River Contamination Research Articles

Quantifying the Landscape’s Ecological Benefits—An Analysis of the Effect of Land Cover Change on Ecosystem Services

The increasing pressure from land cover change exacerbates the negative effect on ecosystems and ecosystem services (ES). One approach to inform holistic and sustainable management is to quantify the ES provided by the landscape. Using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, this study quantified the sediment retention capacity and water yield potential of different land cover in the Santee River Basin Network in South Carolina, USA. Results showed that vegetated areas provided the highest sediment retention capacity and lowest water yield potential. Also, the simulations demonstrated that keeping the offseason crop areas vegetated by planting cover crops improves the monthly ES provision of the landscape. Retaining the soil within the land area prevents possible contamination and siltation of rivers and streams. On the other hand, low water yield potential translates to low occurrence of surface runoff, which indicates better soil erosion control, regulated soil nutrient absorption and gradual infiltration. The results of this study can be used for landscape sustainability management to assess the possible tradeoffs between ecological conservation and economic development. Furthermore, the generated map of ES can be used to pinpoint the areas where ES are best provided within the landscape.

ANÁLISE BIBLIOMÉTRICA DE ALTERNATIVAS PARA REMOÇÃO DE NUTRIENTES DE ÁGUAS RESIDUAIS NAS BASES SCOPUS, WEB OF SCIENCE E SCIELO

O crescimento exponencial da população e o uso excessivo dos recursos hídricos vêm gerando problemas tanto ambientais, como a contaminação de rios, mares e solo, quanto para as pessoas no quesito escassez da água. Logo o presente trabalho se justifica pela importância de geração de informações sobre as ações que podem ser realizadas para reaproveitamento das aguas contaminadas. Assim, objetiva-se a realizar uma análise bibliométrica sobre quais são as principais alternativas de remoção de nutrientes em corpos d’água utilizando as bases Scopus, Web of Science e SciELO. Para isso, realizou-se uma revisão de literatura para fundamentação teórica e identificação das bases de dados, definição das palavras-chave que seriam utilizadas nas bases de dados e aplicação de filtros para selecionar os artigos que condiziam com o tema e consequentemente formar o portfólio de trabalhos mais relevantes. A partir disso, foram obtidos 9 artigos na base Scopus, 5 na WoS e 3 na SciELO para composição do portfólio. Com base na análise bibliométrica realizada nas bases Scopus, Web of Science e SciELO foi possível visualizar o crescimento de pesquisas visando à solução de problemas ambientais causados pela liberação de nutrientes no meio ambiente.

Evidence that watershed nutrient management practices effectively reduce estrogens in environmental waters

We evaluate the impacts of different nutrient management strategies on the potential for co-managing estrogens and nutrients in environmental waters of the Potomac watershed of the Chesapeake Bay. These potential co-management approaches represent agricultural and urban runoff, wastewater treatment plant effluent, and combined sewer overflow replacements. Twelve estrogenic compounds and their metabolites were analysed by gas chromatography–mass spectrometry. Estrogenic activity (E2Eq) was measured by in vitro bioassay. We detected estrone E1 (0.05–6.97 ng L−1) and estriol E3 (below detection-8.13 ng L−1) and one conjugated estrogen (estrone-3-sulfate E1-3S; below detection-8.13 ng L−1). E1 was widely distributed and positively correlated with E2Eq, water temperature, and dissolved organic carbon (DOC). Among nonpoint sources, E2Eq, and concentrations of E1, soluble reactive phosphorus (SRP) and total dissolved nitrogen (TDN) decreased by 51–61%, 77–82%, 62–64%, 4–16% in restored urban and agricultural streams with best management practices (BMPs) relative to unrestored streams without BMPs. In a wastewater treatment plant (Blue Plains WWTP), >94% of E1, E1-3S, E3, E2Eq and TDN were removed while SRP increased by 305% during nitrification/denitrification as a part of advanced wastewater treatment. Consequently, E1 and TDN concentrations in WWTP effluents were comparable or even lower than those observed in the receiving stream or river waters, and the effects of wastewater discharges on downstream E1 and TDN concentrations were minor. Highest E2Eq value and concentrations of E1, E3, and TDN were detected in combined sewer overflow (CSO). This study suggests that WWTP upgrades with biological nutrient removal, CSO management, and certain agricultural and urban BMPs for nutrient controls have the potential to remove estrogens from point and nonpoint sources along with other contaminants in streams and rivers.

Roadside snowmelt: a management target to reduce lake and river contamination

ABSTRACT Major ion concentrations have greatly increased in many north temperate lakes and rivers over the last 3 decades as the result of deicing materials applied to their surrounding roads in winter. Salt-based deicing will likely continue or increase in the future, and preventative management strategies require an improved understanding of the flow pathways and timing of road salt and associated contaminant fluxes to downstream receiving waters. In the present study, we focused on the catchment of Saint-Charles River and its reservoir that provides drinking water for Quebec City, Canada. Major ion concentrations were measured in river waters and snowbanks along roads in subcatchments that differed in degree of urbanization, and during the same winter–spring period a mooring system was installed in the reservoir to continuously record conductivity. Large significant differences were found in the concentration and temporal behavior of ions between urbanized and forested watersheds. Snow sampled at 1 m from the roads had elevated concentrations of salts and other contaminants, and the highest solute concentrations in the reservoir and river waters occurred during snowmelt events. The results indicate that management of roadside snowmelt runoff during thawing events may largely prevent salt-associated contamination, and that winter snowmelt will require increasing attention as the climate continues to warm.

Potential role of veterinary flea products in widespread pesticide contamination of English rivers

Little is known about the environmental fate or impact of pesticides used to control companion animal parasites. Using data from the Environment Agency, we examined the occurrence of fipronil, fipronil metabolites and imidacloprid in 20 English rivers from 2016 to 2018, as indicators of the potential contamination of waterways from their use as ectoparasiticides on pets. Water samples were collected by the Environment Agency as part of their chemical surveillance programme and analysed using Liquid Chromatography Mass Spectrometry / Quadrupole-Time-of-Flight Mass spectrometry (LC/Q-TOF-MS) methods. A total of 3861 chemical analyses were examined, and the significance and potential sources of this contamination were assessed. Fipronil, fipronil sulfone, fipronil sulfide (collectively known as fiproles) and imidacloprid were detected in 98.6%, 96.5%, 68.7% and 65.9% of samples, respectively. Across the river sites sampled, the mean concentrations of fipronil (17 ng/l, range <0.3–980 ng/l), and fipronil sulfone (6.5 ng/l, range <0.2–39 ng/l) were 5.3 and 38.1 times their chronic toxicity limits of 3.2 and 0.17 ng/l, respectively. Imidacloprid had a mean concentration of 31.7 ng/l (range <1–360 ng/l), which was below its chronic toxicity limit of 35 ng/l, however seven out of 20 sites exceeded that limit. Chronic risk quotients indicate a high environmental risk to aquatic ecosystems from fiproles, and a moderate risk from imidacloprid. Sites immediately downstream of wastewater treatment works had the highest levels of fipronil and imidacloprid, supporting the hypothesis that potentially significant quantities of pesticides from veterinary flea products may be entering waterways via household drains. These findings suggest the need for a reevaluation of the environmental risks associated with the use of companion animal parasiticide products, and the risk assessments that these products undergo prior to regulatory approval.

River contamination shapes the microbiome and antibiotic resistance in sharpbelly (Hemiculter leucisculus).

Animals living in urban river systems play critical roles in the dissemination of microbiome and antibiotic resistance that poses a strong threat to public health. This study provides a comprehensive profile of microbiota and antibiotic resistance genes (ARGs) of sharpbelly (Hemiculter leucisculus) and the surrounding water from five sites along the Ba River. Results showed Proteobacteria, Firmicutes and Fusobacteria were the dominant bacteria in gut of H.leucisculus. With the aggravation of water pollution, bacterial biomass of fish gut significantly decreased and the proportion of Proteobacteria increased to become the most dominant phylum eventually. To quantify the contributions of influential factors on patterns of gut microbiome with structural equation model (SEM), water bacteria were confirmed to be the most stressors to perturb fish gut microbiome. SourceTracker model indicated that deteriorating living surroundings facilitated the invasion of water pathogens to fish gut eco-environments. Additionally, H.leucisculus gut is an important reservoir of ARGs in Ba River with relative abundance up to 9.86×10-1/copies. Among the ARGs, tetracycline and quinolone resistance genes were detected in dominant abundance. Deterioration of external environments elicited the accumulation of ARGs in fish gut. Intestinal class I integron, environmental heavy metal residues and gut bacteria were identified as key drivers of intestinal ARGs profiles in H.leucisculus. Analysis of SEM and co-occurrence patterns between ARGs and bacterial hosts indicated that class I integron and bacterial community played vital roles in ARGs transmission through water-fish pathway. In general, this study highlighted hazards of water contamination to microbiome and ARGs in aquatic animals and provided a new perspective to better understand the bacteria and ARGs dissemination in urban river ecosystems.

Impact of informal settlements and wastewater treatment plants on helminth egg contamination of urban rivers and risks associated with exposure

The quality of surface water could be influenced by both anthropogenic and natural factors. This study was designed to determine the impact of informal settlement and wastewater treatment plants on helminth egg contamination of urban rivers and the risks associated with everyday use. We also ascertained the accumulation of these eggs in the river sediments. The study was carried out in two rivers in the eThekwini Municipality of South Africa. Grab samples were taken at different points over a 10-month period. Ascaris spp., hookworm, Toxocara spp., Trichuris spp. and Taenia spp. were the helminth eggs detected in both the water column and sediments, with mean Ascaris spp. eggs of 0–6.3 (± 5.1)/L in the water and 0–6.8 (± 5.2)/kg in sediment samples. The helminth egg concentrations showed seasonal variation, probably due to changes in infection levels of the populations or natural factors, such as rainfall. The informal settlements had a greater impact than treated wastewater. For every 10,000 recreational users of the rivers 19 to 58 may be infected under undisturbed conditions, increasing to 29–88 individuals when the riverbed is disturbed. The risk from agricultural use of the rivers was above the tolerable risk values applicable for wastewater reuse, recommended by the World Health Organization. This calls for a re-evaluation of the policies governing surface water quality assessment, where the inclusion of helminth eggs and sediment monitoring will be critical.

Potentially harmful heavy metal contamination in Babolrood river: evaluation for risk assessment in the Mazandaran province, Iran

ABSTRACT Rivers,as the kind of freshwater resources throughout the world, play a key role in the lives of living things. Heavy metal contamination of river water is primarily attributed to human activities, and there is anincreasing need to conduct risk assessments to characterise the nature and magnitude ofrisks to humans and ecological receptors from these contaminants.The PG990 nuclear absorption spectrophotometer measured concentrations of heavy metals. Trace metals (Cd, Pb, Ni, Zn) in Babolrood river from the Babol region of North Iran were analysed to assess pollution using the Hazard Quotients (HQ), Hazard Index (HI) and the Incremental Lifetime Cancer Risk (ILCR).The Environmental Protection Agency (EPA) model was applied to calculate human health risk (HHR). Heavy metal concentration varied considerably Cd (0.004 to 89.287 µg/L), Ni (0.89–49.78 µg/L), Pb (3.4–181.75 µg/L) and Ni (0.0–243.3 µg/L). The oral Hazard quotients (HQ) values for Pb were ranged from 1.04–7.83 µg/L, therefore indicated in all sampled stations HQ values above 1 for children group. In contrast, the oral and dermal HQ values for both groups were less than 1 for Zn and Ni in all sampling stations. The Hazard Index (HI) values demonstrate that total HI values were above 1 for children group in water samples of all stations. Generally, total HI values for children were much higher than that of adults among Babolrood River. The Excess Lifetime Cancer Risk (ELCR) values for Cd and Pb in all sample stations for children were higher than the EPA risk assessment guideline limit (10−6-10−4).

URANIUM AND OTHER TOXIC ELEMENTS IN TRANSBOUNDARY WATERS NEAR KAMYSHANOVSKY DEPOSIT

The paper is devoted to revealing the signs of negative impact from the territory of the Kamyshanovskoye deposit (Kyrgyzstan) on the level of contamination with uranium and other hazardous elements in transboundary water bodies, in the first place in the Shu River. For this, six control points along the irrigation canal at this territory were chosen together with 9 control points along the Shu river within the area. The elemental composition of water samples was studied employing MS-ICP and OES-ICP; concentration values of 22 elements were determined. The calculations were performed based on the obtained contents of toxic elements of the 1st and 2nd classes. Corresponding sanitary standards exceed the corresponding values by 1.5 – 6.7 times. At that, uranium makes the main contribution to the toxicity level of the studied water in the Shu River (46%) and in the canal (61%). The toxicity of the water canal is for ~3 times higher than that of the Shu River. The highest toxicity indicator was found in the water delivered to the agricultural irrigation at the territory of the Kamyshanovskoye deposit. This peculiarity and the obtained data may be of interest to the Ministry of Agriculture of the Kyrgyz Republic. The distribution of chemical elements in water along the irrigation canal and along the Shu River bed was studied. It is established that the canal water do not become contaminated with toxic elements while passing through the deposit lands. It was established in the 3 control points of the Shu River that an increase (by 28 – 130%) in the concentration of Ca, Ni, Li, Sr, U, Mg, Cr, Ba over their concentrations at the control points is higher upstream of this river. The results obtained convincingly indicate the presence of a serious influence of the Kamyshanovskoye deposit territory on the Shu River contamination with these elements. It is unlikely that such significant contamination is caused by the irrigation system discharge waters. One of the possible mechanisms of water contamination in the Shu River in its segment may be the entry of groundwater in contact with the ore body of this deposit.

Water quality of the Meuse watershed: Assessment using a multi-biomarker approach with caged three-spined stickleback (Gasterosteus aculeatus L.)

The use of a multi-biomarker approach with three-spined sticklebacks (Gasterosteus aculeatus) through an active biomonitoring strategy appears to be a promising tool in water quality assessment. The present work proposes to assess the efficiency of these tools in the discrimination of some sites in a large scale on the Meuse basin in Europe. The study was part of an EU program which aims to assess water quality in the Meuse across the French-Belgian border. Sticklebacks were caged 21 days upstream and downstream from the wastewater treatment plants (WWTPs) of Namur (Belgium), Charleville-Mézières (France), Bouillon (Belgium) and Avesnes-sur-Helpe (France). First, the state of a variety of physiological functions was assessed using a battery of biomarkers that represented innate immunity (leucocyte mortality and distribution, phagocytosis activity, respiratory burst), antioxidant system (GPx, CAT, SOD and total GSH content), oxidative damages to the membrane lipids (TBARS), biotransformation enzymes (EROD, GST), synaptic transmission (AChE) and reproduction system (spiggin and vitellogenin concentration). The impacts of the effluents were first analysed for each biomarker using a mixed model ANOVA followed by post-hoc analyses. Secondly, the global river contamination was assessed using a principal component analysis (PCA) followed by a hierarchical agglomerative clustering (HAC). The results highlighted a small number of effects of WWTP effluents on the physiological parameters in caged sticklebacks. Despite a significant effect of the “localisation” factor (upstream/downstream) in the mixed ANOVA for several biomarkers, post-hoc analyses revealed few differences between upstream and downstream of the WWTPs. Only a significant decrease of innate immune responses was observed downstream from the WWTPs of Avesnes-sur-Helpe and Namur. Other biomarker responses were not impacted by WWTP effluents. However, the multivariate analyses (PCA and HAC) of the biomarker responses helped to clearly discriminate the different study sites from the reference but also amongst themselves. Thus, a reduction of general condition (condition index and HSI) was observed in all groups of caged sticklebacks, associated with a weaker AChE activity in comparison with the reference population. A strong oxidative stress was highlighted in fish caged in the Meuse river at Charleville-Mézières whereas sticklebacks caged in the Meuse river at Namur exhibited weaker innate immune responses than others. Conversely, sticklebacks caged in the Helpe-Majeure river at Avesnes-sur-Helpe exhibited higher immune responses. Furthermore, weak defence capacities were recorded in fish caged in the Semois river at Bouillon. This experiment was the first to propose an active biomonitoring approach using three-spined stickleback to assess such varied environments. Low mortality and encouraging results in site discrimination support the use of this tool to assess the quality of a large number of water bodies.

Combined use of native and transplanted moss for post-mining characterization of metal(loid) river contamination

Abandoned mine sites are a cause of great environmental concern, being potential sources of toxic elements for adjacent aquatic ecosystems with intrinsic difficulties for their management (i.e. episodic nature of pollution, technical difficulties and high costs of monitoring, remoteness). Aquatic macrophytes can find effective application in these situations, providing cost-effective data for instream water quality assessment. In this study, native and transplanted specimens of the aquatic moss Platyhypnidium riparioides were used to evaluate metal(loid) contamination in a river receiving multiple acidic and metalliferous drainages from sulphide mineralized areas and derelict mines. Analysis of native P. riparioides thalli was used to identify, in the upland course of the river, the pattern of contamination (As, Cd, Cu, Pb and Zn) which was related to the geo-environmental features of the watershed and the nearby historical mining areas. Attenuation of metal(loid) availability in the lowland river, apparently due to eco-hydrological and physic-chemical processes, was also highlighted by spatial trends of concentrations data of native and transplanted moss. The latter, deployed for 21 days at specific stretches of the river and in a tributary hydrologically connected with a dismissed mine, supported the identification of point sources (i.e. mine effluents, metallurgical waste piles amassed on the banks of the river) and the reckoning of their quantitative impact on different segments of the watercourse. By exploring multi-elemental and native-to-transplant relationships, differences in metal(loid) accumulative capacities were recognized between sampled thalli and exposed moss bags in relation to the severity of the contamination. The observed discrepancy in the accumulation of As, Fe, Ni and Pb in highly contaminated areas between native and transplanted moss of P. riparioides raises questions on the possible competing mechanisms of element uptake and retention. These findings prompt studies to discern possible limitations of the transplanting moss technique under extreme stream-quality conditions.

Heavy metal contamination trends in surface water and sediments of a river in a highly-industrialized region

Surface water and sediment samples from the most contaminated river in Taiwan, Houjing River, were collected for five years (2015 to 2019) and from five locations to study the contamination trends of eight heavy metals (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn). Five locations along the river were picked based on their potential of being contaminated by nearby industrial activities. The monitoring data, geo-accumulation index (Igeo), contamination factor (CF), modified degree of contamination (mCd), pollution load index (PLI), and metal index (MI) were used to provide a detailed assessment of the heavy metal contamination. Demin (L3) and Chuwai (L4), two sampling sites close to the Nanzih Export Processing Zone (NEPZ) discharge points, were the most contaminated. The most contaminated periods were 2015–2016 and 2018–2019 for surface water and sediment samples, respectively. The surface water showed signs of heavy metal contamination in 2016 with mCd > 1.5. For the sediment samples, the heavy metal concentration fingerprints for the five years were similar. This implied that the natural attenuation process was not adequate, and treatment technologies are required to improve sediment quality. This study provides a basis for comprehensive risk assessments and integrated environmental management measures for the river’s surface water and sediment quality. Also, it would contribute to a more inclusive evaluation of heavy metal contamination in global rivers.

Impact of Illegal Crude Oil Refining in Jike-ama River of Bille Kingdom, Rivers State, Nigeria

Oil exploration and exploitation is a lucrative business and one of the major sources of revenue in Nigeria. Each year, hundreds of post-impact assessment (PIA) studies are conducted to assess the impact of the hazards generated by the oil industry on social environment and on human health. This hazardous impact is the associated with the activities of illegal refining of crude oil. Thus, this work examined the impact of illegal crude oil refining activities in Jike-Ama river of Jike-Ama community. Shellfish, fish, surface water and sediment samples were randomly collected in triplicates. Physiochemical parameters, heavy metal content, polycyclic aromatic hydrocarbons (PAHs) and total hydrocarbon content of the water in addition to heavy metal content and PAHs in fish, Shellfish and sediment were determined. The results of the physicochemical parameters showed that pH, total suspended solids, biological oxygen demand, turbidity and total hydrocarbon content of water were above FEPA permissible limits while chloride, nitrate and sulphate detected in water were within FEPA permissible limits. Dissolved oxygen was observed to be below FEPA permissible limit. The mean concentration of heavy metals and PAHs in sediment showed significant difference (p&lt;0.05) when compared with values for Shellfish and fish and were above FEPA and WHO permissible limits. Shellfish had higher concentrations of heavy metals and PAHs than fish. PAHs values in shellfish showed significant difference (p&lt;0.05). Heavy metals concentration in fish were above permissible limits except Cr, Zn and Pb. Concentration of PAHs in fish, shellfish, surface water and sediment were generally above FEPA and WHO permissible limits. This findings suggests high concentration of contaminants in Jike-Ama river.

Human Health Risk Assessment of Heavy Metal Contamination in New Calabar River.

Concentration and human health risks of heavy metals (Pb, Cu, Cr, Cd, As, Ni) in water, sediment, crab (Tympanotonus fuscatus) and periwinkle (Callinectes amnicola) were assayed in New Calabar River, Nigeria. Results revealed that concentration (mg/L) of the metals in water in the two seasons studied, ranged from 1.1E-2 ± 1.0E-3…for Cd to 2.90 ± 0.03…for Cu. In sediment, the concentration (mg/kg) ranged from 1.1E-2 ± 1.0E-3…for As to 5.17 ± 0.04… for Ni. In biota, the concentration (mg/kg) ranged from 0.01…for As in crab to 19.22…for Cu also in crab. Estimated human health riskfrom the metals contaminationdue to consumption of biota gave each of HQ and HI as < 1, indicating no risk except at Agip's sample location where HI was > 1. Estimated human health risk due to dermal absorption through swimming, indicated no risk as each of HQ and HI was < 1. These make the river unpolluted except at Agip's sample location.

The hydrogeological situation after salt-mine collapses at Solotvyno, Ukraine

Study regionThe study site is located in the south-western part of the Ukraine, in the area of the historical rock-salt mining town Solotvyno. The former mining area is situated in close vicinity to the River Tisza, the main tributary of the Danube River, the largest river in Europe. Study focusAfter uncontrolled flooding of several salt mines, a one month advisory mission was launched by the European Commission to estimate the impact of the abandoned salt mines (containing large quantities of salt water) on the environment. As a consequence of the flooding, dozens of sinkholes formed and sinkhole forming processes are ongoing, with sinkhole diameters reaching 250 m. As river contamination by the release of large quantities of saltwater would lead to an international disaster, hydrogeological measurements were taken on-site to study the system. New hydrological insights of the regionAt the study site, saturated (hyper-saline) water as well as fresh surface and groundwater were encountered in close vicinity to each other. Electrical conductivity, as a proxy for salinity, and temperature were measured on-site and water samples taken from surface-, ground- and mine waters were analyzed for chemistry and stable isotopes, providing new insights into groundwater flow dynamics. A conceptual model shows the salt dome, and potential flow paths from the mining area to the Tisza River, in the context of the mines and associated sinkholes potentially impacting the river water quality.

Green Economy a Design for Sustainable Development of India

Industrial revolution turned India into a source of rare, raw materials for British industries as well as a market for their finished products. The British only concentrated on the use of production factors and mass production for earning profit and collecting wealth for selfish development and it has led to a depletion of certain natural resources, leaving the environment permanently damaged and injured. The environmental issues in India become more serious every day like that lack of environmental education, reducing fertility of agricultural land, declining water level on earth, mass deforestation, land degradation, excess use of fertilizers and chemical in food production and river contamination and pollution. Green economy is a design and remedy on sustainable development, sustainable environment and environmental balance. It is against this backdrop, the present research study analyses the state of green economy and its linkages with sustainable development, environmental sustainability with reference to India. The present study concludes that the depletion of natural resources in India was not over or excessive is a move towards a green economy in connection with the indicator of natural resource depletion. The state of sanitation facilities in India is not very much happy and satisfactory. Access to water shows for India it is good, but not better which reveals India has failed in providing drinking water, consequently economic transformation and green economy for sustainable development of India. The important and policy suggestions of the present study are; planned extensive and intensive efforts are very much necessary from India as well for the development of health, water supply and sanitation facilities. Government of India should be more active and dynamic in realizing their green economy. Participation and involvement of people should be obligatory and enhanced in undertaking various activities useful for attaining the green economy and there by sustainable development.

Spatial distribution, risk assessment, and source identification of heavy metals in water from the Xiangxi River, Three Gorges Reservoir Region, China.

Heavy metals (HMs) contamination in rivers has attracted wide concern due to its persistence and potential risks to the natural environment and human health. In this study, eight HMs (As, Hg, Cu, Pb, Ca, Zn, Mn, and Ni) were measured by inductively coupled plasma mass spectrometry in 24 water samples to investigate HMs contamination levels in the Xiangxi River of the Yangtze River basin. A geographic information systems kriging interpolation method was used to reveal the spatial distribution of HMs contamination. The results indicate that most HMs occurred at acceptable levels below the Surface Water Quality Standard (GB 3838-2002), with the highest concentration (23.23mgkg-1) of Mn being observed at sampling site X20. The values of the potential ecological risk index (RI) suggest that high potential ecological risks were present at sampling sites X1, X3, X4, X14, X16, X17, and X24, which reached moderate risk level. The highest value of RI (279.56) was observed at site X17. HM spatial distributions show that upstream pollution is more severe than downstream. The hazard index was below 1 for all HMs except for Mn, indicating that HMs in Xiangxi River pose a low risk to human health. HM source identification was accomplished using principal component analysis and Pearson's correlation. Cu, Cd, Ni, and Hg originate primarily from agriculture, while Pb, Zn, and As originate primarily from transportation and mining. This research provides a reference on the risks posed by HMs in Xiangxi River and will support efforts to protect and improve water quality in Xiangxi River.

Reproduction of sediment deposition and prediction of 137Cs concentration in the major urban rivers of Tokyo

Radioactive caesium- 137 (137Cs) can be used as a tracer to infer sediment dynamics due not only to its long radioactive half-life but also its affinity for fine sediment. A novel advanced interpolation assessment was conducted to examine radionuclide activity in terraced land covered with volcanic ash soil in Tokyo, Japan, which had a time-dependent input function and incorporated the effects of mixed-sediment particle dynamic behaviour on radioactive decay. In addition, transport parameters derived from Chernobyl measurements were applied as predictors of the long-term contamination of the cardinal urban rivers by the fallout from the Tokyo Electric Power Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in 2011. The behaviour of suspended sediment substances, incorporating the effects of deposition and pickup, was assessed using a mixed-sediment particle dynamics model. The concentrations of 137Cs adsorbed on fine sediment particles of each size fraction were determined. Removal of 137Cs from the cardinal urban river channel had significant effects on both long-term decline, including extreme flash flood events, and the dynamic and time-dependent behaviours of interspersed 137Cs and sediment activity. A novel advanced interpolation assessment method was used to examine radionuclide activity in terraced land covered with volcanic ash soil in Tokyo, Japan. The assessment procedure has a time-dependent input function and incorporates the effects of mixed-sediment particle dynamics on this time dependence. The results indicated that sediment and 137Cs concentrations could decline more rapidly than observed in the Fukushima and Chernobyl regions. This rate of decrease depended on terraces covered with volcanic ash soil, which incorporated the effects of fine sediment behaviour for particle adsorption. In addition, comparatively large impacts were observed during extreme flash flooding events, which were associated with the land cover of the major urban river catchments in Tokyo. This work provides a new perspective for understanding 137Cs behaviour associated with reproduction of sediment deposition and prediction of 137Cs concentration in the major urban rivers of Tokyo, incorporating the effects of baseline 137Cs behaviour with the impact of sediment particle adsorption in a volcanic ash soil-covered terrace.

Development of microspheres using water hyacinth (Eichhornia crassipes) for treatment of contaminated water with Cr(VI)

The chemical contamination of water is increasingly evident, and the lack of alternatives for water treatment is one of the main problems that leads to the contamination of rivers, lagoons, wetlands and others. The biomass of Eichhornia crassipes is an alternative, since it retains heavy metals due to its great bioadsorption capacity in its vegetal structure. The objective of this research is to develop microspheres with dry and pulverized biomass of the roots E. crassipes, combining them with sodium tripolyphosphate for the adsorption of chromium from the waters of tanneries. The pH, the initial concentration and the ideal amount of these microspheres were evaluated together with the adsorption isotherms and the second-order adsorption model. There was an interesting capacity of chromium(VI) adsorption of 7.7 mg/g. The best adjusted isotherm model was the Langmuir model, and the different eliminations were adjusted to a second-order adsorption model, demonstrating that this process of adhesion is governed by a chemisorption process. It was concluded that those microspheres are one alternative for treatment of water contaminated with different heavy metals and could be used in great-scale industry.

Cyanide Contamination of the Puyango-Tumbes River Caused by Artisanal Gold Mining in Portovelo-Zaruma, Ecuador.

To examine cyanide (CN-) contamination of a large river in southeastern Ecuador that has been severely impacted by the indiscriminate discharge of untreated gold processing effluents. Poor environmental stewardship of cyanide (CN-) use by 87 gold processing centers in Portovelo-Zaruma in southern Ecuador to leach residual gold from Hg-contaminated tailings has resulted in high CN- contamination of the Puyango-Tumbes River downstream from the centers. Free CN- concentrations were high in river surface waters for 50km below the processing plants, with the highest concentration 9088 times above the CCME standard of 5μg/L and 1136 times above the 24-h LC50 concentration of 40μg/L free CN- for some fish species. Due to cyanidation of mercury-contaminated tailings, the formation of Hg-CN complexes is a grave concern, as these complexes have been shown to be highly bioavailable. Preliminary tests conducted in a laboratory using bioassays with Danio rerio sp. and varying concentrations of synthetic Hg(CN)2 salt have shown significant THg bioaccumulation in muscle and kidney fish tissues exposed to concentrations >0.12mg/L. Furthermore, low MeHg results in fish tissues demonstrated little occurrence of methylation and that the bulk of the total mercury content was in the form of inorganic mercury. Although construction of a communal tailings facility (CTF) in Portovelo is a positive development to reduce riverine pollution, the requirement to truck tailings up to the CTF likely results in inadequate compliance of environmental regulations that are poorly enforced.