Ecological Water Quality Research Articles

Adapting classical water quality diagrams for ecohydrological and policy applications

Ecological values of water have gained increasing attention over the past decades in both (eco)hydrological research and water resources management. Water quality is an important ecological steering variable, and graphical water quality diagrams may aid in rapid interpretation of the hydrochemical status of a site. Traditionally used water quality diagrams for showing multiple variables (e.g. Stiff, Maucha) were developed primarily for hydrogeological purposes, with limited information on ecologically relevant nutrient parameters.This paper presents adapted classical water quality diagrams that retain the traditional information on ions for hydrogeological characterization, and additionally provide information on nutrients for ecological water quality characterization.A scaling factor is used for the minor ions to visually get them across more equally compared to the macro-ion ions in the water quality diagram. Scaling of minor ions is presented based on average concentrations, as well as on water quality policy norms. Four different water quality diagrams are presented, all with the same ions included, but with different appearances to suit different preferences of individual users. Regional, national and continental scale data are used to illustrate how the different diagrams show spatial and temporal water quality characteristics.The adapted diagrams are innovative with respect to adding comprehensive visual information on the four ecohydrologically relevant nutrient species levels (NO3, NH4, PO4, K), advanced insight in redox status from the combination of four redox sensitive parameters (Fe, NO3, SO4, NH4) and the option to scale minor ions relative to average measured concentrations or to water quality policy norms. Using policy norms for scaling has the advantage of providing an ‘alarm function’ of exceedance of norms when concentrations surpass the ring used in the diagram. We discuss possible standardisation of scaling factors to enable comparability between sites.

Effects of Submerged Macrophyte Decomposition on Water Quality

Submerged macrophytes play an important role in aquatic ecosystems and are widely used in aquatic ecological restoration. However, when submerged macrophytes fade, litter, or even decompose, they may cause adverse effects on water quality. In this article, indoor experiments were carried out to study the quantitative influence of submerged plant decomposition on water quality. Six submerged macrophytes commonly used in aquatic ecological restoration in Sichuan Province, including Elodea canadensis Michx., Potamogeton wrightii Morong, Potamogeton crispus L., Vallisneria spinulosa, Ceratophyllum demersum L., and Potamogeton pectinatus L., were selected to measure the change processes of nutrients during macrophyte decomposition at 10°C, 20°C and 30°C. The results showed that the decomposition of submerged plants released nutrients into the water body, causing water pollution. At 10°C, the total phosphorus (TP) concentration of water bodies containing submerged plant litter increased by 1.97 to 5.97 times on the 50th day compared to the 5th day, while the TP concentration of the blank control group without hydrophytes decreased from 0.39 mg.L-1 to 0.22 mg.L-1 due to self-purification. The ammonia nitrogen (NH3-N) concentration increased by 3.82-9.58 times on the 50th day compared with the 5th day, while the value in the blank control group decreased from 1.42 mg.L-1 to 0.78 mg.L-1. This result indicated that the water body had a certain self-purification ability, but the decomposition of aquatic macrophytes had a negative impact on this progress. Increasing temperatures could accelerate plant decay processes. Initially, the concentrations of NH3-N and TP were high with high temperatures. After 45 days of reaction, the NH3-N and TP concentration in the water bodies appeared to be 30°C<20°C<10°C, indicating that decomposition was further advanced when the temperature was higher. This study provides a theoretical basis for water ecological management and water quality protection.

Determination of the ecological water quality in the Orienco stream using benthic macroinvertebrates in the Northern Ecuadorian Amazon.

In recent years, pollution of watercourses in nearby protected ecosystems has increased due to urbanization. Standard physiochemical methods and probes are one way to monitor watercourses for quality. However, they often do not provide the full ecological status of the body of water. In this work, we set out to assess the ecological water quality of an urban stream by using benthic macroinvertebrates as bioindicators. We conducted the work on the Orienco stream in Lago Agrio in the province of Sucumbíos in the Northern Ecuadorian Amazon (NEA). The stream has become a sink of raw domestic sanitary wastewater from rural and urban areas. A total of 4511 macroinvertebrates from 10 families were identified across 17 sampling points. We compared our results from the biotic indices derived from the macroinvertebrates to standard water-quality parameters (temperature, conductivity, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids, ammonia-nitrogen, and pH) simultaneously sampled in the stream. The standard parameter results indicated that the water-quality levels of the stream met the Ecuadorian water-quality criteria most of the time. However, the results from the biotic indices classified the stream water as poor or very poor water quality. The results from the Biological Monitoring Working Party, Average Score per Taxon, and Family Biotic Indices had overall scores of heavily polluted waters of 45, 4.5, and 8.74, respectively. Furthermore, these results were consistent with reduced richness and evenness, and overall lower Shannon diversity and relatively higher Simpson Dominance indices of 0.71 and 2.56, respectively. We conclude that the macroinvertebrates were better indicators of the ecological water quality of the Orienco stream than the water-quality parameters from standard methods and probes alone. Our findings highlight the need for more integrated ecological assessments, which can provide critical information to the management and conservation strategies of urban watercourses in the NEA region. Integr Environ Assess Manag 2023;19:615-625. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Synergic use of neural networks model and remote sensing algorithms to estimate water clarity indicators in Khanpur reservoir, Pakistan

Freshwater reservoirs are limited and facing issues of over-exploitation, climate change effects and poor maintenance which have serious consequences for water quality. Developing countries face the challenge of collecting in situ information on ecological status and water quality of these reservoirs due to constraints of cost, time and infrastructure. In this study, a practical method of retrieval of two water clarity indicators, total suspended matter and secchi disk depth, using Sentinel-2 satellite data is adopted for preliminary assessment of water quality and trophic conditions in Khanpur reservoir, Pakistan. The study explores the synergy of utilizing two independent models, i.e., case 2 regional coast color analytical neural network model and semiempirical remote sensing algorithms to understand the spatiotemporal dynamics of water clarity patterns in the dammed reservoir, in the absence of ground measurements. The drinking water quality and trophic state of the reservoir water is determined based purely on satellite measurements. Out of the five months studied, the reservoir water has high turbidity and poor eutrophic status in three months. The results from both computational models are compared, which exhibit a high degree of statistical agreement. The study demonstrates the effective utilization of relevant analytical and semiempirical methods on satellite data to map water clarity indicators and understand their dynamics in both space and time. This solution is particularly useful for regions where routine ground sampling and observation of environmental variables are absent.

Physicochemical characterization of the waters of the Lep'oo river in Mbanda (Bot-Makak) and structuring of the benthic macroinvertebrate community

A study on the characterisation of the Lep'oo stream waters in Mbanda (BotMakak) by physicochemical parameters and benthic macroinvertebrates community was conducted from February to July 2016. Physicochemical parameters were measured according to Rodier's recommendations, while benthic macroinvertebrates were collected using the multihabitat approach. The physicochemical analysis showed that the waters of the Lep'oo stream were well oxygenated (71.16%), slightly acidic (6.36 UC), with low values of nitrogen and orthophosphates reflecting litter decomposition. A total of 2019 benthic macroinvertebrates were collected, divided into 4 phyla, 7 classes, 15 orders, 40 families and over 60 genera. The phylum Arthropoda was the most abundant with 98.61% relative abundance, followed by Molluscs (0.99%) and Annelids (0.29%). The greatest number of organisms collected belonged to the class Hexapoda, which represented 56.76% of relative abundance, followed by Malacostraca (41.75%). Within the Hexapoda class, the order Hemiptera predominated with 18.22% relative abundance and in the Malacostraca class, the order Decapoda predominated with 41.75% relative abundance. These two orders were dominated by the families Atyidae, Libellulidae, Gerridae, Leptophlebidae and Hydroptilidea. In the upper part of the Lep'oo stream, the families Libellulidae and Belostomatidae were dominant. The station Lep2 was most colonised by the families Atyidae, Libellulidae, Belostomatidae, Hydrometridae, and Gerridae, while station Lep3 was dominated by the families Atyidae, Hydroptilidae and Leptophlebidae. The Shannon and Weaver (H') and Piélou equitability (J) index showed a greater diversity of taxa downstream of the stream at station Lep3, where conditions seem more favourable to the development of benthic macroinvertebrates as indicated by the physicochemical results. The NGBI index characterized water quality from mediocre to excellent. Finaly, the Lep'oo watercourse had a poor and diversified population of benthic macroinvertebrates, showing a relative good ecological quality of water.

Elemental composition and microbial decomposition of different angling baits

AbstractRecreational fishing, through groundbaiting, provides a potentially important trophic subsidy to freshwater ecosystems that could promote eutrophication. To date, our understanding of the role of bait properties on their fate when they are not consumed remains limited. The present study aimed to determine if the C:N:P composition of some of the most commonly used angling baits modulated microbial decomposition. The C:N:P composition of 28 models of four commercially available angling baits was assessed and a microcosm experiment was used to quantify microbial decomposition. Elemental composition strongly varied among angling baits, with N content varying by a factor of three and P content varying by a factor of five. Microbial decomposition of angling baits was highly variable and faster for more industrialised baits. Microbial decomposition was five times faster for angling baits rather than natural subsidies (leaves) and was not significantly correlated with high N or P content. Compared to natural subsidies, angling baits were a favourable substrate for bacterial growth. Angling baits represent a source of highly available nutrients and the most‐enriched angling baits might affect ecological processes and water quality in ecosystems with high angling pressure, especially when their use is not regulated.

A systematic study of zooplankton-based indices of marine ecological change and water quality: Application to the European marine strategy framework Directive (MSFD)

• An indicator-metrics-index framework was used to minimize ambiguity. • Additional frameworks were developed to synthesize existing zooplankton indices. • Several biodiversity and pressure indices were identified and critically appraised. • Application of zooplankton indices to the EU-MSFD was elucidated. • Challenges of zooplankton indices development and use were highlighted. Marine zooplankton are central components of holistic ecosystem assessments due to their intermediary role in the food chain, linking the base of the food chain with higher trophic levels. As a result, these organisms incorporate the inherent properties and changes occurring atall levels of the marine ecosystem, temporally integrating signatures of physical and chemical conditions. For this reason, zooplankton-based biometrics are widely accepted as useful tools for assessing and monitoring the ecological health and integrity of aquatic systems. The European Marine Strategy Framework Directive (EU-MSFD) requires the use of different types of bio-monitors, including zooplankton, to monitor progress towards achieving specific environmental and water quality targets in EU. However, there is currently no comprehensive synthesis of zooplankton indices development, use, and associated challenges. We addressed this issue with a two-step approach. First, we formulated the indicator-metrics-indices cycle (IMIC) to redefine the closely related but often ambiguously utilized terms - indicator, metric and index, highlighting the convergence between them and the iterative nature of their interaction. Secondly, we formulated frameworks for synthesizing, presenting and systematically applying zooplankton indices based on the IMIC framework. The main benefits of the IMIC are twofold: 1). to disambiguate the key elements: indicators, metrics, and indices, revealing their links to an operational ecological indicator system, and 2) to serve as an organizing tool for the coherent classification of indices according to the MSFD descriptors. Using the IMIC framework, we identified and described two broad categories of indices namely the core biodiversity indices already in use in the Baltic Sea and North Atlantic regions, including the ‘Zooplankton Mean Size and Total Stock (zooplankton MSTS)’ and 'Plankton Lifeforms index (PLI)', and stressor-response indices retrieved from the existing literature, elucidating their applicability to different MSFD descriptors. Finally, major challenges of developing new indices and applying existing ones in the context of the MSFD were critically addressed and some solutions were proposed.

Spatio-Temporal Dynamics in Physico-Chemical Properties, Phytoplankton and Bacterial Diversity as an Indication of the Bovan Reservoir Water Quality

The study aimed to investigate the physico-chemical properties as well as phytoplankton and bacterial community diversity of Bovan Lake reservoir in Serbia to gain insight into the seasonal dynamic of water quality. All analyses were performed at three localities and water depths in spring, summer, autumn, and winter 2019. Seven phytoplankton phyla comprising 139 taxa were detected at all three localities (Chlorophyta 58%, Bacillariophyta 14%, Cyanobacteria 9%, Chrysophyta 5%, Dinophyta 5%, Euglenophyta 5%, and Cryptophyta 4%). Winter 2019 was characterized by the presence of 36 unique species in all phyla except Euglenophyta. Bacterial diversity analyses showed that Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Verrucomicrobia dominated the water intake locality at all three water depths (0.5, 10, and 20 m below the surface). In general, the physico-chemical parameters, phytoplankton, and bacterial community composition depended on the season and the water depth and showed that Bovan Lake was of satisfactory ecological status and water quality at all localities, and meets the needs for all intended purposes.

The relevance of European Biota Quality Standards on the ecological water quality as determined by the multimetric macro-invertebrate index: A Flemish case study

European Biota Quality Standards (EQSbiota), for compounds with low water solubility and high biomagnification, were created to sustain water quality and protect top predators and humans from secondary poisoning. In reality, for multiple compounds, an exceedance of these standards is often reported in literature without a decrease in ecological water quality determined by biotic indices. In the present study, threshold concentrations were defined in biota (from 44 sampling locations throughout Flanders (Belgium)), above which a good ecological water quality, assessed by the Multimetric Macroinvertebrate Index Flanders (MMIF), was never reached. Threshold values were compared to current EQSbiota. Accumulated perfluoroctane sulfonate (PFOS), mercury (Hg), hexabromocyclododecane (HBCD), polybrominated diphenyl ethers (PBDEs), dioxins and polychlorinated biphenyls (PCBs) concentrations were measured in muscle tissue of European yellow eel (Anguilla anguilla) and perch (Perca fluviatilis). Fluoranthene and benzo(a)pyrene were also analyzed in translocated mussels (Dreissena bugensis, D. polymorpha and Corbicula fluminea). Threshold values could only be calculated using a 90th quantile regression model for PFOS (in perch; 12 µg/kg ww), PCBs (in eel; 328 µg/kg ww) and benzo(a)pyrene (in mussels: 4.35 µg/kg ww). The lack of a significant regression model for the other compounds indicated an effective threshold value higher than the concentrations measured in the present study. Alternatively, the 95th percentile of concentrations measured in locations with a good ecological quality (MMIF≥0.7), was calculated for all compounds as an additional threshold value. Finally, fish concentrations were standardized for 5% lipid content (or 26% dry weight content for PFOS and Hg). Threshold values for PFOS and benzo(a)pyrene and the 95th percentiles for dioxins and fluoranthene were comparable to the existing standards. For all other compounds, the 95th percentile was higher than the current EQSbiota, while for HBCD, it was lower. These results strongly advise revising and fine-tuning the current EQSbiota, especially for ∑PBDE and HBCD.

Chemical and ecological quality of water and bottom sediments in small rivers of Belgorod oblast

Belgorod Oblast has limited water resources. The paper explores the chemical and ecological characteristics of water and bottom sediments in the Oskol River tributaries. In samples of water taken from small rivers, Maximum Allowable Concentrations (MAC) for pollutants was excessive, including suspended matter, ammonium ions, nitrite ions, phosphate ions, BOD5 and mineral elements. A hydrochemical water pollution index (WPI6) ranges from 1.0 to 1.9, which characterizes water bodies in the categories from clean to moderately polluted watercourses. A comparatively high WPI6 index is recorded in summer for the Kotel River – 1.4, for the Belenkaya River – 2.3, which is attributed to a high concentration of ammonium ions, nitrites and phosphates found to be present in the water. This indicates recent pollution and a changing trophic status of the reservoir. The amount of metals in river water exceeds the MAC norms: for iron – 1.7 -6 MAC; for copper – 1.6 - 8 MAC; for manganese – 0.8 - 22 MAC; for zinc – 1.9 - 9.9 MAC. Concentrations of micronutrients are subject to significant seasonal fluctuations. No excess of lead is found to be present in surface waters. In the samples of bottom sediments taken from the Oskol River tributaries, no excess of MAC values is found, except for lead (1.1 - 2.9 MAC), manganese (1.6 - 2.2 MAC), copper (1.2 - 1.6 MAC) and phosphate ions (1.3 - 2.3 MAC). It is obvious that the sources of pollution for small rivers are runoffs from agricultural land, livestock farms and household wastewater of nearby settlements.

Assessment of the ecological state and quality of spring waters in West Kazakhstan, taking into account the risk to the population

Drinking water is the most important factor that has a direct impact on human health. The population quite often uses spring water as drinking water. Groundwater, like surface one, is largely subject to anthropogenic impact, which negatively affects water quality. Substandard water can pose a health risk to consumers. In this connection, it is advisable to study and assess the quality of groundwater, since monitoring studies allow one to establish the fact and cause of changes in water quality, to take timely measures to eliminate the adverse pollution effects. The article presents the results of a study of the ecological state and quality of water in 40 springs of West Kazakhstan in terms of hydrochemical and toxicological indicators. In the water of most springs, the standards for pH, ammonium, turbidity, chloride ions, sulfate ions, magnesium, total hardness, permanganate oxidizability, dry residue and total mineralization, cadmium, iron, chromium, manganese, nickel, oil products, phenols are exceeded. The calculation of the magnitude of the non-carcinogenic risk to public health made it possible to establish that the majority of springs have an unacceptable level of organoleptic risk for the population. The water of the springs Taskala-3, No. 2 (near Krutoy), No. 1 (in Krutoy) is safe and can be used by local residents for cultural and domestic purposes.

Human Fecal Contamination Corresponds to Changes in the Freshwater Bacterial Communities of a Large River Basin.

ABSTRACTMicrobial water quality is generally monitored by culturable fecal indicator bacteria (FIB), which are intended to signal human health risk due to fecal pollution. However, FIB have limited utility in most urbanized watersheds as they do not discriminate among fecal pollution sources, tend to make up a small fraction of the total microbial community, and do not inform on pollution impacts on the native ecosystem. To move beyond these limitations, we assessed entire bacterial communities and investigated how bacterial diversity relates to traditional ecological and human health-relevant water quality indicators throughout the Milwaukee River Basin. Samples were collected from 16 sites on 5 days during the summer, including both wet and dry weather events, and were processed by 16S rRNA gene amplicon sequencing. Historical water quality at each sampling location, as opposed to upstream land use, was associated significantly with bacterial community alpha diversity. Source partitioning the sequence data was important for determining water quality relationships. Sewage-associated bacterial sequences were detected in all samples, and the relative abundance of sewage sequences was strongly associated with the human Bacteroides fecal marker. From this relationship, we developed a preliminary threshold for human sewage pollution when using bacterial community sequence data. Certain abundant freshwater bacterial sequences were also associated with human fecal pollution, suggesting their possible utility in water quality monitoring. This study sheds light on how bacterial community analysis can be used to supplement current water quality monitoring techniques to better understand interactions between ecological water quality and human health indicators.IMPORTANCE Surface waters in highly developed mixed-use watersheds are frequently impacted by a wide variety of pollutants, leading to a range of impairments that must be monitored and remediated. With advancing technologies, microbial community sequencing may soon become a feasible method for routine evaluation of the ecological quality and human health risk of a water body. In this study, we partnered with a local citizen science organization to evaluate the utility of microbial community sequencing for identifying pollution sources and ecological impairments in a large mixed-use watershed. We show that changes in microbial community diversity and composition are indicative of both long-term ecological impairments and short-term fecal pollution impacts. By source partitioning the sequence data, we also estimate a threshold target for human sewage pollution, which may be useful as a starting point for future development of sequencing-based water quality monitoring techniques.

Ecological and health risk assessments and water quality criteria of heavy metals in the Haihe River

Heavy metal pollution is an issue of wide concern owing to the toxic and bioaccumulative properties of many heavy metals and their tendencies to persist in the environment. The Haihe River is an important river in the Beijing–Tianjin–Hebei region, and heavy metal pollution of the basin has attracted considerable attention. This study determined the concentrations of 14 heavy metals (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, and Zn) in water, sediments, and fish samples from the Haihe River basin. The results showed that the concentrations ranged from 0.08 μg L−1 to 60.49 μg L−1 in water, 0.11 mg kg−1 to 229.20 mg kg−1 in sediments, and 0.01 mg kg−1 to 11.72 mg kg−1 in fish. We derived the ambient water quality criteria (AWQC) value of each heavy metal with respect to human health, and then performed a comprehensive risk assessment according to the native parameters. The human health AWQC values for the assessed 14 heavy metals ranged from 0.16 μg L−1 to 726.53 μg L−1. The health risks posed by As, Cr, Hg, and Sb and the ecological risks associated with Ni, Cu, Cr, Zn, Cd, Co, Hg, and Sn were found to be issues of concern. The results of a sensitivity analysis revealed that the highest contributing parameter was i) the concentration in water (Cw) for Cd, Co, Mn, Sb, and Sn; ii) the intake rate of water (IRw) for As, Ba, Cr, Hg, Ni, Pb, and Se; and iii) the concentration in fish (Cf) for Cu and Zn. The results of this research could contribute to the information required for water quality assessments and the development of water quality standards.

The neglected zooplankton communities as indicators of ecological water quality of Mediterranean lakes

The neglected zooplankton communities as indicators of ecological water quality of Mediterranean lakes

Through the dam into troubled waters: Combined effects of stream fragmentation, habitat deterioration, and poor water quality on lowland stream fish distribution

AbstractThis study aimed to distinguish the contribution of stream fragmentation and poor habitat and water quality to the decline in riverine fish species. The species presence was related to the number of barriers between a specific lowland stream section and the main river and to the length of the stream section remaining between two barriers. To investigate the relationship between the absence of fish species and poor ecological water quality, the EQR and stream velocity indices were compared between accessible sites where the fish was either present or absent. 79% of the 1039 km lowland stream length was disconnected from the river Meuse by one or more barriers and 34% by more than 5 barriers, while 28% of all stream sections were shorter than 2.5 km. Only 2% of sites scored a very good water quality, while all study sites were characterized by (very) slow flowing waters (<0.15 m/s). As many fish passages are built to improve connectivity, fish passages do not improve habitat quality. Gudgeon and stone loach were hardly affected by stream fragmentation, and only slightly by too short stream sections. Ide was moderately affected, while the migratory species chub and dace were severely affected by stream fragmentation. Chub and dace were also sensitive to poor habitat and water quality. Distinguishing the effects of stream fragmentation, habitat deterioration, and poor water quality on lowland stream fish distribution increased the understanding of the reasons for the presence and absence of species and may aid effective management and restoration efforts.

Forests protect aquatic communities from detrimental impact by volcanic deposits in the tropical Andes (Ecuador)

Volcanic activity impacts ecosystems sometimes with multiple, complex and long-lasting consequences, including volcanic tephra (airborne material) causing widespread disruptions. We study the effects of tephra deposition around two tropical lakes of Ecuador using a multi-proxy analysis of lake sediment archives spanning the last 2000 years. We present the dynamics of terrestrial vegetation (pollen), aquatic macroinvertebrate fauna (chironomids) and organic matter (stable isotopes) in: (i) a high elevation, stream-connected, open alpine grassland (Andean páramo) and (ii) a mid-elevation, stream-isolated, pre-montane forest. Páramo vegetation showed a slight increase in herbs and quick recovery after the tephra deposition; however, the aquatic community suffered a regime shift not reversed today c. 1500 years after the event. In the pre-montane location, the canopy opened up following tephra deposition, and it took c. 150 years to return to pre-impact levels. At the forested site, no major changes in the aquatic fauna were observed related to the tephra deposition. We hypothesise that the forest acted as a protective barrier preventing a large fallout of ash into the aquatic system. Forest not only acted as a buffer for ash falling into the water from the air, but also prevented landslides of tephra by enhancing soil stability, contrary to what was observed in the open system. We demonstrate the protective ecosystem service that forests play in sustaining ecological resilience and water quality facing natural (volcanic) disturbance. The ongoing deforestation of tropical regions therefore might increase the vulnerability of aquatic ecosystems, threatening the water quality for ecosystems and human populations.

Change in ecological water quality of West Dvina River under the impact of urban waste water

In determining the quality of surface waters and, first of all, rivers, along with physical and chemical pollution, the analysis of the hydrobiological component of river ecosystems is becoming increasingly important. The aim of the work was to assess the ecological quality of the river ecosystems from the impact of wastewater discharge from the cities of Vitebsk, Polotsk and Novopolotsk on the Western Dvina River based on the macrozoobenthos community. The studied river sections are inhabited by rare for Belarus and protected in Europe species of aquatic organisms. A relatively high abundance (from 30 to 80 %) of the group of rheophilic species Plecoptera, Ephemeroptera, and Trichoptera was noted, which represent the three highest priority indicator groups of aquatic organisms. Biotic indices and the water purity class of the r. Western Dvina were determined. In accordance with the EU Water Framework Directive, the water purity class at the studied stations has a good and high value. It is concluded that the negative impact of wastewater from the cities of Vitebsk, Polotsk and Novopolotsk has a very local significance and weakly affects the biota and the ecological quality of the water of the Western Dvina River already at a distance of 18 km. below the discharge of water from the treatment facilities of the Novopolotsk refinery.

Smart Nutrient Retention Networks: a novel approach for nutrient conservation through water quality management

ABSTRACT Nutrients are essential resources for food production but are used inefficiently, and thereby they pollute inland and coastal waters and are lost into the oceans. Nutrient conservation by retention and consecutive reuse would prevent nutrient losses to the atmosphere and downstream ecosystems. We present Smart Nutrient Retention Networks (SNRNs) as a novel management approach to achieve nutrient conservation across networks of connected waterbodies through strategic water quality management. To present the key features of SNRNs, we review existing knowledge of nutrient retention processes in inland waters, water quality management options for nutrient conservation, and nutrient retention models to develop SNRNs. We argue that successful nutrient conservation, even at a local level, through SNRN management strategies requires clearly formulated goals and catchment-wide system understanding. Waterbody characteristics, such as hydraulic residence time and the presence of macrophytes, shape local nutrient retention with potential network-wide cascading effects of improved water quality and are therefore key targets of SNRN management strategies. Nutrient retention models that include the self-reinforcing feedback loop of ecological water quality, nutrient retention, and nutrient loading in networks of inland waters in relation to management options can support the development of SNRNs. We conclude that SNRNs can contribute to sustainable use of nutrients in human food production.

Estimating species sensitivity distributions on the basis of readily obtainable descriptors and toxicity data for three species of algae, crustaceans, and fish.

Estimation of species sensitivity distributions (SSDs) is a crucial approach to predicting ecological risks and water quality benchmarks, but the amount of data required to implement this approach is a serious constraint on the application of SSDs to chemicals for which there are few or no toxicity data. The development of statistical models to directly estimate the mean and standard deviation (SD) of the logarithms of log-normally distributed SSDs has recently been proposed to overcome this problem. To predict these two parameters, we developed multiple linear regression models that included, in addition to readily obtainable descriptors, the mean and SD of the logarithms of the concentrations that are acutely toxic to one algal, one crustacean, and one fish species, as predictors. We hypothesized that use of the three species’ mean and SD would improve the accuracy of the predicted means and SDs of the logarithms of the SSDs. We derived SSDs for 60 chemicals based on quality-assured acute toxicity data. Forty-five of the chemicals were used for model fitting, and 15 for external validation. Our results supported previous findings that models developed on the basis of only descriptors such as log KOW had limited ability to predict the mean and SD of SSD (e.g., r2 = 0.62 and 0.49, respectively). Inclusion of the three species’ mean and SD, in addition to the descriptors, in the models markedly improved the predictions of the means and SDs of SSDs (e.g., r2 = 0.96 and 0.75, respectively). We conclude that use of the three species’ mean and SD is promising for more accurately estimating an SSD and thus the hazardous concentration for 5% of species in cases where limited ecotoxicity data are available.

Water Ecosystem Service Quality Evaluation and Value Assessment of Taihu Lake in China

Taihu Lake is the third largest freshwater lake in China. Water ecosystems play an important role in the survival and development of human society. The evaluation of water ecosystem services is helpful to understand and grasp the changing rules of Taihu Lake’s ecosystem services value in recent years. First, we used the Water Environment Qualities Index (WQI) to evaluate the water ecological quality of Taihu Lake; second, on the basis of the survey data from 2010 to 2018, we combined economic and ecological methods to evaluate the water ecosystem of Taihu Lake. The evaluation system includes four major service functions, 11 second-class evaluation indicators and 19 index factor. Research indicates that, (1) in the past 8 years, the WQI of Taihu Lake increased year by year and Taihu Lake changed from moderate pollution to light pollution; (2) provisioning services are the main service of Taihu Lake’s water ecosystem and the order of various service values was provisioning service value > regulation service value > cultural service value > support service value, with water supply as the core function of provisioning services; and (3) the total values in 2010, 2014, and 2018 were 115.39 billion yuan, 113.31 billion yuan, and 119.96 billion yuan, respectively, showing a trend of first decreasing and then increasing. To a certain extent, the improvement in Taihu Lake’s water ecological quality has led to an increase in the value of regulation services.