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1.
水源地土壤环境质量状况关乎其流域内居民生命健康安全,是生态环境保护研究中的热点科学问题.选择湘东北典型河源区,采集表层土壤样品共87件,通过GIS技术和潜在生态风险指数法研究了土壤重金属(Cd、Pb、Cr、Hg和As)的空间分布特征和潜在生态风险,并采用多元统计分析和正定矩阵因子分解(PMF)模型解释了其可能来源和贡献率.结果表明:①湘东北典型河源区土壤呈酸性,土壤重金属ω(Cd)、ω(Pb)、ω(Cr)、ω(Hg)和ω(As)平均值分别为0.20、41.07、130.51、0.29和11.63mg ·kg-1,对标背景值,除As外均有富集;②土壤重金属综合潜在生态风险为中等风险等级,其中Cr、Pb和As为轻微风险等级,Cd和Hg均为强风险等级;③土壤Cd和Pb具有同源性,主要来源于农业活动,Cr和As受生活垃圾排放和自然母质的双重影响,Hg主要来源于化石燃烧及交通运输;④生活垃圾排放源、自然母质源、化石燃烧及交通运输源和农业活动源对湘东北典型河源区土壤重金属的贡献率分别为21.36%、35.92%、19.30%和23.42%,人为源贡献率大于自然源.研究结果对湘东北典型河源区的污染防治、生态修复和美丽乡村建设具有参考价值.  相似文献   
2.
Water quality index (WQI) models are generally used in hydrochemical studies to simplify complex data into single values to reflect the overall quality. In this study, deep groundwater quality in the Chittur and Palakkad Taluks of the Bharathapuzha river basin of Kerala, India, was assessed by employing the WQI method developed by the Canadian Council of Ministers of the Environment (CCME). The assessment of overall water quality is indispensable due to the specific characteristics of the study area, such as geography, climate, over-drafting, and prevalent agricultural practices. Forty representative samples were collected from the study area for monsoon (MON) and pre-monsoon (PRM) seasons. The results showed a general increase of contents from MON to PRM. The major cations were spread in the order Ca2+>Na+>Mg2+>K+ and the anions HCO3>Cl>CO32− based on their relative abundance. Among various parameters analysed, alkalinity and bicarbonate levels during MON were comparatively high, which is indicative of carbonate weathering, and 90% of the samples failed to meet the World Health Organization (WHO, 2017)/Bureau of Indian Standards (BIS, 2012) drinking water guidelines. The CCME WQI analysis revealed that nearly 50% of the samples during each season represented good and excellent categories. The samples in the poor category comprised 10% in MON and 15% in PRM. The overall WQI exhibited 15% of poor category samples as well. The spatial depiction of CCME WQI classes helped to expose zones of degraded quality in the centre to eastward parts. The spatial and temporal variations of CCME WQI classes and different physicochemical attributes indicated the influence of common factors attributing to the deep groundwater quality. The study also revealed inland salinity at Kolluparamba and Peruvamba stations, where agricultural activities were rampant with poor surface water irrigation.  相似文献   
3.
细菌是河流生态系统的重要组成部分,在污染物降解、物质循环和能量流动等方面扮演着重要角色.然而亚热带城市河流细菌群落的季节演替和构建机制(确定性和随机性过程)仍不明晰.以流溪河及广州珠江段为研究对象,采用16S rRNA高通量测序分析探讨了不同季节(丰水期和枯水期)水体细菌群落的变化及其构建机制.结果表明:不同季节水体细菌群落的组成存在显著差异,丰水期,变形菌门和异常球菌-栖热菌门的丰度更高;而枯水期,拟杆菌门和厚壁菌门的丰度更高.细菌群落的α和β多样性同样具有显著的季节差异,T、NH4+-N、TOC、pH、EC、DO、NO3--N和DSi是影响细菌群落季节变化的主要环境因子.水体细菌群落的生态网络具有典型的模块化结构,物种间以正相关作用(合作关系)为主,且丰水期物种间的合作关系强于枯水期.随机性过程主导了细菌群落的构建,尤其以扩散限制贡献最大,且细菌群落在枯水期面临的扩散限制要高于丰水期.  相似文献   
4.
Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10–164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15–120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local- and regional-scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes.  相似文献   
5.
This study explores power law relationships to estimate water flow velocity as a function of discharge and drainage area across river networks. We test the model using empirical data from 214 United States (U.S.) Geological Survey gauging stations distributed over the state of Iowa in the U.S. The empirical data are the measurements of the mean cross‐sectional velocity and concurrent discharge. The data are used to estimate parameters for a state‐wide model and to test for spatial variability for 15 large river basins contained within the state. Spatial differences among the basins are small but some parameters significantly differ from the state‐wide model. Using individual station data, the authors also explore a simpler power law model that disregards dependence on the drainage area. Overall, the study shows that including drainage area improves the model. Our study provides parameter values that can be directly incorporated into a regional scale routing model, and provides a framework for developing flow velocity models for hydraulically similar rivers in the U.S. and the world.  相似文献   
6.
岷江上游水电开发特点及其空间格局分析   总被引:1,自引:0,他引:1  
研究流域的水电开发类型与空间格局,可为水库群的累积环境影响评价、流域水电优化布局等提供科学参考。在流域分割的基础上,对岷江上游水电站的基本类型、水电站的空间分布格局进行了全面分析,并构建水电开发率、水电开发密度和水电开发强度3个指标对流域水电开发程度作出综合评价。结果表明岷江上游流域水电站类型以高水头低闸坝的引水式小水电为主,高坝大库相对较少。梯级水电开发已拓展至岷江三级支流,汶川—都江堰河段是干流水电开发程度最高的河段,杂谷脑河是水电开发程度最高的一级支流流域。岷江上游流域的水电开发率远高于全国平均水平,梯级水电开发密度大于国内主要河流。农村小水电占水电站总数的82%,梯级农村小水电对生态环境的累积影响是将来值得深入探讨的问题。  相似文献   
7.
泛长江三角洲地区经济发展与生态环境耦合协调关系分析   总被引:3,自引:0,他引:3  
以泛长三角地区41个地级市以上的政区为例,运用改进熵值法计算经济发展及生态环境系统的综合得分,并运用耦合协调模型分析1999~2013年两系统的耦合协调度及其演变,最后通过经济发展与生态环境系统得分排名划分4种类型,提出未来泛长江三角洲经济发展分类指导建议。研究结果表明:(1)1999~2013年泛长三角地区经济发展与生态环境的耦合度C∈[0.5,0.8],整体位于磨合阶段;而系统协调度D∈[0.3,0.5],整体属于中度耦合协调;(2)1999~2013年泛长三角经济发展与生态环境系统耦合协调度呈现上升态势,但经济发展与生态环境系统综合评价值仍表现负相关的特征;(3)未来苏南地区、皖江地区、杭甬地区需要进一步调整产业分布结构,提升城市经济发展环境;而苏北地区、皖西地区、浙西南地区需要进一步增加城市经济发展的软、硬实力各种要素的投入,并将城市生态环境优势转化为经济增长优势。  相似文献   
8.
水生态环境质量评价体系研究   总被引:4,自引:1,他引:3  
流域水生态环境质量评价体系是为流域环境管理提供基础数据,协助管理者开展流域保护措施的重要技术支持。该文深入剖析了发达国家典型水生态环境质量评价体系,归纳分析了其体系框架、构成特点、方法适用性和借鉴意义。结合前期研究基础,对评价体系的技术内容进行了完善和补充,明确了参照点位的选择原则,补充了评价方法选择的技术路线,提出了增设和实施不同监测计划的方案,最终提出生态环境质量评价技术体系框架。  相似文献   
9.
Nitrogen and phosphorus criteria were developed for 233 km of the Yellowstone River, one of the first cases where a mechanistic model has been used to derive large river numeric nutrient criteria. A water quality model and a companion model which simulates lateral algal biomass across transects were used to simulate effects of increasing nutrients on five variables (dissolved oxygen, total organic carbon, total dissolved gas, pH, and benthic algal biomass in depths ≤1 m). Incremental increases in nutrients were evaluated relative to their impact on predefined thresholds for each variable; the first variable to exceed a threshold set the nutrient criteria. Simulations were made at a low flow, the 14Q5 (lowest average 14 consecutive day flow, July‐September, recurring one in five years), which was derived using benthic algae growth curves and EPA guidance on excursion frequency. An extant climate dataset with an annual recurrence was used, and tributary water quality and flows were coincident with the river's 10 lowest flow years. The river had different sensitivities to nutrients longitudinally, pH being the most sensitive variable in the upstream reach and algal biomass in the lower. Model‐based criteria for the Yellowstone River are as follows: between the Bighorn and Powder river confluences, 55 μg TP/l and 655 μg TN/l; from the Powder River confluence to Montana state line, 95 μg TP/l and 815 μg TN/l. Pros and cons of using steady‐state models to derive river nutrient criteria are discussed.  相似文献   
10.
采用自行研发的泥-水界面微孔曝气系统,开展了底泥表面曝气和覆盖对城市重污染河道底泥磷释放及形态分布规律的影响研究.结果表明,微孔曝气能够有效提高上覆水的溶解氧(DO)和沉积物的氧化还原电位(Eh),能够将泥-水界面Eh维持在-100 m V左右,DO提高到6 mg·L-1以上.与对照比较,原位覆盖处理的上覆水DO和Eh有一定提高,但仍明显低于微孔曝气处理.与对照相比较,微孔曝气处理均有效降低上覆水中总磷(TP)和溶解性正磷酸盐(PO3-4)的含量.试验结束时,微孔曝气(A)和微孔曝气+原位覆盖处理(A+C)上覆水中TP含量由初始的0.201 mg·L-1分别降至0.062 mg·L-1和0.050 mg·L-1;上覆水中PO3-4含量由0.086 mg·L-1和0.078 mg·L-1分别降至0.026 mg·L-1和0.023 mg·L-1.与对照相比,微孔曝气处理明显降低了底泥间隙水中TP的浓度,在整个培养期间,其TP含量平均下降38.8%(A)和47.9%(A+C).底泥原位覆盖处理对抑制泥-水界面磷释放能力要弱于微孔曝气处理,而且在试验后期(50 d),上覆水中TP和PO3-4的含量均有所反弹.不管有无覆盖,泥-水界面微孔曝气处理均显著改变了表层底泥磷形态分布特征,显著降低了底泥中铁铝结合态磷(Fe/Al-P)组分比例,而钙结合态磷(Ca-P)含量比例却出现明显增加.单一的表面覆盖处理对底泥磷形态分布特征没有显著影响(P0.05).研究表明,与单一的处理效果相比较,泥-水界面纳米微孔曝气处理,并结合底泥原位覆盖,更有利于抑制城市重污染河道泥-水界面中磷的释放风险.  相似文献   
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