基于ArcGIS的下辽河平原地下水脆弱性评价及空间结构分析

以下辽河平原为研究区,通过选取1991、2000和2010年3个代表年的相关参数,在DRASTIC模型基础上构建评价指标体系进行地下水脆弱性评价,并以地下水中氮元素浓度为响应指标通过显著性检验,在此基础上借助GS+、Arc GIS和Geoda095i等软件的制图功能和空间统计分析功能,对下辽河平原地下水脆弱性的空间分布特征、变异规律以及空间关联格局进行研究分析,结果表明:11991—2010年下辽河平原地下水脆弱性总体上呈先增后减趋势,空间分布上以沈阳市为中心的地下水高脆弱区向南部沿海方向扩散;21991—2010年研究区地下水脆弱性Moran's I表现为较强正相关现象,且关联程度呈略微下降趋势;31991—2010年研究区地下水脆弱性局部空间自相关和显著性水平均发生了明显的变化;4研究区内地下水脆弱性受结构性因素和随机性因素共同作用,且随机性因素在3个时期内有逐步上升趋势。研究成果反映了研究区地下水脆弱性空间结构的变异规律及驱动机制,为决策者在未来地下水污染防治方面提供相关参考依据。     

下辽河平原地下水脆弱性的时空演变

地下水脆弱性受相关因子变化的影响,在时空分布上具有动态变化性,因此分析地下水脆弱性的时空演变及结构变化规律对于地下水有针对性地污染防治具有重要意义。以下辽河平原为研究区,选取1991、2000和2010年的相关人为因子参数,结合DRASTIC模型计算这3个年份的地下水脆弱性综合指数,利用Arc GIS的地理统计工具分析地下水脆弱性的演变状况。在此基础上计算G指数得到地下水脆弱性的空间热冷点分布,结合重心和标准差椭圆对热点的变动情况进行定量分析。研究结果表明:(1)1991年地下水脆弱性以较低脆弱性和高脆弱性区为主,分别占研究区面积的36.5%和31.3%,到2000年以一般脆弱性和较高脆弱性区为主,面积比例分别达到31.6%和25.9%,发展到2010年主要以较高脆弱性为主,面积比例占41.71%;(2)1991—2010年下辽河平原地下水脆弱性总体上呈现先增后减的趋势,沈阳市及周边长期处于高值状况,南部沿海地区逐步演化为高值脆弱性区;(3)1991和2000年的热点集中区主要分布在新民市和辽中县的西部地带,期间变化较小,2010年的滨海地区也发展成热点集中区,各时期内冷点分布面积比较少,且零散;(4)1991年至2000年,热点重心向西南方向位移了2.264km,热点分布格局进一步趋于东—西方向;2000年到2010年,热点重心向西南方向位移了30.787km,标准差椭圆长轴旋转角逆时针转动了32.44°,整体热点分布格局为东北—西南方向。     

A GIS-based LVF model for semiquantitative assessment of groundwater pollution risk: A case study in Shenyang,NE China

Groundwater pollution risk assessment is a useful tool to prevent and control groundwater pollution, but its quantitative research is still relatively immature. In this study, a geographic information system based LVF model for a semiquantitative assessment of groundwater pollution risk is established, based on the groundwater pollution source load (L), groundwater vulnerability (V), and groundwater function value (F). Further, the pollution source load is characterized by seven specific pollution sources, the vulnerability is calculated by the modified DRASTIC method, and the groundwater function value is evaluated with the water quality and quantity. The model was used to assess the risk of shallow groundwater pollution in Shenyang city, Northeast China, with an area of 8,263 km². The results show that highest risk areas account for 16.3% of the study area and are mainly distributed in the east of the study area. High risk areas are significantly affected by a shallow buried depth of groundwater and many types of harmful pollutants from industrial, agricultural, and domestic pollution sources. The evaluation results reflect the risk of groundwater pollution in the Shenyang area, which is relevant to the management and sustainable use of groundwater resources in the area.     

Pollution risk assessment based on source apportionment in a groundwater resource area,NE China

Pollution risk assessment of a groundwater resource area is instrumental in contributing to groundwater protection. This study considered the evaluation results of source apportionment by combining a principal component analysis (PCA) with a factor analysis (FA) to identify potential risk sources. The vulnerability was evaluated using a DRASTIC model as the main pollution pathway, and groundwater quality as a pollution receptor, in order to validate the risk of pollution in a typical groundwater resource area of northeastern China. Results showed that four principal potential pollution sources were point source pollution such as water-rock interaction, dissolution of iron and manganese bearing minerals due to geological processes, non-point source pollution of nitrogen such as agriculture fertilizers, and organic pollution resulting from domestic and industrial wastewater. A “high” and “relatively high” pollution risk occurred mainly at the northwestern and southeastern edges of the region, respectively, with a widely distributed “moderate” pollution risk over the majority of the study area, and a “relatively low” and “low” pollution risk located mainly in the central of the Limin Groundwater Resources area, which showed that the potential pollution sources, especially due to human activity, have significantly changed the distribution of pollution risk in groundwater resource areas.     

塔里木河下游柽柳ABA累积对地下水位和土壤盐分的响应

近年来发现在逆境下(干旱、低温、高温、盐渍等)的植物体内大量积累ABA,从而引导人们去研究ABA与植物抗逆性之间的关系。在塔里木河下游地区影响植被正常生长发育的各种胁迫因子中,地下水位和土壤盐分是导致"绿色走廊"衰败的主要因素。柽柳是塔里木河下游荒漠植被的主体,对于改善生态环境、遏制沙漠化、保护生物多样性等诸多方面具有重要作用。因此,研究柽柳和地下水位以及土壤盐分的关系,对于维护塔里木河流域天然植被赖以生存的环境,保护柽柳这一重要的生物资源,维持生态平衡的良性循环具有重要意义。运用国际通用软件SAS6.12对塔里木河下游柽柳ABA和地下水位以及土壤盐分进行相关分析表明,柽柳ABA含量与地下水位呈极显著正相关,相关系数R=0.80305(显著性程度P=0.0003);与土壤盐分呈显著负相关,相关系数R=-0.59036(显著性程度P=0.0205)。由各断面柽柳ABA含量变化与地下水位和土壤盐分关系分析结果可以初步推断:3.12m的地下水位和0.96g/L的土壤盐分已经威胁到柽柳的正常生长发育,地下水位超过5.59m、土壤盐分大于1.61g/L则会对柽柳造成严重胁迫。在恢复和保育塔里木河流域天然植被的过程中,应该把对植被造成胁迫的外界条件的成因和植被自身的抗旱、抗盐等抗逆特性结合起来进行考虑:根据耐旱耐盐植被的合理生态水(盐)位,在主河道两岸维持一定范围的地下水位,使乔木、灌木、草本植被能良好地生长,发挥多种生态功能,这样既可以避免水资源的浪费又能充分发挥生态输水的功效,有利于从根本上解决"绿色走廊"的问题。     

浑河河水及其沿岸地下水污染特征

选择沈阳地区重要河流浑河及其沿岸地下水进行定量分析,研究并探讨了包括无机物和有机物在内的水质综合污染特征。结果表明,浑河河水中氨氮、硝氮、亚硝氮和酚超过了地表水环境质量标准,最大超标倍数分别为15.8、1.5、82.4和1.8倍,检测出的11种卤代烃、氯苯和六六六等有机物均未超标。浑河沿岸地下水中氨氮、硝氮、亚硝氮、化学需氧量、酚和铅超过地下水质量标准,超标率分别为31.6%、10.5%、26.3%、36.8%、47.4%和26.8%,检测出的4种卤代烃和六六六等有机物均未超标。河水及其沿岸地下水中的污染物,尤其是有机污染物种类和浓度高值基本出现在城西的谟家—大祝断面之间。浑河水质主要受城市工业废水、居民生活污水排放的影响,沿岸地下水的污染来源包括工业生产或农村居民生活造成的地表污染物垂直入渗式的点源污染、浑河水侧向渗透补给式的线源污染以及农药化肥使用产生的面源污染,而有机污染物主要通过点源污染地下水。浑河各区段的使用功能、包气带岩性及沿岸水源地开采井布局等因素都为受污染的河水对沿岸几百米范围内的浅层地下水的补给提供了条件,造成浅层地下水的污染,对当地生态系统及人类健康构成潜在威胁。     

Suitability for developing riverside groundwater sources along Songhua River,Northeast China

Riverbank filtration is a natural water treatment technology that consists of extracting water from rivers by pumping wells located in the adjacent alluvial aquifer. It is vital to choose the most appropriate from multiple potential candidate sites, which is a complex procedure and seldom paid attention to. In this study, a method system including multicriteria evaluation indexes was developed with which the suitability of bank filtration along the Songhua River of China for developing riverside groundwater sources was assessed. The system was comprised of main suitability indexes for water quantity, water quality, interaction intensity between surface water and groundwater, and the exploitation condition of aquifer condition, weights of which were determined by specialist marking methods. Based on this assessment system, the suitability of the study area was divided into five grades. Results show that riversides along Lalin River, Hulan River, and the middle part of Songhua River are suitable for developing riverside groundwater sources.     

古尔班通古特沙漠西部地下水位和水质变化对植被的影响

通过对比分析古尔班通古特沙漠西部3a地下水位和水质的变化特点,研究了地下水位和水质变化对地表土壤理化性质、植物多样性、及建群种梭梭种群生长与更新的影响。发现地下水位和土壤理化性质空间变异较大,最浅地下水位为3.3 m,最深可达24.2 m,主要集中在6-8 m;土壤电导率、pH值、Cl^-和SO₄^2-均在表层0-40 cm含量较高,变异系数随土层深度的增加而减小。在时间上地下水位受准噶尔盆地上游农田用水的影响,水位呈季节性波动。一年中最高水位出现在4月,最低水位在7月。玛纳斯河向下游输水对提高盆地地下水位具有明显作用,地下水位平均可升高4.3 cm,地下水矿化度平均增幅1 g/L。地下水位对退化区物种多样性影响不大,但对梭梭生长产生显著影响。梭梭生长的适宜地下水位为5-8 m,且地下水矿化度小于4 g/L。地下水位大于8 m导致梭梭种群衰退,而地下水位小于4 m时,地下水矿化度影响土壤表层积盐,进而显著地降低物种多样性,阻碍梭梭幼苗更新,导致梭梭种群衰败。总结认为准噶尔盆地上游的玛纳斯河断流和农业灌溉对古尔班通古特沙漠西部平原地区的地下水位和水质产生显著影响,梭梭退化与地下水位变化显著相关,必须引起高度重视。     

污染场地地下水渗流场模拟与评价——以柘城县为例

地下水数值模拟技术可以定性、定量描述地下水系统中大量的不确定性和模糊因素。由于不合理的开发利用水资源,拓城县土壤和地表水受到污染严重。以拓城县作为研究区,通过探讨研究区的水文地质概念模型、地下水流运动的数学模型,求解该模型,确定研究方法。同时,结合地下水各类监测因子,对研究区的污染场场地地下水进行模拟评价,包括了参数率定和模型预测两部分,从而确定最合理的地下水开采方案。     

基于主成分回归的河南省地下水硝酸盐脆弱性评价

根据水文与地貌特征将河南省分为山区和平原区,选取富水程度、降水入渗、单位面积施肥量、蔬菜种植面积比例和土壤质地作为共性指标,坡度和地下水埋深作为个性指标,利用主成分回归分析确定指标权重,在ArcGIS 9.2的支持下对河南省地下水硝酸盐脆弱性进行评价. 结果表明,河南省地下水硝酸盐脆弱性程度以中低水平为主,中等脆弱性以下地区占总面积的68.4%,高脆弱性地区占19.8%,极高脆弱性地区占11.8%.影响河南省平原地区地下水脆弱性的主要因素依次为土壤质地、施肥水平和降水入渗,而影响山区地下水脆弱性的主要因素依次为施肥水平、土壤质地和坡度.研究结果为合理施肥和农业环境管理提供了理论依据.     

高寒内陆河流域植被覆盖增加对地下水补给的影响

地下水是干旱区内陆河流域的主要基础性资源,对流域生态安全、可持续发展等具有重要意义。干旱/半干旱区的地下水补给比湿润地区更易受到地表覆盖条件的影响。为揭示干旱区内陆河流域植被覆盖增加对地下水补给的影响,以巴音河中下游为例,针对土壤和水评价工具(SWAT)模型未有效考虑降水、地形等因素对植被覆盖影响的缺陷,改进SWAT模型,采用全球地表卫星叶面积指数(GLASS LAI)数据代替其LAI计算模块,再结合SWAT土地利用更新模块,准确刻画区域植被覆盖变化。将改进后的SWAT模型与模块化有限拆分地下水流耦合(MODFLOW)模型耦合,准确模拟并分析植被覆盖增加对流域地下水补给的影响。结果表明：基于植被动态变化的土壤和水评价工具与模块化有限拆分地下水流耦合模型(DVSWAT-MODFLOW)模型的月蒸散发及月地下水位模拟效果较好;巴音河中下游2019年林地及草地面积以及LAI较2001年明显增加;2019年植被覆盖情况对应的年际及月际尺度地下水补给量较2001年分别减少了6.1—26.52 mm以及0—15.03 mm;植被覆盖增加对年际尺度地下水补给量的影响强弱在一定程度上取决于年降水量,对...     

Identification of major sources controlling groundwater chemistry from a multilayered aquifer system

Abstract

The Maknassy basin is a typical example of an arid area in Central Tunisia. The geology of the area is mainly composed of Cretaceous calcareous formations. To identify the major process involved in controlling the groundwater chemistry, 53 groundwater samples for three different aquifer levels have been examined. The groundwater chemistry is dominated by SO₄ (Na + Mg) and (Cl + SO₄). The presence of (Ca + Mg) and (Na + K) with HCO₃ indicates the domination of dolomitic rock weathering as the major source of cations. The plots for Na to Cl indicate a fine correlation and reflects their release from halite dissolution during groundwater transition. An ion exchange process is also activated in study area which is indicated by a shift to the right in a plot for Ca + Mg to SO₄ + HCO₃. The plot of Na – Cl to Ca + Mg – (HCO₃ + SO₄) confirms that Ca, Mg and Na concentrations in groundwater are derived from aquifer materials. Saturation indexes of groundwater samples indicate undersaturation for gypsum and anhydrite, and oversaturation for calcite, dolomite and aragonite confirming waterrock interactions by dissolution and dilution processes. In general, water chemistry is guided by weathering process, ion exchange and water-rock interaction during groundwater transition.     

基于ArcView-WOE的下辽河平原地下水生态系统健康评价

地下水生态系统是生态系统的重要类型,随着社会经济的发展,地下水资源与环境压力日益增大,地下水生态系统健康问题已经成为人类重点关注的环境问题之一。以ArcView为平台,以下辽河平原硝酸盐氮浓度为响应因子,并从地下水系统结构特征、区域自然条件、外界压力、资源与保护和生态环境5个方面建立证据因子的图层数据库,利用证据权重法(WOE)对下辽河平原地下水生态系统健康进行评价,得到硝酸盐氮后验概率分布图。结果表明:下辽河平原的西北、东北部、东南部及抚顺和辽阳地区地下水生态系统健康处于相对高和较高概率区,东部山前冲洪积平原及下辽河平原的周边地区处于中等概率区,下辽河平原的中部平原、南部滨海平原地区处于相对低和较低概率区。将地下水水质监测点硝酸盐氮含量与后验概率分布图进行对比分析,发现二者对应性较好,这说明WOE可以用于地下水生态系统健康评价,其概率表现形式能够有效的弥补传统生态系统健康评价结果是一个具体值(或等级)而无法反映生态系统健康不确定性的不足。     

Microbial Populations of the River-Recharged Fredericton Aquifer

The City of Fredericton, New Brunswick, Canada obtains its water from the Saint John River-recharged Fredericton aquifer. Water quality improves as it flows from the river into the aquifer in a process called bank filtration. Microorganisms contribute to water quality improvements during bank filtration by removing organic carbon. In the Fredericton aquifer, microbially catalyzed reductive dissolution of manganese oxide minerals negatively affects water quality. Aerobic and anaerobic microorganisms were cultured from Fredericton aquifer production well water, from associated bedrock groundwater, and from Saint John River sediment core and sediment groundwater samples. Aerobes were the largest culturable groups in all samples. The ratio of aerobes to other microbial groups, i.e., those reducing nitrate, Mn^{4 +}, Fe^{3 +}, or sulfate, did not vary significantly along the water flow path from the river to the aquifer. Analysis of microbial community composition along the flow path indicated an essentially identical community except in the immediate vicinity of the aquifer. This is in agreement with the absence of macroscale redox zones in the sediment below the Saint John River as determined by groundwater geochemical data. Bacteria isolated from groundwater samples, identified by 16S ribosomal RNA gene sequencing, were α -, β -, γ -, and δ -Proteobacteria, Actinobacteria, and Firmicutes. In contrast to groundwater samples, the majority of bacteria isolated from sediments were γ -Proteobacteria. Numbers of manganese-reducing bacteria, including Aeromonas spp., were small, however Mn^{4 +} reduction ability was widespread in bacteria enriched and isolated with other electron acceptors. The diverse Fredericton aquifer microbial community likely uses manganese oxide minerals as a sink for electrons derived from organic carbon oxidation.     

塔里木河下游胡杨径向生长与地下水的关系

本文通过分析塔里木河下游地区地下水位与胡杨径向生长量的相互关系,建立胡杨径向生长量随地下水位变化的函数模型,并从数理统计学的角度验证了胡杨生长的胁迫水位和临界水位。结果表明：1）随着地下水位的下降,胡杨径向生长量的均值逐渐减小。2）胡杨径向生长量与地下水位之间存在极显著的回归关系,其最佳回归模拟函数为四次多项式Y=0.003X4-0.080X3 0.731X2-3.060X 6.934,判定系数R2为0.857,P值为0.0001。3）通过分析可知：胡杨生长的胁迫水位是4.71 m,临界水位是8.62 m。胡杨正常生长的水位区间为0.5—4.71 m,受到胁迫的水位区间为4.71 m—8.62 m,当地下水位大于8.62 m时,胡杨将会呈现出衰败景象,此时,胡杨径向生长量的变化率逐渐向0接近,表明胡杨径向生长趋向停止。     

Source apportionment of pollution in groundwater source area using factor analysis and positive matrix factorization methods

By means of factor analysis (FA) and positive matrix factorization (PMF) methods, groundwater pollution sources were identified in the Jinji groundwater source area, which is beside the Yellow River and is the only urban water supply source for the city of Wuzhong in Northwestern China. The sources of groundwater were quantified based on 16 samples of shallow groundwater from the source area. The source apportionment with the PMF model identified three dominant groundwater pollution sources. These were anthropogenic activities of agricultural and industrial pollution with a pollution contribution of 53.0%, water–rock interaction of 24.6%, and evaporation and concentration of 22.4%. The source apportionment with the FA model identified four sources which were evaporation and concentration, with the largest contribution (42.6%), followed by anthropogenic activities (29.2%), mineral dissolution and industrial pollution (22.4%), and natural effects (5.8%). Specific attention should be paid to these natural (fluoride, TH, etc.) and anthropogenic sources (NH₄⁺, NO₂^?, turbidity, total bacterial count, etc.), and pertinent measures should be taken to control local groundwater pollution. The most significant trait of the PMF is its scientific interpretation and physical explanation of the results, depending on non-negative restriction of the pollution source profiles and contributions.     

黄河流域内蒙古段植被时空变化特征及条带状分布成因

监测干旱、半干旱地区植被覆盖度的动态变化,评估大尺度区域地质背景,尤其是活动构造在植被变化过程中发挥的作用对植被时空格局的认识具有重要意义。黄河流域内蒙古段地处干旱半干旱区,植被多依赖于地下水;且该地区活动构造较发育,是认识植被非地带性特征的理想区域。基于中分辨率成像光谱仪（MODIS）、归一化植被指数（NDVI）、气象与土地利用数据,对2000-2018年黄河流域内蒙古段植被覆盖度（FVC）的时空变化及稳定性进行分析,在此基础上针对河套段植被条带状特征及其成因进行讨论。结果表明,近20年研究区的FVC总体表现为增加趋势。降雨增加是大黑河流域、浑河流域及十大孔兑区域FVC增加的主要原因,沙漠地区FVC的增加得益于三北防护林工程建设。大黑河与浑河流域水分条件较好,物种多样性丰富,植被覆盖度高,能较好的抵御气候变化;而十大孔兑区域和沙漠地区FVC较低,生态系统脆弱,对气候波动的响应较大。河套灌区受人类活动主导,对气候变化的敏感性较低。河套段山前植被赋存环境为条带状地下水溢出带,在地下水储量增多条件下呈条带状增加趋势;而在山前过渡带,新构造运动及其造成的较大地表高差使得土壤层薄且储水能力较差,表现为FVC的高波动。现今黄河干流沿岸植被受土地利用转变影响整体减少;且在河流摆动、河道变迁扰动下,稳定性较差。河套盆地与鄂尔多斯台地边界处,受隐伏断裂和地震活动影响,地下水易沿带状透水断裂下渗,难以维持浅表水分和稳定的补给条件,使得FVC呈线状显著降低,且稳定性较差。研究从宏观水文地质条件和地表过程的角度,更加深入认识了植被空间分布的非地带性特征,为相似地区的研究提供了较好的科学依据。     

Peat characteristics and groundwater geochemistry of calcareous fens in the Minnesota River Basin, U.S.A.

Calcareous fens in Minnesota are spring-seepage peatlands with adistinctive flora of rare calciphilic species. Peat characteristics andgroundwater geochemistry were determined for six calcareous fens in theMinnesota River Basin to better understand the physical structure andchemical processes associated with stands of rare vegetation. Onset of peataccumulation in three of the fens ranged from about 4,700 to 11,000 ¹⁴C yrs BP and probably resulted from acombination of climate change and local hydrogeologic conditions. Most peatcores had a carbonate-bearing surface zone with greater than 10%carbonates (average 27%, dry wt basis), an underlyingcarbonate-depleted zone with 10% or less carbonates (average4%), and a carbonate-bearing lower zone again with greater than10% carbonates (average 42%). This carbonate zonation washypothesized to result from the effect of water-table level on carbonateequilibria: carbonate precipitation occurs when the water table is above acritical level, and carbonate dissolution occurs when the water table islower. Other processes that changed the major ion concentrations inupwelling groundwater include dilution by rain water, sulfate reduction orsulfide oxidation, and ion adsorption or exchange. Geochemical modelingindicated that average shallow water in the calcareous fens during the studyperiod was groundwater mixed with about 6 to 13% rain water.Carbonate precipitation in the surface zone of calcareous fens could bedecreased by a number of human activities, especially those that lower thewater table. Such changes in shallow water geochemistry could alter thegrowing conditions that apparently sustain rare fen vegetation.     

Influences of the petroleum-recovering activity on the arsenic level in groundwater of Kuitun,Xinjiang, China

Increasing demands of groundwater in petroleum-recovering regions could elevate the level and mobility of arsenic in groundwater as a result of the enhanced dissolution of arsenic-bearing iron or manganese oxide due to the accelerated sulfate reduction by microorganisms in a reductive environment. To substantiate this possibility, groundwater samples were collected from 220 water wells in the nearby petroleum wells in Kuitun. Dissolved arsenic, iron, manganese, and sulfate levels and pH in groundwater samples were analyzed. The dissolved arsenic levels in groundwater varied from <2.3 to 789.4 μg·L^?1, in which approximately 96.4% of the measured values exceeded the allowed limits of the World Health Organization. An inverse relation existed between dissolved arsenic and sulfate levels. Most of the high arsenic-level samples (>300 μg·L^?1) were found in wells at close proximity to petroleum wells where a high iron or manganese level was also detected. The oil-exploring activity in the study region seemed to have enhanced the microbial reduction of sulfate in underground environment and hence the level of arsenic in groundwater. The microbial sulfate reduction coupled with the reduction of arsenic-bearing iron oxides in the groundwater environment may explain the spatial heterogeneity of the arsenic level in groundwater.