土壤水库和森林植被对水资源的调节作用

以湖南省土地、森林利用状况等有关资料为基础,从土壤和森林对降水形成径流的影响,调节水资源的数量和方式,防洪抗旱减灾方面的作用3个层次,详细地剖析了土壤水库和森林植被对水资源的调节作用。结果指出,土壤水库和森林植被能够调节水资源,其潜力非常大。合理利用土壤水库和森林植被可以蓄水保土减蚀,削减洪峰,减少自然灾害。     

保水剂对番茄生长及水分利用效率的影响

在砂与木屑复合基质中加入不同用量的保水剂,测定基质物理性状,并进行不同水分处理条件下番茄盆栽试验,以研究保水剂对番茄生长及水分利用效率的影响。结果表明:在每1 L基质分别加入1、2、4、8 g保水剂时,与对照(未加保水剂)相比,基质持水量分别增加16.35%、34.00%、61.29%和135.16%,容重分别降低3.61%、5.37%、9.42%和14.64%;在水分耗竭试验中,番茄萎蔫天数分别延长13.92%、22.79%、31.65%和45.5%,干物质量分别增加7.90%、21.60%、57.08%、179.50%,株高、叶片数、茎粗、鲜质量也都随保水剂用量的增加而明显增加;在基质相对水分质量分数分别为55%、70%、85%及100%4种处理下的番茄水分胁迫试验中,每1 L基质施用2 g保水剂时,与对照(未加保水剂)相比,水分利用效率分别提高29.93%、28.06%、14.36%、7.42%,株高、生物量也随水分胁迫程度加重而明显提高。     

论生态环境用水与生态环境需水的区别与计算问题

针对生态环境用水与生态环境需水概念和计算中存在的问题，从生态与环境概念分析入手，对生态环境用水、生态环境需水的概念进行界定和区分，对其内涵和计算关键问题进行评述。文章认为生态环境用水与生态环境需水既有区别又有联系，生态环境用水是其“实际用水”之意，生态环境需水是其“需求水”之意，生态环境需水是生态环境达到某一水平时的“用水量”。文章还介绍了生态环境用（需）水的分类及计算方法，指出生态环境用（需）水计算的两个关键问题，即尺度问题和阈值问题，认为生态环境用（需）水总量不是分类或分区生态环境用（需）水量的简单相加；提出了“基于水循环模拟的生态环境用（需）水量计算方法”的初步思想。     

污染水体中鱼体内三聚氰胺的累积及其在清洁水体中的消除

以吉富罗非鱼（Oreochromis niloticus）为受试动物,在室内用水族箱进行模拟养殖试验,设定污染水体中三聚氰胺初始浓度为0.2 g·L-1,考察罗非鱼在其中饲养1周期间体内三聚氰胺的累积情况。再将鱼转移至不含三聚氰胺的清洁水体中饲养1周,考察鱼体内三聚氰胺在其中的消除情况。结果表明,三聚氰胺能在鱼体内迅速富集,鱼肉及内脏中三聚氰胺的含量均与鱼在污染水体中暴露的时间成正相关。其中,鱼肉中三聚氰胺的浓度几乎成线性增大,拟合所得方程为y=5.598 8x＋12.897,相关系数为0.995 9。内脏对三聚氰胺的富集速率先快后慢,且其中三聚氰胺的浓度为鱼肉的2~3倍。在试验后期,鱼肉及内脏中三聚氰胺的浓度分别高达51.55 mg·kg-1和93.89 mg·kg-1,此时罗非鱼表现出明显的中毒迹象。将罗非鱼转移至清洁水体中养殖后,鱼肉及内脏中三聚氰胺的残留量均迅速下降,尤其是后者的消除速度甚快,一周后两者的浓度分别降至0.13 mg·kg-1和0.21 mg·kg-1。此时,罗非鱼中毒症状逐渐消失,活动趋向正常。     

Comparative genotoxicity of water processed by three drinking water treatment plants with different water treatment procedures

• Genotoxicity of substances is unknown in the water after treatment processes. • Genotoxicity decreased by activated carbon treatment but increased by chlorination. • Halogenated hydrocarbons and aromatic compounds contribute to genotoxicity. • Genotoxicity was assessed by umu test; acute and chronic toxicity by ECOSAR. • Inconsistent results confirmed that genotoxicity cannot be assessed by ECOSAR. Advanced water treatment is commonly used to remove micropollutants such as pesticides, endocrine disrupting chemicals, and disinfection byproducts in modern drinking water treatment plants. However, little attention has been paid to the changes in the genotoxicity of substances remaining in the water following the different water treatment processes. In this study, samples were collected from three drinking water treatment plants with different treatment processes. The treated water from each process was analyzed and compared for genotoxicity and the formation of organic compounds. The genotoxicity was evaluated by an umu test, and the acute and chronic toxicity was analyzed through Ecological Structure- Activity Relationship (ECOSAR). The results of the umu test indicated that biological activated carbon reduced the genotoxicity by 38%, 77%, and 46% in the three drinking water treatment plants, respectively, while chlorination increased the genotoxicity. Gas chromatograph-mass spectrometry analysis revealed that halogenated hydrocarbons and aromatic compounds were major contributors to genotoxicity. The results of ECOSAR were not consistent with those of the umu test. Therefore, we conclude that genotoxicity cannot be determined using ECOSAR .     

The potential role of virtual water in solving water scarcity and food security problems in China

Water, as a source of food security, plays an essential role in ensuring sustainable food resources for a growing population. However, water scarcity has increasingly become a constraint to economic development, particularly food production. The water-food challenge is impending because of China's increasing population and water demand. The concept of virtual water is useful to analyze this problem. In this paper, the implications and policy relevance of virtual water are expounded. Based on imported food volumes, it is calculated that an annual average of 10.52 × 10⁹ m³ of virtual water embodied in imported wheat and maize in the period between 1990 and 2000 is equivalent to 23% of the annual average transfer water volume of the South-North Water Transfer (SNWT) project. Consequently, this 29.3 × 10⁶ ha of virtual land is equivalent to 19% of China's arable land in 2000. Using the grain import prediction and the agricultural production conditions of China, the virtual water equivalents of China in 2010 and 2020 are evaluated, and are about 88 × 10⁹ m³ in 2010 and 95 × 10⁹ m³ in 2020, respectively. Importing virtual water embedded in traded food can alleviate water stress and even achieve food security. Virtual water trade may compensate for water demands for not only the past but also the future. Meanwhile, water trade can store water in its virtual water form, enabling food storage to play a potential role in solving food problems, as well as promoting sustainability of water resources in China.     

黄河流域农业水资源与水环境问题及技术对策

对黄河流域农业水资源与水环境现状和存在问题进行了分析,并针对这些问题,提出了改善黄河流域农业水资源利用与水环境安全的技术对策。研究指出,黄河流域水资源贫乏、水质污染严重、灌溉水水质劣化、农业水资源供需矛盾突出,水环境日趋恶化,产生了严重的生态环境问题;而目前我国缺乏有效的农业水资源和水环境监测预警系统,节水农业和水污染防治技术水平低,基础设施落后,信息平台建设不够,农业种植结构和水资源不匹配。今后应加快建立农业水资源与水环境监测预警系统与信息平台,积极推进农业水资源高效利用技术升级,全面提高农业污染防控技术水平,加强农业水环境保护,调整种植结构,建立节水高效种植制度。     

北京北部水源地水化学特征及硫同位素变化

分析了北京市北部水源地所在流域丰水期和枯水期的水化学特征和硫同位素变化.结果表明,研究区地表水pH值呈弱碱性,水化学组成以HCO3-和Ca2+为主,Mg2+和SO24-次之.通过对主离子组成的分析,发现研究区水化学特征的主要控制因素是岩石风化,其中绝大部分是受碳酸盐岩的影响.研究区内δ34S值在4.9‰—10.7‰之间,平均值为7.9‰,其中密云水库库区及潮河、白河δ34S平均值分别为8.7‰、6.0‰、8.2‰.研究区内SO24-离子浓度与δ34S值在一定程度上呈负相关,SO24-离子浓度十分集中,降水中的SO24-离子浓度很低,而δ34S值较高.根据质量守恒原理计算出硫元素来源于硫酸盐岩的溶解比例为30.72%—42.47%;来源于硫化物氧化的比例为21.74%—33.49%;来源于大气输入的比例为35.77%.     

Molecular analysis of bacterial community in the tap water with different water ages of a drinking water distribution system

The increase of water ages drove the deterioration of drinking water quality. The relative abundance of Rhizobiales uniquely increase during distributing process. Rhizobiales order was helpful for inhibiting corrosion under high chlorine level. New disinfecting strategies should be developed to ensure drinking water safety. Bacterial community in the drinking water distribution system (DWDS) was regulated by multiple environmental factors, many of which varied as a function of water age. In this study, four water samples with different water ages, including finished water (FW, 0 d) and tap water (TW) [TW1 (1 d), TW2(2 d) and TW3(3 d)], were collected along with the mains of a practical DWDS, and the bacterial community was investigated by high-throughput sequencing technique. Results indicated that the residual chlorine declined with the increase of water age, accompanied by the increase of dissolved organic matter, total bacteria counts and bacterial diversity (Shannon). For bacterial community composition, although Proteobacteria phylum (84.12%-97.6%) and Alphaproteobacteria class (67.42%-93.09%) kept dominate, an evident regular was observed at the order level. In detail, the relative abundance of most of other residual orders increased with different degrees from the start to the end of the DWDS, while a downward trend was uniquely observed in terms of Rhizobiales, who was inferred to be chlorine-resistant and be helpful for inhibiting pipes corrosion. Moreover, some OTUs were found to be closely related with species possessing pathogenicity and chlorine-resistant ability, so it was recommended that the use of agents other than chlorine or agents that can act synergically with chlorine should be developed for drinking water disinfection. This paper revealed bacterial community variations along the mains of the DWDS and the result was helpful for understanding bacterial ecology in the DWDS.     

Cooling water chlorination and productivity of entrained phytoplankton

A study to determine the effects of various concentrations of chlorine on the productivity of entrained marine phytoplankton was carried out at a nuclear power station on northeastern Long Island Sound, USA. Chlorine is a biocide used to control the growth of marine fouling organisms on the walls of many power station cooling systems. Chlorine concentrations considerably below those required to eliminate fouling organisms produced large decreases in the productivity of entrained phytoplankton. Generally, between 0.25 and 0.75 ppm residual chlorine at the cooling water discharge, continuously applied, is required to eliminate fouling organisms. At the highest chlorine concentration tested, 0.4 ppm residual at discharge (addition of chlorine at 1.2 ppm at cooling water intake), there was an 83% decrease in productivity as compared with the productivity at the intake. Productivity measurements were made at 6 other continuously applied chlorine concentrations. At the lowest concentration tested, too low to measure with our analytical method (addition of chlorine at 0.1 ppm at the intake), we measured a production decrease of 79%. Thus, a decrease in chlorination dosage of over an order of magnitude produced essentially no reduction in the damage done to entrained phytoplankton. Application of chlorine intermittently produced somewhat less of a decrease in primary productivity. When there was no chlorine addition during the period of study, there was essentially no effect on productivity. These data indicate that chlorine cannot be used effectively as a biocide for fouling organisms without having adverse effects on entrained phytoplankton.Contribution No. 2838 of the Woods Hole Oceanographic Institution.     

Perspectives and applications of nanotechnology in water treatment

Industrialization and excessive use of pesticides for boosting agricultural production have adversely affected the ecosystem, polluting natural water reserves. Remediation of contaminated water has been an area of concern with numerous techniques being applied to improve the quality of naturally available water to the level suitable for human consumption. Most of these methods, however, generate by-products that are sometimes toxic. Heterogenous photocatalysis using metal oxide nanostructures for water purification is an attractive option because no harmful by-products are created. A discussion on possible methods to engineer metal oxides for visible light photocatalysis is included to highlight the use of solar energy for water purification. Multifunctional photocatalytic membranes are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. An overview of water remediation techniques is presented, highlighting innovations through nanotechnology for possible addressing of problems associated with current techniques.     

Depletion of heavy isotopes of oxygen and hydrogen in tissue water of intertidal plants: implications for water economy

Stable oxygen and hydrogen isotope ratios of leaf and thallus water of the intertidal seagrasses Phyllospadix scouleri and P. torreyi and the marine algae Egregia menziesii, Gelidium coulteri, and Corallina vancouverensis from three locations in California, USA, were determined in 1987. Compared with subtidal seawater, most plant-water samples were depleted in the heavy isotopes ¹⁸O and deuterium. Depletion of heavy isotopes was greatest in plants growing at the highest intertidal elevations. This was an unexpected result, because enrichment of heavy isotopes occurs during evapotranspiration in terrestrial plants. Two possible mechanisms for this isotopic depletion are proposed: direct uptake of heavy isotope-depleted water vapor and preferential diffusion of ¹⁶O and ¹H into littoral plants from water remaining in the intertidal zone at low tide.     

Improvement of detection method of and in reclaimed water

Cryptosporidium and Giardia are two typical species of pathogenic protozoans that seriously endanger water quality. Previous works indicated that detection of Cryptosporidium and Giardia with modified United States Environmental Protection Agency (USEPA) method-1623 using a membrane filtration-elution for sample concentration attained better recovery and lower cost compared to the USEPA method-1623. Several improvements of membrane filtration-elution step as well as immunomagnetic separation (IMS) steps were investigated and an optimized method for detection of Cryptosporidium and Giardia in wastewater reclamation system was recommended in this paper. The experimental results show that an overnight soak of the membrane after scraping and vortex agitation before elution could enhance and stabilize the recovery. Increasing turbidity to 4 NTU by adding kaolin clay before filtration could effectively improve the recovery of low-turbidity water. Washing the concentrate after centrifugation and twice acid dissociation both reduced the impact of water quality to protozoan recovery. Protozoans in different water samples were determined by this optimized method, and the recovery of Cryptosporidium and Giardia were above 70% and 80% respectively, much higher than the acceptance of method-1623.     

Salinity exchange between seawater/brackish water and domestic wastewater through electrodialysis for potable water

● Present a general concept called “salinity exchange”. ● Salts transferred from seawater to treated wastewater until completely switch. ● Process demonstrated using a laboratory-scale electrodialysis system. ● High-quality desalinated water obtained at ~1 mL/min consuming < 1 kWh/m ³ energy. Two-thirds of the world’s population has limited access to potable water. As we continue to use up our freshwater resources, new and improved techniques for potable water production are warranted. Here, we present a general concept called “salinity exchange” that transfers salts from seawater or brackish water to treated wastewater until their salinity values approximately switch, thus producing wastewater with an increased salinity for discharge and desalinated seawater as the potable water source. We have demonstrated this process using electrodialysis. Salinity exchange has been successfully achieved between influents of different salinities under various operating conditions. Laboratory-scale salinity exchange electrodialysis (SEE) systems can produce high-quality desalinated water at ~1 mL/min with an energy consumption less than 1 kWh/m³. SEE has also been operated using real water, and the challenges of its implementation at a larger scale are evaluated.     

Dynamic simulation of urban water metabolism under water environmental carrying capacity restrictions

A revised concept for urban water metabolism (UWM) is presented in this study to address the inadequacies in current research on UWM and the problems associated with the traditional urban water metabolic process. Feedback loops can be analyzed to increase the water environmental carrying capacity (WECC) of the new urban water metabolism system (UWMS) over that of a traditional UWMS. An analysis of the feedback loops of an UWMS was used to construct a system dynamics (SD) model for the system under a WECC restriction. Water metabolic processes were simulated for different scenarios using the Tongzhou District in Beijing as an example. The results for the newly developed UWM case showed that a water environment of Tongzhou District could support a population of 1.1926 × 10⁶, an irrigation area of 375.521 km², a livestock of 0.7732 × 10⁶, and an industrial value added of ¥193.14 × 10⁹ (i.e. about US$28.285× 10⁹) in 2020. A sensitivity analysis showed that the WECC could be improved to some extent by constructing new sewage treatment facilities or by expanding the current sewage treatment facilities, using reclaimed water and improving the water circulation system.     

焦化废水缓冲体系的存在证明与集水调节池中水质结构调控

采用FeSO4对焦化废水原水进行pH调节,发现焦化废水原水中存在酸碱缓冲体系,具有很强的酸碱缓冲能力.焦化废水原水pH值约为9.6时,HCO3-、CN-、HS-、S2-、NH3、C6H5O-和胺类等以共轭碱的形式存在,对应的缓冲容量较高;随着pH的降低,共轭碱所占比例逐渐减少,对应的弱酸分布分数逐渐增多,缓冲容量逐渐减小;当pH调节至中性时,pH与pKa值接近,共轭碱与弱酸的分布分数近似相等,废水的缓冲容量有升高的趋势.在调节pH的过程中,由于FeSO4的水解、沉淀与络合作用,在投加量为2.0 g.L-1,反应时间15 min时,焦化废水中的氰化物、硫化物、油分及COD的去除量分别为1.5 mg CN-.g-1、27.3 mg S2-.g-1、15 mg总油.g-1及504 mg COD.g-1,pH影响各种污染物的形态分布而实现水质结构的调控.     

Variability in the chemistry of private drinking water supplies and the impact of domestic treatment systems on water quality

Tap water from 497 properties using private water supplies, in an area of metalliferous and arsenic mineralisation (Cornwall, UK), was measured to assess the extent of compliance with chemical drinking water quality standards, and how this is influenced by householder water treatment decisions. The proportion of analyses exceeding water quality standards were high, with 65 % of tap water samples exceeding one or more chemical standards. The highest exceedances for health-based standards were nitrate (11 %) and arsenic (5 %). Arsenic had a maximum observed concentration of 440 µg/L. Exceedances were also high for pH (47 %), manganese (12 %) and aluminium (7 %), for which standards are set primarily on aesthetic grounds. However, the highest observed concentrations of manganese and aluminium also exceeded relevant health-based guidelines. Significant reductions in concentrations of aluminium, cadmium, copper, lead and/or nickel were found in tap waters where households were successfully treating low-pH groundwaters, and similar adventitious results were found for arsenic and nickel where treatment was installed for iron and/or manganese removal, and successful treatment specifically to decrease tap water arsenic concentrations was observed at two properties where it was installed. However, 31 % of samples where pH treatment was reported had pH < 6.5 (the minimum value in the drinking water regulations), suggesting widespread problems with system maintenance. Other examples of ineffectual treatment are seen in failed responses post-treatment, including for nitrate. This demonstrates that even where the tap waters are considered to be treated, they may still fail one or more drinking water quality standards. We find that the degree of drinking water standard exceedances warrant further work to understand environmental controls and the location of high concentrations. We also found that residents were more willing to accept drinking water with high metal (iron and manganese) concentrations than international guidelines assume. These findings point to the need for regulators to reinforce the guidance on drinking water quality standards to private water supply users, and the benefits to long-term health of complying with these, even in areas where treated mains water is widely available.     

Suitability and water quality criteria of an open drainage municipal sewage water at Coimbatore, used for irrigation

Sanganur canal is the major open drainage system which has intricate linkage with storm water supply, domestic sewage and industrial effluent disposal. Water samples from various stations were collected and analysed for physicochemical parameters to assess the water quality of the Sanganur canal system. The study revealed that physicochemical parameters like pH, EC, TDS, DO, BOD, COD exceeded the permissible limit, clearly indicating the need of proper treatment of waste water before discharge into the Noyyal river.     

Duckweeds for water remediation and toxicity testing

The presence of toxic substances in wastewaters and outdoor bodies of water is an important ecotoxicological issue. The aim of this review is to illustrate how duckweeds, which are small, simply constructed, floating aquatic plants, are well suited to addressing this concern. The ability of duckweeds to grow rapidly on nutrient-rich water and to facilitate the removal of many substances from aqueous solution comprises the potential of these macrophytes for the remediation of wastewater and polluted aqueous reservoirs, while producing usable biomass containing the unwanted substances having been taken up. Their ease of cultivation under controlled and even sterile conditions makes duckweeds excellent test organisms for determining the toxicity of water contaminants, and duckweeds are important as model aquatic plants in the assessment of ecotoxicity. Duckweeds are also valuable for establishing biomarkers for the toxic effects of water contaminants on aquatic higher plants, but the current usefulness of duckweed biomarkers for identifying toxicants is limited. The recent sequencing of a duckweed genome holds the promise of combining the determination of water contaminant toxicity with toxicant diagnostics by means of gene expression profiling via DNA microarrays.