环境健康风险评估在某市河流型饮用水源中的应用

根据某市连续5年生活饮用水的常规监测数据,应用EPA健康风险评价模型对饮用水中的污染物进行健康风险评价,定量评估饮水途径对某市不同人群健康产生的潜在危害。结果表明:致癌物中的砷和非致癌物中的硝酸盐分别为日均暴露剂量最大的化学物,致癌及非致癌化学物通过饮水途径对不同人群所致暴露剂量大小顺序均为:儿童成年男性成年女性;致癌物健康风险总值排序为:砷四氯化碳三氯甲烷,非致癌物健康风险总值排序为:硝酸盐氨氮氟化物硒锰挥发酚汞。某市河流型饮用水中化学物的人群健康总风险连续5年的风险值都低于最大可接受水平,不会对人体产生较大的健康危害。     

环境健康风险评估在水源重金属污染中的应用

采用原子荧光分光光度计和原子吸收光谱仪测定某校生活饮用水中As、Hg、Cd、Pb、Cu、Zn、Fe的含量,并应用美国环保局推荐的健康风险评估模型,对饮用水途径所引起的健康风险做初步评估,评价其对人群健康带来的风险大小。结果显示,该校4个采样点的饮用水中重金属污染物对人体健康产生的个人年总风险均未超过国际防辐射委员会规定的最大可接受健康风险水平。     

双极铝电极电凝聚除氟研究

一种投资不大的脱氟方法——双极铝电极电凝聚脱氟法,用模拟水样研究电极间距、氟化物浓度、温度以及溶液的ｐＨ值对电凝聚的影响,并对其优化条件进行了探讨。同时,用南阿尔及利亚水样讨论了电流密度和面积／体积比率对脱氟作用的影响。研究表明：用双极铝电极电凝聚法去除撒哈拉水中的氟化物不需加可溶性盐。铝与氟化物的质量比为１７：１。     

广元市嘉陵江干流重金属特征研究

为了解嘉陵江干流(广元段)水体中重金属污染状况,对其水中重金属含量变化进行分析,并探讨了水体温度、pH及DO对重金属(Pb、Zn、Cd、Cu)含量变化相关性和重金属之间的相互关系。结果表明:2012年到2015年重金属Pb、Zn、Cd、Cu总含量变化整体呈现下降趋势,Hg含量呈上升趋势;枯水期重金属含量低于平水期和丰水期;不同水文时期对水体温度、pH及DO对重金属含量变化影响不同;重金属含量之间存在一定的显著相关性,可能具有一定的同源性。     

饮水氟中毒的防治措施

地方性氟中毒是一种主要由饮用水含超量氟引起的世界性病害,各大洲都有分布,涉及的国家及地区较多。在我国,该病的分布很广,受害人数也比较多,其中有的省区病害相当严重,对人民身体健康的损害和对生产力的破坏是很大的。本文从饮用水中氟的来源、存在状态及氟与人体健康的关系,说明地方性氟中毒的病害程度与饮用水中氟的含量高低有直接关系,并根据我国具体情况提出几项切实可行的地方性氟中毒防治措施,最后就做好地方性氟中毒防治工作提出几点建议。     

沧州输油处饮水降氟有成效

<正> 氟是人体生命活动所必须的微量元素,其中65％来自水,30％来自食品。如果长期饮用氟化物含量超过1.0mg/L的水,将发生慢性疾病即氟中毒。华东输油局沧州输油处及其所辖三个泵站,共有职工、家属两千多人,以往因饮用氟化物含量高达3.8～5.0mg/L的水,有200多人程度不同地患了氟骨症,肩、腰、脚底板疼痛,有的骨质疏脆,极易骨折,7～16岁的小孩氟斑牙普遍。人们的身心健康受到摧残,工作、生活和学习受到影响。 1987年以来,随着治理整顿、深化改革的发展,该处的环境治理、饮水净化工作步步深入。采用了专为该处(站)设计的具有除     

氟化物污染对降水中氟离子浓度的影响分析

采用石灰滤纸法监测分析包头市区大气环境中的氟化物污染与降水中氟离子浓度的影响,结果显示,降水中氟离子与空气中氟化物浓度的变化存在着明显的正相关,该结论对于包头市空气的氟污染规律和优化监测分析研究有重要意义。     

饮用水中高氯酸盐污染现状与去除技术的综述

高氯酸盐作为强氧化剂,在广泛的应用中造成了严重的环境污染,并会在人体富集,当在人体内含量超过0．0007mg／kg人体体重,相当于饮用水中的浓度为24．5μg／L时,就会对健康造成影响,尤其会破环甲状腺机能。美国、日本等国已开始采取措施加强对高氯酸盐的控制,我国许多水源也受到此污染但尚未引起重视。本文分析了饮用水中高氯酸盐的物理化学性质及毒理特性,对环境的污染状况以及目前常用的去除技术,其中以生物处理和离子交换膜生物反应器较为有效。     

对电解铝厂周边氟污染的环境影响评价

通过测定广西某电解铝厂周边大气、土壤和农作物中氟化物含量,对该厂周边的氟化物污染进行了评价,结果表明：电解铝厂周围大气氟污染与采样点的方位成显著相关关系;农作物玉米叶片氟污染主要来自于电解铝厂无组织排放的氟化物,而土壤中总氟含量除受大气中氟化物的影响外,还与当地的地质构造、土壤类型等因素有关,与主导风向无明显的相关关系,土壤中水溶氟含量与采样点到电解铝厂距离呈负相关。     

饮用水中氟浓度测定方法改进及影响因素分析

提出了一种测定水中氟化物电极的洗涤方法,实验结果表明:利用稀盐酸代替蒸馏水对氟电极和参比电极进行洗涤,可以缩短电极的洗涤时间,提高工作效率3～4倍.同时对用稀盐酸洗涤电极法测定水中氟化物浓度的影响因素进行了分析.     

重庆市城区饮用水源健康风险评价

通过对重庆市8个饮用水源地枯水期水体中NH3-N、CN、As、Hg、Cr^＋6、Pb、Cd、Cu、F和挥发酚的浓度进行了调查研究，应用美国环保局推荐的健康风险评价模型对重庆市饮用水源水中污染物引起的健康风险作了评价。结果表明，污染物平均浓度范围分别为NH3-N：0．119—0.740mg／L，CN：0．002—0．004mg／L，As：0．001—0．007mg／L，Hg：0．000001—0．00005mg／L，Cr^＋6：0．004—0.023mg／L．Pb：0．004—0．053mg／L．Cd：0．00035—0．005mg／L．Cu：0．0005—0．0254mg/L，F：0．140—0．335mg／L，挥发酚：0．001—0．0027mg／L。重庆市通过饮水途径引起的非致癌健康风险中Pb的风险最大，F次之，两者风险水平在10^-8～10^-9／a；Cr^＋6引起的致癌风险最大达到10^-4／a；以长江为饮用水源的人群总健康风险大于嘉陵江，其健康风险达到EPA要求，但高于国际辐射防护委员会（ICRP）的最大可接受风险水平。     

Fluoride removal and its impact on oral health in Sri Lanka's dry zone: Discussion and recommendation

Fifty percent of the dry zone areas in Sri Lanka have fluoride levels above 1 ppm. This paper discusses the ground conditions and recommends an appropriate range of fluoride in drinking water which can support preventive practices for improving the oral health of children 8-years old and younger. In efforts to address the Chronic Kidney Disease of Unknown etiology (CKDU), water treatment to reduce contaminant level in potable water has been implemented. Such treatment would also remove fluoride and has resulted in potable water with various fluoride levels, depending on concentrations in the raw water. While it is important to reduce fluoride levels, it is important to have appropriate residual levels for prevention of dental caries. It needs, however, to be noted fluoride in excess can cause dental fluorosis. In Sri Lanka's dry zone areas increasing prevalence of dental fluorosis with decreasing prevalence of dental caries has been noted. Consumption of tea and powdered milk could increase total intake of fluoride. Fluoridated toothpaste, when used properly, may, however, result in negligible intake of fluoride. Sri Lanka's hot tropical climate which results in substantial intake of fluids reinforces the need to consider reduction in water fluoride. Consideration of local studies and international standards indicate fluoride levels should be in the range of 0.225–0.500 ppm. In the range of 0.225–0.500 ppm, the prevalence of dental fluorosis and caries was only 14% and 8%, respectively, in an endemic district. When fluoride levels are above 0.500 ppm, the issue of dental fluorosis shall need to be addressed. When levels are below 0.225 ppm, oral health care services shall need to be directed at preventing dental caries.     

Veterinary drugs in groundwater in a dairy region of central Argentina and risk assessment for human health

Veterinary drugs used in dairy production are potential contaminants of surface or groundwater sources, being able to affect human and environmental health. It is known that chronic exposure to antibiotics in low concentrations present in water can generate microbial resistance. This study aimed to evaluate the presence of veterinary drugs in 53 groundwater samples used for animal and human consumption, collected in dairy milking parlors, in an important milk-producing area of central Argentina, and to assess the risk to human health when they are used as drinking water. In 75% of the total samples analyzed, at least one veterinary drug was detected. The most frequently found drugs in water samples were the antibiotics tetracycline in 58.5% and oxytetracycline in 56.6%, and an anti-inflammatory, flunixin in 39.6%. In the water samples, the tetracycline and oxytetracycline concentrations were between 0.1 and 5.3 μg/L and flunixin concentrations were between 0.01 and 2.1 μg/L. The frequency of appearance and the concentration levels of the substances found in the water samples were evaluated according to the productivity, size, and production system (confined or pasture) of the dairy farms. Higher concentrations and proportions of water samples containing antibiotics were observed when the number of animals per dairy farm was >182 and when the productivity was high (>25 liters per animal per day). In the case of flunixin, the percentage of detection was similar in all evaluated categories. The risk assessment for children and adults, considering the intake of drinking water containing residues of these drugs, did not indicate a significant health risk. It would be advisable to evaluate other sources of drinking water, both surface and underground, in other regions of the country, to provide data to assess the impact of these substances and the other contaminants on environmental and human health.     

TEMPORAL AND SPATIAL CHARACTERIZATION OF RAINFALL OVER CENTRAL AND SOUTH FLORIDA1

requency evaluation and spatial characterization of rainfall in Central and South Florida are presented. Point frequency analysis performed at all available sites has shown that the 2‐parameter Gamma probability density function is the best model for monthly rainfall frequency over Central and South Florida. The model's parameters estimated at 145 stations were used to provide monthly rainfall estimates for 10‐ and 100‐year dry and wet return periods. Experimental and theoretical variograms computed for these estimates, as well as the Kriging estimation variance maps, show that the existing rain gage network is less capable of resolving monthly rainfall variation in the wet season than the dry season. May is the dry‐to‐wet transition month, while October is the wet‐to‐dry transition month with average rainfall of 4.5 inches. Monthly average rainfall is above 7 inches during the wet season and below 3 inches during the dry season. Two‐thirds of the annual rainfall is accumulated in the wet season. Annual average rainfall is maximum (above 60 inches) in many areas along the east coast, and is minimum (below 45 inches) in many areas over Lake Okee‐chobee and Central Florida. Rainfall maps show a changing pattern between the wet and the dry seasons. Frontal rainfall occurs in the dry season, while convective rainfall, tropical depression, and hurricanes occur in the wet season. Average rainfall is higher along the east coast area in the dry season and it is higher along the west coast area in the wet season.     

Forecast optimal fluoride concentration data in drinking water according to the ambient temperature in Golestan,Iran

Controlling fluoride concentrations in drinking water at optimal levels could be effective in preventing certain negative health effects in humans. This study investigated optimal fluoride concentrations in potable water in Golestan province, according the ambient temperatures in the province. The study used data on fluoride concentrations in drinking water supplied by the Water and Wastewater Company of Golestan Province. The annual mean maximum temperatures were extracted from a website that recorded daily ambient temperature. The optimal value of fluoride in drinking water for each county of Golestan province was calculated by the Galgan and Vermillion formula. The results show that all of the counties should contain fluoride concentrations ranging from 0.73 to 0.766 milligrams per liter (mg/L) according to the calculation formula, while fluoride concentrations were instead reported to range between 0.23 and 0.53 mg/L by the Water and Wastewater company. In addition, according to World Health Organization (WHO) recommendations, the concentrations of fluoride in potable in all of the cities in Golestan province fall below the WHO standard. In conclusion, we suggest that the fluoride concentrations in Golestan province's drinking water should be taken into account by the appropriate authorities and that optimal fluoride concentrations in drinking water according to ambient temperatures be set to avoiding negative health impacts.     

Evaluation of water quality in the Ouémé River (Bénin)

Water is an essential element for humankind, animals, and plants. It is also an important element of the aquatic environment (the natural habitat of multiple species), where its quality plays a determining role in their protection and conservation. Unfortunately, the water quality of natural environments has worsened in the last decades. In sub-Saharan Africa and particularly in Bénin, in contrast to river discharges, monitoring the quality of surface water is a very rare activity. Thus, knowledge about physical and chemical properties as a basis for evaluation of the state of the environment and protection measures needed is almost absent. This article presents the results of the first structured, regular monitoring campaign on surface waters in the whole basin of the Ouémé River in Bénin Republic. With 510 km, the Ouémé River’s water quality fluctuates from upstream (Taneka Koko mountains in the north) to downstream (gauging station Bonou in the south) sources. This is due to soil erosion, lack of water treatment plants, and the use of significant quantities of fertilizer in the cotton zone. The present research was initiated to study the resource degradation of this area through chemical and physical water analysis. The monitoring of water quality has been followed for 5 years on twenty physicochemical parameters, from samples taken at four gauging stations on the main channel of the Ouémé River. Means and standard deviations of water analysis results were compared to both the recommendations of the World Health Organization (WHO) and the Maximum Permissible Concentrations (MPC) for drinking water (WHO 1987). Thus, high values were observed for physical parameters, i.e., color and turbidity had peaks of 697.5 uC and 129 FTU at Bétérou station in the wet season, although certain parameters, such as total hardness, present low values compared to the recommended standards. Moreover, excluding the concentrations of NO₂ ⁻ and NH₄ ⁺ with values above the MPC, nutrient concentrations posed no direct risk for human consumption. However, together with phosphate concentrations (which are up to ten times higher than permissible ecological thresholds), they can cause eutrophication of the aquatic ecosystem. Due to the current flow regime, which has very low discharge rates in the dry season and torrential rainfall and high sediment loads in the wet season, the risk of eutrophication, i.e., excessive concentrations of ammonium and phosphates, is present throughout the year. Accumulation of ammonium and the distribution of nitrate and nitrites in the river water suggest that nitrification is impeded due to a lack of oxygen in both dry and wet seasons. Finally, the investigations show that the risk of water pollution exists and it is necessary to take measures of sanitation and water treatment to prevent the further degradation of water along the Ouémé River.     

The status and importance of crude protein and macro minerals in native pastures growing on Vertisols of the central highlands of Ethiopia

The effects of pasture management, season and soil nutrient status on crude protein (CP) and macro mineral concentration of native pasture was studied in the Vertisol areas of the central Ethiopian highland. Soil and herbage samples from 18 continuously grazed (CG) and 12 seasonally grazed (SG) pasture sites were analyzed for N, P, Ca, Mg, K and Na. Soil and dry season CG pasture samples were collected in January and February 2001 (dry season: November-February), while wet season CG and SG pasture samples were collected during September 2001 (wet season: April-October). The Potassium concentration (2.55%) of mixed herbage samples from SG pasture exceeded the K values (1.80%) from CG pasture (P?相似文献   

Seasonal variation of herbicide concentrations in prairie farm dugouts

Prairie farm dugouts are frequently constructed for use as potable water sources. Consequently, cumulative pesticide inputs via atmospheric deposition and surface runoff may constitute a risk to human health. Since, relative to other pesticides, herbicides are used in greatest amount on the Canadian prairies, herbicide concentrations were intensively monitored in three dugouts over three growing seasons. Herbicides were detected in the water of all three dugouts each growing season which may reflect cumulative inputs from atmospheric and surface processes over the lifetimes of the dugouts, which varied from 11 to 22 yr. Detections, which were not continuous, tended to be seasonal in nature. During the 3-yr study, detections were most frequent during the spring application period and late fall following dugout turnover. Between these periods, herbicide concentrations generally decreased to below detection limits. The reappearance of herbicides in the dugout water during fall turnover and in concentrations generally greater than those present during the spring application period suggest that, under appropriate environmental conditions, the bottom sediments may act as a source of herbicides to the water column. In general, herbicide inputs due to deposition of application drift did not result in detectable concentrations of herbicides in the dugouts. In the only year that winter samples were monitored, herbicides were also detected during ice cover. On the basis of monthly sampling over each growing season, median concentrations of 9 of the 10 herbicides monitored were less than 0.05 microg L(-1). The exception, 2,4-D, which has been used extensively on the Canadian prairies for more than 50 yr and in greatest amounts, was the most frequently detected herbicide. In no case did herbicide concentrations exceed Canadian drinking water guidelines; however, on occasion maximum herbicide concentrations did exceed aquatic life and irrigation water guidelines.     

Use of Landsat Thematic Mapper Data to Assess Seasonal Rangeland Changes in the Southeast Kalahari, Botswana

/ Management problems arise in semiarid rangeland that are characterized by marked wet and dry seasons because of forage deficiencies in the dry season. These natural vegetation rangelands can sustain livestock all year long when forage and senesced grass are available into the dry season. Seasonal range condition data are required to provide a basis for pasture management to help locate dry season cover and thereby minimize overstocking and degradation. The generation of seasonal data using Thematic Mapper (TM) imagery was undertaken to assess changes in natural vegetation cover in the southern Botswana Kalahari. Visual analysis of spectral reflectance curves, the development of spectral separability indexes, and conventional classification analysis techniques were used to identify and differentiate rangeland features. Results from reflectance curves indicated that most rangeland cover types could be preferentially distinguished using mainly wet season data, especially on the longer TM wavebands, and that range feature differentiation was more problematic on darker soils than on lighter soils. Spectral separability indexes (SSIs) confirmed that range feature separation varied considerably as a function of waveband and was more effective in the wet than the dry season. The SSIs also showed that range feature differentiation in both seasons was most effective using a combination of the chlorophyll absorpance band (TM3) and two mid-infrared bands (TM5 and TM7). Wet season data were more effectively classified in terms of range features than dry season data although some class similarity was inferred across the two classified data sets. The work shows that overall trends may be generated by comparing seasonal data sets, thereby providing an overall basis for dry season decision making. However, particular problems arise within the dry season data sets probably because of spectral similarities between shadow and darkened vegetation cover, thereby implying that further work is needed. KEY WORDS: Semiarid rangelands; Botswana; Kalahari; Spectral differentiation; Seasonal change; Darkened vegetation cover     

When does nitrate become a risk for humans?

Is nitrate harmful to humans? Are the current limits for nitrate concentration in drinking water justified by science? There is substantial disagreement among scientists over the interpretation of evidence on the issue. There are two main health issues: the linkage between nitrate and (i) infant methaemoglobinaemia, also known as blue baby syndrome, and (ii) cancers of the digestive tract. The evidence for nitrate as a cause of these serious diseases remains controversial. On one hand there is evidence that shows there is no clear association between nitrate in drinking water and the two main health issues with which it has been linked, and there is even evidence emerging of a possible benefit of nitrate in cardiovascular health. There is also evidence of nitrate intake giving protection against infections such as gastroenteritis. Some scientists suggest that there is sufficient evidence for increasing the permitted concentration of nitrate in drinking water without increasing risks to human health. However, subgroups within a population may be more susceptible than others to the adverse health effects of nitrate. Moreover, individuals with increased rates of endogenous formation of carcinogenic N-nitroso compounds are likely to be susceptible to the development of cancers in the digestive system. Given the lack of consensus, there is an urgent need for a comprehensive, independent study to determine whether the current nitrate limit for drinking water is scientifically justified or whether it could safely be raised.