Molecular assessment of bacterial pathogens - a contribution to drinking water safety

Human bacterial pathogens are considered as an increasing threat to drinking water supplies worldwide because of the growing demand of high-quality drinking water and the decreasing quality and quantity of available raw water. Moreover, a negative impact of climate change on freshwater resources is expected. Recent advances in molecular detection technologies for bacterial pathogens in drinking water bear the promise in improving the safety of drinking water supplies by precise detection and identification of the pathogens. More importantly, the array of molecular approaches allows understanding details of infection routes of waterborne diseases, the effects of changes in drinking water treatment, and management of freshwater resources.     

厦门市资源水与虚拟水耦合代谢效率评价

自然水循环与社会水循环的关联研究是制定系统性水代谢对策的前提。从水资源代谢过程与格局角度,用物质流分析法(MFA)剖析了亚热带季风气候雨影区缺水城市枯水年份资源水与虚拟水耦合代谢的路径、数量,提取代谢效率评价所需的过程与结构指标,以社会、经济、生态环境效益最优化为评价原则构建了城市水资源代谢效率评价指标体系,采用层次分析法赋权,评价了近10年来枯水年份厦门市资源水与虚拟水耦合代谢效率。结果表明,厦门水资源代谢效率呈加速提高趋势,主要由用水效率类和水代谢过程与结构类指标驱动。说明提高水资源代谢效率的根本对策在于用水行为和用水过程与结构的改善。采用情景分析法设计主导驱动指标不同组合下水资源代谢效率情景方案,提高了方案的可操作性,可基于这些指标制定水资源管理对策。基于MFA结果提取指标丰富了指标体系构建理论。     

Agricultural use of water

Irrigation for agricultural purposes is one of the essential claims on available water resources. Those resources have not been adequately utilized in many countries for a variety of reasons. Where finance has been allocated to irrigation schemes, the schemes have tended to be large-scale, and the performance often disappointing. Alternatively, small-scale irrigation schemes, while receiving less support and encouragement, can often be more effective. For both large-scale and small-scale irrigation schemes, the responses of individual farmers and village communities are critical factors. More technologies need to be developed that are adapted to local needs, resources and aspirations within the context of current socio-economic practices. Obviously, the wider the range of technologies available, the more likely it will be that the technology most appropriate to existing conditions will be identified and used.     

Managing water resources for crop production

Increasing crop production to meet the food requirements of the world''s growing population will put great pressure on global water resources. Given that the vast freshwater resources that are available in the world are far from fully exploited, globally there should be sufficient water for future agricultural requirements. However, there are large areas where low water supply and high human demand may lead to regional shortages of water for future food production. In these arid and semi-arid areas, where water is a major constraint on production, improving water resource management is crucial if Malthusian disasters are to be avoided. There is considerable scope for improvement, since in both dryland and irrigated agriculture only about one-third of the available water (as rainfall, surface, or groundwater) is used to grow useful plants. This paper illustrates a range of techniques that could lead to increased crop production by improving agricultural water use efficiency. This may be achieved by increasing the total amount of water available to plants or by increasing the efficiency with which that water is used to produce biomass. Although the crash from the Malthusian precipice may ultimately be inevitable if population growth is not addressed, the time taken to reach the edge of the precipice could be lengthened by more efficient use of existing water resources. <br>     

Toxin-producing cyanobacteria in freshwater: A review of the problems, impact on drinking water safety, and efforts for protecting public health

Cyanobacteria have adapted to survive in a variety of environments and have been found globally. Toxin-producing cyanobacterial harmful algal blooms (CHABs) have been increasing in frequency worldwide and pose a threat to drinking and recreational water. In this study, the prevalence, impact of CHABs and mitigation efforts were reviewed, focusing on the Lake Erie region and Ohio’s inland lakes that have been impacted heavily as an example so that the findings can be transferrable to other parts of the world that face the similar problems due to the CHABs in their freshwater environments. This paper provides a basic introduction to CHABs and their toxins as well as an overview of public health implications including exposure routes, health effects, and drinking water issues, algal bloom advisory practices in Ohio, toxin measurements results in Ohio public water supplies, and mitigation efforts.     

Genetic and management approaches to boost UK wheat yields by ameliorating water deficits

Faced with the challenge of increasing global food production, there is the need to exploit all approaches to increasing crop yields. A major obstacle to boosting yields of wheat (an important staple in many parts of the world) is the availability and efficient use of water, since there is increasing stress on water resources used for agriculture globally, and also in parts of the UK. Improved soil and crop management and the development of new genotypes may increase wheat yields when water is limiting. Technical and scientific issues concerning management options such as irrigation and the use of growth-promoting rhizobacteria are explored, since these may allow the more efficient use of irrigation. Fundamental understanding of how crops sense and respond to multiple abiotic stresses can help improve the effective use of irrigation water. Experiments are needed to test the hypothesis that modifying wheat root system architecture (by increasing root proliferation deep in the soil profile) will allow greater soil water extraction thereby benefiting productivity and yield stability. Furthermore, better knowledge of plant and soil interactions and how below-ground and above-ground processes communicate within the plant can help identify traits and ultimately genes (or alleles) that will define genotypes that yield better under dry conditions. Developing new genotypes will take time and, therefore, these challenges need to be addressed now.     

A dynamic assessment of water scarcity risk in the Lower Brahmaputra River Basin: An integrated approach

Many international river basins are likely to experience increasing water scarcity over the coming decades. This water scarcity is not rooted only in the limitation of resources, i.e. the shortage in the availability of freshwater relative to water demand, but also on social factors (e.g. flawed water planning and management approaches, institutional incapability to provide water services, unsustainable economic policies). Therefore, the assessment of water scarcity risks is not limited to the assessment of physical water supply and demand, but it requires also consideration of several socio-economic factors. In this study, we provide a comprehensive dynamic assessment of water scarcity risks for the Lower Brahmaputra river basin, a region where the hydrological impact of climate change is expected to be particularly strong and population pressure is high. The basin area of Brahmaputra River lies among four different countries: China, India, Bangladesh and Bhutan. For water scarcity assessment, we propose a novel integration of different approaches: (i) the assessment of water scarcity risk, considering complex social-ecological system; (ii) the analysis of dynamic behaviour of the system; (iii) exploration of participatory approach in which limited number of stakeholders identify the most relevant issues with reference to water scarcity risks and provide their preferences for the aggregation of risk assessment indicators. Results show that water scarcity risk is expected to slightly increase and to fluctuate remarkably as a function of the hazard signal. Social indicators show trends that can at least partially compensate the increasing trend of the drought index. The results of this study are intended to be used for contributing to planned adaptation of water resources systems, in Lower Brahmaputra River Basin.     

Shifts in small-bodied fish assemblages resulting from drought-induced water level recession in terminating lakes of the Murray-Darling Basin, Australia

Over-abstraction of water places unsustainable pressures on river ecosystems, with the impacts amplified under drought conditions. Freshwater fishes are particularly vulnerable due to associated changes in water quality, and habitat availability, condition and connectivity. Accordingly, fish assemblages are ideal indicators of the impacts of drought and over-abstraction. The Murray-Darling Basin (MDB), south-eastern Australia, terminates at the Ramsar listed Coorong and Lower Lakes, which comprise Lake Alexandrina and Lake Albert. Over-abstraction and extreme drought during the last decade has placed these lakes under severe environmental stress. The purpose of this study was to investigate shifts in fish assemblages caused by substantial water level recession and salinization in the Lower Lakes. Small-bodied fish assemblages were sampled at the beginning and several years into the drought. Off-lake habitats held diverse fish assemblages in 2003, but most sites were dry by 2009. Remaining habitats were disconnected, salinities increased substantially, and aquatic vegetation shifted from freshwater to salt-tolerant species. There was a substantial decline in the proportion of specialist species, especially diadromous and threatened species, and an emerging dominance of generalist freshwater and estuarine species. The findings warn of the inevitable ecological impact of over-allocating water for human use in drought-prone regions, and highlight the need for adequate environmental water allocations. This study also emphasises that understanding the ecological attributes of a fish species, and the subsequent assignment to a functional group, will help predict vulnerability to decline and extirpation.     

The sharing of water between society and ecosystems: from conflict to catchment-based co-management

Human uses of freshwater resources are increasing rapidly as the world population rises. As this happens, less water is left to support aquatic and associated ecosystems. To minimize future human water shortages and undesirable environmental impacts, more equitable sharing of water resources between society and nature is required. This will require physical quantities and social values to be placed on both human and aquatic ecosystem requirements. Current water valuation systems are dominated by economic values and this paper illustrates new quantification and valuation methods that take more account of human well-being and environmental impacts. The key to the effective implementation of these more equitable water allocation methods is the use of catchment-based integrated water resources management. This holistic framework makes it possible for human and ecosystem water requirements and the interactions between them to be better understood. This knowledge provides the foundation for incorporating relevant social factors so that water policies and laws can be developed to make best use of limited water resources. Catchment-based co-management can therefore help to ensure more effective sharing of water between people and nature.     

Improving plant drought tolerance and growth under water limitation through combinatorial engineering of signalling networks

Agriculture is by far the biggest water consumer on our planet, accounting for 70 per cent of all freshwater withdrawals. Climate change and a growing world population increase pressure on agriculture to use water more efficiently (‘more crop per drop’). Water‐use efficiency (WUE) and drought tolerance of crops are complex traits that are determined by many physiological processes whose interplay is not well understood. Here, we describe a combinatorial engineering approach to optimize signalling networks involved in the control of stress tolerance. Screening a large population of combinatorially transformed plant lines, we identified a combination of calcium‐dependent protein kinase genes that confers enhanced drought stress tolerance and improved growth under water‐limiting conditions. Targeted introduction of this gene combination into plants increased plant survival under drought and enhanced growth under water‐limited conditions. Our work provides an efficient strategy for engineering complex signalling networks to improve plant performance under adverse environmental conditions, which does not depend on prior understanding of network function.     

Physiological responses of wheat to drought stress and its mitigation approaches

Drought is a polygenically controlled stress and a major agricultural risk that reduces crop productivity and limits the successful insight of land potential throughout the world. This review article has been divided into two parts, i.e., effect of drought stress on physiology of wheat and potential drought mitigation approaches. In the first part, physiological responses of wheat to stress were discussed. Cell membrane stability, relative water content, early maturity, decreased leaf area, small plant size, increased dry weight and root–shoot ratio, and the whole-plant transpiration rate response to enhanced atmospheric vapor pressure deficit are physiological traits associated with drought tolerance in wheat. Reduction of relative water content closes stomata and thereby reduces stomatal conductance. Osmotic adjustment improves drought tolerance by allowing cell enlargement, plant growth, and stomata to stay partially open and by maintaining CO₂ fixation under severe water deficit. The wheat plant accumulates several organic and inorganic solutes in its cytosol to lessen its osmotic potential for maintenance of cell turgor. Drought affects photosynthesis negatively by changing the inner structure of chloroplasts, mitochondria, and chlorophyll content and minerals. Destruction of the photosystem II (PSII) oxygen releasing complex and reaction center can disturb production and use of electrons, causing lipid peroxidation of cell membrane through the production of reactive oxygen species. In the second part, drought mitigation approaches were discussed. Seed, drought, bacterial, and hormonal priming are common approaches used to lessen the effects of water deficit. Physiological trait-based breeding, molecular breeding, marker-assisted backcrossing, aerial phenotyping, water budgeting, and resource allocation are modern approaches used to develop drought tolerant wheat cultivars. Wheat genotypes produced as a result of a combination of all these methodologies will increase food security regarding the currently changing climate.     

Co‐benefits,trade‐offs,barriers and policies for greenhouse gas mitigation in the agriculture,forestry and other land use (AFOLU) sector

The agriculture, forestry and other land use (AFOLU) sector is responsible for approximately 25% of anthropogenic GHG emissions mainly from deforestation and agricultural emissions from livestock, soil and nutrient management. Mitigation from the sector is thus extremely important in meeting emission reduction targets. The sector offers a variety of cost‐competitive mitigation options with most analyses indicating a decline in emissions largely due to decreasing deforestation rates. Sustainability criteria are needed to guide development and implementation of AFOLU mitigation measures with particular focus on multifunctional systems that allow the delivery of multiple services from land. It is striking that almost all of the positive and negative impacts, opportunities and barriers are context specific, precluding generic statements about which AFOLU mitigation measures have the greatest promise at a global scale. This finding underlines the importance of considering each mitigation strategy on a case‐by‐case basis, systemic effects when implementing mitigation options on the national scale, and suggests that policies need to be flexible enough to allow such assessments. National and international agricultural and forest (climate) policies have the potential to alter the opportunity costs of specific land uses in ways that increase opportunities or barriers for attaining climate change mitigation goals. Policies governing practices in agriculture and in forest conservation and management need to account for both effective mitigation and adaptation and can help to orient practices in agriculture and in forestry towards global sharing of innovative technologies for the efficient use of land resources. Different policy instruments, especially economic incentives and regulatory approaches, are currently being applied however, for its successful implementation it is critical to understand how land‐use decisions are made and how new social, political and economic forces in the future will influence this process.     

Biomass production in plantations: Land constraints increase dependency on irrigation water

Integrated assessment model scenarios project rising deployment of biomass‐using energy systems in climate change mitigation scenarios. But there is concern that bioenergy deployment will increase competition for land and water resources and obstruct objectives such as nature protection, the preservation of carbon‐rich ecosystems, and food security. To study the relative importance of water and land availability as biophysical constraints to bioenergy deployment at a global scale, we use a process‐detailed, spatially explicit biosphere model to simulate rain‐fed and irrigated biomass plantation supply along with the corresponding water consumption for different scenarios concerning availability of land and water resources. We find that global plantation supplies are mainly limited by land availability and only secondarily by freshwater availability. As a theoretical upper limit, if all suitable lands on Earth, besides land currently used in agriculture, were available for bioenergy plantations (“Food first” scenario), total plantation supply would be in the range 2,010–2,300 EJ/year depending on water availability and use. Excluding all currently protected areas reduces the supply by 60%. Excluding also areas where conversion to biomass plantations causes carbon emissions that might be considered unacceptably high will reduce the total plantation supply further. For example, excluding all areas where soil and vegetation carbon stocks exceed 150 tC/ha (“Carbon threshold savanna” scenario) reduces the supply to 170–290 EJ/year. With decreasing land availability, the amount of water available for irrigation becomes vitally important. In the least restrictive land availability scenario (“Food first”), up to 77% of global plantation biomass supply is obtained without additional irrigation. This share is reduced to 31% for the most restrictive “Carbon threshold savanna” scenario. The results highlight the critical—and geographically varying—importance of co‐managing land and water resources if substantial contributions of bioenergy are to be reached in mitigation portfolios.     

Soil water content, maize yield and its stability as affected by tillage and crop residue management in rainfed semi-arid highlands

Rainfed crop management systems need to be optimized to provide more resilient options to cope with projected climatic scenarios forecasting a decrease in mean precipitation and more frequent extreme drought periods in Mexico. Soil water content (0?C60 cm) was measured during three crop cycles in maize plots with different agronomic management practices in a long-term rainfed experiment (established in 1991) in the highlands of Mexico. Maize yields of 1997?C2009 were reported. Crop management practices varied in (1) tillage (conventional [CT] vs. zero tillage [ZT]) and (2) residue management (full or partial retention and removal). ZT with residue retention had higher soil water content than management practices involving CT and ZT with residue removal which provided a buffer for drought periods during the growing seasons. In 2009, a cycle with a prolonged drought during vegetative growth, this resulted in yield differences of up to 4.7 Mg ha^?1 between ZT with (partial) residue retention and the other practices. Averaged over 1997?C2009, these practices had a yield advantage of approximately 1.5 Mg ha^?1 over practices involving CT and ZT with residue removal. ZT with (partial) residue retention used rainfall more efficiently and resulted in a more resilient agronomic system than practices involving either CT or ZT with residue removal.     

北京市水足迹及农业用水结构变化特征

运用水足迹的理论和方法计算评价了1990—2005年北京市水足迹及水资源利用的可持续性,在此基础上进一步分析了北京市农业用水结构的变化特征。结果表明:(1)北京市水足迹从1990年的81.5亿m3上升至2005年的168.6亿m3,人均水足迹由750.1m3上升为1096.0m3;(2)北京市水资源匮乏度不断升高,1995年以来水资源自给率呈下降趋势,与之相对应的水资源依赖度越来越高;(3)农业部门用水量在本地用水量中的比例平均每年为55.1%,虚拟水净输入量在虚拟水净输入总量中的比例平均每年达到89.1%;(4)高耗水型作物产品生产用水比例升高加大了农业用水压力,动物产品生产用水量呈增加趋势,2001—2005年动物产品生产引入的虚拟水占到其虚拟水总量的81.3%。北京市水资源利用呈不可持续状态,通过农业系统内部结构的优化调整,实现农业部门水资源的高效利用是缓解北京市水资源紧缺问题的关键。     

我国极端干旱天气变化趋势及其对城市水资源压力的影响

随着全球气候变化和水循环的改变,降水不均和持续干旱等极端天气事件的频度和强度增加,对水资源,尤其是人口和社会经济密度高的城市的水资源带来很大的影响和压力。为了探究我国干旱天气的变化趋势、区域特征、及其对城市水资源压力的影响,采用全国917个气象站点1951—2014年的逐日降水量数据集,分析了我国水资源及干旱的变化趋势和空间分布特征,并以我国289个主要地级市为研究对象,构建了气候变化情境下的城市基于区域降水禀赋的水资源压力评估方法,预测并展望了不同时段和不同代表性浓度路径(RCPs)情景下的未来城市水资源压力的情况。结果显示,我国极端干旱情况整体是随着全球气候变化增加的,年最长连续无降水天数变化速度的平均值为2.3d/100a,但是具有区域性,具体表现为南部地区干旱减缓而北部地区干旱严重。我国城市水资源压力受水资源禀赋的影响,呈现北方高而南方低的分布,除此之外水资源消耗大的大城市资源压力也比较大。随着气候变化,近期我国整体城市水资源压力相对现阶段增加了2%左右,具体水资源压力上升的城市有170个,水资源压力减少的城市有110个,剩下的9个城市水资源压力受气候变化的影响比较小。在低应对的RCP8.5情景下的城市水资源压力远远高于在RCP2.6情景,这说明减缓气候变化工作对降低我国城市水资源压力有积极作用;城市水资源压力的变化并不是均匀的,呈现南部减少而北部增加的变化趋势,我国华北地区城市的水资源压力最大,随着气候的变化,该地区的水资源压力也在随着时间不断增加,需要政府积极行动,提出有针对性和前瞻性的水资源规划方案,并依据方案采取措施,以应对气候变化造成的城市干旱增加。     

Impacts of upstream drought and water withdrawals on the health and survival of downstream estuarine oyster populations

Increases in the frequency, duration, and severity of regional drought pose major threats to the health and integrity of downstream ecosystems. During 2007-2008, the U.S. southeast experienced one of the most severe droughts on record. Drought and water withdrawals in the upstream watershed led to decreased freshwater input to Apalachicola Bay, Florida, an estuary that is home to a diversity of commercially and ecologically important organisms. This study applied a combination of laboratory experiments and field observations to investigate the effects of reduced freshwater input on Apalachicola oysters. Oysters suffered significant disease-related mortality under high-salinity, drought conditions, particularly during the warm summer months. Mortality was size-specific, with large oysters of commercially harvestable size being more susceptible than small oysters. A potential salinity threshold was revealed between 17 and 25 ppt, where small oysters began to suffer mortality, and large oysters exhibited an increase in mortality. These findings have important implications for watershed management, because upstream freshwater releases could be carefully timed and allocated during stressful periods of the summer to reduce disease-related oyster mortality. Integrated, forward-looking water management is needed, particularly under future scenarios of climate change and human population growth, to sustain the valuable ecosystem services on which humans depend.     

Clean water: a fading resource

Fresh waters of the world are collectively experiencing markedly accelerating rates of qualitative and quantitative degradation. The primary types of degradation are reviewed in a historical manner to illustrate the technological and social responses, and the rates at which they can be applied, under different societal structures. Effective utilization of extant freshwater resources is complicated by distributions of humans and their exploitation in regions low in water availability, and by accelerating changes in hydrological patterns associated with on-going and impending climatic changes. Certain societies can cope with pollution and availability constraints, and even reduce freshwater degradation. In most of the world, however, human population growth continues to accelerate without any significant reduction of rates. Until human growth is stabilized, either by intelligence or catastrophes, further losses and degradation of fresh waters can be controlled only partially on a global basis. Control and reversal of degradation requires a proper economic valuation of fresh waters. With proper valuation, methods for effective utilization of existing supplies can be applied to agricultural, industrial, and residential uses.     

Maintaining customary harvesting of freshwater resources: sustainable Indigenous livelihoods in the floodplains of northern Australia

Freshwater resources underpin multiple livelihood systems around the world, particularly in highly productive tropical floodplain regions. Sustaining Indigenous people’s access to freshwater resources for customary harvesting, while developing alternative livelihood strategies can be challenging. The sustainable livelihoods approach was applied to examine the ways in which multiple livelihoods in the East Alligator River floodplain region in northern Australia influence Aboriginal people’s access to freshwater resources for customary harvesting. Interviews with Aboriginal residents were conducted to understand changes to freshwater customary harvesting practices. The dominant floodplain-based livelihoods analysed were pastoralism, biodiversity conservation and tourism and they were found to generate both opportunities and constraints for sustaining freshwater customary harvesting. Opportunities were provided through facilitating regular access to floodplain country and opportunistic access for harvesting, which assists in sustaining bio-cultural knowledge. Partnerships developed through these mainstream livelihoods built human capacity that enhanced all livelihood resource capitals (natural, human, social, financial and physical). Three key ways the dominant livelihoods constrained access to key freshwater resources were identified. Tourism required sacrificing certain hunting places and had to accommodate recreational fishing pressure. The successful recovery of the saltwater crocodile population through biodiversity conservation policy has inadvertently reduced people’s customary access to in-stream resources. Pastoralism on the floodplain had restricted traditional floodplain burning practices associated with accessing aestivating long-necked turtles, affecting access and abundance. These findings highlight the need for the development of remote Indigenous livelihood strategies to make explicit their influences on freshwater customary harvesting practices, to better support their maintenance amongst multiple, non-customary floodplain livelihoods.     

Analysis of long-term water quality changes in the Kis-Balaton Water Protection System with time series-, cluster analysis and Wilks’ lambda distribution

Lake Balaton is the largest shallow freshwater lake in Central Europe. Its water quality is mainly affected by the supplying rivers and other water sources. The primary source is the Zala River. Its water used to be filtered by the Kis-Balaton Wetland (KBW) before entering Lake Balaton. During the nineteenth century, as a result of artificial water level modifications, the KBW disappeared and the Zala River's waters became partially unfiltered. It is for this reason that the Kis-Balaton Water Protection System (KBWPS) had to be constructed as a mitigation wetland.The aim of the study is to examine the available physical, chemical and biological parameters to get a more comprehensive picture of the processes evolving in the functioning of the KBWPS, and to make suggestions concerning the management and preservation of the system's wetland habitat.The central concept of the present study was to group the sampling points of the KBWPS and to determine which parameters had the greatest effect on the groups, and where. Multivariate data analysis was applied to the data concerning 25 chemical, biological and physical parameters for the time period 1984-2008 from 13 monitoring stations. The sampling locations were clustered then grouped. The groups were formed annually. The change of alignment of similar sampling points shows how the border between the determining groups (covering the eutrophic pond and wetland habitats) changed over the years. This change followed the transition from macrophyte vegetation to an open water area which took place as a result of the water level being kept artificially constant, and which did not therefore follow the weather conditions (rain, drought, etc.). Using Wilks’ λ distribution it was possible to determine that the parameters responsible for eutrophication were primarily responsible for forming the groups of the sampling points. The next most important factors determining the groups were the variables in close relation with the parameters characteristic of eutrophication. The inorganic chemical components affected the conformation of the groups the least. Finally, by examining the phosphorous forms and chlorophyll-a we tried to show the milestones in the history of the mitigation wetland, the KBWPS.The result of this research was that it points out changes in the KBWPS over a long time period, which had not been done previously. This research could hopefully help scientists to gain a broader perspective on processes evolving in the KBWPS. When it comes to finishing the second phase of the reservoir system, more knowledge will be available on what can be expected regarding the quality of the water entering Lake Balaton, and the conservation of the nature preserve wetland area.