Energy-dispersive X-ray fluorescence spectrometry technique as an efficient monitoring tool for mercury contamination

This paper illustrates the useful early-warning role of the energy-dispersive X-ray fluorescence technique against a potential health hazard being posed by dumping effluents from an industrial unit involved in the manufacture of lead-batteries, in a nearby water-canal used for irrigation purposes by surrounding villages. These effluents were shown to contain mercury at a potentially unsafe level, resulting in timely initiation of necessary preventive measures. The standard fundamental parameter method was invoked for a quantitative estimation of the mercury (Hg) concentration. In addition, L-series (rather than the usual K-series) X-rays were used for excitation, mainly on account of the type of the available excitation source.     

Effect of mercury and arsenic from industrial effluents on the drinking water and comparison of the water quality of polluted and non-polluted areas: a case study of Peshawar and Lower Dir

The purpose of the present study was to find out the sources of mercury and arsenic pollution of water in the industrial area of Peshawar, the capital of Khyber Pakhtunkhwa, Pakistan. Samples of effluents, mud, and water were collected from the target area (industrial area of Peshawar), the area of water supply source, and from the less polluted area, the Lower Dir district, as the control. Hg was determined by the cold vapor generation technique, while arsenic was determined using the electrothermal atomic absorption technique. Data of the water from the industrial area were compared with that of the source area, control area, as well as with the WHO and some international drinking water quality standards. The results show that some parameters, i.e., TDS, DO, pH, and hardness, were more than the permissible limits. Textile and glass industries were found to be the major sources of Hg and As pollution. Downstream dilution of these contaminants was also observed.     

Drainage Planning and Control in the Urban Environment the Singapore Experience

Singapore is situated 137 km north of the equator and is subject to heavy tropical rainstorms, particularly during the North-east monsoon season between November and January. Flooding was prevalent in the past as the older parts of the city were built on relatively low-lying areas and the drainage systems were not adequate to convey storm water runoff effectively. Rapid urbanisation in the 1970's and 1980's brought about drastic transformations of the hydrological characteristics of the drainage catchments in Singapore. More areas were paved up, resulting in increased storm water runoff being generated during heavy downpour. This paper deals with the strategies adopted by Singapore to keep the flood situation under control despite the vast extent of new land developments that are continuously taking place. It discusses the drainage master plan and the drainage development programmes that were implemented over the years for flood alleviation and prevention, including the drainage control policies being pursued by the Drainage Department as a land drainage authority. The paper also covers the integration of drainage projects with land developments to maximize land use and the creation of aesthetic waterways to enhance the urban environment.     

Phosphate run-off in the Nevezis River (Lithuania)

The long-term (40 yr) observation results of phosphates–phosphorus concentration and its runoff in the Lithuanian fourth largest river Nevezis are analysed. Amounts and peculiarities of background runoff, agricultural runoff, andpoint source pollution from towns were studied for various periods. It has been determined that phosphates enter into the river Nevezis mainly from towns (76.5%), from agricultureonly up to 16%, and the background runoff for 7.5%.Considerable agricultural influence was observed in 1979–1991,when the phosphate runoff increased to 22 kg P km^-2 a^-1 and formed in 1984 33% of the entire runoff. A relation of the phosphates runoff from agriculture, for the entire study period, was obtained with the number of animals in the river's basin. Since 1990, when the number of animals started to decrease, the runoff of phosphates decreased too. Now the phosphatesrunoff from agriculture formed only 2% of the entire runoff. Water in the river Nevezis is heavily polluted with phosphate,according to the EU general classification of the water quality of rivers, although the Lithuanian pollution norms for effluentsdischarging to surface water are not exceeded. Norms for effluents discharging in the rivers from point-sources pollution should be made stricter and the highest permitted ratiobetween the phosphorus load in the river and its waterdischarge should be established.     

Storm water contamination and its effect on the quality of urban surface waters

We studied the effect of storm water drained by the sewerage system and discharged into a river and a small reservoir, on the example of five catchments located within the boundaries of the city of Poznań (Poland). These catchments differed both in terms of their surface area and land use (single- and multi-family housing, industrial areas). The aim of the analyses was to explain to what extent pollutants found in storm water runoff from the studied catchments affected the quality of surface waters and whether it threatened the aquatic organisms. Only some of the 14 studied variables and 22 chemical elements were important for the water quality of the river, i.e., pH, TSS, rain intensity, temperature, conductivity, dissolved oxygen, organic matter content, Al, Cu, Pb, Zn, Fe, Cd, Ni, Se, and Tl. The most serious threat to biota in the receiver came from the copper contamination of storm water runoff. Of all samples below the sewerage outflow, 74 % exceeded the mean acute value for Daphnia species. Some of them exceeded safe concentrations for other aquatic organisms. Only the outlet from the industrial area with the highest impervious surface had a substantial influence on the water quality of the river. A reservoir situated in the river course had an important influence on the elimination of storm water pollution, despite the very short residence time of its water.     

Background Mercury Concentrations in River Water in Maine, U.S.A.

Mercury concentrations in 58 rivers in Maine was measured to range from below detection up to 7.01 ng L^-1 and averaged 1.80±1.29 ng L^-1. The concentration gradient for mercury in rivers across the state was not uniform. Mercury strongly correlated with dissolved organic carbon (DOC) and aluminum, and less strongly with copper, lead, and zinc. Mercuryexhibited significant differences in correlations with chemical variables and local geology when partitioned by flow state (high or low). Mercury concentrations were greatest in rivers flowingacross either wacke-type bedrock at low metamorphic grade, or glacial-till deposits. Elevated concentrations of mercury formed a locus in northern Maine under both high and low-flow states while in southwestern Maine a locus formed only during high-flowstates. These regional differences were statistically significantwhen compared by geographical location. We suggest that there is a bedrock source of mercury in northeastern Maine that is dilutedduring periods of high runoff. The elevated concentrations detected under high-flow states, as noted in southwestern Maine, may reflect mercury released from storage in association withDOC during periods of high runoff. The association of mercury with flow state indicates that watershed processes and local geology can modulate the concentration of mercury in rivers.     

Hydrology of mountainous areas in the upper Indus Basin, Northern Pakistan with the perspective of climate change

Mountainous areas in the northern Pakistan are blessed by numerous rivers that have great potential in water resources and hydropower production. Many of these rivers are unexploited for their water resource potential. If the potential of these rivers are explored, hydropower production and water supplies in these areas may be improved. The Indus is the main river originating from mountainous area of the Himalayas of Baltistan, Pakistan in which most of the smaller streams drain. In this paper, the hydrology of the mountainous areas in northern Pakistan is studied to estimate flow pattern, long-term trend in river flows, characteristics of the watersheds, and variability in flow and water resource due to impact of climate change. Eight watersheds including Gilgit, Hunza, Shigar, Shyok, Astore, Jhelum, Swat, and Chitral, Pakistan have been studied from 1960 to 2005 to monitor hydrological changes in relation to variability in precipitation, temperature and mean monthly flows, trend of snow melt runoff, analysis of daily hydrographs, water yield and runoff relationship, and flow duration curves. Precipitation from ten meteorological stations in mountainous area of northern Pakistan showed variability in the winter and summer rains and did not indicate a uniform distribution of rains. Review of mean monthly temperature of ten stations suggested that the Upper Indus Basin can be categorized into three hydrological regimes, i.e., high-altitude catchments with large glacierized parts, middle-altitude catchments south of Karakoram, and foothill catchments. Analysis of daily runoff data (1960-2005) of eight watersheds indicated nearly a uniform pattern with much of the runoff in summer (June-August). Impact of climate change on long-term recorded annual runoff of eight watersheds showed fair water flows at the Hunza and Jhelum Rivers while rest of the rivers indicated increased trends in runoff volumes. The study of the water yield availability indicated a minimum trend in Shyok River at Yogo and a maximum trend in Swat River at Kalam. Long-term recorded data used to estimate flow duration curves have shown a uniform trend and are important for hydropower generation for Pakistan which is seriously facing power crisis in last 5 years.     

Storm runoff quality and pollutant loading from commercial, residential, and industrial catchments in the tropic

Information on the pollution level and the influence of hydrologic regime on the stormwater pollutant loading in tropical urban areas are still scarce. More local data are still required because rainfall and runoff generation processes in tropical environment are very different from the temperate regions. This study investigated the extent of urban runoff pollution in residential, commercial, and industrial catchments in the south of Peninsular Malaysia. Stormwater samples and flow rate data were collected from 51 storm events. Samples were analyzed for total suspended solids, 5-day biochemical oxygen demand, chemical oxygen demand, oil and grease (O&G), nitrate nitrogen (NO₃-N), nitrite nitrogen, ammonia nitrogen, soluble reactive phosphorus, total phosphorus (TP), and zinc (Zn). It was found that the event mean concentrations (EMCs) of pollutants varied greatly between storm characteristics and land uses. The results revealed that site EMCs for residential catchment were lower than the published data but higher for the commercial and industrial catchments. All rainfall variables were negatively correlated with EMCs of most pollutants except for antecedent dry days (ADD). This study reinforced the earlier findings on the importance of ADD for causing greater EMC values with exceptions for O&G, NO₃-N, TP, and Zn. In contrast, the pollutant loadings are influenced primarily by rainfall depth, mean intensity, and max 5-min intensity in all the three catchments. Overall, ADD is an important variable in multiple linear regression models for predicting the EMC values in the tropical urban catchments.     

Urban stormwater harvesting and reuse: a probe into the chemical, toxicology and microbiological contaminants in water quality

Stormwater is one of the last major untapped urban water resources that can be exploited as an alternative water source in Australia. The information in the current Australian Guidelines for Water Recycling relating to stormwater harvesting and reuse only emphasises on a limited number of stormwater quality parameters. In order to supply stormwater as a source for higher value end-uses, a more comprehensive assessment on the potential public health risks has to be undertaken. Owing to the stochastic variations in rainfall, catchment hydrology and also the types of non-point pollution sources that can provide contaminants relating to different anthropogenic activities and catchment land uses, the characterisation of public health risks in stormwater is complex, tedious and not always possible through the conventional detection and analytical methods. In this study, a holistic approach was undertaken to assess the potential public health risks in urban stormwater samples from a medium-density residential catchment. A combined chemical–toxicological assessment was used to characterise the potential health risks arising from chemical contaminants, while a combination of standard culture methods and quantitative polymerase chain reaction (qPCR) methods was used for detection and quantification of faecal indicator bacteria (FIB) and pathogens in urban stormwater. Results showed that the concentration of chemical contaminants and associated toxicity were relatively low when benchmarked against other alternative water sources such as recycled wastewater. However, the concentrations of heavy metals particularly cadmium and lead have exceeded the Australian guideline values, indicating potential public health risks. Also, high numbers of FIB were detected in urban stormwater samples obtained from wet weather events. In addition, qPCR detection of human-related pathogens suggested there are frequent sewage ingressions into the urban stormwater runoff during wet weather events. Further water quality monitoring study will be conducted at different contrasting urban catchments in order to undertake a more comprehensive public health risk assessment for urban stormwater.     

Fractionation and ecological risk of metals in urban river sediments in Zhongshan City, Pearl River Delta

Surface sediments collected from nine urban rivers located in Zhongshan City, Pearl River Delta, were analyzed for total concentration of metals with digestion and chemical fractionation adopting the modified European Community Bureau of Reference (BCR) sequential extraction procedure. The results showed that concentration and fractionation of metals varied significantly among the rivers. The total concentration of eight metals in most rivers did not exceed the China Environmental Quality Standard for Soil, Grade III. The potential ecological risk of metals to rivers were related to the land use patterns, in the order of manufacturing areas > residential areas > agriculture areas. The concentration of Pb in the reducible fraction was relatively high (60.0-84.3%). The dominant proportions of Cd, Zn and Cu were primary in the non-residual fraction (67.0%, 71.8% and 81.4% on average respectively), while the percentages of the residual fractions of Cr and Ni varied over a wide range (43-85% and 24-71% respectively). The approaches of the H?kanson ecological risk index and Secondary Phase Enrichment Factor were applied for ecological risk assessment and metal enrichment calculation. The results indicated Hg and Cd had posed high potential ecological risk to urban rivers in this region. Meanwhile, there was widespread pollution and high enrichment of Cu in river sediments in this region. Multiple regression analysis showed that five water quality parameters (pH, DO, COD(Mn), NH(4)(+)-N, TP) had little influence on the distribution of metal fractionation. This result revealed that the ecological risk of metals was not eliminated along with the improvement in water quality. Correlation studies showed that among the metals, Group A (Cd, As, Pb, Zn Hg, r = 0.730-0.924) and Group B (Cr, Cu, Ni, r = 0.815-0.948) were obtained, and the metal contaminations were from industrial activities rather than residential.     

长湖流域水质时空分布特征及影响因子

利用2009—2014年长湖5个水质监测点数据,采用时间序列法分析了长湖水质的时间变化规律,采用相关性分析法,分析了流域水污染的影响因子。结果表明:在时间上,长湖水污染物质量浓度季节变化明显,COD、TN、NH3-N均为7、9月较低,1、3月较高,丰水期水质好于枯水期。入湖地区TP质量浓度7月达最高值,且7月份入湖地区的桥河口、关沮口的NH3-N、TN含量稍高于5月。空间上,西北部入湖地区水质劣于湖心及东南部出湖地区。工业、生活等点源污水,以耕地为主的农业非点源以及天然降水量和径流量是影响水质的主要因素,入湖排污量、降水量和径流量与长湖水质呈显著相关关系(P0.05)。     

北京市水环境非点源污染监测与负荷估算研究

文章对北京全市域范围开展水环境非点源污染监测以及污染负荷估算研究。监测结果表明,天然降雨氨氮、总氮污染程度高;城区典型下垫面降雨径流的有机污染十分严重,其中屋面降雨径流总氮和氨氮污染最严重,路面降雨径流COD和总磷污染最严重;下垫面降雨径流汇入城市排水管网后,由于冲洗下水道中的沉积物,使得水质污染进一步恶化。农业典型小流域面源污染对水质影响也很明显。城市非点源污染负荷估算选用SWMM暴雨径流模型,农业非点源污染负荷模型选用改进的输出系数模型,估算结果表明:城市非点源污染主要来自大气湿沉降、综合用地、路面和屋面等,农业非点源污染主要来自耕地和林地;全市污染物排放总量中,点源排放总量与非点源排放总量基本各占50％左右。为进一步挖掘污染减排空间,完善总量减排体系提供了依据。     

Assessment of polycyclic aromatic hydrocarbon influx and sediment contamination in an urbanized estuary

Sediments from the Patos Lagoon Estuary in Southern Brazil and sludge from incoming effluents were assessed for the distribution of polycyclic aromatic hydrocarbons (PAHs). Shallow sediments adjoining the City of Rio Grande were found to be contaminated by PAHs mainly near urban effluent discharge, as well as in the port area. Effluents clustered into four groups according to their sources (sewage, industrial, runoff, and mixed), with each demonstrating different contributions of PAHs to the estuary. There was a predominance of runoff and mixed sources. Navigation activity was the second most important source of PAHs to sediments. The PAHs ratio identified the origin of these contaminants as essentially pyrolytic. The impact of PAHs as a result of uncontrolled disposal or accidental discharge of PAH-rich residues was suggested for several points. These points were primarily near gas stations and motor workshops. In about 30% of sampled sediments, the concentration of benzo[a]pyrene surpassed the Threshold Effects Level adopted for marine environments.     

Deterioration of water quality of Surma river

Surma River is polluted day by day by human activities, poor structured sewerage and drainage system, discharging industrial and household wastes. The charas (natural channels) are responsible for surface runoff conveyance from its urban catchments to the receiving Surma River. Water samples have been collected from a part of Surma River along different points and analyzed for various water quality parameters during dry and monsoon periods. Effects of industrial wastes, municipal sewage, and agricultural runoff on river water quality have been investigated. The study was conducted within the Chattak to Sunamganj portion of Surma River, which is significant due to the presence of two major industries – a paper mill and a cement factory. The other significant feature is the conveyors that travel from India to Chattak. The river was found to be highly turbid in the monsoon season. But BOD and fecal coliform concentration was found higher in the dry season. The water was found slightly acidic. The mean values of parameters were Conductivity 84–805 μs; DO: dry-5.52 mg/l, monsoon-5.72 mg/l; BOD: dry-1mg/l, monsoon-0.878 mg/l; Total Solid: dry-149.4 mg/l, monsoon-145.7 mg/l. In this study, an effort has been taken to investigate the status of concentration of phosphate (PO⁻⁴) and ammonia–nitrogen (NH₄–N) at four entrance points of Malnichara to the city, Guali chara, Gaviar khal and Bolramer khal. Data has been collected from March–April and September–October of 2004. Concentrations have been measured using UV Spectrophotometer. Although the phosphate concentration has been found within the limit set by DOE for fishing, irrigation and recreational purposes, however ammonia–nitrogen has been found to exceed the limit.     

Trace elements in the livers of cod (Gadus morhua L.) from the Baltic Sea: levels and temporal trends

This paper presents and discusses the levels and temporal trends of concentrations of Cd, Pb, Hg, Cu, Zn, and As in livers and Hg in the muscle tissues of cod (Gadus morhua L) from the Baltic Sea during the period 1994–2010. Concentrations of Pb, Hg, and Cd exhibited significant downward trends. Cu and Zn concentrations exhibited upward trends in the period 1994 to 2010. No trends were detected for concentrations of As. The temporal trends identified in heavy metal concentrations in cod livers corresponded to the directions of changes in concentrations of these elements introduced into the Baltic Sea via river runoff and atmospheric emission, and those in surface and deep waters of the Baltic. Downward trends in the concentrations of toxic metals in cod livers suggest that advantageous changes are occurring in concentrations of heavy metals in the environment of the southern Baltic Sea.     

Mercury in rivers in NW England: from rural headwaters to the heartlands of the historic industrial base

Total mercury (T-Hg) concentrations in rivers are described across a rural to urban/industrial and agricultural landscape gradient in NW England. T-Hg ranges between 0.2 and 230 ng L(-1). The regional median was 3.6 ng L(-1) with individual river medians ranging between 1.9 and 8.3 ng L(-1). Median T-Hg concentrations were sometimes moderately higher for the lowland areas and at higher flows. Our estimates suggest that the Ribble estuary receives 9.2 kg y(-1) and the Wyre estuary 0.7 kg y(-1). In order to examine regional inputs from urban/industrial components, regression analysis was undertaken by comparing three types of hydrochemical signature: suspended sediments (SS), which provide a measure of the particulate component, dissolved organic carbon (DOC) that provides an indication of humic/fulvic acids that are part of the organic colloids and strong chelating agents, and boron a marker of sewage effluents and population density. The results show high positive relationships of T-Hg with both SS and DOC, but no relationship with the urban/industrial signal. The regression analysis with T-Hg indicated on average a gradient of 0.33 ng mg(-1) for DOC and 0.2 ng mg(-1) for SS. They indicate the primary importance of a diffuse source of T-Hg. For the upland areas and cleaner river systems, the linkages between T-Hg and DOC were particularly strong, while for the lowland areas, the linkage with SS proved stronger. Analysis of a latter subset of data that partition the SS into organic and inorganic fractions indicated that the T-Hg was primarily linked with the organic fraction. Indeed, multiple regression of T-Hg with DOC and POM reveals gradients similar to other parts of the World.     

菏泽市主要河流中氟的分布及其影响因素

菏泽市地处鲁西南高氟地区,其河流中的高浓度氟化物不仅会通过径流过程影响南四湖水质,还会影响当地水生态平衡及人体健康。通过分析菏泽市主要河流中氟化物的时空分布特征,并结合地下水、土壤及废污水调查结果,探讨了影响河流中氟化物分布的主要因素。结果表明:研究区河流中氟化物的平均浓度在0.98~1.45 mg/L之间,氟化物浓度分布呈现出枯水期＞平水期＞丰水期、下游＞上游、支流＞干流的特征。氟化物浓度较高的河流呈现高pH、低钙的特点,水化学组分以Na-HCO₃型、Na-SO₄型为主。河流中氟化物的浓度主要受蒸发浓缩和岩石风化作用的影响。研究区地下水和土壤中氟化物的背景浓度整体较高。枯水期高氟地下水可能通过直接补给河流对河流水体产生影响,丰水期土壤中的氟也会通过径流过程汇入河流。人类工农业生产过程大量开采利用当地高氟地下水,而高氟废水最终则会进入河流,导致河流中氟化物的含量升高。     

Influence of land use and climate on the load of suspended solids in catchments of Andean rivers

Understanding the interaction between anthropogenic land use and the rainfall pattern can be crucial to predict changes in total suspended solids (TSS) in streams and rivers. We assessed the effects of land use and annual rainfall on the TSS load of 19 southern Chilean catchments. The results indicated that the concentration of TSS increased in catchments with a rainy regime and greater annual precipitation. TSS load also increased as the surface of open areas increased at the catchment scale and decreased with increasing cover of glaciers and perennial snow. However, we did not find support for models with interaction terms between climate and land use. Results suggest that a regional decrease in annual rainfall accompanied by an increase in the altitude of the zero isotherms, as predicted by climate models, should have multiple effects on TSS. In particular, increased TSS load can be expected from a contraction of glaciers and perennial snow areas as well as the intensification of new crops and urban expansion.     

Estimation of riverine loads of nitrogen and phosphorus to the Baltic Sea, 1970–1993

This article presents the results of the first critical examination of time series of riverine nutrient-load data for the entire Baltic Sea drainage area. Water quality data collected by or for the different national environmental agencies were compiled and analysed statistically to identify and remove inconsistent or obviously incorrect observations. Moreover, sampling tours were undertaken to acquire additional information about the present nutrient concentrations in the largest rivers in the study area. Gaps in the time series of approved data were then filled in by employing statistical interpolation and extrapolation methods. Thereafter, the concentration and runoff data were combined to obtain estimates of monthly nutrient loads for the time period 1970–93. The results of the calculations showed that although there had been substantial changes in land use, atmospheric deposition and wastewater treatment in many parts of the study area, the total riverine loads of nitrogen (N) and phosphorus (P) to the Baltic Sea have been fairly constant since 1980, and most likely also since 1970. Moreover, the interannual variation was clearly correlated to the runoff. The mean annual loads for the time period 1980–93 were found to be about 825 000 tonnes N and 41 000 tonnes P, respectively. This implies that (i) several other investigators have strongly underestimated the riverine loads of nutrients, especially the nitrogen, and that (ii) the riverine loads by far exceed the input to the Baltic Sea from other sources, {i.e.} atmospheric deposition, direct emissions from cities and industries along the Baltic Sea coast and nitrogen fixation by marine algae.     

Investigation of urban water quality using simulated rainfall in a medium size city of China

Road-deposited sediment (RDS) is an important environmental medium for impacting the characteristics of pollutants in stormwater runoff; it is of critical importance to investigate the water quality of urban environments. The paper develops a rainfall simulator as an important research tool to ensure homogeneity and reduce the large number of variables that are usually inherent to urban water quality research. The rainfall simulator was used to experiment runoff samples from typical residential and traffic areas in the Zhenjiang. The data show that land use is one of the major factors contributing to the difference in the pollutants concentration in the RDS. The maximum mean EMC for TN, TDN, TP, and TDP at residential area was 5.52, 3.07, 1.65, and 0.36 mg/L, respectively. The intense traffic area displayed the highest metal concentrations. Concentrations of runoff pollutants varied greatly with land use and storm characteristics. The correlation of pollutant concentrations with runoff times was another predominant phenomenon. Peaks in pollutants concentration occurred at 1 and 10 min during the whole storm event. A concentration peak that correlates with a peak in runoff flowrate correlates with rainfall intensity. The pollutant loadings (kilograms per hectare) in the Zhenjiang were 11.39 and 55.28 for COD, 8.42 and 57.48 for SS, 0.11 and 0.88 for TN, 0.02 and 0.14 for TP, 0.02 and 0.09 for Zn, and 0.01 and 0.04 for Pb. The higher rainfall contribute to the higher pollutant loading at the residential and intense traffic areas, as a result of the pollutant loadings direct dependence on rainfall intensity. The results confirmed that the rainfall simulator is a reliable tool for urban water quality research and can be used to simulate pollutant wash-off. These findings provide invaluable information for the development of appropriate management strategies to decrease nonpoint source contamination loading to the water environment in urban areas.