Quality Standards For Surface Water Research Articles

Variation Analysis of Long-term TN concentration and influencing factors in Miyun Reservoir in China

<p>The total nitrogen (TN) is the key indicator for the eutrophication of Miyun Reservoir. Base on the long-term series of remote sensing, hydrological and water quality observation data, this paper comprehensively analyzed the trend of water quality especially the TN concentration and its influencing factors over 30 years in Miyun reservoir. The development trends of the TN concentration during the 14th Five Year Plan Period were predicate with the designed water quality scenarios simulations. The results showed that the water covered area of Miyun reservoir was reduced from 1986 to 2004 and enlarged from 2004 to 2020, and the smallest water covered area was about 56.4km2 in 2004 while the largest was about 170.7km2 in 2020. For the regional rainfall and artificial water storage, the inflow of Miyun reservoir is much greater than the water intake, and this is the main reason for the water covered area increased. From 1988 to 2020, TN contents in the inflow water of Chaohe river and Baihe river were generally in upward trends, with annual upward rates of 0.16 mg/L and 0.05 mg/L at the 99% confidence levels separately. However, the TN concentrations from Chaohe river and Baihe river presented downward trends for the recent 5 years. And this is own to the emission control and river ecological control measures in the upstream basin of Miyun reservoir. From 1988 to 2020, the annual averaged TN concentration of the main dams in Chaohe and Baihe (BHZB and CHZB) was 1.10±0.32 mg/L and 1.17±0.31 mg/L respectively and in recent 5 years, and significant positive trends were also identified at both two stations with the steadily rising the water level and volume in Miyun reservoir. The lightly increase of TN concentration in recent years in Miyun reservoir was the comprehensive results of external input and self purification capacity. Based on the MIKE21 model of four scenario simulations, the TN concentration of Miyun reservoir will meet the class Ⅱ water quality level (China’s Environmental Quality Standards for Surface Waters, GB3838-2002) under the comprehensive implementation of rural domestic source control and agricultural non-point emission control measures in the upstream basin of Miyun reservoir during the 14th Five Year Plan period.</p>

Formulation of water pollutant discharge limits for malathion based on nonsensitive aquatic organism protection

The “Integrated Wastewater Discharge Standard” was implemented for water pollutant discharge in China’s pesticide industry, which has no control requirements for particular wastewater pollutants in the industry. In the standard, certain pollutants discharge limits are limited strictly or loosely, resulting in practical management implementation difficulties. In view of the highly selective targeting characteristics of organic pesticide active ingredients in fungicides, insecticides, and herbicides, a method for deriving discharge limits based on the water quality criteria for pesticides for the protection of nonsensitive species is established based on the idea of fully protecting aquatic organisms beyond sensitive objects. Through the use of malathion as an example, by screening its toxicity data in different species of aquatic organisms, the sequence point with the most significant change in the acute toxicity sensitivity of the species is taken as the variation point in the cumulative frequency of the sensitive and nonsensitive species to derive the water quality criteria, using the species sensitivity distribution method as the scientific basis for determining the discharge limits. After a comparative analysis of different simulation models, the sigmoid model, with the best fit, is selected to determine that the sensitive species hazard concentration (HCs) of malathion to aquatic organisms in China is 46.4 µg/L, and the discharge limit derived from the HCs based on the relationship between the environmental capacity and emissions is rounded to 250 µg/L. Studies showed that the relationship between the emissions limit derived from the water quality criteria for protecting nonsensitive species and malathion limit stipulated in the “Environmental Quality Standards for Surface Water” conforms to the corresponding relationship of the quality standard and discharge standard, which can be achieved by current pollution control technology, combined with water quality improvement. The discharge limit offers the advantages of technical accessibility and economic rationality.

Simultaneous removal of macromolecular microbial metabolites and nitrogen in a receiving river of wastewater treatment plants lacking ecological base flow via the combination of anaerobic and aerobic biofilters

Efficient removal of macromolecular microbial metabolites and nitrogen in receiving rivers lacking ecological base flow is needed to meet the stringent surface water quality standards in northwestern China. This study investigated the characteristics of water quality of a receiving river, further, the conversion of microbial metabolites and its influences on denitrification in pilot anaerobic biofilter (ABF) and biological aerated filter (BAF) were revealed. On this basis, the feasibility of using the combination of ABF and BAF to purify the receiving river was verified. Results showed that organics dominated by macromolecular microbial metabolites and nitrogen severely polluted the receiving river. Microbial metabolism along the river aromatized the organics and enlarged their molecular weight but failed to effectively remove them. In ABF, the bioavailability of organics was at least triply improved by cleaving macromolecular aromatic rings into small molecular aliphatic compounds. Under this circumstance, denitrifiers utilized aromatic carbon sources preferentially and generated aliphatic products. Low hydraulic loading (HL) enhanced not only the hydrolysis of macromolecular ingredients but the dearomatization. Similarly, although high HLs allowed retaining more aromatic compounds, they worsened the conversion of macromolecules. When the HL was 0.2 m/h, the balance was achieved and more than 80% of the nitrates were removed in ABF. Nearly 90% of both ammonia nitrogen and small molecular organics were removed in BAF under the optimal operating conditions, but the refractory macromolecules impeded the removal of organics and nitrogen. AFB and BAF showed a complementation. The effluent from BAF that followed ABF could meet the latest surface water quality standards. This combination is feasible to efficiently and stably purify the polluted receiving rivers of wastewater treatment plants.

Effects of Nitrogen Speciation Transformation on Microbial Community Succession in Input Rivers of Miyun Reservoir

The Miyun Reservoir is the major source of surface drinking water in Beijing. However, the total nitrogen (TN) concentrations in the Miyun Reservoir and inflowing rivers have recently been increasing. In this study, the Mangniu River, a typical inflow river in the upper reaches of the Miyun Reservoir, was selected as the study area to investigate the spatial distribution and transformation of various nitrogen forms from the perspective of microbial community composition and predicting function, aimimg at providing a scientific reference for nitrogen pollution control of the Miyun Reservoir. The results indicated that except for TN, all the other physical and chemical water quality indicators in the upper reaches of the Miyun Reservoir met the Class II criteria of the environmental quality standards for surface water in China (GB 3838-2002). Additionally, NO3--N was the primary constituent of TN, ranging from 77.7% to 92.9%. Banchengzi Reservoir has a certain self-purification ability because its high C/N ratio promotes denitrification. Significant differences in microbial community structure were observed between the water and sediments of Mangniu River along with spatial distribution. High NO3--N concentration was the major environmental factor affecting the succession of microbial community structure. Many nitrification and denitrification microorganisms existed in Mengniu River, and the relative abundance of denitrification bacteria (DNB) was higher than that of nitrification bacteria, and that in the sediments was slightly higher than that in the water. Nitrosopumilus and Pseudomonas were the dominant nitrification and denitrification bacteria in Mengniuhe River, respectively. The results of phylogenetic investigation of communities by the reconstruction of unobserved states (PICRUSt2) showed that NO3--N reduction module was the major nitrogen metabolism module, which primarily occurred in water. The abundance of the functional genes for nitrification (i.e., narGH) was the highest in water, and the major functional gene involved in NO3--N reduction was nirBD of DNRA, which was primarily present in the sediments; however, the main functional gene involved in denitrification was nirK.

Efficient low-concentration phosphate removal from sub-healthy surface water by adsorbent prepared based on functional complementary strategy

The remediation of low-concentration phosphorus polluted surface water (LP-SW) is one of most challenging environmental issues worldwide. Adsorption is more suitable for LP-SW remediation due to its low cost and operability. Based on the strategy of functional complementation among industrial solid wastes (ISWs), ISW-based phosphate absorbent material (PAM) was prepared from coal ash (CA, binder), rich‑calcium (Ca) carbide slag (CS, active component) and iron salt (functional reagent) by optimizing materials ratios and roasting conditions. PAM prepared under optimal conditions (Fe/CC-2opt) had good phosphate adsorption efficiency. Notably, Fe/CC-2opt not only ensured that the effluent met Environmental Quality Standards for Surface Water (pH = 6.0–9.0), but also facilitated the formation of brushite instead of hydroxyapatite due to FeSO4 addition. Compared with hydroxyapatite, brushite had greater potential application value as fertilizer due to its solubility and high P/Ca ratio. The possible mechanisms of phosphate adsorption by PAM included surface precipitation, surface complexation, electrostatic adsorption and release of Ca2+/OH−. Preparation cost of PAM was 80 US$/ton, and treatment cost was 0.07 US$/g P. Regeneration efficiency of PAM was still above 80 % after five cycles. The design idea and result of this study provide theoretical basis and technical support for the preparation of PAM with low cost, commercial production and great adsorption capacity.

Distribution, Site-Specific Water Quality Criteria, and Ecological Risk Assessment of Heavy Metals in Surface Water in Fen River, China.

Due to a lack of toxicity reference values that match the regional environmental characteristics, the ecological risk of metals in water bodies cannot be accurately assessed. The Fen River is the second-largest tributary of the Yellow River in China, and the sustainability of this area is threatened by heavy metal pollution caused by intensive industrial and agricultural activities. In this study, site-specific water quality criteria (WQCs) for heavy metals in the Fen River were derived considering toxicity data from native aquatic organisms and regional water quality factors (e.g., water hardness). Short-term WQCs for Mn, Cu, Cd, Zn, Cr, Pb, and Ni were 2026.15, 98.62, 10.02, 63.07, 6.06, 166.74, and 132.73 μg/L, respectively, and long-term WQCs were 166.53, 29.71, 2.18, 19.29, 4.15, 6.38, and 14.76 μg/L, respectively. The distribution characteristics of these metals during the wet season in 2020 were explored, and their average concentrations in the river water did not exceed the environmental quality standards for surface water in China but were higher than the world average levels. Cr was the main pollutant in the sampling sites of Yaodu region, Hongdong Shitan, Xiao River, and Duanchun River, as was Pb in Duanchun River. Based on the site-specific WQCs, using hazardous quotient (HQ) and margin of safety (MOS10) approaches, a high risk of Pb was identified in the Duanchun River, and a medium risk of Cr might occur at midstream and downstream of Yaodu and Xiaodian. The results will provide a reference basis for heavy metal pollution control and water quality management in the Fen River.

Sulfidic schist release of As, Cu, and Pb in laboratory experiments and across eleven watersheds in central Massachusetts, USA.

Sulfidic schists are important rock formations due to their trace metal and metalloid (TMM) content and carry the potential for pyrite and pyrrhotite to hydrate and oxidize leading to acid-enhanced chemical weathering. The objectives of this study were to compare TMMs in sulfidic schists to other co-occurring bedrock, evaluate conditions that optimize TMM rock weathering, and examine streamwater TMMs in relation to bedrock lithology and human development in eleven streams across central Massachusetts. Sulfidic schists samples had the highest As (72 ± 46mgkg-1), Cu (63 ± 21mgkg-1), and Pb (63 ± 33mgkg-1) concentrations. Electron Probe Microanalysis (EPMA) images show As and Pb were widely distributed across silicate and sulfide minerals in both the mica schist and sulfidic schists, not exclusively hosted in sulfide minerals as hypothesized. Batch reactors had TMM dissolution rates an order of magnitude higher for sulfidic schists than granite and mica schists. Furthermore, TMM dissolution was greatest under pH 9 than pH 7 or pH 5 and dissolution rates were two times greater under anoxic conditions compared to oxic conditions. Streamwater concentrations of As (0.01 to 10.3μg L-1), Cu (0.2 to 206μg L-1), and Pb (0.001 to 8.3μg L-1) were below Massachusetts Surface Water Quality Standards. Across the eleven watersheds, % sulfidic schists were positively correlated with mean streamwater S and Cu concentrations and area-normalized annual export. Streamwater As and Pb concentrations were significantly correlated with %Developed land and %Mica schist, which strongly covaried. Our study confirmed the elevated abundance of TMMs in sulfidic schists but laboratory experiments suggest the precipitation of amorphous Fe oxyhydroxide phases decreased dissolved TMMs during oxic weathering. Future work will need to incorporate groundwater and stable isotope systems to separate anthropogenic and geogenic analyses.

Analysis of The Impact of Handwashing with Soap Policy on Water Quality in Public Facilities: A Case Study in Palangka Raya, Indonesia

Coronavirus disease 2019 (Covid-19) has changed lifestyles. One of the new habits practiced by the community is washing hands. The government had issued a policy stipulated in the decree of the Minister of Health of the Republic of Indonesia number HK.01.07/Menkes/382/2020 concerning Health Protocols for Communities in Public Places and Facilities in the Context of Prevention and Control of Covid-19. Washing hands with soap is an effective step to break the chain of transmission of Covid-19. This research obtained samples of handwashing disposal and surface water at three public facilities in Palangka Raya city, i.e. G. Obos XX market, Pasar Besar, and KPD Supermarket that examined for the parameter of BOD, COD, TSS, and detergent content in the area. The result was the handwashing disposal and the surface water of three public facilities had BOD, COD, TSS, and detergent levels exceeding the surface water quality standard. Disposal of handwashing with soap waste directly into surface water causes a decrease in surface water quality

Cooling and purification effect of permeable pavements

Abstract Permeable pavement is a widely used stormwater runoff blocking technology in sponge city construction. Its application to urban motorized/non-motorized roads is expected to reduce runoff and pollution loads. This study aimed to analyze the nutrient pollution, thermal pollution reduction efficiency and removal pathways of cement permeable bricks (CP-B-Cement), steel slag permeable bricks (SP-B), ceramic permeable bricks (CP-B-Ceramic) and permeable asphalt pavement (PAP) under different pollution loads and rainfall intensities by simulating the different stormwater runoffs. Results indicated that the effluent concentration of different permeable pavements increased with the extension of rainfall duration. Compared with impermeable pavements, the infiltration and water storage capacities of permeable pavements could effectively remove typical pollutants from stormwater runoff. However, the effluent concentrations of all pollutants did not reach the threshold of Class V according to the Environmental Quality Standards for Surface Water except for TP and Zn. Meanwhile, the thermal pollution removal capacity of the permeable pavements ranking from the highest to the lowest was SP-B > CP-B-Cement > CP-B-Ceramic > PAP. The findings in this study provide references for the selection of stormwater source reduction facilities and the development of surface source pollution countermeasures.

Анализ и оценка качества поверхностных вод Приозерского района Ленинградской области

Purpose: The study of water quality indicators of surface water bodies of the Priozersky district of the Leningrad region using laboratory studies, as well as the assessment of the ecological state of water sources based on various integral characteristics of surface water pollution. To determine the quality indicators of surface waters for cultural and household purposes in the laboratory. Assess the ecological state of a polluted reservoir based on the calculated integral indicators: the reservoir pollution index, the trophic state assessment index and the specific combinatorial index of surface water pollution. Consider possible options for improving the environmental situation of the studied water bodies. Methods: Water sampling from five water bodies of the Priozersky district of the Leningrad region for further laboratory studies. Analysis of selected samples from water sources to determine the composition of surface water for the presence of pollutants and water quality parameters using standardized methods. Comparison of the obtained results with the norms of maximum permissible concentrations for given indicators. Results: It has been established that in three of the five studied water bodies, excesses of the standard values for several indicators are found. One of the polluted water sources, the Vuoksa River, has been selected for further calculation of integral indicators of surface water quality. An assessment of the ecological state of this water body is given according to three calculated indicators. Measures have been proposed to improve the environmental situation of water bodies in the region. Practical significance: It is shown that the insufficiently studied water bodies of the Priozersky district of the Leningrad region generally meet the quality standards for surface waters, however, some objects still belong to the category of moderately polluted, which requires further in-depth study of their condition in order to prevent an increase in pollution.

Bioavailability-based Environmental Quality Standards for metals under the Water Framework Directive

Metals are naturally present in surface waters. By considering the bioavailability of a metal in an aquatic environment, we can more precisely predict the effect of a selected metal on aquatic organisms. This enables us to make a more reliable assessment of the compliance of the metal's concentration in inland surface waters with the environmental quality standard for that metal. In addition to complex-forming inorganic and organic ligands, the bioavailability of metals in water is also influenced by physicochemical conditions in the water. Metals occur in different concentrations and in different forms in aquatic environments. This is referred to as metal speciation. The bioavailability of a metal in water depends mainly on its speciation. Normally, a dissolved free metal ion is more bioavailable than a metal ion bound in a complex. The risks posed by given metals to aquatic environments are addressed under EU legislation in the Water Framework Directive (Council of the European Union, 2000) (WFD). The WFD’s purpose is to direct Member States to protect and improve the status of all water bodies throughout the European Union. Directive 2013/39/EC (Council of the European Union, 2013), which refers to priority substances as regards water policy, supplements the WFD and the Directive on environmental quality standards (Council of the European Union, 2008). For nickel and lead, Directive 2013/39/EC sets the annual average environmental quality standards (AA-EQS) for inland surface waters, which refer to biologically available concentrations of metals (AA-EQSbioavailable). In this way, uniform environmental quality standards for the entire European Union are determined for metals, allowing for a compliance assessment of metals for surface waters. In the article, we have presented an analysis of inland surface water monitoring data for nickel and lead, examining how the introduction of AA-EQSbioavailable affects the consistency of monitoring data for these metals. We used monitoring data from 2018 to 2021. To calculate bioavailable concentrations for nickel and lead, we used the bioavailability assessment model bio-met bioavailability tool v.2.3 (Bio-met, 2017). Additionally, for lead, we used equations (1), (2), and (3) to calculate the bioavailable concentration (European Commission, 2019). Based on the analysis conducted, we recommend the utilization of the bio-met model instead of the equations for calculating the concentration of bioavailable lead in the context of the annual compliance assessment of inland surface water monitoring data carried out by ARSO. Using the mentioned bioavailability assessment model, we have provided an upgrade in the methods used to assess metal’s concentration compliance with the EQS for that metal for surface waters. As a result, the requirements of Directive 2013/39/EC relating to biologically available concentrations of metals could be transferred to the Slovenian legal system.

Comprehensive Monitoring and Ecological Risk Assessment of Heavy Metals in Soil and Surface Water of Chishui River Basin in Upper Reaches of the Yangtze River

Chishui River is an important ecological security barrier area in the upper reaches of the Yangtze River in China. Therefore, it is of great significance to conduct research on soil and water ecological risks in the Chishui River basin. In this paper, the risk of heavy metals pollution and its control factors was evaluated systematically by using surface water and soil samples from 16 tributaries in the Yunnan section of the Chishui River basin. The method of soil environmental capacity and ecological risk index were studied. The results showed that the average concentration of heavy metals in the surface water of the main stream was in the order of Fe > Mn > Zn > Cu > Pb > Cd > Hg. Except for Hg, all the concentrations of heavy metals were far lower than the Class I water limits in the Environmental Quality Standards for Surface Water (GB3838-2002) issued by the Ministry of Ecology and Environment, PRC. The average concentration of Hg concentration was 0.056 μg·L−1, which was slightly higher than the limit value of Class II. Heavy metals in the surface water were distributed in a point-like manner in the main stream of the Chishui River, which was mainly affected by mining drainage, township sewage, and human production activities. Meanwhile, the environmental capacity study showed that the heavy metals in soil were in the order of Zn > Pb > Cr > Ni > As > Hg > Cu > Cd, and the environmental capacity were significant differences among different soils: purple soil > limestone soil > loess > yellow-brown soil. Soil Cd tended to migrate out of the soil under the control of the occurrence form, vegetation coverage, and human production activities, while Cr, Cu, and Ni tended to accumulate in the soil. The average comprehensive ecological risk index (RI) of heavy metals in all tributaries ranged from 44.86 to 154.15, mainly distributed in medium and low ecological risk. Therefore, it is recommended to dynamically monitor and control these pollution points in the Chishui River basin to prevent the risk of heavy metals from escalating.

A practice study of land and water comprehensive remediation in urban-rural fringe-with Sichuan River Shaanxi Province, Northwest China, as an example.

Urban-rural fringe area (URFa) is an active and expansive region, and its environment is complex and frangible. Previous studies have focused on the landscape spatial pattern changes, the spatial-temporal variability of soil pollutants and the land management and policy issues, etc., but it is lack of the practice study of land and water comprehensive remediation in URFa. This article is taking the Sichuan River, a typical URFa, as an example. Based on field investigation and lab tests, the main characteristic form of the URFa and land and water comprehensive remediation measures are summarized in this paper. The results show that it is feasible to turn wasteland, low-efficiency land, and old deserted beach into farm land, residential land, and ecological land by comprehensive land improvement. For the farm land reconstruction, the texture is an important indicator. The content of soil organic matter (SOM), carbon, nitrogen, and phosphorus has increased after remediation. For the SOM, 58.3% are more than 10.0g·kg-1, and 79.2% are more than 8.0g·kg-1. For the frequent dry-off and polluted low flow river channels in URFa, the river bottom consolidation and water purification is the important measures. The water quality meets IV standard of the "Environmental Quality Standards for Surface Water" (GB3838-2002) (State EPA of China, 2002) by pollution treatment after remediation, and water volume keeps balance. The findings of this study are expected to provide support for better construction practices in arid and semiarid area in China and for the improvement of the ecological environment in URFa.

The investigation of the physiochemical factors and bacterial communities indicates a low-toxic infectious risk of the Qiujiang River in Shanghai, China.

The overall water quality of urban rivers is closely related to the community structure and the physiochemical factors in them. In this study, the bacterial communities and physiochemical factors of the Qiujiang River, an important urban river in Shanghai, were explored. Water samples were collected from nine sites of the Qiujiang River on November 16, 2020. The water quality and bacterial diversity were studied through physicochemical detection, microbial culture and identification, luminescence bacteria method, and 16S rRNA Illumina MiSeq high-throughput sequencing technology. The water pollution of the Qiujiang River was quite serious with three water quality evaluation indexes, including Cd2+, Pb2+, and NH4+-N, exceeding the Class V standard set by the Environmental Quality Standards for Surface Water (China, GB3838-2002), while the luminescent bacteria test indicated low toxicity of nine sampling sites. Through 16S rRNA sequencing, a total of 45 phyla, 124 classes, and 963 genera were identified, in which Proteobacteria, Gammaproteobacteria, and Limnohabitans were the most abundant phylum, class, and genus, respectively. The Spearman correlation heatmap and redundancy analysis showed that the bacterial communities in the Qiujiang River were correlated with pH; the concentrations of K+, and NH4+-N, and the Limnohabitans were significantly correlated with the concentrations of K+, and NH4+-N in the Zhongyuan Road bridge segment. In addition, opportunistic pathogens Enterobacter cloacae complex and Klebsiella pneumoniae in the samples collected in the Zhongyuan Road bridge segment and Huangpu River segment, respectively, were successfully cultured. The Qiujiang River was a heavily polluted urban river. The bacterial community structure and diversity were greatly affected by the physiochemical factors of the Qiujiang River, and it displayed low toxicity while a relatively high infectious risk of intestinal and lung infectious diseases.

Microbial source tracking using molecular and cultivable methods in a tropical mixed-use drinking water source to support water safety plans

Microbial contamination deteriorates source water quality, posing a severe problem for drinking water suppliers worldwide and addressed by the Water Safety Plan framework to ensure high-quality and reliable drinking water. Microbial source tracking (MST) is used to examine different microbial pollution sources via host-specific intestinal markers for humans and different types of animals. However, the application of MST in tropical surface water catchments that provide raw water for drinking water supplies is limited. We analyzed a set of MST markers, namely, three cultivable bacteriophages and four molecular PCR and qPCR assays, together with 17 microbial and physicochemical parameters, to identify fecal pollution from general, human-, swine-, and cattle-specific sources. Seventy-two river water samples at six sampling sites were collected over 12 sampling events during wet and dry seasons. We found persistent fecal contamination via the general fecal marker GenBac3 (100 % detection; 2.10–5.42 log10 copies/100 mL), with humans (crAssphage; 74 % detection; 1.62–3.81 log10 copies/100 mL) and swine (Pig-2-Bac; 25 % detection; 1.92–2.91 log10 copies/100 mL). Higher contamination levels were observed during the wet season (p < 0.05). The conventional PCR screening used for the general and human markers showed 94.4 % and 69.8 % agreement with the respective qPCR results. Specifically, in the studied watershed, coliphage could be a screening parameter for the crAssphage marker (90.6 % and 73.7 % positive and negative predictive values; Spearman's rank correlation coefficient = 0.66; p < 0.001). The likelihood of detecting the crAssphage marker significantly increased when total and fecal coliforms exceeded 20,000 and 4000 MPN/100 mL, respectively, as Thailand Surface Water Quality Standards, with odds ratios and 95 % confidence intervals of 15.75 (4.43–55.98) and 5.65 (1.39–23.05). Our study confirms the potential benefits of incorporating MST monitoring into water safety plans, supporting the use of this approach to ensure high-quality drinking water supplies worldwide.

Scale Effect of Sloping Landscape Characteristics on River Water Quality in the Upper Reaches of the Si River in East-Central China

Landscape composition and configuration determine the source of pollutants. They also determine the interception and pollution-holding potential of the surface landscape. Using the upper reaches of the Si River Basin, a major grain-producing region in Shandong province in east-central China, as a case study, this study analyzed the influence of landscape characteristics on river water quality (RWQ) after superimposing topographic slope factors for 2017, and investigated which spatial scale had the strongest influence on RWQ. The landscape indices of three spatial scales (riparian zone, river reach and sub-catchment) and three slope scales (general land, flat ground and steep slope) were extracted. Correlation analysis and redundancy analysis were used to reveal the effects of landscape characteristics on RWQ at different scales. The results indicate that the landscape types were dominated by arable land and construction land in 2017. Landscape indices at different scales were significantly different. The RWQ generally met Class II or III surface water quality standard. Arable land and construction land had a negative impact on RWQ, both of which were “source” landscapes, while forest was a “sink” landscape that can effectively alleviate the deterioration of RWQ. The eight landscape indices which indicated heterogeneity, fragmentation level, landscape diversity, and shape information had different degrees of correlation with NO3−-N, NH4+-N, CODMn and BOD5. Different scales of landscape features had different correlations with RWQ, with the strongest correlation in the riparian zone, followed by the river reach, and the weakest in the sub-catchment. The influence of steep slope land was higher than that of flat ground land. The study confirmed that landscape structure and configuration had a scale effect on RWQ. It thus has great significance for water resources protection and land use management in the study area.

Bioaccumulation and Health Risk Assessment of Metals in Small-Sized Fish (Rhodeus sinensis, Ctenogobius giurinus) and Mussel (Cristaria plicata) from a River Reservoir, Southwest China.

In order to assess the bioaccumulation and health risk of metals in a river reservoir, concentrations of copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in the water, sediments, two small-sized fish, and a freshwater mussel from the Zhoubai reservoir were examined. The results indicated that all of these metals conform with class one of environmental quality standards for surface water (State Environmental Protection Administration of China, GB 3838-2002). There were no significant differences for total metal concentrations in sediment between the three sampling sites (p > 0.05), but the bioavailable concentrations in S3 were the lowest. The Cd was dominated with exchangeable fraction and showed considerable risk. All metal concentrations except for Pb in Rhodeus sinensis were significantly higher than those in Ctenogobius giurinus (p < 0.05). The metal concentrations in Cristaria plicata showed a similar pattern of bioavailable metals in sediment, indicating that the metal concentrations in aquatic organisms were determined by the bioavailable forms of metals. Negative correlations were observed between the size of fish and concentrations of Cu, Zn, Pb, Cd, and As. However, significant positive correlations were found between the size of mussel and concentrations of Cd (p < 0.01), As (p < 0.05), and Hg (p < 0.01). Zn had the highest BCF values in fish and mussel. The aquatic organisms showed lower ability of metal bioaccumulation from the sediment. Low values of target hazard quotient (THQ), hazard index (HI), and carcinogenic risk (CR) indicated that these metals do not pose a health risk to public through fish and mussel consumption in this study area.

Water Quality Evaluation and Prediction Based on a Combined Model

Along with increasingly serious water pollution, water environmental problems have become major factors that hinder the sustainable development of our economy and society. Reliable evaluation of water quality and accurate prediction of water pollution indicators are the key links in water resource management and water pollution control. In this paper, the water quality data of Lanzhou Xincheng Bridge section in the Yellow River Basin and Sichuan Panzhihua Longdong section in the Yangtze River Basin were used to establish a water quality evaluation model and a prediction model. For the water quality evaluation model, we constructed the research samples by means of equal intervals and uniform distribution of interpolated water quality index data according to Environmental Quality Standards for Surface Water. The training samples were determined by a stratified sampling method, and the water quality evaluation model was established using a T-S fuzzy neural network. The experimental results show that the highest accuracy achieved by the evaluation model in water quality classification was 94.12%. With respect to the water quality prediction model, we propose ARIMA-WNN, which combines the autoregressive integrated moving average model (ARIMA) and a wavelet neural network (WNN) with the bat algorithm (BA) to determine the optimal weight of each individual model. The experimental results show that the highest prediction accuracy of ARIMA-WNN is 68.06% higher than that of the original model.

Reducing the water residence time is inadequate to limit the algal proliferation in eutrophic lakes

The eutrophication problem now threatens many lakes and reservoirs. To avoid the occurrence of algal blooms, some cities try to increase the flow rate or directly choose lakes or reservoirs with a short water residence time (WRT) as drinking water sources. However, up to now, whether such a strategy can achieve its goal is still unclear. In this study, a newly restored lake with a WRT of approximately 3 days was chosen to investigate algal growth potential as well as its responses to external nitrogen (N) and phosphorus (P) inputs. The results suggested that although the water quality of the lake could generally meet the environmental quality standards for surface water, dissolved inorganic nitrogen reached a high level with an average value of 1.58 mg/L. Meanwhile, a considerable increase in Chl-a concentration was observed across the flow direction. Especially, in July, Chl-a concentration at the site near the outlet was 8.1 times higher than that at the inlet, and cyanobacteria became the dominant species accounting for 83% of the total cell density. Nutrient enrichment experiments showed that algae could grow rapidly within 3 days with average specific growth rates (μ) of 0.36–0.42 d−1. The addition of N and P furtherly promoted the algal growth, and μ values of the treatments with P addition were the highest at 0.67–0.83 d−1. These results indicated that even if the WRT was reduced to 3 days, the risk of the occurrence of algal blooms still exists, and this undesirable trend would be enhanced by the short-term external nutrient input. Our findings indicated that the hydrodynamic control measures may not be entirely successful in protecting the drinking water source from algal blooms, especially when its influent has already been under eutrophication.

Study on temporal and spatial distribution characteristics of urban non-point source pollution in Hohhot

The non-point source pollution is not easy to be controlled, and it is one of the important environmental problems facing the world. Taking Hohhot, a typical city in the arid semi-arid region in China, as an example, four monitoring sites in the city were selected, water samples from six rainfall events were collected, and pollutants such as heavy metals, ammonia, nitrate nitrogen, phosphorus and suspended matter were examined, and the water quality of the rain runoff was comprehensively evaluated by the principal component analysis and the correlation analysis. The results showed that the total phosphorus contents of monitoring points in the street were the largest and those of monitoring points in gas stations were the smallest in rainfall runoff. Arsenic, cobalt, and chromium were less than the Class I standard for environmental quality standards for surface water according to Chinese standard (GB 3838-2002). Concentrations of cadmium, copper, and iron were greatest in street monitoring sites, while nickel, lead, and zinc were greatest in roof monitoring sites, and manganese was greatest in car park monitoring sites. There was minimal contamination at gas station monitoring sites and the greatest contamination at street monitoring sites. Heavy metals and phosphorus were the main contributing factors to pollution at street monitoring sites, while the main contributing factors at gas station monitoring sites were total suspended substances.