水生植物腐烂分解对水质的影响

对6种水生植物进行64 d的腐烂分解试验,对比不同水生植物腐烂分解过程中水体营养盐浓度的变化.结果表明： 6种水生植物的腐烂分解速率差别较大,浮叶植物分解速度最快,沉水植物次之,挺水植物最慢.不同水生植物腐解过程对水质影响不同,并与植物生物量密度相关.挺水植物芦苇腐解过程中的水体化学需氧量、总氮和总磷浓度最低;在茭草分解后期,水体化学需氧量和总氮浓度上升,水质变差.浮叶植物荇菜和莲腐解过程中,水体化学需氧量和总氮浓度高于其他植物.沉水植物菹草和狐尾藻腐解过程中,水体铵态氮、硝态氮和总磷浓度最高.对于同一种植物,不同生物量密度处理下,主要水质指标变化趋势相似.适量的植物残体的存在可以有效促进水体氮、磷等营养元素的循环,一定程度上去除硝态氮,降低水体氮负荷.     

河流干支流水质与土地利用的相关关系

为探索不同等级河流水质状况及其对土地利用构成响应的差异,以江苏北部的灌河流域为研究对象,基于2006—2007年两个年度灌河及其支流的水质监测数据和研究区的Landsat TM影像,在河流两侧长度0.0—10.0 km、宽度0.0—0.5 km的范围内,运用多元回归分析,对研究区干、支流主要水质指标及其与相应土地利用构成的关系进行了研究。结果表明:2006—2007年间,研究区干流水质总体上显著好于支流,支流的总氮(TN)、总磷(TP)等营养盐指标显著高于干流,而干流的有机污染指标显著高于支流;比较不同观测尺度上土地利用构成对河流水质变化的方差贡献率发现,缓冲区宽度一定时,支流在所有观测尺度上的土地利用构成与水质变化皆存在显著相关关系,而干流仅在缓冲区长度0.0—4.0 km的观测尺度上其土地利用构成与水质变化的相关关系显著;缓冲区长度一定时,干、支流河道两侧0.0—0.3 km间土地利用状况对水质变化的解释能力较大。同时发现,氮、磷等营养盐浓度多与较大尺度上的土地利用构成相关,而化学需氧量(COD)、生化需氧量(BOD)等多与较小尺度上的土地利用构成相关。研究结果显示,有必要区分不同河流等级,选择适宜的观测尺度,分别研究不同水质指标与土地利用构成间的相关关系。     

北京陶然亭湖水质的时空变化

应用聚类分析、判别分析和因子分析方法,评估了2011年城市典型富营养化景观湖泊——北京陶然亭湖水质的时空变化特征.结果表明:陶然亭湖水质在时间尺度上可划分为3个时期,分别与北京地区的雨季、平水期和枯水期相对应,说明陶然亭湖水质具有明显的时间变化特征;在空间尺度上,研究区5个采样点可划分为2类,反映了不同的污染程度和水质水平.温度、pH、透明度、化学需氧量、总固体悬浮物浓度和叶绿素a浓度是陶然亭湖水质出现时间差异的主要影响因子.陶然亭湖水体富营养化主要受叶绿素a浓度、温度、总磷和总氮控制,同时,总固体悬浮物浓度和有机物污染也不容忽视.     

流溪河流域景观空间特征与河流水质的关联分析

人类活动影响或改变流域景观空间结构,并有可能对河流水质产生不同程度的影响,以流溪河流域为研究区,分析流域景观空间格局特征与水质指数之间的相关关系。将流域划分为27个子流域,采集水样分析水质状况,所选用的水质指标有氨氮(NH3-N)、硝态氮-亚硝态氮(NO3-N+NO2-N)、总磷(TP)、化学需氧量(CODCr)。结果表明:1)该流域土地利用结构与水质具有显著相关性,其中居住用地对水质的影响作用最强,林地对河流水质具有净化功能,与水质指标之间的关系表现为负相关,园地与水质指标关系具有不确定性;2)流域景观特征从上游到下游之间表现为城市化增强的梯度,水质状况响应这个梯度变化表现为上游优于下游,人类活动及城市化发展引起的土地利用变化及土地管理方式对水质变化有显著影响;(3)景观破碎度与水质呈现显著正相关性,是影响水质的重要指标,景观聚集程度和斑块形状复杂程度与水质有负相关关系;子流域尺度和河岸带尺度景观空间特征对水质的影响差异不明显。     

城市土地利用异质性对湖泊水质的影响

土地利用类型与水体水质之间存在显著相关关系,这种相关关系受到土地利用类型及其空间分布的影响.人类活动造成流域中不同汇水单元间土地利用异质性,进而影响和改变了汇水单元水质状况.在自然或半自然区域内,采用多个汇水单元的综合分析能够体现出流域土地利用类型与水质的相关关系.然而,在城市区域中,可能存在由于土地利用特征差异而导致这种相关关系的抵消和降低,致使分析结果与实际存在偏差.为证实这一现象的存在,选取武汉市汉阳地区龙阳湖等4个湖泊流域为研究对象,分别从汇水单元综合分析、以影响水质的主要用地类型作为变量进行聚类分析和以湖泊流域为对象的分析等3个角度,分析汇水单元间的土地利用特征差异对水质的影响,结果显示土地利用异质性影响甚至改变了土地利用类型与水质的相关关系.因此,在研究城市土地利用与水体水质相关性时,需要同时考虑土地利用类型的特征和格局.     

厦门后溪水质与流域景观特征沿城乡梯度的变化分析

基于河流水质观测数据和Landsat 8影像数据,分析厦门后溪2013至2017年干季和湿季的水质时空变化特征,研究沿城乡梯度河流水质变化与流域景观特征的关系。结果表明:后溪上游(饮用水水源地水体)和下游(景观水体)溶解氧(DO)分别符合《地表水环境质量标准(GB3838—2002)》Ⅱ类标准和Ⅴ类标准,但是总氮(TN)和总磷(TP)有不同程度的超标,其中TN的超标比例较高。后溪上游土地利用类型中70%以上为林地,具有涵养水源、保护水质的作用;下游建设用地和耕地比重增加,TN、TP和叶绿素a (Chl a)显著高于上游。耕地和建设用地是提高TN、TP和Chl a等水质参数的主要土地利用类型,斑块密度、香农多样性指数和源汇景观指数与各水质指标也显著相关。冗余分析表明,流域景观特征可解释70%以上水质变化,对TN和TP的影响在湿季更大,而对Chl a的影响在干季较大。土地利用组成、配置、距离、高程和坡度对流域水质均有较大影响,其中土地利用组成对Chl a的影响较大,而景观指数则对TN和TP的影响较大。因此,在流域尺度加强土地利用的规划与综合管理,通过减少和控制地表径流面源污染的途径在一定程度上可降低人类活动对水质的不良影响。     

广西刁江流域主要河流水质评价

为研究广西刁江水质污染现状, 从刁江流域上游到下游共设置 9 个水质监测断面。于 2013 年 12 月-2014 年 12月对河流的 pH、溶解氧、高锰酸盐指数、叶绿素 a、总氮、总磷、氨氮、硝酸盐氮、亚硝酸盐氮、正磷酸盐、重金属(砷、铅、镉、汞、铬)水质指标进行监测。采用单因子和综合污染指数对刁江水质进行评价, 同时开展水体富营养化评价。单因子污染指数评价结果表明刁江流域主要污染物为总氮和砷。综合污染指数评价结果表明刁江流域水质整体较好, 但上游的平村河污染较严重。从时间分布来看, 秋季水质最差, 冬季较好。从营养化状态指数来看, 平村河为中度富营养化状态, 其余河流为中营养状态, 富营养化程度呈现春夏高, 冬季低的特点。对评价结果进行主成分分析, 结果表明刁江流域总氮最大的贡献者可能来源于居民的生活污水。     

太湖流域河流水质状况对景观背景的响应

为探索流域水质对景观背景的响应,以太湖流域为研究对象,在0.5—24 km共9个尺度上运用冗余分析研究了土地利用、河网密度、降水量、地形等景观背景因子与河流水化学指标的关系。结果表明:2006—2010年太湖流域河流水质状况总体较差,但整体有逐渐改善的趋势,超标水质指标主要包括总磷(TP)、氨氮(AN)、生化需氧量(BOD)、化学需氧量(COD)和溶解氧(DO),上游地区主要表现为林区和平原水网区的差异,下游地区主要表现为河段上下游间的差异。河流水质受到多种景观背景因子的综合影响,并表现出尺度依赖性和区位差异性。AN、TP、DO在流域上游与聚落用地正相关,在下游则与耕地、河网密度正相关。COD、BOD在流域上游主要与自然湿地负相关,与人工湿地正相关,在下游则与坡度负相关,与河网密度正相关。总方差贡献率在上下游表现出一致的尺度依赖特征,均在较小(0.5—1 km)和较大(16 km)两个尺度上具有较高的解释能力。自然湿地和坡度,河网密度和耕地分别为上游、下游地区在较小和较大尺度上解释能力最高的景观因子。     

南淝河叶绿素 a 时空分布特征及环境因子影响分析简

2009年8月至2012年4月,采样测试了南淝河上游8个位点的水质状况等,分析了南淝河叶绿素a(Chl.a)的时空分布特点及其与环境因子的关系。结果表明,南淝河研究河段Chl.a平均值为83.46μg/L,已处于严重富营养化状态。南淝河Chl.a浓度与总磷(TP)、化学需氧量(COD)、酸碱度(pH)、总固体悬浮物(TSS)、水温(WT)显著性正相关(P0.05),与透明度(SD)、氨氮/总磷比值(4NH+–N/TP)、水深(WD)、降雨(Rain)及风速(Wind)显著性负相关(P0.05)。逐步回归分析表明,影响南淝河上游河段Chl.a浓度的主导环境因子依次为水温、风速、降雨、总磷和氨氮。对南淝河与其他富营养化水体Chl.a的主要影响因子进行比较,结果表明水温是影响Chl.a的最重要因子,氮磷比、营养盐、降雨、风速、生物因子均对富营养化水体Chl.a有影响。     

富营养化水体中N、P浓度对浮游植物生长繁殖速率和生物量的影响

在浮游植物生长繁殖的高峰期（7—10月份）对3个富营养化水体的总氮、总磷和浮游植物生物量进行调查,统计分析了生物量与氮和磷浓度的关系。利用3种水样和梯度稀释的东湖水样培养玫瑰拟衣藻（Chloromonas rosae）,研究了氮、磷浓度对生长繁殖速率的影响。结果表明磷是生长繁殖速率的限制因子,求出了生长繁殖速率与磷浓度的对数回归方程y=0．08061nx＋0．4658,当磷浓度小于0．05mg／L时,生长繁殖速率随着磷浓度的升高而直线上升,当磷浓度进一步升高,生长繁殖速率仍然随之增加,但增加的幅度越来越小,当磷浓度达到0．2mg／L时,生长繁殖速率基本不再随着磷浓度的增加而升高。计算出生长速率为零时磷的浓度是0．003mg／L,接近贫营养化湖泊磷浓度的下限,计算结果与坂本的调查统计结果相吻合,说明回归方程具有代表性。在凋查的3个富营养化水体中,浮游植物中的氮占全部氮元素的53％,磷占全部磷元素的85％,是氮、磷存在的主要形式,所以,评价水体的营养程度,必须同时考虑水中溶解的氮、磷和生物体内的氮、磷。统计分析表明,3个富营养化水体中浮游植物的生物量由氮（溶解氮＋胞内氮）和磷（溶解磷＋胞内磷）的浓度共同决定,生物量与氮浓度的直线回归方程y=10．687x-7．8304,生物量与磷浓度的直线回归方程y=122．11x-12．069。实验结果为根据氮、磷浓度以Redfield值判断浮游植物限制性营养元素的相对性和绝对性提供了例证。对3个富营养化水体的比较表明,防止水体富营养的唯一办法是维持水体氮、磷等主要营养元素收支平衡,治理富营养化的根本办法是从水体中移走过量的氮、磷等主要营养元素。     

Aggregating land use quantity and intensity to link water quality in upper catchment of Miyun Reservoir

Eutrophication resulting from nutrient enrichment decreases water quality and harms ecosystem structure and function, and its degree is significantly affected by land use in the catchment. Quantifying the relationship between eutrophication and land use can help effectively manage land use to improve water quality. Previous studies principally utilized land use quantity as an indicator to link water quality parameters, but these studies lacked insight into the impact of land use intensity. Taking the upper catchment of Miyun Reservoir as a case study, we developed a method of aggregating land use quantity and intensity to build a new land use indicator and tested its explanatory power on water quality. Six nutrient concentrations from 52 sub-watersheds covering the whole catchment were used to characterize the spatial distribution of eutrophication. Based on spatial techniques, empirical conversion coefficients, remote sensing data, and socio-economic statistical data, land use intensity was measured and mapped visually. The new land use indicator was calculated and linked to nutrient concentrations by Pearson correlation coefficients. Results demonstrated that our new indicator incorporating intensity information can quantify the different nutrient-exporting abilities of different land use areas. Compared to traditional indicators that only incorporate land use quantity, most Pearson correlation coefficients between the new indicator and water nutrient concentrations increased. This new information enhanced the explanatory power of land use on water nutrient concentrations, and so will be able to help us understand the impact of land use on water quality and guide decision making for better land use management.     

Spatial-based assessment of land use,soil erosion,and water protection in the Jeneberang valley,Indonesia

Soil erosion by water is considered as one of the most significant forms of land degradation that affects sustained productivity of agricultural land use and water quality. It is influenced by a considerable number of factors (including climate, soil, topography, land use and types of land management), so that the information on the spatial distribution of soil erosion rate and its related effects can be effectively employed as a baseline data for land use development and water protection. The principal aim of this study is three-fold: (i) to map existing land use; (ii) to assess and map the spatial distribution of average annual rate of soil losses in the study area; (iii) to evaluate spatial matching between existing and proposed land use including a distance analysis from the water body (the Bili-Bili Dam). An analytical procedures used, respectively, include supervised classification of satellite imagery, application of RUSLE (Revised USLE), and overlay analysis in a raster GIS environment, utilising available information in the region covering some parts of Jeneberang catchment, South Sulawesi, Indonesia. The results suggest that the outputs of this study can be used for the identification of land units on a cell-basis with different land use types, rate of soil loss, inconsistency between proposed and planned land use, as well as the threat of land degradation to the main river and the dam. The analytical procedures developed in this research may be useful in other areas, particularly in the studies related to the assessment and mapping of land use and erosion for the importance of sustainable land use at a relatively large area.     

密云水库流域多尺度景观生态风险时空演变趋势

密云水库作为北京重要的地表饮用水水源地、水资源战略储备基地受到广泛关注,相关研究多基于流域尺度,缺乏多尺度针对水源保护区的生态风险评价,开展多尺度生态风险评价有利于指导密云水库流域高质量和可持续发展。以1990、2000、2010和2018年4期土地利用数据为基础,基于景观指数,采用地统计学方法,分析流域土地利用类型及变化,从流域尺度、水源保护区尺度构建生态风险评价模型,揭示生态风险时空变化。结果表明：(1)流域内主要土地利用类型为林地和草地,随着城市扩张和“退耕还林”等政策实施,耕地和未利用地面积减少,建设用地面积增加,流域景观趋于复杂和分散,破碎化程度加剧;(2)生态风险区域在流域尺度呈“边缘高、中间低”的空间分布规律,高风险区域面积逐渐向低风险区域转移,高风险区域集中分布在流域边缘的南部密云区、兴隆县、赤城县和流域北部丰宁县,生态安全逐渐提高。(3)水源保护区尺度呈“中间高、边缘低”的空间分布规律,高风险面积逐渐减少且空间分布集中,生态风险趋于减弱。(4)流域景观生态风险呈正相关关系,Moran’s I指数均大于0,分别为0.322、0.305、0.298和0.317,1990年...     

太湖流域宜兴片河流生境质量评价

建立包含河道生境、河岸生境和滨岸带生境3方面共10项的河流生境质量评价指标体系,对太湖流域宜兴片42个样点进行生境评价及空间差异比较,分析不同土地利用类型下河流生境各参数的差异性,探讨河流生境质量指数与富营养化综合指数的相关关系。结果表明:河流生境质量指数分值介于29～79,31.0%样点生境质量处于较差和很差等级,57.1%样点为一般等级,表明整体上生境退化明显;南部丘陵山区河流的生境质量状况好于广大的平原河网区;不同土地利用类型下河流生境质量差异显著,林地区域的生境质量明显好于耕地和建设用地;河流生境质量指数与富营养化综合指数显著负相关,说明水质状况对河流生境质量具有较大贡献。     

Invertebrate community responses to land use at a broad spatial scale: trait and taxonomic measures compared in New Zealand rivers

1. Large‐scale comparative studies of ecological responses to anthropological stressors in rivers require measures that are consistent across a range of spatial scales. The biological trait profile of communities offers an alternative approach to traditional measures of macroinvertebrate taxonomic identity and is less constrained by biogeographic influences. 2. We compared the capacities of taxonomic composition and biological trait composition to discriminate the effects of land use (measured as percentage of the catchment in pasture) across a large geographic zone (the whole of New Zealand) in 30 sub‐catchments grouped into five ecoregions throughout the North and South Islands of New Zealand. In addition, we investigated trait consistency (i.e. whether similar traits had similar trait responses to land use at local (catchment) and broad scales). 3. The analysis of taxonomic composition showed that community structure was indeed influenced by land‐use intensity, but that relationships differed among ecoregions. In contrast, traditional assessment metrics (Macroinvertebrate Community Index, richness in Ephemeroptera, Plecoptera and Trichoptera taxa) and trait composition were uninfluenced by region. Trait responses were consistent at the broad and catchment scales, with similar traits responding to pastoral land use at both scales. 4. We used general linear modelling to investigate individual trait responses to land‐use intensity, catchment area and region, focussing on 15 trait categories known to be influenced by land‐use intensity at the catchment scale. Several trait categories varied with land‐use intensity and demonstrated consistency at both catchment and broad scales. Of these, the representation of shorter generation time, asexual reproduction and hermaphroditism, ability to lay eggs beneath the water surface, egg protection and respiration types tolerant of oxygen depletion generally increased in assemblages exposed to more intense pastoral land use. At the same time, the representation of short life duration of adults, prevalence of laying eggs at the water surface, sexual reproduction and low body flexibility decreased in assemblages exposed to land‐use intensification. 5. Our results highlight the value of developing predictive response measures that are relevant at multiple scales and provide the basis for new measures of river condition that are as effective as taxonomic identity in terms of response reliability.     

土地利用变化对生态系统服务功能的影响——以密云水库流域为例

生态系统服务功能与人类福利息息相关,土地利用变化是生态系统服务功能退化的主要驱动力之一,以人地关系紧张,生态系统服务功能变化剧烈的密云水库流域为对象,分析流域1990-2009年土地利用的变化,采用空间显式的生态系统服务功能评估软件InVEST中的“产水量”、“土壤保持”、“水质净化”模型,研究流域土地利用变化对生态系统服务功能的影响.结果表明1990-2009年密云水库流域土地利用变化剧烈,农田、草地和水体的面积分别减少了30％、48％、61％,林地、建筑用地和裸地的面积增加,增幅分别为30％、230％、282％.随着土地利用变化,生态系统服务功能相应产生着显著变化,研究期内,土壤保持功能和固碳服务分别增加46％和19％,但水资源供给服务和水质净化功能分别减少了3％和25％.农田面积的减少和森林的扩张改善了土壤保持服务,森林面积的增加同时也改善了固碳服务,但会削弱水资源供给服务,建筑用地的扩张会大幅度削弱水质净化功能,为维持和改善流域整体的生态系统服务功能,应加强对森林和建筑用地的控制.其研究为密云水库流域土地利用科学管理决策提供参考.     

Importance of scale,land‐use,and stream network properties for riparian plant communities along an urban gradient

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Rise of toxic cyanobacterial blooms is promoted by agricultural intensification in the basin of a large subtropical river of South America

Toxic cyanobacterial blooms are globally increasing with negative effects on aquatic ecosystems, water use and human health. Blooms' main driving forces are eutrophication, dam construction, urban waste, replacement of natural vegetation with croplands and climate change and variability. The relative effects of each driver have not still been properly addressed, particularly in large river basins. Here, we performed a historical analysis of cyanobacterial abundance in a large and important ecosystem of South America (Uruguay river, ca 1900 km long, 365,000 km² basin). We evaluated the interannual relationships between cyanobacterial abundance and land use change, river flow, urban sewage, temperature and precipitation from 1963 to the present. Our results indicated an exponential increase in cyanobacterial abundance during the last two decades, congruent with an increase in phosphorus concentration. A sharp shift in the cyanobacterial abundance rate of increase after the year 2000 was identified, resulting in abundance levels above public health alert since 2010. Path analyses showed a strong positive correlation between cyanobacteria and cropland area at the entire catchment level, while precipitation, temperature and water flow effects were negligible. Present results help to identify high nutrient input agricultural practices and nutrient enrichment as the main factors driving toxic bloom formation. These practices are already exerting severe effects on both aquatic ecosystems and human health and projections suggest these trends will be intensified in the future. To avoid further water degradation and health risk for future generations, a large-scale (transboundary) change in agricultural management towards agroecological practices will be required.     

A comparison of spatially explicit landscape representation methods and their relationship to stream condition

1. Biodiversity, water quality and ecosystem processes in streams are known to be influenced by the terrestrial landscape over a range of spatial and temporal scales. Lumped attributes (i.e. per cent land use) are often used to characterise the condition of the catchment; however, they are not spatially explicit and do not account for the disproportionate influence of land located near the stream or connected by overland flow. 2. We compared seven landscape representation metrics to determine whether accounting for the spatial proximity and hydrological effects of land use can be used to account for additional variability in indicators of stream ecosystem health. The landscape metrics included the following: a lumped metric, four inverse‐distance‐weighted (IDW) metrics based on distance to the stream or survey site and two modified IDW metrics that also accounted for the level of hydrologic activity (HA‐IDW). Ecosystem health data were obtained from the Ecological Health Monitoring Programme in Southeast Queensland, Australia and included measures of fish, invertebrates, physicochemistry and nutrients collected during two seasons over 4 years. Linear models were fitted to the stream indicators and landscape metrics, by season, and compared using an information‐theoretic approach. 3. Although no single metric was most suitable for modelling all stream indicators, lumped metrics rarely performed as well as other metric types. Metrics based on proximity to the stream (IDW and HA‐IDW) were more suitable for modelling fish indicators, while the HA‐IDW metric based on proximity to the survey site generally outperformed others for invertebrates, irrespective of season. There was consistent support for metrics based on proximity to the survey site (IDW or HA‐IDW) for all physicochemical indicators during the dry season, while a HA‐IDW metric based on proximity to the stream was suitable for five of the six physicochemical indicators in the post‐wet season. Only one nutrient indicator was tested and results showed that catchment area had a significant effect on the relationship between land use metrics and algal stable isotope ratios in both seasons. 4. Spatially explicit methods of landscape representation can clearly improve the predictive ability of many empirical models currently used to study the relationship between landscape, habitat and stream condition. A comparison of different metrics may provide clues about causal pathways and mechanistic processes behind correlative relationships and could be used to target restoration efforts strategically.