WHO Guideline Value Research Articles

Physicochemical and microorganism analysis of some hand pump water in Pelengana, Segou, Mali

Groundwater from hand pump could be a principal supply of potable in the large part of rural areas of Mali. Indeed, it was found that this source was the safest to meet water request in remote areas (i.e., rural) of the low-income countries like Mali. However, groundwater quality is changed once external substances are available to contact with the water table. An evaluation of physicochemical and microbial qualities of hand pump water in the rural commune of Pelengana, Mali, was performed. The parameters analyzed include: physical (temperature, pH, and turbidity), chemical (nitrate, and phosphate) and microbiological (both fecal and total coliform bacteria), using standard procedures of analysis. Moreover, API 20E test was used to determine the identities of isolates. Findings have been compared with the WHO drinking water guidelines (or other) values. All physicochemical parameters in hand pump water samples were within the limit recommended by the WHO guideline (or other) values except to turbidity, and nitrate, whereas microbial concentrations during the rainy season were above the WHO acceptable limits. The presence of species such as Escherichia coli, Salmonella and Klebsiella in hand pump waters suggests that water from these sources constitute a threat to public health and is inappropriate for drinking without treatment.

Iron-based subsurface arsenic removal (SAR): Results of a long-term pilot-scale test in Vietnam

The principle of subsurface arsenic removal (SAR) from groundwater is based on oxidation and adsorption reactions by infiltrating oxygen into the anoxic aquifer and the immobilization of arsenic (As) onto freshly formed iron (Fe)-(hydr)oxides. In this study, a pilot-scale plant for SAR has been subject to long term testing in the Mekong Delta, Vietnam. Initial concentrations of Fe (8.4 ± 1.3 mg L−1) and As (81 ± 8 μg L−1) in the exploited groundwater were successfully lowered to below the WHO guideline value limits for drinking water of 0.3 mg L−1 and 10 μg L−1, respectively. Adsorption and co-precipitation of As with Fe-(hydr)oxides could be identified as the principal mechanism responsible for the As removal from groundwater, demonstrating the feasibility of SAR as a low-cost and zero-waste solution over a period of two years. However, naturally occurring geochemical reducing conditions and high ammonium levels in the groundwater delayed the removal of manganese (Mn). An additional post-treatment filtration for Mn-removal was temporarily used to comply with the Vietnamese drinking water standard until a Mn-mitigation was achieved by the SAR process. In contrast to most As-remediation technologies, SAR appears to be a long-term, sustainable treatment option with the salient advantage of negligible production of toxic waste, which with ex-situ processes require additionally management costs.

Concentrations of Trace Elements in Daily Life Water Consumed in Angono, Rizal, Philippines

Objective. The present study aims to determine the concentrations of seven trace elements [chromium (Cr), arsenic (As), cadmium (Cd), cesium (Cs), lead (Pb), thorium (Th), and uranium (U)] in tap, well, spring, river, and lake waters in the town of Angono, Rizal in the Philippines, consumed for drinking, cooking, bathing, and washing. In the town of Angono, both of the tap and purified tap waters produced in the refilling station are consumed as the water for drinking.Methods. Water samples from six unpurified tap, six purified taps, 10 wells, two springs, two rivers, and one lake water were obtained in October 2015. Samples were analyzed using solution nebulization inductively coupled plasma mass spectrometry. Results were evaluated for health risks of the trace elements in the water samples using WHO guideline values. The provisional WHO guideline values are as follows: Cr: 50 µg/L, As: 10 µg/L, Cd: 3 µg/L, Pb: 10 µg/L, and U: 30 µg/L. That of Cs has not been proposed yet. The WHO guideline value for the naturally occurring radioactive isotope 232Th in drinking water is 1 Bq/L, which is equivalent to 250 μg/L.Results. The concentrations of the trace elements in the tap water samples were <0.5% of the WHO guideline values, except Cs and Cd, with those of Cd being ~9% of the WHO guideline value. Purified tap waters contained the seven trace elements in lower concentrations, with the exception of Pb, which may have been added in small amounts from equipment used for water purification. The concentrations of the trace elements in water samples from the wells and springs in Angono were more variable than those of the tap waters, and these were also below the WHO guideline values. The concentrations of Cs in all water samples were <0.3 µg/L. The trace-element concentrations of the waters from Angono River and Laguna Lake were almost the same as those of the well and spring waters. Conclusion. At present, the concentrations of trace elements in daily life water consumed in Angono are at safe levels.

Distribution of uranium in drinking/ground waters in Narsipatnam Revenue Division of Visakhapatnam District of Andhra Pradesh, India and consequent ingestion dose

Uranium is a naturally occurring radioactive element. The higher concentrations of U in waters can cause chemical as well as radiological toxicity. In the present study 48 water samples were collected from the drinking/ground water sources in Narsipatnam Revenue division of Visakhapatnam District of Andhra Pradesh during pre and post monsoon seasons. Distribution of U has been measured and consequent ingestion dose was assessed. The observed U values range from < 0.2 to 25.4 ppb with a mean value of 4.9 ppb during pre monsoon season and U values range from < 0.2 to 19.4 ppb with a mean value of 2.7 ppb during post monsoon season. These values are compared with the AERB and WHO guideline values of 60 ppb and 30 ppb, respectively. The research results indicated that the waters are safe for drinking and domestic purposes.

Arsenate removal from drinking water using by-products from conventional iron oxyhydroxides production as adsorbents coupled with submerged microfiltration unit

Arsenic is among the major drinking water contaminants affecting populations in many countries because it causes serious health problems on long-term exposure. Two low-cost micro-sized iron oxyhydroxide-based adsorbents (which are by-products of the industrial production process of granular adsorbents), namely, micro granular ferric hydroxide (μGFH) and micro tetravalent manganese feroxyhyte (μTMF), were applied in batch adsorption kinetic tests and submerged microfiltration membrane adsorption hybrid system (SMAHS) to remove pentavalent arsenic (As(V)) from modeled drinking water. The adsorbents media were characterized in terms of iron content, BET surface area, pore volume, and particle size. The results of adsorption kinetics show that initial adsorption rate of As(V) by μTMF is faster than μGFH. The SMAHS results revealed that hydraulic residence time of As(V) in the slurry reactor plays a critical role. At longer residence time, the achieved adsorption capacities at As(V) permeate concentration of 10 μg/L (WHO guideline value) are 0.95 and 1.04 μg/mg for μGFH and μTMF, respectively. At shorter residence time of ~ 3 h, μTMF was able to treat 1.4 times more volumes of arsenic-polluted water than μGFH under the optimized experimental conditions due to its fast kinetic behavior. The outcomes of this study confirm that micro-sized iron oyxhydroxides, by-products of conventional adsorbent production processes, can successfully be employed in the proposed hybrid water treatment system to achieve drinking water guideline value for arsenic, without considerable fouling of the porous membrane.Graphical abstract

Prediction of source contributions to urban background PM&amp;lt;sub&amp;gt;10&amp;lt;/sub&amp;gt; concentrations in European cities: a case study for an episode in December 2016 using EMEP/MSC-W rv4.15 and LOTOS-EUROS v2.0 – Part 1: The country contributions

Abstract. A large fraction of the urban population in Europe is exposed to particulate matter levels above the WHO guideline value. To make more effective mitigation strategies, it is important to understand the influence on particulate matter (PM) from pollutants emitted in different European nations. In this study, we evaluate a country source contribution forecasting system aimed at assessing the domestic and transboundary contributions to PM in major European cities for an episode in December 2016. The system is composed of two models (EMEP/MSC-W rv4.15 and LOTOS-EUROS v2.0), which allows the consideration of differences in the source attribution. We also compared the PM10 concentrations, and both models present satisfactory agreement in the 4 d forecasts of the surface concentrations, since the hourly concentrations can be highly correlated with in situ observations. The correlation coefficients reach values of up to 0.58 for LOTOS-EUROS and 0.50 for EMEP for the urban stations; the values are 0.58 for LOTOS-EUROS and 0.72 for EMEP for the rural stations. However, the models underpredict the highest hourly concentrations measured by the urban stations (mean underestimation of 36 %), which is to be expected given the relatively coarse model resolution used (0.25∘ longitude × 0.125∘ latitude). For the source attribution calculations, LOTOS-EUROS uses a labelling technique, while the EMEP/MSC-W model uses a scenario having reduced anthropogenic emissions, and then it is compared to a reference run where no changes are applied. Different percentages (5 %, 15 %, and 50 %) for the reduced emissions in the EMEP/MSC-W model were used to test the robustness of the methodology. The impact of the different ways to define the urban area for the studied cities was also investigated (i.e. one model grid cell, nine grid cells, and grid cells covering the definition given by the Global Administrative Areas – GADM). We found that the combination of a 15 % emission reduction and a larger domain (nine grid cells or GADM) helps to preserve the linearity between emission and concentrations changes. The nonlinearity, related to the emission reduction scenario used, is suggested by the nature of the mismatch between the total concentration and the sum of the concentrations from different calculated sources. Even limited, this nonlinearity is observed in the NO3-, NH4+, and H2O concentrations, which is related to gas–aerosol partitioning of the species. The use of a 15 % emission reduction and of a larger city domain also causes better agreement on the determination of the main country contributors between both country source calculations. Over the 34 European cities investigated, PM10 was dominated by domestic emissions for the studied episode (1–9 December 2016). The two models generally agree on the dominant external country contributor (68 % on an hourly basis) to PM10 concentrations. Overall, 75 % of the hourly predicted PM10 concentrations of both models have the same top five main country contributors. Better agreement on the dominant country contributor for primary (emitted) species (70 % is found for primary organic matter (POM) and 80 % for elemental carbon – EC) than for the inorganic secondary component of the aerosol (50 %), which is predictable due to the conceptual differences in the source attribution used by both models. The country contribution calculated by the scenario approach depends on the chemical regime, which largely impacts the secondary components, unlike the calculation using the labelling approach.

Spatial distribution, sources, and risk assessment of major ions ad trace elements in rainwater at Puchuncaví Valley, Chile: The impact of industrial activities

This article presents the results of a study on the chemical composition of rainwater as an environmental pollution factor in the surroundings of the Puchuncaví - Ventanas industrial complex (V Region, Chile), with the main objectives of assessing acidification and neutralisation factors, measuring elemental pollutant levels including calculation of enrichment factors and pollution sources assignment, and assessing the risk derived from elemental pollutant loads in rainwater, both for human use and natural ecosystems. Forty-seven weekly rainwater samples were collected during the winter (May–August) 2010 (24 samples) and 2011 (23 samples) at three sampling location with different degree of impact from the main emission sources. The pH, conductivity and major ions were analyzed by ion chromatography, as well as 18 traces and main elements by ICP-MS. Most rainwater samples had pH below 5.6, indicating the risk of acidification, but neutralisation factors, mainly by Na+ and NH4+ were also noticed. The elements emitted by anthropogenic activities had significant enrichment values in the rainwater of the area studied, and the principal component analysis (PCA) identified four sources related to the metallurgical industry – crustal material, marine material, traffic -industry and industrial activities. The risk assessment showed that As content in rainwater is above the WHO guideline value for drinking water at some points in the study area. The contribution of Pb and Cd in rainwater to the soil critical loads turned out to be relatively low, with a maximum of 22.1% for Pb in the vicinity of the industrial complex.

Evaluation of potable groundwater zones identification based on WQI and GIS techniques in Adyar River basin, Chennai, Tamilnadu, India

The main objective of this study is to identify the potable groundwater zones in Adyar River Basin (ARB) that forms the major river of Chennai metropolitan and significantly contributes to the demands of this big city's water supply. Twenty eight groundwater samples were collected during postmonsoon and premonsoon seasons in 2016 from the wells of ARB which is downstream of Chembarambakkam Lake, which supplies drinking water to Chennai metropolitan city. All the water samples were analyzed using Portable meter and Ion Chromatography for physico-chemical parameters and major ions such as pH, TDS, Ca, Mg, Na, K, Cl, HCO3, SO4 and NO3. The analytical results were compared with the WHO, USEPA & BIS guideline values and reported that some of the samples exceeds these guideline values for drinking water quality. Spatial distribution maps were prepared to identify the potable groundwater available regions based on these water quality parameters. Piper and Gibbs plots are generated to identify the nature and type of groundwater with processes controls the groundwater chemistry. Principal component analysis was done to interpret the possible sources of chemical compounds present in the groundwater. To precisely delineate the potable groundwater region in ARB, Water Quality Index (WQI) approach is employed with the basic water quality parameters and spatial distribution maps were prepared using GIS for the obtained indexes. It is found that only 10.71% and 17.86% of the study area groundwater is within the excellent water quality for drinking during postmonsoon and premonsoon respectively, whereas 42.86% in postmonsoon and 14.29% in premonsoon is found as poor quality groundwater for drinking. The groundwater of the northwestern and western part of ARB is under very poor and unsuitable category for drinking in both the seasons. This region of ARB is recommended for implementation of artificial groundwater recharging to improve the groundwater quality and make it suitable for drinking.

Trend Characteristics of Atmospheric Particulate Matters in Major Urban Areas of Bangladesh

The urban areas of Bangladesh suffer from severe air quality problem especially in dry season (November–April) when the PM concentrations frequently rise to 7–8 times of the WHO guideline value. The Clean Air and Sustainable Environment (CASE) Project of the Department of Environment has deployed countrywide continuous air monitoring systems to regularly monitor the air quality of the urban areas of Bangladesh. In this paper hourly concentrations of PM10 and PM2.5 captured using β-attenuation method from 2013 to April 2018 in six important cities located in different regions of the country were exhaustively analyzed. Statistical analyses, diurnal and seasonal trends, and polar plots of PM concentrations were examined. Long range sources were spotted by Concentration Weighted Trajectory (CWT) method, where the trajectories were calculated using HYSPLIT-4 model. The analyses identified cities in the middle of the country (Dhaka, Narayanganj, Gazipur) as the most polluted ones while the city to the northeast region (Sylhet) was the least polluted. Average PM10 concentrations at Dhaka, Chattogram, Narayanganj, Gazipur, Sylhet and Barisal stations in dry seasons (November–April) were found 238.7±155.4, 190.7±108.5, 303.6±161.4, 227.3±142.7, 151.7±105.0 and 170.7±108.4 μg m−3 respectively whereas those in wet seasons (May–October) were 75.0±51.6, 55.5±40.8, 102.4±84.4, 60.6±48.5, 52.7±38.3, and 54.4±41.6 μg m−3 respectively. Correlative study of diurnal variations in PM concentrations and meteorological parameters revealed that the congenial meteorology aided in developing higher concentrations of both PM10 and PM2.5 during nighttime. Sources located to the northwestern districts (Naogao, Rangpur, Bogura) were traced by the CWT method contributing to the air pollution in other regions of the country. Outside the boundary, sources in Nepal, and Delhi-NCR and Uttar Pradesh regions of India could have contributed to fine particles at the middle of the country.

Investigating the occurrence of algae in the drinking water supply system of Harare, Zimbabwe

Abstract This study assessed the quality of drinking water in the water supply system for the City of Harare (Zimbabwe) by investigating the occurrence of algae and other water quality parameters that affect its growth. At Morton Jaffray Water Treatment Works (MJWTWs), samples were collected from the raw water inlet and treated water outlet points. In the distribution system, samples were collected from selected sites and grouped into four zones (1, 2, 3 and 4). The algal taxonomic groups that were found in both raw and treated water comprised of Cyanophyceae, Chlorophyceae, Bacillariophyceae, Euglenophyceae and Dinophyceae. It was found out that Microcystis aeruginosa followed by Anabaena were the most abundant species in both raw water and in the distribution system. All measured water quality parameters were within the Standards Association of Zimbabwe and WHO guideline values except for chlorine which had an average residual chlorine concentration that was lower than the WHO recommended lower value of 0.2 mg/L in parts of Zone 2. Morton Jaffray Water Treatment Works does not completely remove algae, and there is a carry-over of algae into the distribution system. Boosting of chlorine is recommended for Zone 2 that had residual chlorine less than the WHO minimum threshold of 0.2 mg/L.

Nitrate contamination of water in dug wells and associated health risks of rural communities in southwest Bangladesh.

Consumption of drinking water with high nitrate may pose a serious health hazard. This study examined nitrate concentration in the water of dug wells at the Jashore district of Bangladesh. A total of 58 water samples were collected from dug wells which are currently in use for drinking water. Concentrations of nitrate in the water range from 0.05 to 430mg/l and from 0.24 to 206mg/l respectively in the wet and dry seasons. About 17% and 14% of the samples during the wet and dry seasons respectively showed nitrate concentration above the WHO guideline value of 50mg/l. The wells with high nitrate concentration showed health risks for adults and children. About 17% of the samples showed a health hazard index (HQnitrate) values above the acceptable limit (HQnitrate values > 1) for adults, in both the wet and dry seasons, whereas 26% and 33% of the water samples in the wet and dry seasons respectively showed HQnitrate values > 1 for children. Therefore, children are more likely to be affected by intaking nitrate-contaminated dug well water. Health risks of elevated nitrate concentration in the dug wells require proper attention to ensure reliable water supply.

An investigative study on subsurface water chemistry near agricultural and aquaculture areas

ABSTRACT Water is essential for all types of living beings. Application of fertilisers in agriculture became a prime source for contamination of subsurface waters. Backwaters from aquaculture can also contaminate the groundwater sources. The study aimed at assessing the chemical and metal toxicity for evaluating water quality. The quality of water was assessed during pre monsoon season between February and May 2017 and post monsoon season between October 2017 and January 2017. pH is measured using portable pH metre, electrical conductance(EC) is measured using portable EC sensor, total dissolved solids (TDS) is measured by portable TDS sensor, DO is measured by DO metre, total hardness (TH), total alkalinity (TA), CO3 2−, HCO3 −, Cl−, Ca2+, Mg2+ are measured by titrimetry, SO4 2− and PO4 3− are measured by spectrophotometer, NO3 − by using ion selective electrode, Na+ and K+ by Flame photometer and metal ions like Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, As and Hg by inductively coupled plasma optical emission spectroscopy technique (ICP-OES). The analytical results showed that during pre monsoon season in both agricultural and aquaculture areas Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, Hg are below the guideline values of IS and WHO. The concentration of As and Cu metal ions during post monsoon season are higher than the guideline value of WHO. In waters near agricultural areas TDS and TH were observed to be higher than the guideline values of IS. In waters near aquaculture areas TDS, TH, TA, Chloride, Magnesium, Sodium and Potassium were observed to be higher than the guideline values of IS.

Use of low-enthalpy and waste geothermal energy sources to solve arsenic problems in freshwater production in selected regions of Latin America using a process membrane distillation – Research into model solutions

The challenge for many communities in Latin America is to find adequate solutions which are feasible given the local economic and technical conditions and which enable them to source water with arsenic concentrations below the WHO guideline value for drinking water (<10 μg/L) of arsenic (As) pollution, suitable for human consumption and the irrigation of crops. Three regions where geothermal fields are present were selected for study out of the several hundred locations in Latin America where the water environment is contaminated with As and where there is a critical water shortage problem. These are Cerro Prieto in Mexico, Momotombo in Nicaragua and Lake Poopó in Bolivia. The paper presents the results of research on the use of low-enthalpy geothermal energy sources and waste heat from geothermal power plants in membrane distillation (MD) processes, which is the only heat-powered membrane technology, in order to obtain potable water and/or water for crop irrigation. It was concluded that MD could be considered as a solution for obtaining water of good quality with a high retention of toxic solutes such as As as well as other different species found in groundwater. In addition, it is not only geothermal energy, but also the geothermal water itself that can be considered as a source of freshwater produced through the MD process, a process which is most suitable to be used in areas where cheap sources of heat are available.

Fast Optical Sensing of Metals: A Case Study of Cu2+ Assessment in Soils

In this paper we report an application of a novel porphyrin ligand, Zn(II)TPP-BPI-crown (ZnPC), functionalized with two dibenzo-crown-ether moieties as cation-sensitive ionophore. The test on the optical response of ZnPC ligand inside PVC-based polymeric membranes towards different cations (Na+, K+, Li+, Ca2+, Mg2+, Co2+, Cd2+, Pb2+, Zn2+, Cu2+ and NH4+) were performed. The influence of the lipophilic site functionalization on the ZnPC optode response was investigated. The visibly (naked eye) observed color change of sensing material from green to red demonstrated the suitability of the ZnPC-based optodes to perform fast monitoring of Cu(II) ions in the concentration range between 6.6 × 10−7 and 2.4 × 10−2 mol l−1, with a low detection limit (estimated by s/n = 3 method) of 0.03 mg l−1, which is lower than WHO guideline value of 2 mg l−1 for natural waters. The membranes with the best composition were deposited onto paper support and employed for the express analysis of copper(II) ion in aqueous soil extracts. The results obtained were in a good agreement with a standard ASS method, thus suggesting the utility of developed sensors for aims of express environmental monitoring.

Bushfires in Australia: a serious health emergency under climate change

Bushfires in Australia: a serious health emergency under climate change

Characterizing atmospheric controls on winter urban pollution in a topographic basin setting using Radon-222

Abstract Using hourly meteorological, air quality and radon observations over two winters (2016–2017 and 2017–2018), we combine diurnal and synoptic timescale radon-based mixing classification techniques, for the first time, to better understand air quality variability in the sub-Alpine city of Ljubljana. Of the two winters, only the second experienced significant snow cover (>1 month). A total of six mixing classes were defined for each winter: 5 diurnal and 1 synoptic (“persistent temperature inversion”, PTI); the latter being internally categorised as “strong” or “weak”. Diurnal and synoptic changes in mixing state played an important role in air quality variability in both winters. Little diurnal accumulation of local pollutants (CO, NO2, PM10 and BC) was observed for wind speeds ≥1.5 m s−1 (mixing classes #1 to #3). Under these windy conditions significant remote contributions to SO2 and O3 concentrations in Ljubljana were observed, primarily from the Po Valley region. The most stable conditions (class #5 and PTI days), characterized by nocturnal wind speeds ≤0.5 m s−1 or rates of 2 m air temperature change ≥1.5 °C h−1, were associated with the worst air quality conditions. Only under class #5 and PTI conditions did daily-mean PM10 concentrations exceed both EU and WHO guideline values. The absence of snow cover in the first winter resulted in stronger thermodynamic stability and higher pollution concentrations. Other contributing factors included a 28% larger traffic source near the monitoring site and a 17% greater consumption of heating fuel that winter in Ljubljana.

An Exposure Assessment of Arsenic and Other Trace Elements in Ha Nam Province, Northern Vietnam.

Concentrations of As and other trace elements were measured in groundwater, rice, hair, urine, and blood samples of people consuming As-contaminated groundwater in a village of Ha Nam province, northern Vietnam to understand the recent status of contamination and assess the possible risks of human exposure. Elevated concentrations of As in groundwater were still observed, exceeding the WHO guideline value in most of the tube wells investigated. Significant positive correlations between As concentrations in groundwater and human samples (hair and urine) were observed. Arsenic concentrations in human and hair appeared to be related to the groundwater usage habit, with higher levels found in drinking group than those in the washing group. Significant good correlations were also encountered between cumulative intakes of As, Mn, and Ba through groundwater consumption and hair concentrations. All these results indicate the chronic exposure to As and some other elements such as Mn and Ba. The total intakes of As, Mn, and Ba through rice and groundwater consumption were estimated to be ranged from 80–836, 49.3–1850, and 311–97100 µg/day, respectively. The daily intakes of As of the study area ranged from 1.6–16.7 µg/kg body wt./day, mean: 7.15 µg/kg body wt./day, in which about 85% of the subjects were above the provisional tolerable daily intake proposed by WHO.

Arsenic distribution and pathway scenarios for sediments and water in a peri-urban Mongolian small-scale coal mining area (NalaikhDistrict, Ulaanbaatar).

The distribution of arsenic (As) in environmental compartments is investigated in the Nalaikh Depression of N-Mongolia. In Nalaikh, lignite coal is mined by artisanal small-scale mining (ASM) approaches. Because As is often associated with sulfuric minerals in coal, it was hypothesized that enrichment of As is related to coal ASM. A second hypothesis considered coal combustion in power plants, and stoves are a key source of As in the local environment. Three mobilization and distribution scenarios were developed for potential As pathways in this semiarid environment. About 43 soil and 14 water sites were analyzed for As concentrations and meaningful parameters in soil and water. About 28 topsoil samples were analyzed in surface-subsurface pairs in order to identify potential eolian surface enrichment. Additionally, fluvial-alluvial sediments and geogenic and anthropogenic deposits were sampled. Water was sampled as surface water, groundwater, precipitation, and industrial water. Results show that As does not pose a ubiquitous risk in the Nalaikh Depression. However, locally and specifically in water, As concentrations may exceed the WHO guideline value for drinking water by up to a factor of 10. A carefully selected sampling strategy allows the evaluation of the distribution scenarios, which reveals a combination of (a) geogenic As in groundwater and distribution via surface water with (b) anthropogenic As redistribution via eolian pathways. An immediate linkage between As redistribution and coal mining is not evident. However, As distribution in fly ash from coal combustion in the local power plant and yurt settlements is the most likely As pathway. Hence, the results indicate the potential influence of diffuse, low-altitude sources on As emission to the environment. As such, this study provides a good example for As distribution under semiarid climate conditions influenced by geogenic and anthropogenic factors.

Heavy metals in water, sediment and three fish species of Dhaleshwari river, Savar

The study was conducted to assess the pollution of five heavy metals, namely arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu). Their concentrations in water and sediments as well as in three fish species such as Labeo rohita (herbivorous), Wallago attu (carnivorous) and Heteropneustes fossilis (omnivorous) were recorded. During wet and dry seasons As, Pb, Cd, Cr, Cu concentrations in river water ranged from the ‘below detection level (BDL)’- 0.0019, 0.3702 - 0.4163, 0.0285 - 0.0294, 1.204 - 1.36, 0.0315 - 0.0807 ppm and 0.0016 - 0.0180, 0.1305 - 0.1889, 0.0297 - 0.0309, BDL, 0.0381 - 0.0543 ppm, respectively. There was no significant seasonal variation in As and Cu conc. in river water but Cr and Pb conc. were significantly higher during the wet season and Cd conc. was significantly higher during dry season. During the wet and dry seasons As, Pb, Cd, Cr, Cu conc. in river sediments ranged from 3.67 - 7.13, 21.58 - 64.96, 1.36 - 1.72, 1126.66 - 1199.46, 45.91 - 115.57 ppm and 5.10 - 8.88, 19.27 - 30.75, 1.39 - 1.48, 99.67 - 446.72, 68.98 - 442.78 ppm, respectively. There were no significant seasonal variations in As, Pb, Cd and Cu concentrations of river sediment but Cr concentration was significantly higher during the wet season. Among muscle, gill and gut tissues of three selected fish species, Pb showed the highest level of accumulation in gill tissues while As showed the lowest level of accumulation in muscle tissues in all three species. Pb, Cd and Cr concentrations in the river water were above WHO Guideline values while As and Cu concentrations were below WHO Guideline values. As, Pb, Cd, Cr and Cu concentrations in the river sediment were above the environmental protection agency’s threshold effect level. In all the three studied fish species, As conc. was below FAO guideline value. Pb, Cd and Cr conc. were higher than FAO guideline value in all three fish species and Cu conc. was above FAO guideline value in one species (H. fossilis). At least three heavy metal concentrations were above FAO guideline value in all three fish species. Therefore, all three fish species were not safe for human consumption.&#x0D; Bangladesh J. Zool. 47(2): 263-272, 2019

Environmental contamination of heavy metals in some dried fish of coastal regions of Bangladesh

Heavy metals are non-biodegradable substances which cause serious carcinogenic effects on animals and humans. As fish occupy top position of aquatic food chain, it is a major source of heavy metal contamination. The concentration of Cd, Cr, Pb, Mn, Fe, Cu, and Zn were 0.0156 - 0.1428, 0.163 - 8.53, 0.0924 - 0.4026, 9.38 - 65.9382, 0.0473 - 0.1981 and 0.1473 - 1.8148 ppm respectively for the fish samples of Cox’s Bazar region while 0.0191 - 0.1386, 0.8445 - 0.1743, 0.102 - 0.4625, 0.102 - 0.4675, 9.7269 - 60.5267, 0.3108 - 0.046 ppm for the fish samples of Saint Martin’s region. Comparatively high concentrations of heavy metals were found to be accumulated in Mola (Amblypharyngodon mola), Rupchanda (Stromateus chinensis) and Chhuri (Trichiurus lepturus). The order of heavy metal concentrations were Fe &gt; Zn &gt; Cr &gt; Cu &gt; Mn &gt; Cd. The concentration of heavy metals varied from species to species and most of the metals were not significantly correlated, even some metals showed negative correlation among them. Concentration of Fe in some fishes (Mola, Rupchanda and Chhuri) was found higher than WHO guideline values, while other metals exhibited the value below the WHO standard. The results of this study will assist in acquiring information about the level of toxic metals in these regions and to improve the coastal management in these areas in future.&#x0D; Bangladesh J. Zool. 47(2): 293-304, 2019