困地区可持续发展研究

研究表明，中国贫困地区的分布与脆弱生态环境的分布存在一种地理空间意义上的耦合，这种耦合是一种非良性的耦合，存在着诸多问题并我着当地的社会经济发展，要改变这一现状，实现区域社会经济可持续发展，必须革新现有的贫困人口生存方式和社会经济发展模式，据此，本文提出了实现贫困地区社会经济可持续发展的战略措施应是依托现有的资源优势，推广生态农业技术，发展绿色食品和开展生态旅游。