Environmental Water Quality Research Articles

Change of drinking water quality in Shijiazhuang South-to-North Water Diversion area from 2014 to 2021

To analyze the change of drinking water quality in the receiving area of Shijiazhuang South-to-North Water Transfer Project. 2029 monitoring data of drinking water in the receiving areas of the South-to-North Water Transfer Project in Shijiazhuang from 2014 to 2021 were collected and collated according to the Sanitary Standard for Drinking Water(GB 5749-2006). Off-work water and pipe water before and after the total coliform group of South-to-North Water Transfer Project, heat-resistant coliform bacteria, escherichia coli, the total number of colonies, arsenic, cadmium, chromium, lead, mercury, nitrate, fluoride, selenium, cyanide, chloroform, carbon tetrachloride, chromaticity and turbidity, odor and taste, visible to the naked eye, pH, aluminum, iron, manganese, copper, zinc, chloride, sulfate, total soluble solids, total hardness, oxygen consumption, volatile phenols, anionic synthetic detergent, ammonia nitrogen, residual chlorine and chlorine dioxide were evaluated and compared. χ~2 test was used to compare the qualified rate, Mann-Whitney rank sum test was used to compare the test values of each index, and simple superposition comprehensive water environmental quality index method was used to evaluate the water quality comprehensively. Before the South-to-North Water Transfer Project, the total qualified rate of drinking water was 84.21%, that of factory water was 81.29%, and that of end water was 85.97%. The total qualified rate of drinking water after the South-to-North Water Transfer Project was 98.72%, that of factory water was 98.89%, and that of end water was 98.66%. The total qualified rate of water quality, the qualified rate of factory water and the qualified rate of end water after the South-to-North water transfer were higher than those before the transfer(P<0.05). The qualified rates of microbial indexes and total hardness of ex-factory water before the South-to-North Water Transfer Project were 94.37% and 89.94%, and those of microbial indexes and total hardness of end water were 94.32% and 93.35%, respectively. After the South-to-North Water Transfer, the qualified rates of microbial indexes and total hardness of the ex-factory water were 100.00% and 98.90%, and the qualified rates of microbial indexes and total hardness of the end water were 100.00% and 99.24%, respectively. After the South-to-North water transfer, the qualified rate of microbial indexes and total hardness of factory water and peripheral water were higher than those before the transfer(P<0.05). After the South-to-North Water Transfer, the M of total coliform group, total colony number, total hardness, fluoride, nitrate nitrogen, chloride, sulfate and dissolved total solids were lower than those before water transfer(For example, the median number of colonies and total hardness of factory water before the South-to-North Water Transfer were 20.00 CFU/100 mL and 248.00 mg/L, respectively. After the South-to-North Water Transfer, the median number of colonies and total hardness were 1.00 CFU/100 mL and 129.00 mg/L, respectively), while the M of trichloromethane, aluminum, pH and oxygen consumption were higher than those before water transfer(For example, the median of trichloromethane and aluminum before the South-to-North Water Transfer is 0.04×10~(-2) and 0.04×10~(-1) mg/L, respectively. After the South-to-North Water Transfer, the median of chloroform and aluminum were 0.06×10~(-2) and 0.25×10~(-1) mg/L, respectively)(P<0.05). The median WQI of comprehensive water environmental quality index before and after the South-to-North Water Transfer was 4.58 and 2.37(P<0.05), respectively. The introduction of the South-to-North Water Transfer has significantly improved the quality of drinking water in Shijiazhuang city. Microbial contamination and total hardness exceedance have been greatly improved.

The Main Problems of the Water Ecological Environment and Protective Countermeasures in the River Basin of the Altay Region, Xinjiang

This study systematically sorted out the situation of the water ecological environment in the river basins of the Altay region, and analyzed the main problems that exist concerning water environmental quality, water ecology, water resources, and other aspects. The Altay region has three major river systems: the Irtysh River, the Ulungur River and the rivers of Jimunai County. The water environmental quality of major rivers in the region remained stable, and the total amount of water resources in the Altay region is at the forefront of Xinjiang. However, insufficient ecological flow in the Altay basin, serious water ecological damage and water environmental risks are still prominent. Based on the main problems which were identified and the distribution of the river system, the Altay region would be divided into four areas: the Irtysh River Basin, the Ulungur River Basin, the river basins of Jimunai County, and the desert control unit in the south, and the four areas was divided into eleven water ecological environment control units. In order to provide scientific and technological support for the improvement of the water ecological environmental quality of the river basins in the Altay region, general ideas and countermeasures are put forward for protecting the water ecological environment of the river basin from the three aspects of enhancing water pollution prevention and control, strengthening the protection of water resources, and reinforcing water ecological protection and restoration.

The Migration Rules of Malathion during Indoor Simulated Lake Freezing.

The effect of malathion in ice is a poorly researched area, and ice is an important habitat for organisms at the base of the food web. This study presents laboratory-controlled experiments designed to investigate the migration rule of malathion during lake freezing. Concentrations of malathion were determined in samples of melted ice and in under-ice water. The effects of the initial sample concentration, freezing ratio, and freezing temperature on the distribution of malathion in the ice-water system were investigated. The concentration effect and migration capacity of malathion during freezing was characterized by the concentration rate and distribution coefficient. The results showed that the formation of ice led to the concentration of malathion appearing as follows: concentration in under-ice water > concentration in raw water > concentration in ice. This implied that malathion tended to migrate from the ice to the under-ice water during the freezing process. The increase in the initial malathion concentration, freezing ratio, and freezing temperature caused a more pronounced repulsion of the malathion by the ice and increased the migration to the under-ice water. When the solution of malathion with an initial concentration of 50 μg/L was frozen at -9 °C and the freezing ratio reached 60%, the concentration of malathion in the under-ice water was concentrated to 2.34 times the initial concentration. The migration of malathion to under-ice water during freezing may pose a potential threat to under-ice ecology; therefore, the environmental quality and impact of under-ice water in icebound lakes needs to be given more attention.

Analysis of changing trend of water resources and water environment quality in china from 2009 to 2019

Based on the statistical analysis of China Water Resources Bulletin, China environmental situation Bulletin and national environmental statistics yearbook during 2008-2019, we summarized the water resources and water environment quality of seven major basins, and the proportion, main pollutants and change trend of various types of water quality are discussed. Meanwhile, wastewater discharge and pollution discharge are also analyzed. The results show that in the recent years, the overall water environment quality in China is improving, but the overall water environment quality is still not optimistic. Water resources are not only the basis for human survival and development, but also a strategic resource for the development of the national economy. According to the <<World Water Development Report 2018>> issued by the United Nations, the current global water demand is increasing at a rate of 1% per year. This demand will continue to increase, and my country's water resources are even scarcer, and the per capita consumption is only 1/4 of the global average. In the face of this situation, understanding the state and changing trends of my country's water resources and water environment, and putting forward targeted resource conservation and pollution control measures are of great significance to alleviating the problem of my country's water shortage.

Forest buffer-strips mitigate the negative impact of oil palm plantations on stream communities

The global area cultivated with oil palm has doubled in the past two decades, causing deforestation, land-use change, freshwater pollution, and species loss in tropical ecosystems worldwide. Despite the palm-oil industry been linked to severe deterioration of freshwater ecosystems, most studies have focused on terrestrial environments, while freshwaters have been significantly less studied. We evaluated these impacts by contrasting freshwater macroinvertebrate communities and habitat conditions in 19 streams from primary forests (7), grazing lands (6), and oil palm plantations (6). In each stream, we measured environmental characteristics, e.g., habitat composition, canopy cover, substrate, water temperature, and water quality; and we identified and quantified the assemblage of macroinvertebrates. Streams in oil palm plantations lacking riparian forest strips showed warmer and more variable temperatures, higher turbidity, lower silica content, and poorer macroinvertebrate taxon richness than primary forests. Grazing lands showed higher conductivity and temperature, and lower dissolved oxygen and macroinvertebrate taxon richness than primary forests. In contrast, streams in oil palm plantations that conserved a riparian forest, showed a substrate composition, temperature, and canopy cover more similar to the ones in primary forests. These habitat improvements by riparian forests in the plantations increased macroinvertebrate taxon richness and maintained a community resembling more the one in primary forests. Therefore, the conversion of grazing lands (instead of primary forests) to oil palm plantations can increase freshwater taxon richness only if riparian native forests are safeguarded.

Innovative electrochemical biosensor with nitrifying biofilm and nitrite oxidation signal for comprehensive toxicity detection in Tuojiang River

Water toxicity detection, as a valuable supplement to conventional water quality measurement, is an important method for evaluating water environmental quality standards. However, the toxicity of composite pollutants is more complicated due to their mixture effects. This study developed a novel, rapid and interference-resistant detection method for water toxicity based on an electrochemical biosensor using peak current from nitrite oxidation as a signal. Toxicants could weaken the characteristic peak current of nitrite to indicate the magnitude of toxicity. The proof-of-concept study was first conducted using a synthetic water sample containing trichloroacetic acid (TCAA), and then the results were compared with those of the traditional toxicity colorimetric method (CCK-8 kit) and laser confocal microscopy (CLSM). The accuracy of the biosensor was further verified with water samples containing individual pollutants such as Cd2+ (50–150 μg/L), Cr6+ (20–80 μg/L) mixture, triclosan (TCS; 0.1–1.0 μg/L) and TCAA (10–80 μg/L), or a mixture of the above. The viability of the sensor was further validated with the actual water sample from the Tuojiang River. The results demonstrated that although the concentration of a single conventional pollutant in water did not exceed the discharge standard for surface water, the comprehensive toxicity of natural water should not be ignored. This method could be a beneficial supplement to conventional water quality detection to understand the characteristics of the water, and thus contribute to the next stage of water treatment.

Water Environment Characteristics and Water Quality Assessment of Water Source of Diversion System of Project from Hanjiang to Weihe River

The water source of the water diversion project from the Hanjiang River to the Weihe River is one of the most important drinking water sources in China. Its water quality is related to the water safety of the long-distance water diversion system from the Hanjiang to Weihe Rivers. In order to explore the spatiotemporal change trend of the water environment characteristics of the water source area and analyze the key factors that have a greater impact on it, this study collected 9 types of water environment physical and chemical parameters from 10 water quality monitoring sections from 2017 to 2019; the water environment characteristics of the water source area of the water diversion system from the Hanjiang River to the Weihe River were analyzed and evaluated by using the variance analysis method, the hierarchical cluster analysis method and the water quality identification index evaluation method. The results were as follows. (1) There was spatiotemporal heterogeneity in a number of physical and chemical parameters in the water body of the water source. In terms of time, the concentrations of CODMn, COD, BOD5 and F- were higher in the flood season (July-October) than in the non-flood season (November-June). The concentrations of DO, TP and TN in the non-flood season were higher than those in the flood season. Spatially, the concentration of physical and chemical parameters of the water body in the Huangjinxia Reservoir area was higher than that in the Sanhekou Reservoir area. (2) The water quality of the water source area was good. The comprehensive water quality reached the Class II water quality standard of surface water environmental quality. Time showed that the comprehensive water quality in the non-flood season was better than that in the flood season. Spatially, the overall water quality of the tributaries was better than that of the mainstream. TN is a key indicator that affects water quality. (3) The spatial and temporal differences in water quality in water source areas are mainly affected by factors such as rainfall, temperature and human activities. This study can provide a scientific and data basis for related research on maintaining and improving the quality of the ecological environment of the water source areas of the Hanjiang to Weihe River Water Diversion System.

Recent advances in constructed wetlands methane reduction: Mechanisms and methods.

Constructed wetlands (CWs) are artificial systems that use natural processes to treat wastewater containing organic pollutants. This approach has been widely applied in both developing and developed countries worldwide, providing a cost-effective method for industrial wastewater treatment and the improvement of environmental water quality. However, due to the large organic carbon inputs, CWs is produced in varying amounts of CH4 and have the potential to become an important contributor to global climate change. Subsequently, research on the mitigation of CH4 emissions by CWs is key to achieving sustainable, low-carbon dependency wastewater treatment systems. This review evaluates the current research on CH4 emissions from CWs through bibliometric analysis, summarizing the reported mechanisms of CH4 generation, transfer and oxidation in CWs. Furthermore, the important environmental factors driving CH4 generation in CW systems are summarized, including: temperature, water table position, oxidation reduction potential, and the effects of CW characteristics such as wetland type, plant species composition, substrate type, CW-coupled microbial fuel cell, oxygen supply, available carbon source, and salinity. This review provides guidance and novel perspectives for sustainable and effective CW management, as well as for future studies on CH4 reduction in CWs.

A Study on Paldang Reservoir Water Quality Improvement Effect by Pollutant Source Location Regulation Using Watershed-Reservoir Integrated Prediction

Objectives:Since the enactment of the 「Han-River Watershed Act」, comprehensive analysis about direct and indirect contributions and effects of various environmental policies and water quality improvement projects for the preservation of water quality in the Han-River watershed is insufficient. Especially, effect of pollutant source location regulation should be inferred and estimated through model prediction because it does not exist unregulated conditions. As development pressure in non-urban areas near the metropolitan area is increasing, it is necessary to analyze the effects of pollutant source location regulation.Methods:In this study, average pollutant density of Gangwon-do, Gyeonggi-do, and Chungcheongbuk-do, where the regulation areas located, and average pollutant density of water source management areas were compared and analyzed. After that changes in pollutant sources in regulation areas were estimated by assuming load of pollutant sources in unregulated areas that load of pollutant sources in regulation areas. Since many reservoirs are located in Han-river watershed, it is difficult to simulate the water quality of Paldang reservoir using only watershed model, BASINS/WinHSPF and EFDC-WASP were linked. Through this, change in water quality of Paldang Lake was tried to predict when the pollutant location regulation was not implemented, and to analyze the effect of the pollutant location regulation.Results and Discussion:Water quality improvement of Paldang reservoir was evaluated by applying the discharge load when the pollution source location regulation was not implemented to the calibrated model. As a result of the pollution source location regulation, discharge load in the location regulation area was analyzed to reduce by 53.90% and T-P by 48.58%, and the BOD and T-P improvement effect of Paldang Dam was analyzed 6.77% and T-P 6.62%. Since the water quality improvement effect of Paldang Lake is accumulated to the entire upstream, it is evaluated relatively less than pollutant load reducing effect.Conclusion:It was analyzed that pollutiont source location regulation has water quality improvement effect, despite the small area which only located in near Paldang reservoir compared to the total area of the Han-River watershed.

ECOLOGICAL WATER QUALITY

Water quality – is a description of water’s chemical and biological composition and physical properties, which characterize it as an abiotic component of aquatic ecosystem and determine its suitability for specific consumption purposes.
 Ecological water quality (environmental water quality) – refers to the ecological well-being of an aquatic ecosystem, with the main focus on protection of the aquatic environment and human life and health. It comprises a complex of physical, chemical, biological and other parameters reflecting specific features of abiotic and biotic components of aquatic ecosystems.
 The requirements for physical, chemical and biological properties of water are set in the water quality standards, which may be developed by particular countries or introduced by international organizations.
 Ecological water quality depends upon natural and human factors. Natural factors are in their turn divided into abiotic (for example, geological, meteorological, hydrological) and biotic (for example, the ratio of primary production and organic matter destruction). The main human factors affecting water quality include artificial modification of aquatic ecosystems’ hydrological conditions and their pollution with diverse chemical compounds.
 There are a lot of approaches to ecological water quality assessment according to both abiotic (physical and chemical) and biological parameters. Physical and chemical methods take into account such parameters as water transparency, suspended particulate matter concentration (turbidity), ion composition, water hardness, total dissolved salts content, nutrients and organic matter content, dissolved gases concentration, pH. Biological methods are based upon assessing the living organisms’ (biological indicators’) response to mineral and organic substances, present in water. Various living organisms can be used as biological indicators: algae, in particular – diatoms, higher aquatic plants, different species of aquatic invertebrates and fishes. While physical and chemical methods characterize water quality at the moment of sampling, biological methods provide an integral picture of water quality for a certain time period. Besides, biological methods are more informative, because they reflect the aquatic ecosystem’s response to pollution.
 On the whole, the most reliable data on ecological water quality can be obtained by combining physical, chemical and biological methods.

PHYTOPLANKTON PRIMARY PRODUCTIVITY

Primary productivity is an important integral parameter describing energy potential of aquatic organisms’ vital activity. Primary productivity determines the quality of water environment, its self- purifying capacity – from the Global Ocean to various continental ecosystems (Odum 1953, Williams et al. 2002, Bott et al. 2006, Kuehl and Troelstrup 2013).
 Primary productivity is a bioenergy process transforming the solar energy into the energy of chemical bonds in organic matter, newly synthesized by the autotrophic link. The autotrophic link is mainly formed by algae from different ecological groups (phytoplankton, phytobenthos, phytoperiphyton) and higher aquatic plants.
 As any process of energy production and transition, primary production in aquatic ecosystems is regulated by the laws of thermodynamics: the first law – the Lomonosov-Lavoisier law, the second law – the entropy law (Odum 1953). It is necessary to state clearly, that green plants do not transform the total amount of the Sun’s radiant energy, but only a part of it, within the spectral range between 480 and 720 nm (within the wavelength band of photosynthetically active radiation).A simplified equation describing the primary production process can be represented as follows:Proceeding from the above equation, primary productivity may be considered equivalent to (analogous to) the photosynthesis intensity.
 There is a range of various methods for estimating PP: according to algal cell number, according to nutrient dynamic in water, according to diurnal dynamics of dissolved oxygen, according to chlorophyll a content, light-and-dark bottle method in oxygen or radiocarbon modification. With consideration taken of these methods’ advantages and disadvantages, researchers will be able to obtain the most reliable and unbiased primary productivity data.

A water quality assessment method based on an improved grey relational analysis and particle swarm optimization multi-classification support vector machine.

Most of the water quality indicators that affect the results of river water quality assessment are gray and localized, thus the correlation between water quality indicators can be calculated using gray correlation analysis (GRA).However, GRA takes equal weighting for water quality indicators and does not take into account the weighting of the indicators. Therefore, this paper proposes a river water quality assessment method based on improved grey correlation analysis (ACGRA) andparticle swarm optimization multi-classification support vector machine (PSO-MSVM) for assessing river water environment quality. Firstly, the combination weights of water quality indicators were calculated using Analytic Hierarchy Process (AHP)AHP and Criteria Importance Though Intercrieria Correlation (CRITIC)CRITIC, and then the correlation between water quality indicators was calculated for feature selection. Secondly, the PSO-MSVM model was established using the water quality indicators obtained by ACGRA as input parameters for water environment quality assessment. The river water environment assessment methods of ACGRA and PSO-MSVM were applied to the evaluation of water environment quality in different watersheds in the country. Accuracy, precision, recall and root mean square errorRMSE were also introduced as model evaluation criteria. The results show that the river water environment assessment methods based on ACGRA and PSO-MSVM can evaluate the water environment quality more accurately.

Comprehensive evaluation of water resources and environmental carrying capacity based on dualistic water cycle analysis and its application in the Tuo River Basin, China

Maintaining water quantity and quality are two problems that occur during water resource development. Considering the reciprocal relationship, the threshold of water resource development urgently needs to be evaluated to guarantee environmental water function. In this study, the water resources and environmental carrying capacity (WRECC) evaluation method was proposed based on dualistic water cycle analysis. Nine indicators from 4 aspects, including the water resource utilization proportion, water use efficiency, pollutant treatment efficiency, river flow, and mutual coupling in the dualistic water cycle processes, were selected to represent the comprehensive WRECC. The first-order tributary of the Yangtze River, the Tuo River Basin, was chosen to validate the method. During the year 2009 to 2018, the water environment quality was improving in the study area, and WRECC evaluation results were in accordance with the change in the water system, which showed a decreasing trend during the study periods. WRECC revealed that the upstream area had severer water pressure than the middle area, mainly coming from insufficient freshwater to support social development and provide dilution capacity. The study proposed a human water cycle intervention scenario by increasing the recycled water use rate and wastewater treatment rate to improve the WRECC, and the improvement effects can reach 30%. The WRECC method provides a useful tool for water environment management and water resource planning.

Study on the influence of industrial structure optimization on water environment and economy: A case study of Changzhou city

Economic development and large amounts of industrial production have led to environmental deterioration. The assessment and prediction of water environment capacity (WEC) are crucial supports for water quality target management. Therefore, this study aims to improve WEC via changes in the industrial structure and to analyze the economic changes. For this purpose, the economic efficiency (EE), water use efficiency (WUE), and water treatment efficiency (WTE) are estimated by the EE–SBM (slack-based measure)–DEA (data envelopment analysis) model. Based on the proposed model, the industry is divided into three types: green enterprises, yellow enterprises, and red enterprises. Yellow enterprises and red enterprises are the major supervision subjects, and the spatial distribution of different environmental risks is identified. The WECs of the main canals are analyzed based on dynamic changes in the industrial structure by integrating the 0-D and MIKE11 models. The results showed that after adjusting the industrial structure, the maximum added values of the WEC of chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH3–N), and total phosphorus (TP) are 1,744.66 t/a, 536.14 t/a, 24.81 t/a, and 4.16 t/a, respectively. The results show that the canals (R40, R41, R20, R19, and R17) are overloaded with pollutants and indicate that TN is included as a water environment quality assessment target. Furthermore, after the optimization of the industrial structure, the loss of industrial output value is 174.44 million yuan, and the added value of the environmental economy is 232.12 million yuan. The findings provide important technical support for achieving industrial upgrading and sustainable development.

China's improving total environmental quality and environment-economy coordination since 2000: Progress towards sustainable development goals

Improving China's total environmental quality is an important means to implement the United Nations 2030 Agenda for Sustainable Development. How to quantify the environmental quality evolution progress scientifically, and ensure realizing the goals of fresh air, clean water, soil safety, good ecology, and fine human settlement environment in China is an urgent and significant issue. Here, according to Sustainable Development Goals (SDGs) and China's development characteristics, we construct an integrated environmental quality evaluation index system, comprising 5 dimensions—air environmental quality, water environmental quality, soil environmental quality, ecological environmental quality, and human settlement environmental quality—to measure the progress in achieving the SDGs over the past 20 years. Findings show China has made substantial improvements in environmental quality, with an average growth rate of 2.4% annually, presenting high in southeast and low in northwest. Human settlement environmental quality improved to the largest extent, 6.5% annually, followed by ecological, water, soil, and air environmental quality, with an annual rate of 2.46, 2.45,1.83, and 0.84%, respectively. All regions present an increasing trend in total environment. However, large gaps still existed between diverse regions across China. Furthermore, coordination development level between environment and economy rose constantly across China, and 23 provinces have reached the primary coordination development status. Targeted practical measures are proposed to promote environmental quality improvement. It will provide a policy-related assessment tool to help develop sound development strategies and balance national and local capacities for sustainable development.

Portable Multi-Channel Electrochemical Device with Good Interaction and Wireless Connection for On-Site Testing.

It is very important to rapidly test the key indicators of water in the field to fully evaluate the quality of the regional water environment. However, a high-resolution measuring device that can generate small currents for low-concentration analytes in water samples is often bulky, complex to operate, and difficult for data sharing. This work introduces a portable multi-channel electrochemical device with a small volume, good interaction, and data-sharing capabilities called PMCED. The PMCED provides an easy-to-operate graphical interactive interface to conveniently set the parameters for cyclic voltammetry or a differential pulse method performed by the four electrode channels. At the same time, the device, with a current sensitivity of 100 nA V-1, was applied to the detection of water samples with high background current and achieved a high-resolution measurement at low current levels. The PMCED uses the Narrow Band Internet of Things (NB-IoT) to meet the needs for uploading data to the cloud in remote areas. The electrochemical signal preprocessing and chemometrics models run in the cloud, and the final results are visualized on a web page, providing a remote access channel for on-site testing results.

Long-term Macrobentos Responses to Environmental Flows and Water Quality improvement along River Jarama

The Jarama River, due to its proximity to Madrid, has been a highly regulated and polluted for decades; we evaluated the effects of changing multi-pressures over time and along the fluvial continuum. Changes in macrobenthic composition and structure in response to alterations in river habitat have been analyzed from two macroinvertebrate sampling campaigns carried out 42 years apart at 11 locations along the Jarama River. Results show that the macrobenthic communities follow a similar pattern along the river continuum in both periods. Richness and diversity were higher at mountain reaches without pollution and unregulated. The minimum values are reached at San Fernando de Henares, although in the lower part of the river, after receiving all the pollution discharges from the Manzanares River, there are no macrobenthos since the Jarama bottoms are anoxic sludge.Comparing the communities at the same localities we have detected clear temporal changes. In the upper zone, the total number of taxa and diversity decreased, but the fauna richness is maintained. In the section just below large reservoirs we find an increase in macrobenthos richness. In all the medium sections there is a recovery in all the macrobenthos parameters, but this improvement does not reach good ecological status, due to the high concentrations of ammonia. In the lower section, no changes are detected because the accumulated sludge is still present.

Rapid Determination of Nitrate Nitrogen Isotope in Water Using Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) Coupled with Deconvolution Algorithm.

Nitrate is a prominent pollutant in water bodies around the world. The isotopes in nitrate provide an effective approach to trace the sources and transformations of nitrate in water bodies. However, determination of isotopic composition by conventional analytical techniques is time-consuming, laborious, and expensive, and alternative methods are urgently needed. In this study, the rapid determination of 15NO3- in water bodies using Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) coupled with a deconvolution algorithm and a partial least squares regression (PLSR) model was explored. The results indicated that the characteristic peaks of 14NO3-/15NO3- mixtures with varied 14N/15N ratios were observed, and the proportion of 15NO3- was negatively correlated with the wavenumber of absorption peaks. The PLSR models for nitrate prediction of 14NO3-/15NO3- mixtures with different proportions were established based on deconvoluted spectra, which exhibited good performance with the ratio of prediction to deviation (RPD) values of more than 2.0 and the correlation coefficients (R2) of more than 0.84. Overall, the spectra pretreatment by the deconvolution algorithm dramatically improved the prediction models. Therefore, FTIR-ATR combined with deconvolution and PLSR provided a rapid, simple, and affordable method for determination of 15NO3- content in water bodies, which would facilitate and enhance the study of nitrate sources and water environment quality management.

Multi-indicator water quality prediction with attention-assisted bidirectional LSTM and encoder-decoder

Accurate and real-time prediction of water quality not only helps to assess the environmental quality of water, but also effectively prevents and controls water quality emergencies. In recent years, neural networks represented by Bidirectional Long Short-Term Memory (BiLSTM) and Encoder-Decoder (ED) frameworks have been shown to be suitable for prediction of time series data. However, traditional statistical methods cannot capture nonlinear characteristics of the water quality, and deep learning models often suffer from gradient disappearance and gradient explosion problems. This work proposes a hybrid water quality prediction method called SVABEG, which combines a Savitzky-Golay (SG) filter, Variational Mode Decomposition (VMD), an Attention mechanism, BiLSTM, an ED structure, and a hybrid algorithm called Genetic Simulated annealing-based Particle Swarm Optimization (GSPSO). SVABEG first adopts the SG filter and VMD to remove noise and deal with nonlinear features in the original time series, respectively. Then, SVABEG combines BiLSTM, the ED structure and the attention mechanism to capture bi-directional long-term correlations, realize dimensionality reduction and extract key information, respectively. Furthermore, SVABEG adopts GSPSO to optimize its hyperparameters. Experimental results with real-life datasets demonstrate that the proposed SVABEG outperforms current state-of-the-art algorithms in terms of prediction accuracy.

Peculiarities of Clarias gariepinus Physiological State under Conditions of Food Deprivation and Water Environment Quality

The paper is dealt with the study of <i>Clarias gariepinus</i> physiological state under conditions of food deprivation, and also of the influence of the products of its metabolism on the formation of water environment quality in turnover systems. The performed experimental studies suggest that fish cultivation under conditions of deprivation accompanied by the deterioration in water quality results in the decrease in its fatness indices, including primarily liver and abdominal fat mass, and also in the use of energy reserves of the organism -glycogen, proteins, and lipids. The influx of fish metabolites into the water results in the deterioration in its quality, including primarily the increase in the concentration of inorganic nitrogen and phosphorus phosphates, and worsens <i>Clarias gariepinus</i> living conditions. Ammonium and nitrite transformation into less dangerous nitrate is registered at a sufficient level of water saturation with oxygen.