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排序方式: 共有849条查询结果,搜索用时 31 毫秒
1.
The concern related to the drinking of reverse osmosis (RO) water containing low levels of minerals is growing day by day. This study involves the analysis of water samples from various drinking water sources in a rural site, Mirchpur village, an Indus Valley civilization site (grid location: 29° 18′ 42.3″ N, 76° 10′ 33.0″ E) of Hisar, India, along with the health survey of human subjects. The hydrochemistry of water collected from hand pumps, river canals, tube wells, submersibles, and the RO systems installed in various homes was explored for pH, EC, TH, TDS, turbidity, cations (Na+, Ca2+, Mg2+), anions (CO32−, HCO3, Cl, SO42−, NO3, F), and elements (Fe, Pb, Se) employing the ion chromatography, flame photometry, and ICP-AES techniques. Lead (Pb) and Selenium (Se) were detected in trace amounts (0.30–2.6 μg L−1; 0.10–4.1 μg L−1, respectively) in all the samples, including the samples collected from RO purifiers, but Iron (Fe) was not detected in RO samples even in trace amounts. The F-levels in hand pump water (HPW) and submersible water (SW) (1.9  and 1.7 mg L−1, respectively) and TDS levels in SW (3048 mg L−1) were found to be above WHO and BIS safe limits. TDS levels in the river canal (900 mg L−1), tube well (1104 mg L−1), hand pump (1170 mg L−1), and submersible samples (3048 mg L−1) were found significantly higher as compared to the RO personal water (ROPW; 216 mg L−1) and RO supply water (ROSW; 90 mg L−1). The collected epidemiological data reveals that 21%, 19%, 13%, and 12% of natives reported skin, kidney, hair fall, liver, and stomach issues, respectively, suspecting the crucial role of high TDS and fluoride levels in the area. This study also provides a comparison between the quality of RO and the direct supply water, along with correlation matrices for different parameters, which gives a rationale for the limitations of drinking direct supply water without any purification and RO water containing low mineral content.  相似文献   
2.
Harmful algal blooms (HABs) diminish the utility of reservoirs for drinking water supply, irrigation, recreation, and ecosystem service provision. HABs decrease water quality and are a significant health concern in surface water bodies. Near real-time monitoring of HABs in reservoirs and small water bodies is essential to understand the dynamics of turbidity and HAB formation. This study uses satellite imagery to remotely sense chlorophyll-a concentrations (chl-a), phycocyanin concentrations, and turbidity in two reservoirs, the Grand Lake O′ the Cherokees and Hudson Reservoir, OK, USA, to develop a tool for near real-time monitoring of HABs. Landsat-8 and Sentinel-2 imagery from 2013 to 2017 and from 2015 to 2020 were used to train and test three different models that include multiple regression, support vector regression (SVR), and random forest regression (RFR). Performance was assessed by comparing the three models to estimate chl-a, phycocyanin, and turbidity. The results showed that RFR achieved the best performance, with R2 values of 0.75, 0.82, and 0.79 for chl-a, turbidity, and phycocyanin, while multiple regression had R2 values of 0.29, 0.51, and 0.46 and SVR had R2 values of 0.58, 0.62, and 0.61 on the testing datasets, respectively. This paper examines the potential of the developed open-source satellite remote sensing tool for monitoring reservoirs in Oklahoma to assess spatial and temporal variations in surface water quality.  相似文献   
3.
分析了环境统计工作的定位和内容,以及第二次全国污染源普查、排污许可证与排污税制度、环境质量考核制度给环境统计工作带来的改革契机。针对固定源、城镇生活源与农业面源、移动源,提出了统计调查工作的设想。建议改变环境统计调查焦点,实现污染源统计空间格局"一张图";开拓环境统计分析品牌,推动环境统计方法研究;以政策管理需求为导向,完成环境统计工作体系的重构。  相似文献   
4.
ABSTRACT

Citizens’ attitudes toward science are related to their use of science-related information from various sources. Evidence is scarce regarding citizens’ individual media repertoires for staying informed about science as segmentation studies so far have primarily focused on scientific attitudes. In this paper, we explore audience segments regarding their science-related information behavior and whether such segments are comparable or vary between two countries with similar information environments. Based on two surveys in Switzerland and Germany, we identify national audience segments that differ in their science-related information repertoires, and analyze their sociodemographic characteristics and science-related attitudes. In both countries, we find very comparable information user segments ranging from those who inform themselves frequently about science (“Active Seekers”/“Science Consumers”) to those who hardly get in contact with any information about science and research (“Non-Users”). Those segments which get in contact with information about science frequently show generally more positive attitudes.  相似文献   
5.
青藏高原淡水湖泊水化学组成特征及其演化   总被引:19,自引:12,他引:7  
青藏高原淡水湖具有高生态价值和高脆弱性并存的特点.以海拔5 080 m±10 m的打加芒错湖水为研究对象,测试及分析了湖水化学组分,探讨了其主要离子来源、控制因子和湖泊水化学演化趋势.结果表明,湖水阳离子以Ca2+和Na+为主,阴离子以HCO3-为主,为HCO3-Ca型水;TDS为71.2~199.8 mg·L-1,矿化度低;受地表径流的稀释作用和富铝贫钙的地质背景约束湖区东南部水体的EC、Ca2+和HCO3-浓度均较低.湖水的Na+/(Na++Ca2+)为0.08~0.75,Cl-/(Cl-+HCO3-)为0.11~0.35,Ca/Na值为0.58,Mg/Ca值为0.12,HCO3/Na值为1.46,据Gibbs模型和元素化学计量分析表明,其化学组成主要受硅酸盐岩风化控制.湖区流域参与风化的矿物岩石包括斜长石(钙长石、钠长石)、钾长石、云母、石膏、盐岩等,但以斜长石风化为主,湖水的K/Na值平均为0.059,表明流域钾长石风化程度较低.湖水中方解石、白云石、石英、石膏等矿物饱和指数(SI)大于0,石盐的SI则小于0,揭示了青藏高原上淡水湖泊演变成咸水湖的变化趋势.  相似文献   
6.
城市污染河湖的综合整治技术及应用研究   总被引:1,自引:0,他引:1  
分析了城市污染河流和湖泊污染的原因,将污染河流和湖泊治理的方法分为"物理法、化学法、生物法、生态法"共四大类,介绍了常用技术方法的原理和特点。根据河流和湖泊的污染现状和治理目标,提出了城市污染河湖的综合整治分为"治理"与"生态修复"两个阶段,探讨了采用"截污、清淤、曝气、生物载体、水生植物"等综合应用技术治理河湖的必要性和迫切性,并结合近年来国内河湖综合整治的典型案例,总结了河湖整治过程的"基础措施"和"关键措施"。  相似文献   
7.
采用问卷调查的方法,试图真实反映艾比湖周边居民对艾比湖湿地生态系统退化的认知及对艾比湖湿地生态系统健康保护意识的强弱.结果表明:(1)艾比湖周边居民对湿地生态系统退化带来的危害有较为清晰地认识,99%被调查者意识到了艾比湖湿地生态系统退化对周边环境会带来不同程度的危害,78.2%调查对象认为艾比湖湿地生态系统的退化主要是由人类活动引发的,通过正规渠道获取艾比湖湿地生态系统退化信息不够通畅;(2)调查对象对艾比湖湿地生态系统退化情况持有较高的关注度,但支持度不高,85.6%的被调查者对退化湿地的生态恢复有支付意愿;(3)65.5%调查对象对艾比湖湿地生态恢复有信心,但对当地政府宣传和保护艾比湖湿地的力度满意度不高,因此政府部门还需进一步加强对艾比湖的宣传和保护力度.  相似文献   
8.
Rapid response vertical profiling instrumentation was used to document spatial variability and patterns in a small urban lake, Onondaga Lake, associated with multiple drivers. Paired profiles of temperature, specific conductance (SC), turbidity (Tn), fluorometric chlorophyll a (Chlf), and nitrate nitrogen (NO3?) were collected at >30 fixed locations (a “gridding”) weekly, over the spring to fall interval of several years. These gridding data are analyzed (1) to characterize phytoplankton (Chlf) patchiness in the lake's upper waters, (2) to establish the representativeness of a single long‐term site for monitoring lake‐wide conditions, and (3) to resolve spatial patterns of multiple tracers imparted by buoyancy effects of inflows. Multiple buoyancy signatures were resolved, including overflows from less dense inflows, and interflows to metalimnetic depths and underflows to the bottom from the plunging of more dense inputs. Three different metrics had utility as tracers in depicting the buoyancy signatures as follows: (1) SC, for salinity‐enriched tributaries and the more dilute river that receives the lake's outflow, (2) Tn, for the tributaries during runoff events, and (3) NO3?, for the effluent of a domestic waste treatment facility and from the addition of NO3? solution to control methyl mercury. The plunging inflow phenomenon, which frequently prevailed, has important management implications.  相似文献   
9.
Prospective, community-based surveillance systems for measuring birth, death, and population movement rates may have advantages over the ‘gold-standard’ retrospective household survey in humanitarian contexts. A community-based, monthly surveillance system was established in South Kivu, Democratic Republic of the Congo, in partnership with a local implementing partner and the national ministry of health. Data were collected on the occurrence of births, deaths, arrivals, and departures over the course of one year, and a retrospective survey was conducted at the end of the period to validate the information. Discrepancies between the two approaches were resolved by a third visit to the households with discordant records. The study found that the surveillance system was superior in terms of its specificity and sensitivity in measuring crude mortality and birth rates as compared to the survey, demonstrating the method's potential to measure accurately important population-level health metrics in an insecure setting in a timely, community-acceptable manner.  相似文献   
10.
通过对清查数据的结果分析,确定第二次全国污染源入户普查的对象,基于企业填报、现场入户、资料收集审核、数据核查等具体工作的实施与开展,思考和归总普查工作中影响数据质量的现实问题和难点,初步构建污染源普查质量保证体系,以期为全国污染源普查数据质量保证提供有益参考。  相似文献   
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