River Sediment Quality Research Articles

Structure and Function of Fungal Community in Channel Sediments of Different Sections of Jialing River

This study aimed to explore the effects of different disturbances on the fungal communities in the sediments of the Jialing River in order to provide scientific basis for the protection of the river ecosystem. The fungal community in the sediments of the main stream of the Jialing River was taken as the research object, and high-throughput sequencing and bioinformatics techniques were used to analyze the differences in the composition and function of fungal communities in river sediment of different types of disturbance （project disturbance, tributary disturbance, sand mining disturbance, and reclamation disturbance） and non-disturbance sections. The results showed that： ① The reclamation and project disturbances significantly inhibited the diversity and richness of fungal communities （P<0.05）. The tributary disturbance increased the richness of fungal communities, whereas the impact of sand mining disturbance on sediment fungal communities was not significant. ② The diversity and composition of fungal communities tended to be similar at the different sampling sites in the section with low input of exogenous substances （non-disturbance and sand mining disturbance）, whereas there were obvious differences in the diversity of fungal communities at the different sampling sites of high input of external substances （tributary disturbance, project disturbance, and reclamation disturbance） sections. ③ Ascomycota, Rozellomycota, and Basidiomycota were the main dominant fungal phyla in the sediments of the Jialing River. The relative abundance of Rozellomycota was the highest in the sand mining interference section, and the relative abundance of Basidiomycota was the highest in the tributary interference section. Project disturbance significantly increased the relative abundance of saprotrophs, animal pathogens, plant pathogens, and dung saprotrophs, whereas other disturbances inhibited the relative abundance of fungal parasitic fungi, plant pathogens, and plant saprophytes. In conclusion, human disturbance has caused changes in fungal diversity, community structure, and function in the sediment of the Jialing River, and xenobiotic input was a key factor contributing to this phenomenon. The results can provide a reference for predicting and evaluating the ecological quality of river sediments.

Impact of organic pollutants from urban slum informal settlements on sustainable development goals and river sediment quality, Nairobi, Kenya, Africa

The UN Sustainable Development Goals highlight the myriad of socio-economic and environmental challenges occurring as a result of anthropogenic chemical pollution. Urban sediments from informal settlements (slums) on the Nairobi, Ngong and Mathare Rivers (n = 25), were evaluated for sediment quality. Microtox bioassay identified 8 sites as toxic, 9 as moderately toxic and 8 as non-toxic. Slum sediments were characterised by high total organic carbon and Rock-Eval pyrolysis revealed bound carbon from a mix of raw sewage and domestic refuse. Sediments from Kiambio, Kibera, Mathare and Kawangware slums contained high coprostanol at 55–298 μg/g and epicoprostanol at 3.2–21.7 μg/g confirming appreciable incorporation of untreated human faeces. Hormones, antianalgeiscs, antiinflamatories, antiepileptics and antibiotics most affected Mathare > Kiambio > Kibera > Mukuru > Kawangware slums. Carbamazepine, ibuprofen, diclofenac and acetaminophen concentrations are amongst the highest reported in Kenyan river sediments and were positively correlated with faecal steroids (sewage). Common persistent organic pollutants, such as organochlorine insecticides ΣDDT 1–59 μg/kg, mean 21.2 μg/kg, Σ16PAH 182–2218 μg/kg, mean 822 μg/kg and Σ30 PCB 3.1–157.1 μg/kg, mean of 21.4 μg/kg were between probable effect likely and unlikely sediment quality guidelines (SQG). PAH source ratios and parent to alkyl-PAH distribution suggested vehicle exhaust, power stations (heavy oil), kerosene (cooking oil) and other pollution sources. Trace metal concentrations As, Cd, Cr, Hg and Ni were below SQG whereas Pb exceeded the SQG. This multi-contaminant characterisation of sediment quality in Nairobi supports the development and implementation of policies to improve urban infrastructure to protect ecological and human health. It demonstrates the need for environmental geochemists to engage in the science-policy interface associated with both global and national development frameworks, with particular reference to the Sustainable Development Goals, New Urban Agenda, and Kenya’s Vision 2030.

Assessment of heavy metal levels in an urban river in the Philippines using an unconstrained ordination- and GIS-based approach: evidence of the return of past pollution after the 2013 Typhoon Haiyan (Yolanda)

Abstract Assessment of urban river sediment quality is paramount to understanding the impacts of urbanization on aquatic ecosystems and public health. The study evaluated the health impacts and sources of heavy metal pollutants in the Mangonbangon river, Tacloban City. With the abundance of heavy metal contaminants in the river sediment (Fe&amp;gt;Mn&amp;gt;Zn&amp;gt;Cu&amp;gt;Cr&amp;gt;Ni&amp;gt;Co), Hazard indices (HIs) ranged from 0.04 to 0.10 for adults and 0.31 to 0.90 for children suggesting little or no non-carcinogenic effects to the population. Lifetime cancer risk (LCR) is below the tolerable threshold of 10−4, with Co contributing 61% of the cancer risk. Using unconstrained ordination and the GIS-based method (UOGM), we showed two non-multidimensional scaling groups of pollutants distributed based on dwelling density, presence of informal settlers, and types of activity at the sample sites. Given that sampling was performed three years after the city-wide destruction by Typhoon Haiyan (Yolanda), our analysis indicates the return of anthropogenic activities and pollution-related health problems in Tacloban. Our results reinforce the urgent need for proper river management and economic zoning to help curb the rapidly growing heavy metal pollution problem at its earliest stage.

Geochemistry pollution status and contamination assessment of potentially toxic metals from the sediments of a tropical river of Kerala, India

The contamination of heavy metals within the sediments of a tropical river basin of Kerala, India were studied using pollution indices thereby to examine the level of deterioration. Sediment samples were taken from 20 locations and the major investigations carried out in the sediment samples include geochemical analysis for the determination of major ions and minor (trace) elements by using X-Ray Fluorescence spectrometer (XRF) and textural analysis for the classification of sediment samples into different categories. To understand the pollution loads in the sediments of the study area, the heavy metal and major element contamination of the samples were assessed based on Crustal Enrichment Factor (EFc), geo accumulation index (Igeo), Contamination Factor (CF), Degree of contamination (Cdeg) and Pollution Load Index (PLI). From the analysis, it is seen that the coastal sediments of KRB were polluted mainly by Zirconium which exhibits high values in the pre monsoon season. Among the major elements, Titanium is the only one which manifests slightly higher values in the pre monsoon period. Based on the textural analysis, it is observed that these sediments predominantly come under sandy loam and loamy silt classifications during the three seasons of study. The unplanned urbanization and industrialization have detrimental effects on the quality of river sediments in the recent years. The current work is preferably applied to a river system and the findings will deliver productive evidence for analyzing the plenary catchment areas of Western Ghats.

Key factors influencing metal concentrations in sediments along Western European Rivers: A long-term monitoring study (1945–2020)

Since 1945, a large amount of heterogeneous data has been acquired to survey river sediment quality, especially concerning regulatory metals such as Cd, Cr, Cu, Hg, Ni, Pb, and Zn. Large-scale syntheses are critical to assess the effectiveness of public regulations and the resiliency of the river systems. Accordingly, this data synthesis proposes a first attempt to decipher spatio-temporal trends of metal contamination along seven major continental rivers in Western Europe (France, Belgium, Germany, and the Netherlands). A large dataset (>12,000 samples) from various sediment matrices (bed and flood deposits – BFD, suspended particulate matter – SPM, dated sediment cores – DSC) was set up based on monitoring and scientific research from the 1950s to the 2010s. This work investigates the impact of analytical protocols (matrix sampling, fractionation, extraction), location and time factors (related to geology and anthropogenic activities) on metal concentration trends. Statistical analyses highlight crossed-interactions in space and time, as well as between sediment matrices (metal concentrations in SPM ≃ DSC > BFD) and extraction procedures (also related to river lithology). Major spatio-temporal trends are found along several rivers such as (i) an increase of metal concentrations downstream of the main urban industrial areas (e.g. Paris-Rouen corridor on the Seine River, Bonn-Duisburg corridor on the Rhine River), (ii) a long-term influence of former mining areas located in crystalline zones, releasing heavily contaminated sediments for decades (Upper Loire River, Middle Meuse section), (iii) a decrease of metal concentrations since the 1970s (except for Cr and Ni, rather low and stable over time). The improvement of sediment quality in the most recent years in Europe reflects a decisive role of environment policies, such as more efficient wastewater treatments, local applications of the Water Framework Directive and urban industrial changes in the river valleys.

Remediation of contaminated urban river sediment based to iron-rich substrate: A comparative study with chemical oxidants

In situ sediment remediation is commonly used for controlling the release of pollutants (N, P, C and S) from polluted urban river sediments. The addition of oxidants can effectively solve the odour​ problem and control the conversion of sulphur in sediments. Laboratory experiments were established to explore the effect of improving contaminated urban river sediment quality with hydrogen peroxide, calcium nitrate, calcium hypochlorite and iron-based substrate (IRS). The results verified that the redox potential increased to 161 mV and 90 mV after 30 days of calcium hypochlorite and calcium nitrate treatment, respectively. The addition of calcium hypochlorite or calcium nitrate reached 97.9% and 94.8% high removal efficiency of acid volatile sulphide due to the oxidation. The addition of IRS decreased the ammonia and total organic carbon concentrations, indicating that the IRS were conducive to controlling the release of 73.2% of the total nitrogen (TN) from river sediment. The consequence also showed that compared with other oxidants, IRS had remarkable influences on the interstitial sulphate, iron and nitrate contents in the sediment, clearly showing comprehensive application prospects.

Influence of watershed on the accumulation of heavy metals in sediments of urban rivers under tropical conditions: Case of N’djili and Lukaya rivers in Kinshasa Democratic Republic of the Congo

• Level of heavy metals in sediments from two river receiving systems was examined. • High concentration of Cr, Cu, Zn, As, Pb and Hg was observed in all studied sediments. • Correlation between parameters indicates the eventual common source of contamination. • High level of heavy metals can affect water quality and increase human health risks. The contamination of freshwater resource by heavy metals is still a major environmental and human health concern globally. The release of these contaminants into the aquatic environment can lead to the pollution of water resources and generate risks for aquatic living organisms and human health. The sediments can act as reservoir for heavy metals, thereby they are used to assess the pollution status of the rivers. In the present investigation, surface sediments collected from two urban rivers named, N’djili and Lukaya draining through the city of Kinshasa, Democratic Republic of the Congo were characterized for grain size, organic matter (OM) and heavy metals. Additionally, Sediment Quality Guidelines for the protection of aquatic life (SQGs), enrichment factor (EF) and geoaccumulation index (Igeo) were performed to determine the river pollution status. The results highlight high concentrations of heavy metals in sediment samples mainly from N’djili River, reaching the values (mg kg −1 ) of 180.3 (Cu), 451.5 (Zn), 185.8 (Pb) and 4.1 (Hg). These values exceed the SQGs. Based on EF and Igeo values, the sediments from the two rivers have severe enrichment and polluted with Cu, Zn and Pb, and moderate enrichment of Cr and As. In general, the positive correlation was observed between some heavy metals and OM suggesting that these contaminants could have originated from common sources with a similar transport pathway. Based on the SQGs, EF and Igeo, N’djili River is considered as highly polluted with heavy metals indicating environmental and human health potential risks. The results of this study clearly indicate that the pollution of urban rivers in developing countries can be explained by several anthropogenic activities such as urban runoff, uncontrolled landfills in riverbanks, untreated wastewater from densely populated areas, anarchic commercial and industrial settlements, and heavy road traffic. The approaches used in this study represent a useful tool to assess the river sediment quality of urban river which can be applied to similar environment.

Metal Concentrations in Sediments of the Alinsaog River, Santa Cruz, Zambales, Central Luzon, Philippines.

Background.Efforts are needed to evaluate heavy metal concentrations in aquatic sediments which serve as repositories and as sources of contamination of other habitats.Objectives.The present study assessed temporal changes in the pH, particle size and concentration of metals in sediments of a mining-affected river in Zambales, Philippines.Methods.Sediment samples were collected at different periods in four stations along the river using a modified Van Veen grab. The samples were subjected to quartering, air-drying, and sieved through a mesh of 40 mm prior to X-ray fluorescence spectroscopy analysis using Thermo Scientific Niton XL3t to determine metal concentrations. The sediment particle size was analyzed by the sieve method and soil pH by the electrode method.Results.Measured metal concentrations in the sediment were as follows: iron (Fe)> calcium (Ca)> chromium (Cr)> nickel (Ni)> manganese (Mn) with averages of 174.6 mg/g, 7.89 mg/g, 6.54 mg/g, 4.82 mg/g, and 2.75 mg/g dry matter (DM), respectively. The mean pH of riverine sediments was generally neutral, except for Station 4. In terms of particle size, silt and clay fractions increased in the upstream station but decreased in the midstream and downstream stations across the sampling periods. The flooding brought by Typhoon Koppu resulted in lowered concentrations of Fe, Mn, Cr, and Ni and an upsurge in Ca and potassium levels.Discussion.Most of the heavy metals (Fe, Ni, Cr, Mn) exceeded the probable effect level (PEL) for inorganics in sediments, suggesting that the adverse effects of these metals on the environment and aquatic organisms are expected to occur frequently. In comparison with Station 4, which was less affected by siltation, there was a sign of metal enrichment in the area. This indicates that soil erosion and runoff, which might have been triggered by vegetation loss, mineral extraction, and agricultural activities, had a significant impact on the quality of river sediments.Conclusions.The findings of the study point to the need for the formulation and implementation of appropriate regulatory measures for the protection and rehabilitation of the heavy metal-loaded river.Competing Interests.The authors declare no competing financial interests.

Comparative evaluation of four suspended particulate matter (SPM) sampling devices and their use for monitoring SPM quality.

Representative sampling of suspended particulate matter is fundamental for assessing river sediment quality, including the distribution and physicochemical characterisation of particles at different hydrological events. This study compares time-integrated samplers and discrete sampling methods, focusing on (a) the representativeness of the different methods and (b) the comparability between the various sampling techniques. The study investigates whether different sampling devices used under the same conditions can reproduce the annual mean. Two time-integrated sampling techniques (Binnensammler floating collector (BS); self-constructed Phillips sampler (PS)) and two discrete sampling systems (continuous-flow centrifuge (CFC); hydrocyclone (HC)) were compared. The monitoring program (August 2013 to August 2014) was conducted using a 4-week sampling frequency at two different monitoring stations in the Rhine river basin. The analysis of physicochemical parameters included total organic carbon (TOC), particulate phosphorus (PP), grain size distribution (GSD), metals, and organic pollutants (PCBs, HCB, PAH). A nested analysis of variance (ANOVA) was used to evaluate the dependence of suspended matter quality parameters on the sampling method, the sampling device, and the sampling station. According to ANOVA, physical and chemical parameters as well as persistent organic pollutants are homogenous for the time-integrated samplers PS and BS. Comparing PS and the reference technique CFC, only the mean annual concentration of TOC is significantly higher for CFC (5.91%; PS, 4.53%) due to degradation processes. With the exception of TOC, Ni, and GSD, data of BS was comparable with that of CFC. Comparing CFC and HC, there are significant differences for GSD, Zn, and Ni. An analysis of the time series of GSD < 63 μm and sum of PAHs confirms the findings of the nested ANOVA, showing that HC time series display significant differences compared with the other samplers.

黄河下峪口段表层土壤pH、Eh分布及其主要影响因素

通过对黄河下峪口段河道表层淤积物和沙洲表层土壤pH和Eh的样品采集，分析了该段表层土壤pH及Eh的分布状况，并从底质特性、周边环境和生物扰动等方面深入探讨了pH、Eh的分布特征、影响因素和影响机理。研究表明：黄河下峪口段河道沉积物及沙洲表土呈中性–弱碱性环境，其中pH值变化于7.54~8.12之间，空间分布上具有分带性和不均一性特征，总体表现为河道沉积物pH值低于沙洲表土pH值。黄河下峪口段河道沉积物和沙洲表土总体尚未氧化环境，Eh变化分布于413~521 mV之间，大部分在483 mV左右，空间分布也具有弱分带性和不均一的特点，表现为河道沉积物Eh低于沙洲表土，也就是说河道沉积物氧化性强于沙洲表土。该区域土壤pH和Eh主要受到水动力作用、河道底质特性以及土壤有机质含量的影响，pH和Eh值呈负相关关系。 Based on the collection of surface sediment and the surface pH and Eh of the surface soil of the Xiayukou section of the Yellow River, we analyzed the distribution of the segment of the surface soil pH and Eh, and discussed from the aspects of sediment quality, surrounding environment and bioturbation. PH, Eh distribution characteristics, influencing factors and influencing mechanism. The results show that the sediment in the lower reaches of the Yellow River and the top-soil of the sandbank are neutral-weakly alkaline. The pH value varies between 7.54 and 8.12, and the spatial distribution is characterized by zonality and heterogeneity. The pH value of the sediment is lower than that of the sand surface. The Eh changes are distributed between 413 and 521 mV, most of them are about 483 mV, and the spatial distribution is also characterized by weakly zoning and heterogeneity, which is characterized by the river sediment Eh is lower than the sand surface, that is, the river sediment is stronger than the sand surface. The soil pH and Eh were mainly affected by hydrodynamic action, river sediment quality and soil organic matter content, and the pH and Eh were negatively correlated.

River sediment quality assessment using sediment quality indices for the Sydney basin, Australia affected by coal and coal seam gas mining

Coal mining activities in the Sydney basin have been historically associated with significant environmental impacts. The region is facing more recent coal seam gas extraction activities and the synergetic environmental impacts of the new mining activities are still largely unknown. The aim of this study was to provide environmental assessment of river sediments comparing upstream to downstream areas relative to industrial-discharge sites associated with coal and coal-seam-gas extraction within the Sydney basin. Various contaminants were measured to determine the sediment quality according to the Australian and New Zealand Environment and Conservation Council (ANZECC) guidelines. Arsenic, nickel and zinc were the main sediment contaminants in downstream samples exceeding the ANZECC guidelines. Degree of contamination (Cd), geoaccumulation index (Igeo), enrichment factor (EF), pollution load index (PLI) and sediment environmental toxicity quotients' increment in downstream sediment were estimated for the studied areas. Toxicology indices of metals present in the sediments near industrial discharge sites were used as an additional tool to compare the level of environmental effects with their increment. The study revealed that the sediments from coal mining sites were highly affected by increased concentrations of manganese, zinc, cobalt, nickel and barium. The sediments associated with coal mining activities were found to be substantially more affected than the sediments near coal seam gas production sites, mainly attributed to the different wastewater discharge licencing requirements. The approach applied in this study can be used as an additional model to assess the contribution of industrial and mining activities on aquatic environments.

Platinum group elements in stream sediments of mining zones: The Hex River (Bushveld Igneous Complex, South Africa)

Assessment of the environmental impact of platinum group elements (PGE) and other trace elements from mining activities is essential to prevent potential environmental risks. This study evaluates the concentrations of PGE in stream sediments of the Hex River, which drains the mining area of the Bushveld Igneous Complex (South Africa), at four sampling points. Major, minor and trace elements (Fe, Ca, Al, Mg, Mn, V, Cr, Zn, Cu, As, Co, Ni, Cd, and Pb) were analyzed by FAAS and ETAAS in suspended particulate matter and different sediment fractions (<63, 63–500 and 500–2000 μm), and Pt, Pd, Rh, and Ir were measured by ICP-MS after removal of interfering elements (cation exchange resin 50W-DOWEX-X8). Procedures were blank-corrected and accuracy checked using reference materials. Nickel, Cr, Pt, Pd, Rh and Ir show concentrations 3-, 13- 18-, 28-, 48- and 44- fold the typical upper continental crust levels, respectively, although lower than concentrations reported for the parent rocks. The highest concentrations were observed closer to the mining area, decreasing with distance and in the <63 μm fraction, probably derived from atmospheric deposition and surface runoff of PGE-rich particles released from mining activities.Thus, mining activities are causing some disturbance of the surface PGE geochemical cycle, increasing the presence of PGE in the fine fraction of river sediments. We propose that indicators such as airborne particulate matter, and soil and river sediment quality, should be added to the protocols for evaluating the sustainability of mining activities.

Genetic relatedness of faecal coliforms and enterococci bacteria isolated from water and sediments of the Apies River, Gauteng, South Africa

To date, the microbiological quality of river sediments and its impact on water resources are not included in the water quality monitoring assessment. Therefore, the aim of this study was to establish genetic relatedness between faecal coliforms and enterococci isolated from the river water and riverbed sediments of Apies River to better understand the genetic similarity of microorganisms between the sediment and water phases. Indicator bacteria were subjected to a molecular study, which consisted of PCR amplification and sequence analysis of the 16S rRNA and 23S rRNA gene using specific primers for faecal coliforms and enterococci, respectively. Results revealed that the Apies River had high faecal pollution levels with enterococci showing low to moderate correlation coefficient (r2 values ranged from 0.2605 to 0.7499) compared to the faecal coliforms which showed zero to low correlation (r2 values ranged from 0.0027 to 0.1407) indicating that enterococci may be better indicator than faecal coliforms for detecting faecal contamination in riverbed sediments. The phylogenetic tree of faecal coliforms revealed a 98% homology among their nucleotide sequences confirming the close genetic relatedness between river water and riverbed sediment isolates. The phylogenetic tree of the enterococci showed that Enterococcus faecalis and Enterococcus faecium are the predominant species found in both river water and riverbed sediments with bootstrap values of ≥99%. A high degree of genetic relatedness between sediment and water isolates indicated a possible common ancestry and transmission pathway. We recommend the microbial monitoring of riverbed sediments as it harbours more diverse microbial community and once resuspended may cause health and environmental problems.

The influence of the scale of mining activity and mine site remediation on the contamination legacy of historical metal mining activity.

Globally, thousands of kilometres of rivers are degraded due to the presence of elevated concentrations of potentially harmful elements (PHEs) sourced from historical metal mining activity. In many countries, the presence of contaminated water and river sediment creates a legal requirement to address such problems. Remediation of mining-associated point sources has often been focused upon improving river water quality; however, this study evaluates the contaminant legacy present within river sediments and attempts to assess the influence of the scale of mining activity and post-mining remediation upon the magnitude of PHE contamination found within contemporary river sediments. Data collected from four exemplar catchments indicates a strong relationship between the scale of historical mining, as measured by ore output, and maximum PHE enrichment factors, calculated versus environmental quality guidelines. The use of channel slope as a proxy measure for the degree of channel-floodplain coupling indicates that enrichment factors for PHEs in contemporary river sediments may also be the highest where channel-floodplain coupling is the greatest. Calculation of a metric score for mine remediation activity indicates no clear influence of the scale of remediation activity and PHE enrichment factors for river sediments. It is suggested that whilst exemplars of significant successes at improving post-remediation river water quality can be identified; river sediment quality is a much more long-lasting environmental problem. In addition, it is suggested that improvements to river sediment quality do not occur quickly or easily as a result of remediation actions focused a specific mining point sources. Data indicate that PHEs continue to be episodically dispersed through river catchments hundreds of years after the cessation of mining activity, especially during flood flows. The high PHE loads of flood sediments in mining-affected river catchments and the predicted changes to flood frequency, especially, in many river catchments, provides further evidence of the need to enact effective mine remediation strategies and to fully consider the role of river sediments in prolonging the environmental legacy of historical mine sites.

Sediment quality assessment and dispersion pattern of toxic metals from brewery effluent discharged into the Olosun river, Nigeria

Sediment quality assessment of the Olosun river due to input from brewery effluent was investigated. Heavy metal components, organic carbon, and grain size properties of the sediments were used to determine the extent of contamination by brewery effluent. Sediment metal loadings at the effluent discharge points were generally not remarkable based on the comparison with the sediment quality guideline. Concentrations of Ni, Zn, Cr, Co, Cu, Cd and Pb at the discharge point were 10.4 ± 7.4, 118 ± 70, 24.8 ± 9.2, 6.8 ± 1.7, 12.7 ± 7.1, 0.35 ± 0.10 and 11.4 ± 4.7 mg/kg, respectively. There were, however, marked differences in the levels of Ni, Zn and Co between the downstream sediment and the natural background. This comparison of the characteristics of the contaminated downstream sediments to upstream sediment revealed anthropogenic input on the river traceable to the effluent input. Pollution load index of 1.53 is obtained indicating deterioration of the Olosun river sediment quality. Results of principal component analysis corroborated the effluent input as the major source of metals contamination of the sediment. A regression model was developed for each metal investigated expressing the metal concentration as a function of distance from the discharge point. The model related the observed metal concentrations with predicted metal concentrations, and described the dispersion pattern of the metals in the Olosun river sediment with R2 varying from 0.9360 (Cu) to 0.9999 (Cr). The proposed regression equations find relevance in the quest for sediment quality planning and pollutant’s prediction.

Concentrations of persistent organic pollutants and organic matter characteristics as river sediment quality indices

ABSTRACTSelected persistent organic pollutants – polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides – were determined in sediments, soils, and crops from the Asopos River area, Greece. The river has been receiving industrial effluents for the last 40 years and has been recently found to be polluted with metals. Sediments were collected in the dry (May) and wet (February) season. Agricultural soils and cultivated crops were sampled from adjacent fields. Polychlorinated biphenyls were below the limit of detection in all samples. In one tomato and two soil samples, DDT and DDE were found. Polycyclic aromatic hydrocarbons were observed in 5% of the sediments and in concentrations ranging from 4 to 57 μg kg−1 dry weight, quite below sediment quality guidelines. Diagnostic ratios of polycyclic aromatic hydrocarbons indicated a strong influence of petrogenic point discharges. In the sediments, silicate minerals dominate over carbonates and the organic carbon content ranges from 0.4% to 3.5%, more than 70% being of natural origin. Compared to other rivers worldwide, the Asopos River was found to be not contaminated with persistent organic pollutants. Point loadings of organic pollutants were evident but continuous discharge is not occurring throughout the river basin.

River sediments’ monitoring: impact of tannery discharges

Purpose – The tannery industry impacts strongly on water bodies due to the presence of chemical substances, such as chlorides, sulphates, chromium and other pollutants. This study has been carried out with a view to enhance the environmental compatibility of the Arzignano tannery district (northern Italy) which is the largest in Italy, by improving the quality of the Fratta-Gorzone River. Sediment quality, according to the driving forces-pressure-state-impact-response (DPSIR) scheme, has been developed as a significant impact indicator to be applied at basin level. The purpose of this paper is to discuss the above issues. Design/methodology/approach – Data were produced during institutional monitoring and control activities carried out by ARPAV (Veneto Region Environmental Prevention and Protection Agency) according to official methods. To define the environmental impacts on the river basin, a statistical assessment was performed on water and sediment quality data to establish the degree of correlation for the main pollutants along the river stem. Findings – In the basin considered, sediment quality presents high levels of contamination from heavy metals – in particular chromium (Cr) (III) – as well as organic pollutants. Investigation of the pressure sources revealed that the discharge from the Arzignano tannery district is the main source of Cr (III), according to background studies performed in the same area. Practical implications – The quality of river sediments must be improved in order to avoid the re-suspension/solubility of pollutants; dredged materials with high polluting substances must be managed with specific precautions in order to safeguard the environment. Originality/value – The river studied is currently the only significant water body in which sediment monitoring has been performed in the Veneto Region (Italy) since 2002. This study presents issues linked to the characterization of river sediment and the correlation between sediment quality and water pollution and prior and current pressure sources.

Relating taxonomy-based traits of macroinvertebrates with river sediment quality based on basic and zero-inflated Poisson models

To date, approaches in environmental risk assessment (ERA) are based on taxonomy-based descriptions of ecosystems. Due to the widespread occurrence of numerous types of chemicals in the environment and ensuing environmental risks, there is a need to get insight in the relationship between the response of the ecosystem to pollution and the characteristics (traits) of the organisms. The main hypothesis of the present research is that the trait composition of macroinvertebrate communities changes in a consistent manner along general environmental disturbance gradients. In this study, the relationship between maximal body length of macroinvertebrates and environmental variables (e.g. Cu concentration) reflecting river sediment quality in Flanders (Belgium) was analysed. It was found that the abundance at almost all body lengths decreased with a decreasing quality of the river sediment, which could be associated with a decrease in abundance of macroinvertebrate taxa. It was also observed that the number of different body lengths decreased with increasing pollution, which can be linked to a decrease in diversity of the macroinvertebrate community. At low levels of general environmental pollution especially small taxa (<20mm) experienced negative effects, but with increasing pollution also the abundance of larger taxa (>60mm) decreased. The trend observed for general environmental pollution was further analysed for specific types of metal contamination. Basic and zero-inflated Poisson models showed that with increasing copper pollution, the abundance of larger taxa quickly decreased and only relatively small taxa remained abundant. However, the observed trend was not generally applicable for all contaminants. The results of this research indicate that by using only individual metal concentrations it is not possible to explain the shifts in size distribution of macroinvertebrates. Including other environmental characteristics and other traits could enhance the understanding of how the macroinvertebrate community composition responds to environmental disturbances.

Integrated biological and chemical analysis of organochlorine compound pollution and of its biological effects in a riverine system downstream the discharge point

Pollution in riverine systems, along with its biological effects, may propagate downstream even at considerable distances. We analyzed the organochlorine compound (OC) pollution in a section of the low Ebro River (Northeast Spain) downstream a long-operating chlor-alkali plant. Maximal levels of OCs and of their associated dioxin-like biological activity occurred in residue samples from the plant, and persisted in river sediments some 40 km downstream (Xerta site). Biological analysis at multiple organization levels in local carp ( Cyprinus carpio, EROD, Cyp1A mRNA expression in the liver, hepatosomatic index, condition factor, and micronuclei index in peripheral blood) showed a similar pattern, with a maximal impact in Ascó, few kilometers downstream the plant, and a clear reduction at Xerta. This combination of chemical, molecular, cellular and physiological data allowed the precise assessment of the negative impact of the chlor-alkali plant on the quality of river sediments and on fish, and suggests that sediments may be a reservoir for toxic substances even in dynamic environments like rivers.

Evaluation of the Gravataí River sediment quality (Rio Grande do Sul- Brazil) using Daphnia magna (Straus, 1820) as the test-organism for toxicity assays

AIM: Persistent pollutants released to riverbeds return to the trophic system, damaging living organisms thereof. Ecotoxicological assays express the effect of environmental interactions with organisms found there. Assays were performed with microcrustacean Daphnia magna (Straus, 1820) in sediment samples, from the headwaters to the mouth, in order to evaluate the Gravatai River quality; METHODS: Bottom sediment was used to evaluate the responses of cladocerans to environmental changes in 15 samples collected between Jan./06 and May/09. The microcrustaceans were submitted to stress for 21 days from birth (2-26 hours old). Duncan Test, percentage survival, reproduction and Spearman Correlation were used to evaluate the quality of the sites; RESULTS: Duncan Test showed a significant difference (p < 0.05) in reproduction in 14 of the 15 samplings, and chronic action was more constant (88%) than the acute one (23%). Changes in survival and reproduction related to season or rainfall regime were only observed on a few occasions. The two sites located close to the mouth presented a Spearman Correlation (p < 0.01) for survival and reproduction. There were changes in some samplings in the headwaters as a result of sewage discharges in the area; CONCLUSIONS: Fluctuating responses were observed in this river due to anthropic contaminants, slow flux and current reflux.