Advanced Treatment Technologies in the Remediation of Seleniferous Drainage Waters and Sediments

Bioaccumulation of selenium (Se) in wetlands and evaporation ponds has created serious hazards to fish and waterfowl in the western United States. Agricultural drainage water is the main source for Se contamination in this region. Treatment technologies currently being evaluated to reduce the Se load in agricultural drainage water include physical, chemical and biological methods. This article focuses on ion-exchange, reverse osmosis, solar ponds, chemical reduction with iron, microalgal-bacterial treatment, volatilization, biological precipitation, and flow-through wetlands to remove Se in water. Advantages and disadvantages of each technology are evaluated and assessed in terms of cost-effectiveness and practical applications in dealing with large volumes of drainage water. With intense research in treatment technologies, it is feasible that a combination of biological, chemical and physical techniques may be employed in the development of a cost-effective strategy to treat agricultural drainage water.     

节水防污型农田水利系统方案设计及应用研究

鉴于我国传统的灌排模式及粗放型水稻种植方式,未经任何处理的稻田排水携带高浓度氮磷元素直接排入下游,引起水质恶化,造成水稻灌区严重的农业面源污染。基于农业面源污染的研究现状,构建了由田间水肥综合调控-田间草沟-湿地-骨干生态沟"四道防线"组成的净化农田排水的节水防污型农田水利系统,为验证该系统的净化效果,在广西桂林市青狮潭灌区及桂林灌溉试验中心站开展对比试验研究。试验表明,氮磷排放负荷指标沿程逐级下降,通过"四道防线"后,总氮、铵态氮、总磷负荷分别削减了70.4%、83.5%、61.0%,净化效果明显。研究内容不仅丰富了农业面源污染治理的控制方法和管理措施,也对我国南方水稻灌区面源污染治理具有现实意义。     

生态灌区农田排水沟塘湿地系统的构建和运行管理

建设生态型灌区是灌区现代化发展的重要内容。针对传统灌区农业面源污染日益严重的现状,总结了当前利用农田排水沟渠塘堰系统去除农业面源污染的研究进展,探讨了减污型农田排水沟渠塘堰湿地系统的构建方法,其基本特征包括:水利工程属性(排渍排涝及水流的不冲不淤要求),沟塘末端修建控制排水闸(低坝),种植优势植被,生态护岸(护底)工程,排水闸(退水闸)等水工建筑物减污型工况设计。分析了该系统的运行管理方式。     

国内外暗管排水研究知识图谱可视化分析

【目的】探明国内外暗管排水研究领域的研究内容、发展动态。【方法】基于CNKI与WOS数据库,采用科技文本挖掘可视化软件VOSviwer对国内外暗管排水研究的文献引文数据进行了科学叠加可视化分析,国外机构耦合分析,国内外引文关键词共现分析,国内外研究人员合作网络分析。【结果】通过科学叠加图谱,从学科的宏观角度分析了暗管排水研究学科发展方向;通过国家合作网络分析,得出了该领域的研究强国;USA、Canada、Germany、China、Netherlands、France、Sweden、England、Denmark、Switzerland;通过机构耦合分析,确定了暗管排水研究高影响力研究机构;USDA ARS、Iowa State University、University of Illinois、University of Minnesota、Purdue University、Agriculturea nd Agri-Food Canada、U.S.Geological Survey、Swedish University of Agricultural Sciences、Ohio State University;通过国内外关键词共现网络图比较,揭示了国内外暗管排水研究的主要内容上的差异;通过国内外合作网络图分析,得出了国内外暗管排水核心研究学者之间的合作关系及他们为推动暗管排水研究所做的贡献。【结论】我国的暗管排水研究领域正处于引进吸收与发展的状态,在流域尺度暗管排水的研究、田间尺度农药与磷淋失机制、排水水质净化等方面研究薄弱。未来的新兴趋势是从暗管排水释放源头到排水的末端建立系统的研究体系,考虑多元化因素的排水管理,工程技术上在田间排水源头采用建立反硝化除氮生物反应池改善排水水质,农艺措施上非耕作期进行覆盖作物种植研究,气候变化与暗管排水研究耦合也将成为研究热点。     

河南省氮素农业面源污染风险评价与关键管控区识别

农业面源污染是我国水环境保护面临的重要问题,风险评价对于农业面源污染防治具有重要意义。本研究以河南省为研究区域,采用层次分析法的分级赋值方法,基于熵值法和专家打分确定各影响因子权重,构建河南省氮素农业面源污染风险多因子综合评价模型,计算河南省氮素农业面源污染风险指数并在流域尺度上进行验证,划分氮素农业面源污染的风险等级并识别关键管控区。结果表明：种植源、养殖源和生活源分别贡献河南省31.52%、38.47%和30.01%的氮素流失负荷,流失负荷呈现为西低,中、东部高的特点。河南省有39 429 km²的区域存在中风险,约占河南省总面积的23.61%,有17 318 km²的区域存在高风险,约占总面积的10.37%;划定距河流2 km以内的中、高风险区为一般管控区和重点管控区,面积分别为10 982 km²和9 285 km²。通过与同期水质自动监测数据进行相关分析,决定系数为0.82,表明模型模拟结果具有较高的精准度。综合结果表明,建立的多因子综合评价模型具有科学性和准确性,可用于氮素农业面源污染风...     

Comparative evaluation of phosphorus losses from subsurface and naturally drained agricultural fields in the Pike River watershed of Quebec, Canada

Phosphorus (P) is the limiting nutrient responsible for the development of algal blooms in freshwater bodies, adversely impacting the water quality of downstream lakes and rivers. Since agriculture is a major non-point source of P in southern Quebec, this study was carried out to investigate P transport under subsurface and naturally drained agricultural fields with two common soil types (clay loam and sandy loam). Monitoring stations were installed at four sites (A, B, C and D) in the Pike River watershed of southern Quebec. Sites A-B had subsurface drainage whereas sites C-D were naturally drained. In addition, sites A-C had clay loam soils whereas sites B-D had sandy loam soils. Analysis of data acquired over two hydrologic years (2004-2006) revealed that site A discharged 1.8 times more water than site B, 4 times more than site C and 3 times more than site D. The presence of subsurface drainage in sandy loam soils had a significant beneficial effect in minimizing surface runoff and total phosphorus (TP) losses from the field, but the contrary was observed in clay loam soils. This was attributed to the finding that P speciation as particulate phosphorus (PP) and dissolved phosphorus (DP) remained relatively independent of the hydrologic transport pathway, and was a strong function of soil texture. While 80% of TP occurred as PP at both clay loam sites, only 20% occurred as PP at both sandy loam sites. Moreover, P transport pathways in artificially drained soils were greatly influenced by the prevailing preferential and macropore flow conditions.     

水环境非点源污染的治理与控制对策

非点源污染负荷在水环境污染中所占比例日益增大,而农业生产活动又是最大的非点源污染.由于没有固定的污染源,控制非点源污染要比控制点源污染困难得多.水环境非点源污染能够降低水体的功能、引起水体的富营养化、污染饮用水源、造成建筑物和财产的直接损失.为此,针对目前农业非点源污染存在的问题,提出了污染防治对策和管理措施,为积极地开展非点源污染控制与管理提供参考.     

漳河灌区农田地表排水中磷素流失特征分析

:为了揭示农田面源污染的机理及其成因,该文选取湖北省漳河灌区的典型试验田作为试验对象,在田间试验结果进行分析的基础上,研究了水稻和玉米2种作物在不同处理方式下农田排水磷素流失的影响因子及其规律。试验结果表明,降雨强度、作物类型、农业耕作管理方式（包括灌溉施肥方式等）是农田磷素流失的主要影响因素;另外,土壤物理化学特性和地形地势等也在一定程度上影响农田磷素的流失。     

水田灌排一体化系统的开发与应用

分析国内外农业灌溉和排水领域发展的研究现状和目前常见的灌排装置的特点,针对中国灌溉排水研究领域对节水灌溉、控制排水设施的迫切需求,提出了水田灌排一体化系统的设计方案.该系统能根据农作物不同时期对水位的需求,充分利用灌溉和降雨的水量,较为精确地控制水田的灌溉和排水水位,解决了原有灌排设备无法同时实现灌溉和排水自动控制的难题.实际应用结果表明,水田灌排一体化系统试验区和对照区相比,降雨量增加利用150 mm,降雨利用率提高21%,减少灌水量21%;水稻亩产量增加4.3%;提高肥料的利用效率,减少农业面源污染.该系统结构简单、操作方便,具有可观的经济、生态效益和广阔的应用前景.     

农田不同排水措施地下排水效果模拟试验研究

在地下水位较高、地表易于形成积水的中国南方地区,通过农田排水措施可以及时排除多余地表积水,快速降低地下水位,以达到排涝降渍、协同调控的目的.文中基于室内砂槽试验,揭示暗管排水、明沟排水、不同反滤体高度的反滤体排水及改进暗管排水等措施的地下排水规律及效果.结果表明:将暗管周围土体置换为高渗透性土体介质的改进暗管排水可明显提高排水流量,当土体置换高度达2 cm时(对应于田间条件40 cm),其排水流量均高于相同埋深条件下的其他排水措施,达暗管排水的1.59~1.66倍;改进暗排在地表积水消失时仍保持较大的排水流量,可达相同埋深暗管流量的2倍以上,在积水层消失后,能迅速降低农田土壤水的渍害胁迫,将地下水位降低至暗管埋设高度;各种排水措施,在地表积水即将消失时,出现了流量与水头变化幅度较大的现象.相对于各种地下排水措施,改进暗管排水在除涝降渍中存在明显优势.研究结果可为涝渍灾害易发地区高效除涝降渍减灾工程设计和建设提供参考.     

Influence of subsurface drainage on crop production and soil quality in a low-lying acid sulphate soil

Kuttanad, the low-lying tract in Kerala State of south-west India, is a place where drainage problems have caused the agricultural production to remain low. The problem is more severe in the acid sulphate soils of Kuttanad. Besides the problems inherent to acid sulphate soils, the area also experiences problems of flooding, lack of fresh water and intrusion of saline water from the Arabian Sea. A subsurface drainage system consisting of 10 cm diameter clay tiles, each of 60 cm length, was installed at a depth of 1 m with two different spacings of 15 and 30 m for evaluating its influence in improving soil quality and crop production. Many of the critical crop growth parameters in the subsurface drained area, particularly the grain yield and 100 grain weight, were significantly superior to that of the ill-drained areas. Drain spacings up to 30 m was found to significantly improve the productivity of the area. The overall increase in rice yield due to subsurface drainage was 1.36 t/ha. It was also found that subsurface drainage could remove the chemical heterogeneity of soil which is the root cause for patchy crop growth and uneven ripening of rice crop in the area. Acidity in the subsurface drained area was always lower throughout the cropping season. The salinity in the soil could be controlled considerably by subsurface drainage. The iron transformations were not serious enough to cause concern for rice cultivation when subsurface drainage was adopted. Accumulation of sulphates in insoluble form occurred during drainage due to the oxidation of pyrite. Subsurface drainage was also very efficient in leaching sodium, calcium and magnesium. Chloride content in soil decreased drastically during drainage.     

Radial interval chance-constrained programming for agricultural non-point source water pollution control under uncertainty

Inherent uncertainties in agricultural non-point source water pollution control problems cause great difficulties in relevant modeling processes. A radial interval chance-constrained programming (RICCP) approach was developed in this study for supporting source-oriented non-point source pollution control under uncertainty. The proposed RICCP approach could tackle two-layer uncertainty resulting from temporal and spatial variability of many factors and their uncertain interactions. Based on the concept of radial intervals and chance-constrained programming, RICCP could reflect the randomness in the bounds of interval parameters, with or without known probability distributions. RICCP could also allow decision makers to adjust the conservativeness of solutions via protection and significance levels, helping satisfy environmental, economic and resource-conservation requirements in a holistic and interactive manner. The proposed methodology has been applied to an agricultural water pollution control case. The most-profit agricultural development strategies were explored while restricting environmental impacts to an acceptable level. A series of interval solutions for agricultural practices were generated corresponding to varied risk levels of constraint violations, which could help screen optimal alternatives according to decision makers’ profit and risk considerations as well as various system conditions. RICCP model was also compared to its alternatives. Significant differences in the solutions among the compared models further demonstrated the advantages of the proposed approach.     

大王滩水库饮用水水源地现状及防护对策

大王滩水库2008年列为南宁市水源地,2010年在6个监测断面的枯水期、平水期和丰水期进行水质监测,水库水中的总磷、总氮超标较为严重,主要是由于库区工业废水渗漏、生活污水直接排入库区和养殖污染、农业面源、旅游污染、库岸垃圾污染以及相关管理措施欠完善等原因导致的。为确保大王滩水库饮用水水质,提出做好水源地隔离防护和工业废水、生活污水处理措施,重点进行养殖污染、农业面源、旅游污染、库岸垃圾污染整治,以保护好大王滩水库饮用水水源地。     

厦门市小流域综合治理与“美丽乡村”建设整合研究——以过芸溪为例

流域综合治理是当前环境可持续发展的热点问题。近年来，我国经济的快速发展带动了农村各项产业的发展，但同时也带来一系列的流域面源污染问题。探索中国流域水污染治理新模式，找到解决流域农业面源污染新路径迫在眉睫。国家在2012年底提出了“美丽乡村”建设战略，给乡村建设带来了新的机遇，也对乡村自然环境的改善带来积极的推动作用。以福建省厦门市海沧区过芸溪流域为研究案例，基于该流域的水质监测数据进行分析，讨论该流域“美丽乡村”建设对水质改善，尤其是改善流域农业面源污染状况方面所起的积极作用，分析“美丽乡村”建设与流域综合治理有效整合的关系，探讨其结合的可行性与保障措施。研究认为，“美丽乡村”建设可以“百姓富，生态美”为总体原则，变流域周边的生态环境资源为发展之本，在保护流域自然生态环境可持续发展的同时，推进流域综合治理、村民生活生产水平的提高。      

山区城市建设"海绵城市"探索——以衢州市城区为例

针对山区城市衢州城区蓄水性较差的地质条件和时间上相对集中降水特性,宜采用外蓄内滞同时结合城区内部排水系统的改造和基于低冲击开发措施的面源污染控制等措施,不仅可缓解城市的防洪压力,又可打造具有弹性的山区海绵城市.     

清水河流域农业非点源污染模拟及特征分析

为探讨冬奥核心区所在的清水河流域农业非点源污染特征,利用SWAT模型对清水河流域进行污染模拟及特征分析。通过前期对流域内河流水质监测和评价分析可知,该流域农业非点源是重要污染来源,且降雨和径流会对水质影响较大。借助ArcGIS平台构建清水河流域SWAT非点源污染模型,并利用实测径流数据对模型进行了率定和验证,结果表明SWAT模型在清水河流域的适用性较好。利用模型模拟结果对流域内TN、TP污染负荷进行统计,并对其时空分布特征展开分析。非点源污染的时间分布特征:2011、2013、2015和2016年的年均非点源污染输出负荷表现为TN>TP,并且具有明显的季节性,夏季和冬季分别是非点源污染产生的高峰期和低谷期,各子流域的累积负荷量也呈现出汛期大于非汛期的特点;空间分布特征:污染负荷流失强度较高的关键源区为2、3、5、6、7、10、12、14号子流域,集中分布在东沟和西沟水系两侧,主要土地利用类型为耕地和草地。各子流域的非点源污染输出负荷与降雨量均呈正相关关系,输出负荷与降水相关性较强的区域集中分布在正沟、西沟两侧和东沟上游,该区域内非点源污染物的流失与降水密切相关,高降雨量及强降水都会引起污染物的大量流失。     

黑龙江省地表水灌溉水质评价分析

【目的】合理制定管理策略改善灌溉水质。【方法】以黑龙江省2017年5—8月295个测点的16项水质监测指标为基础,以《地表水水质评价标准》(GB 3838—2002)和《农田灌溉水质标准》(GB5084—2005)为依据进行等级分类,采用Office以及ArcGIS软件分析了黑龙江省灌溉水质(主要指地表水)指标时空变化特征。【结果】①黑龙江省灌溉用水的主要污染物为有机污染物类(BOD5、COD和高锰酸盐指数)和面源污染类(氨氮、TN和TP)指标,其中仅有60.9%～76.7%和68.6%～78.3%测点的灌溉水质中COD和高锰酸盐指数能够达到III类标准以上;而面源污染类指标的表现较差,且TN和TP指标的超标问题较为严重;②时间变化方面,随着生育季的进行,有机物和面源污染类指标的劣类水测点均呈现逐渐增多趋势,且这一现象在TN和TP指标上表现更为明显;③空间变化方面,农业面源污染类指标的高风险区主要集中在佳木斯和七台河市,涉及的灌区主要包括鹤立河灌区、金沙灌区、三合灌区、孟家岗灌区和万家灌区。【结论】黑龙江省灌溉水质主要受农业面源污染类指标影响,且以TN、TP为主。制定合理的水肥管理策略是改善黑龙江省灌溉水质的重要手段。     

农业非点源污染及其防治措施

农业非点源污染是最主要的一类非点源污染,也是最普遍的非点源污染,其主要特征为发生区域的随机性、排放途径及排放污染物的不确定性、污染负荷空间分布的差异性.随着对城市生活点源和工业点源污染的有效治理,农业非点源污染引起了人们的广泛关注.为此,分析了农业非点源的污染现状、机理及来源,并根据农业非点源污染存在的问题,提出了农业非点源污染的防治措施,旨在为非点源污染的防治提供参考.     

改进暗管排水结构型式对排水性能的影响

提出一种占用耕地少、排水流量较常规暗排大且环境友好的改进暗排。基于室内土柱试验,分析改进暗排在地表积水、土体饱和条件下的排水除涝性能及其机理,提出地表积水土体饱和入渗条件下改进暗排排水流量的理论计算公式。结果表明,改进暗排可以有效提高暗管排水能力,试验条件下,反滤体宽度为2~6 cm的改进暗排在自由出流条件下的排水流量为常规暗排排水流量的2~3倍;积水层深度相同时,改进暗排排水性能随反滤体宽度的增加而增大,但增幅逐渐减小;土体介质和反滤体的渗透系数差别越大,改进暗排的排水作用越明显。理论方法计算结果与试验结果相吻合,证明提出的理论计算公式是合理可行的。     

Identifying sources of recharge to shallow aquifers using a groundwater model

The poor water quality of sub-surface drainage, hereafter drainage, water generated in the western San Joaquin Valley in California creates management challenges for farmers and water managers. Elevated concentrations of salt and trace elements in agricultural drainage limit the disposal options. In this constrained environment, determining the original source of drainage water is a crucial step in developing appropriate drainage management policies. Numerical modeling results of near-surface water-table fluctuations indicate that the substantial groundwater rise observed in the vicinity of the region's major water supply canal could not be attributed solely to seepage from overlying irrigated fields. An inverse solution approach is used herein to test the theory that seepage from the canal itself and/or that from surface water retention ponds (designed to protect the structure from flash floods) is responsible for an accentuated groundwater mound. The results suggest that canal seepage is the more likely source of non-agricultural aquifer recharge.