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Adriana Sturion Lorenzi Micheline Kézia Cordeiro-Araújo Mathias Ahii Chia Maria do Carmo Bittencourt-Oliveira 《Environmental Earth Sciences》2018,77(16):595
Changing global climatic conditions and the continuous eutrophication of aquatic ecosystems have led to increased frequency, duration and toxicity of cyanobacterial blooms worldwide. This makes the provision of time series information on cyanotoxins extremely crucial for effective monitoring and management of water resources. The objective of the present study was to investigate seasonal and annual changes in microcystins (MCs), cylindrospermopsins (CYNs), saxitoxins (STXs), neo-saxitoxin (neo-STX) and anatoxin-a (ATX-a) concentrations in 11 public water supply reservoirs in the semiarid region of Brazil, from 2004 to 2011. Per time, at least one cyanotoxin was present in all the investigated reservoirs. High levels of MCs, CYNs, STXs and Neo-STX were detected simultaneously in Carpina, Duas Unas, Ipojuca, and Jucazinho reservoirs. All the investigated reservoirs had significant concentrations of MCs. The highest levels of MCs were found in Carpina (303,300.0 ng g?1) and Duas Unas (122,053.9 ng g?1) reservoirs, while the lowest concentration of the hepatotoxins was recorded in Ipojuca (10.3 ng g?1) reservoir. On the other hand, CYN was detected in four reservoirs, STXs and Neo-STX in ten reservoirs and ATX-a in two reservoirs. The first record of CYN in Carpina reservoir was obtained in 2006. In addition, Carpina reservoir had the highest concentration of STXs and Neo-STX in the dry and rainy seasons, respectively. The high concentration of cyanotoxins observed in most samples obtained from semiarid reservoirs in Brazil demonstrates the need for regular monitoring and updated management programs. 相似文献
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A. Afrasiabian 《Environmental Geology》2007,52(4):673-677
Karst water is one of important potable water especially in arid and semiarid zones. Due to its vulnerability and high sensitivity
to pollution, water resources protection is one of important measures to be observed in karst resources management. One case
study in the The Maharlu Basin, Iran is discussed. Findings are used to postulate regional guidelines for establishing protection
and management measures in important karst pumping fields. Suggested locations for new wells in valleys or depressions should
be selected on the basis of specialized hydrogeological investigation. Recommendations for first, second and third degree
levels of protection based on European standards are suggested and then defined by model. The first degree protection zone
around the pumping field is recommended to be 10 × 10 m2. The second degree protection zone should be established to protect primarily from biological pollution. The third degree
zone is defined to protect from chemical parameters. 相似文献
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Major ion concentrations in 404 springs in carbonate strata were found to exhibit a wide range in sulfate values. Sulfate concentrations are often much larger than would be expected from the analysis of samples from surface outcrops. Springs in the Sierra Madre Oriental (Mexico), the Rocky Mountains Front Range (Canada), and the Peak District (England) show similarities in sulfate concentration and in spatial distribution. Springs with high sulfate concentrations are found close to base level and are thermal. Springs with low sulfate concentration are found at higher elevations above base level and are not thermal. There is a direct relationship between sulfate concentration and spring temperature, and an inverse relationship with discharge. The results from the three areas described support a model of local and regional flow patterns, with deep regional flow providing the warm sulfate-rich water. The initial fracture porosity development in these aquifers may owe as much to the removal of sulfur minerals as to the removal of carbonate minerals. High sulfate values are frequently found in carbonate aquifers, so this model may be of widespread applicability. 相似文献
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Dissolved organic carbon (DOC) is composed of a diverse array of compounds, predominantly humic substances, and is a near ubiquitous component of natural groundwater, notwithstanding climatic extremes such as arid and hyper-arid settings. Despite being a frequently measured parameter of groundwater quality, the complexity of DOC composition and reaction behaviour means that links between concentration and human health risk are difficult to quantify and few examples are reported in the literature. Measured concentrations from natural/unpolluted groundwater are typically below 4 mg C/l, whilst concentrations above these levels generally indicate anthropogenic influences and/or contamination issues and can potentially compromise water safety. Treatment processes are effective at reducing DOC concentrations, but refractory humic substance reaction with chlorine during the disinfection process produces suspected carcinogenic disinfectant by-products (DBPs). However, despite engineered artificial recharge systems being commonly used to remove DOC from recycled treated wastewaters, little research has been conducted on the presence of DBPs in potable groundwater systems. In recent years, the capacity to measure the influence of organic matter on colloidal contaminants and its influence on the mobility of pathogenic microorganisms has aided understanding of transport processes in aquifers. Additionally, advances in polymerase chain reaction techniques used for the detection, identification, and quantification of waterborne pathogens, provide a method to confidently investigate the behaviour of DOC and its effect on contaminant transfer in aquifers. This paper provides a summary of DOC occurrence in groundwater bodies and associated issues capable of indirectly affecting human health. 相似文献
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本文介绍了中国东北地氟病分布规律,以肇源县示范区为例,结合病区水文地质条件,明确了地氟病致病含水层,提出了防病改水供水目的层及钻探成井工艺,为中国东北地区地氟病防病改水提供了示范经验。 相似文献
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实验表明蒙脱石吸附氟的能力与溶液的PH值呈显著的负相关关系:在较低PH值条件下,蒙脱石的吸氟量较大,具有显著的降氟作用;而对中性—碱性溶液来说,蒙脱石对氟的吸附能力则大大降低,基本不具吸氟能力。蒙脱石的吸氟量还与其用量及含氟溶液的浓度有关。吸附原因一方面是由于体系PH值降低,导致其表面带正电荷而吸附F^-;另一方面,随着NaF浓度升高,蒙脱石的双电层变薄,体系ξ电势减少,发生絮凝作用,并携带F^-沉淀下来。另外,F^-与OH^-的离子交换作用也是酸性条件下蒙脱石吸氟的一个重要原因。 相似文献
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Doklady Earth Sciences - 相似文献
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淮南矿区岩溶发育及地下灰岩水径流特征 总被引:1,自引:0,他引:1
淮南矿区地质构造复杂,灰岩水威胁A组煤的安全开采。近年来淮南矿务局、煤科院地勘分院在此区开展了大规模研究试验工作。研究表明,本矿区岩溶发育强弱主要受断裂构造的控制。岩溶发育强带绝大多数分布在断层密集和断层交叉地段;岩层急倾斜或倒转急倾斜区层间岩溶裂隙发育亦强;岩层缓倾斜构造不甚发育地段岩溶发育较弱。 相似文献
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In order to assess the groundwater potentiality and augmentation of water supply schemes, estimation of the safe yield, well loss, formation loss, horse power of pump, depth of pump installation and duration of the pumping are essential. These parameters are estimated either by means of in-situ test or laboratory test. But the applicability of result from the laboratory test has limitations while in-situ tests give real representation of individual well of aquifer. The most common in-situ test is pumping test performed on well, which involves measurement of the fall and rise of water level with respect to time. The changes in water level (drawdown/recovery) and its quality are caused due to pumping of water from the well. Such study was carried out in Salur Mandal, Vizainagaram, Andhra Pradesh, India. 相似文献
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Fog harvesting: An alternative source of water supply on the West Coast of South Africa 总被引:1,自引:0,他引:1
Jana Olivier 《GeoJournal》2004,61(2):203-214
Experiments conducted during the 1990s investigated the feasibility of using fog water to supplement existing water supplies
in the arid west coast region of South Africa. Based on these results, a project was initiated aimed at implementing an operational
fog water collection system to provide potable water to a small, water-poor rural community. A 70 m2 fog water collector was subsequently erected on the crest of the hill located next to the mission station called Lepelfontein.
The volume of water collected was measured by means of a water flow meter and a tipping bucket. An automatic weather station
recorded rainfall, wind speed and direction. The data record spans the period September 1999–August 2001. This paper gives
a brief overview of the methods used to select the experimental site and describes the design of the fog water collection
system. This is followed by a detailed account of the water yields, the contribution of fog and rainfall to the total yield,
the characteristics of wet events, the factors associated with water collection and water quality. On average, yields of around
4.6 l of water were collected per square metre of collecting surface per day with maximum daily yields approaching 4000 l.
The quality of the water was excellent. It thus appears that fog water collection may have considerable potential as an alternative
water source at many other locations on the west coast of South Africa.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Service Opare 《GeoJournal》2012,77(5):695-705
Potable water is a critical for improved health and for the pursuit of various socio-economic activities. Despite its immense usefulness, rural communities in developing countries such as Ghana lack adequate access to potable water. Rainwater harvesting, which has the potential of providing potable water for rural communities in Ghana and can be undertaken largely with local resources is rarely utilized. The purpose of this paper is to present rainwater harvesting as a sustainable water supply strategy for domestic use and is based on research undertaken in two rural communities in Ghana. The paper identifies opportunities such as affordability and user ownership as well as constraining bottlenecks that include poor roofing materials, lack of appropriate harvesting facilities and housing occupancy status as factors influencing rainwater harvesting practices by rural communities. It then proposes measures to resolve these and other difficulties associated with rainwater harvesting and thereby enhance its potential for sustainable rural water supply. 相似文献
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水文地球化学信息对岩溶地下水流动系统特征的指示意义--以山西神头泉域为例 总被引:9,自引:0,他引:9
神头泉域岩溶水的水化学特征显示,岩溶水样的总溶解固体质量浓度、Sr2 质量浓度及宏量组分质量浓度均由泉域北、西、南部向排泄区增大,与岩溶水的流动方向一致.根据c(Sr)/c(Ca)与总溶解固体质量浓度可将神头泉群划分为3个泉组,对应于3个不同的岩溶水子系统,岩溶水样的聚类分析结果与这一结论相符合.研究表明水文地球化学信息对地下水系统的水动力特征分析具有指示意义. 相似文献
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《Applied Geochemistry》2005,20(2):353-365
Residential tap waters were investigated to examine the feasibility of using isotopic ratios to identify dominant sources of water Pb in the Columbus (Ohio, USA) municipal supply system. Overall, both the concentrations, which are generally low (0.1–28 μg/L), and isotopic compositions of tap water Pb show wide variations. This contrasts with the situation for a limited number of available service lines, which exhibit only a limited Pb-isotope variation but contain Pb of two very different types with one significantly more radiogenic than the other. Most tap water samples in contact with Pb service lines have Pb-isotope ratios that are different from the pipe Pb. Furthermore, the Pb isotope compositions of sequentially drawn samples in the same residence generally are similar, but those from separate residences are different, implying dominant Pb sources from domestic plumbing. A separate pilot study at two residences without Pb service lines shows isotopic similarity between water and solders in each house, further suggesting that the major Pb sources are domestic in these cases and dominated by Pb from solder joints. Although complicated by the broad range of overall Pb-isotope variations observed and limited by sample availability, the results suggest that Pb isotopes can be used effectively to constrain the sources of Pb in tap waters, especially for individual houses where multiple source candidates can be identified. 相似文献
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重要的地球化学"信息库" 总被引:2,自引:3,他引:2
金红石是各种岩石特别是地壳组成岩石中重要的副矿物,它在成岩、风化和各种不同程度的变质过程中均能保持极大的稳定性。同时,除主要成分TiO2外,金红石还含有为数众多的其它微量元素(例如: Nb, Ta, Zr, Hf, Sn, Mo, Sb, Cr, V, W, U和Pb等),这些微量元素的变化特征,对于包含金红石的主体岩石所经历的地质过程具有非常重要的指示意义。近二十年特别是近十年来,金红石已成为地球化学研究领域的一个热点。对各种元素和同位素在金红石中变化特征的调查,被广泛地应用于对各种地质过程的了解,其研究应用的范围涉及到了整体地球的元素平衡、大陆地壳的形成机制、含金红石岩石的形成源区、变质岩石的温压条件和形成时代的研究等多个方面,同时其所包含的各种同位素体系也被广泛用于各种地质过程的示踪。本文综合近年来金红石研究的最新进展,系统表述了金红石作为一个近年来发展起来的重要地质信息储库,在地球化学研究中各个方面的应用。 相似文献