Terms Of Water Quality Research Articles

Analisis Pola Aliran dan Kuantitas Air Tanah Dangkal di Kota Madiun

<p><em>The increasing physical development and decreasing water infiltration areas have led to a reduction in groundwater reserves. Groundwater is experiencing a decline both in quantity and quality over time. The rising demand for water is inversely proportional to the diminishing availability of water in terms of quality. This situation also implicates a decrease in the quantity of groundwater. Integrated protection and management efforts must be carried out from upstream to downstream, one of which can be achieved through groundwater conservation. Therefore, the aim of this research is to understand the shallow groundwater flow patterns in the city of Madiun. This study conducted an inventory, identification, and mapping of the area to determine the criticality of shallow groundwater in terms of quantity using the shallow groundwater flow pattern analysis method. The results of the analysis generally indicate that the direction of shallow groundwater flow in the city of Madiun, in the eastern areas of the Madiun River, flows from south to north, while in the western areas of the Madiun River, it flows from west to east, all ultimately leading towards the Madiun River.</em></p>

Performance investigation of a novel design of vertical micro-screen drum filter for a recirculating aquaculture system (RAS)

The present study proposes a new design of mechanical filter to suit the recirculating aquaculture system (RAS) as a high-efficiency alternative filter to the conventional swirl separator (CSS). The new filter is considered the developed version of CSS; thus, it is called thereafter as the swirl-vertical drum filter (SVDF) which is provided with a rotating vertical micro-screen drum equipped with a fixed vertical brush as a self-cleaning tool instead of the conventional backwash system. The performance of SVDF was evaluated under different drum rotational speeds, and drum rotation times using sinking and floating fish feed pellets and magnetic field device, and then, it was compared to CSS in terms of water quality and filtration efficiency under the same operational conditions. Experimental results showed better values of water quality including Dissolved oxygen (DO), pH and unionized ammonia (NH3). Also, the lowest value of COD was found to be 18.33 mg/L by using SVDF with floating feed pellets, whilst the highest value of 100.73 mg/L was found in the case of using the CSS with sinking pellets. Meanwhile, the magnetic field device had no effect on the filtration process. The lowest surface area of the vertical micro-screen drum of 0.217 ± 0.013 m2 was obtained at the drum’s rotational speed of 20 rpm (0.39 m/s), rotation time of 150 min with floating feed pellets. Experimentally, it is found that the new SVDF has higher filtration efficiency than the CSS by about 57.57% under the same operational conditions.

Management of Water Resources and Health Promotion in Drought: An Indigenous Knowledge-Based Qualitative Study

Introduction: Drought is a slow-onset natural disasters and a gradual concern. Throughout the centuries, Iranians have applied various methods to preserve water resources and adjust themselves to the drought. This study was conducted with the aim of preserving water resources by households during a drought with the approach of indigenous knowledge.
 Material and Methods: The study was carried out from April 2017 to June 2018. A qualitative content analysis method was used to obtain insight into personal experiences. A purposive sampling method was used to select 15 participants. The research population consisted of native villagers who lived in rural areas near the three main plains of Yazd province (Yazd-Ardakan plain, Abarkouh plain, and Herat Va Marvast plain). Thematic analysis was used to analyze the data.
 Results: The components related to indigenous knowledge were placed in 4 categories and 15 sub-categories. The main categories were personal hygiene, conservation of scarce resources, prediction of drought, and classification of water in terms of quality and its supply sources.
 Conclusion: Indigenous knowledge reflects several generations of experience. This knowledge is a valuable resource about how local communities interact with their ever-changing environments. We must pay attention to personal health behaviors and how our ancestors used and preserved scarce resources. It is necessary to identify and correct these behaviors and support them through proper management and financial resources at the community level. To preserve water resources in droughts, it is essential to use appropriate management and policy-making and motivational methods, and educate families.

A method for researching the eutrophication and N/P loads of plateau lakes: Lugu Lake as a case

Lugu Lake is one of the best plateau lakes in China in terms of water quality, but in recent years the eutrophication of Lugu Lake has accelerated due to high nitrogen and phosphorus loads. This study aimed to determine the eutrophication state of Lugu Lake. Specifically, the spatio-temporal variations of nitrogen and phosphorus pollution during the wet and dry seasons were investigated in Lianghai and Caohai, and the primary environmental effect factors were defined. Adopting the endogenous static release experiments and the exogenous improved export coefficient model, a novel approach (a combination of internal and external sources) was developed for the estimation of nitrogen and phosphorus pollution loads in Lugu Lake. It was indicated that the order of nitrogen and phosphorus pollution in Lugu Lake was Caohai > Lianghai and dry season > wet season. Dissolved oxygen (DO) and chemical oxygen demand (CODMn) were the main environmental factors causing nitrogen and phosphorus pollution. Endogenous nitrogen and phosphorus release rates in Lugu Lake were 668.7 and 42.0 t/a, respectively, and exogenous nitrogen and phosphorus input rates were 372.7 and 30.8 t/a, respectively. The contributions of pollution sources, in descending order, were sediment > land-use categories > residents and livestock breeding > plant decay, of which sediment nitrogen and phosphorus loads accounted for 64.3 % and 57.4 %, respectively. Regulating the endogenous release of sediment and obstructing the exogenous input from shrubland and woodland are emphasized for the management of nitrogen and phosphorus contamination in Lugu Lake. Thus, this study can serve as a theoretical foundation and technical guide for eutrophication control in plateau lakes.

Evaluation of 3-D spatial distribution of dissolved oxygen concentrations in a eutrophic lake

In this study, three-dimensional (3-D) ordinary kriging of dissolved oxygen (DO) concentrations was performed for a eutrophic reservoir based on 81 sampling points using Stanford Geostatistical Modeling Software (SGeMs). Potential hotspots (problematic zones in terms of water quality with high/low DO concentrations) not only at the surface but also in deeper layers of Porsuk Dam Reservoir (PDR) were evaluated. Moreover, 3-D distributions of DO, and specific conductivity (SC) were examined against the thermocline layer identified using the 3-D temperature data. Thermocline layer existed between 10 and 14m below the surface based on 3-D temperature data. This result showed that the traditional approach of collecting samples from mid-depths may cause incomplete characterization and evaluation of water quality as thermocline layer may not coincide with mid-depth. Although the variation in SC values and temperatures above and below the thermocline layer were relatively homogeneous, this was not the case for DO. 3-D DO distribution suggested a better location for water withdrawal for domestic purposes. 3-D DO maps generated by predicting data at unmeasured locations at different depths could be used as input for 3-D water quality estimation in the reservoir through model simulations in future. Moreover, the outcomes can also be useful in the segmentation (physical configuration) of the water body for future water quality modeling studies.

Separately tracking the sources of hydrophobic and hydrophilic dissolved organic matter during a storm event in an agricultural watershed

The hydrophobicity of dissolved organic matter (DOM) affects various aspects of its environmental impacts in terms of water quality, sorption behaviors, interactions with other pollutants, and water treatment efficiency. In this study, source tracking of river DOM was conducted separately for hydrophobic acid (HoA-DOM) and hydrophilic (Hi-DOM) fractions using end-member mixing analysis (EMMA) in an agricultural watershed during a storm event. EMMA with optical indices of bulk DOM revealed larger contributions of soil (24 %), compost (28 %), and wastewater effluent (23 %) to riverine DOM under high versus low flow conditions. Molecular level analysis of bulk DOM revealed more dynamic features, showing an abundance of CHO and CHOS formulae in riverine DOM under high- and low flow conditions. CHO formulae originated from soil (78 %) and leaves (75 %) and contributed to the increasing CHO abundance during the storm event, whereas CHOS formulae likely originated from compost (48 %) and wastewater effluent (41 %). The characterization of bulk DOM at the molecular level demonstrated that soil and leaves are the dominant contributors for the high-flow samples. However, in contrast to the results of bulk DOM analysis, EMMA with HoA-DOM and Hi-DOM revealed major contributions from manure (37 %) and leaf DOM (48 %) during storm events, respectively. The results of this study highlight the importance of individual source tracking of HoA-DOM and Hi-DOM for the proper evaluation of the ultimate roles of DOM in affecting river water quality and for a better understanding of DOM dynamics and transformation in natural and engineered systems.

Effects of Chemical Fertilizer Application upon the Water Quality Parameters of a Rice–Eel (Monopterus albus) Coculture System

The excessive use of chemical fertilizers causes many problems for which solutions are being sought in a variety of agricultural production systems. From the perspective of paying attention to the health requirements of aquatic animals in terms of water quality, this study investigated the impact of chemical fertilizer application on water quality in a rice (Oryza sativa L.; Cultivar “Qingxiangruangeng,” accession number: 2014004)–eel (Monopterus albus) coculture system in Shanghai, China. Chemical fertilizer was applied four times—as base fertilizer, rejuvenated fertilizer, tiller fertilizer, and ear granule fertilizer—during the production process of a rice–eel coculture system (June to October 2020). Changes in the water quality parameters of rice field’s surface water and ring ditch water in the regular chemical fertilizer group (RF) and no chemical fertilizer group (NF, the control) were compared before and at 24 h, 48 h, and 72 h after the chemical fertilizer application. The results for the analyzed physical and chemical indexes of each water area before and after four fertilizations revealed several consistent trends. First, the pH, dissolved oxygen (DO), water temperature (T), and chemical oxygen demand (COD) of either water area were similar between the NF and RF groups, whereas their total nitrogen (TN), total ammonia nitrogen (TAN), and total phosphorus (TP) levels differed significantly. After adding the above fertilizer containing nitrogen and phosphorus, 24 h later, the TN, TAN, and TP content had already increased significantly in comparison with the control. The maximum average content of TAN and nitrite nitrogen (NO2−-N) in the ring ditch water reached 12.30 mg/L and 0.37 mg/L, respectively, at 24 h after the chemical fertilizer application. Nonlinear regression analysis results showed that there was a significant positive relationship TN (δTN) and TAN (δTAN) vis-à-vis the nitrogen content of the fertilizer. The results of this study provide a timely empirical reference and data support for improving fertilizer management in rice–eel coculture systems.

A study on external pressures of an ancient irrigation cascade system in Sri Lanka

CONTEXTVillage Tank Cascade Systems (VTCSs), which are ancient irrigation systems in Sri Lanka have undergone various pressures over time including climate variability, population growth, land use changes and agricultural intensification. VTCSs have provided irrigation and vital ecosystem services for generations, while facing these pressures. As external pressures have increased drastically over the last century, it is worthwhile to investigate VTCS's current capacity to tolerate pressures exerted on them while sustaining their functions. OBJECTIVEThe objectives of this study were to (i) assess the pressures exerted on Mahakanumulla VTCS due to climate change, population growth, land use changes and agricultural practices, (ii) evaluate the impacts of the pressures on the system in terms of water quality and quantity. METHODSRainfall data from 1906 to 2020 were analyzed to identify the rainfall trends over the last century. Land use maps were developed for 1910, 1979, 2002 and 2018. To identify current farming practices, a questionnaire survey was carried out targeting 357 respondents followed by field investigations. Environmental impacts due to pressures on the system were evaluated using water quantity estimations and quality tests. RESULTS AND CONCLUSIONSPaddy extent has increased from 6.3% to 20.2% while the homestead extent has increased from 1.6% to 11.5% during the last century. The lands used for sustainable shifting cultivation have encroached with permanent agricultural lands and human settlements. The runoff coefficient rose from 0.29 to 0.45, indicating a high outflow of water during rains and limiting water retention within the system. This is an indication of increasing water scarcity in dry periods due to limited recharge capacity. Although the system continues to function without significant water quality deterioration, agricultural activities can cause threats in the future. Hence, the system needs immediate attention in the context of proper land use planning, farmer awareness and integrated nutrient management at the cascade level to minimize these pressures exerted upon the system. SIGNIFICANCEIdentifying and quantifying various pressures exerted on VTCSs is the fundamental step in setting management and mitigation plans. Project planners and policymakers need evidence-based information in this regard. Therefore, this study's findings and the research framework that may be extended to other VTCSs and similar systems are significant in creating a favorable policy environment and implementation programmes to reduce the risks the VTCSs are exposed to.

Reclaimed water use improved polluted water's self-purification capacity --Evidenced by water quality factors and bacterial community structure

Reclaimed water is increasingly adopted around the world to relieve water resource crisis induced by accelerated urbanization process. Compared with natural water bodies, aquatic ecosystems replenished with reclaimed water are usually enriched with organic matter, total nitrogen (TN) and phosphorus (TP). However, whether and how nutrient stoichiometric characteristic can impact receiving waters' self-purification remains poorly addressed. Here, we evaluated the effects of reclaimed water use on water's self-purification capacity in terms of water quality, sedimentary bacterial diversity, bacterial community structure and function. Results showed that reclaimed water use has improved water quality of domestic polluted urban rivers and increased bacterial genus-level abundance, but failed to directly affect bacterial biodiversity indexes and evenness of receiving waters. Water organic matter input from reclaimed water was the decisive factor in shaping sedimentary bacterial community structure rather than temperature. Meanwhile, compared with non-reclaimed water, reclaimed water replenishment enhanced polluted waters' carbon (C)-, N- and P-removing functions, suggesting an improvement of self-purification capacity. Our findings could improve the understanding of the ecological impact of reclaimed water on urban aquatic ecosystem, and inform the rational use of reclaimed water in urban rivers.

Assessment of Water Quality in Selangor, Malaysia during the Pandemic Movement Control Order

The COVID-19 lockdown reduced the amount of human activity in Selangor, resulting in improved water quality, less water pollution, and a restored ecosystem. The purpose of this research was to investigate water quality before and during the COVID-19 pandemic, as well as changes in water pollution. After acquiring all of the data from third-party sources, this study analyzed the data using a methodical and statistical approach to determine the impact of the COVID-19 pandemic in Selangor. The purpose of the data analysis was to determine whether the parameters in the water samples met the Malaysian water quality standard. To summarise, there were positive impacts on DO, TSS, ammoniacal nitrogen, and turbidity during the pandemic lockdown period, but negative impacts on BOD, COD, and pH levels. The National Water Quality Standards (NWQS) (2022) also indicated that typical water resources remained polluted and that moderation activities for pH, ammoniacal nitrogen, and turbidity parameter were required to assure improved water resources in 2023. This observation was further demonstrated and agreed upon as the impact of the blockade became evident and the anthropogenic impact on water quality became apparent. Based on observations and analysis, it is possible to highlight the positive and negative aspects of the pandemic lockdown period in terms of water quality and wastewater in Selangor.

Are We Paying More to Consume Substandard Drinking Water? Crowd-Sourced Water Education Study in a South-Asian Megacity

South. Environment and health-related data are inadequate and strongly rely on governmental-mediated observation. The present work is the first of its kind attempt to gather relevant information on potable water quality using mass citizen engagement over a south Asian megacity, Kolkata. The city has a long history associated with water-borne diseases and presently numerous reports on sickness from drinking water contamination have been published in the local newspapers. The current work crowdsourced water sampling throughout the city and analyzed information regarding biological contaminants for five existing water types. 300 citizens were mobilized and trained in water collection through audio-visual communication workshops and together 570 samples of water have been collected from different parts of the city. Water sample collecting points were created over the city and samples were taken to the analysis hub where it was analyzed for standard coliform test and for total dissolved solid (TDS) and pH. The results show that the most expensive water types (20l commercialized packaged drinking water bottles) are the worst in terms of water quality. Governmental-free drinking water was found to be much safer as compared to packaged drinking water. 44% of the packaged drinking water was found to be contaminated with coliform bacteria and we did a comparative analysis with reports from different developing countries and found that such high occurrence was not reported in any cities across the world. We communicated the results to the participants and further, conducted semi-structured interviews to understand the perception of water quality and the driving force behind the choice of a particular water type. It was also found that logistical feasibility is the primary reason behind selecting the 20l bottle. The blind faith in commercially packaged drinking water has been reflected in the interview. The present studies confirm the potential of crowdsourcing of environmental-health data in the global south and successfully accomplish potable water analysis through crowdsource sampling over a south Asian megacity. Such robust methods could be easily scaled up and follow-up discussions can definitely improve water literacy among the participants in Global South.

Evaluation of the effects of abattoir effluent on the physicochemical and bacteriological quality of River Benue, Nigeria.

This study investigated the impact of continual discharge of untreated abattoir effluents on the water quality of River Benue. Three major abattoirs (Wurukum, Wadata and Northbank) in Makurdi, Nigeria, and their polluting strength in river upstream and downstream were measured and compared. Two water quality parameters: physicochemical and bacteriological were investigated. Water quality index (WQI) was computed for all sampling sites. Results revealed that some of the physiochemical parameters were above recommended limits, especially in downstream river, in particular, the turbidity (24.0-55.5mg/l), TSS (62.6-92.0mg/l), DO (8.0mg/l), and total hardness (160-240mg/l). All sampling sites indicated an increased bacterial population while Salmonella spp. and Escherichia coli were the predominant bacteria among the ten genera identified in water upstream and downstream. Faecal coliforms increased from upstream to downstream in two sampling sites (Wurukum and Wadata). Strong positive correlations were observed between upstream and downstream samples for pH, EC, turbidity, TSS, DO, COD, SO42-, TC, and Shigella spp. WQI revealed that all sampling locations were heavily polluted and unsuitable for drinking purposes (WQI > 300) based on both the physicochemical and bacterial parameters. The sampling sites, however, showed excellent water quality based only on physicochemical properties especially upstream at both Wurukum and Northbank sampling sites (WQI < 50). It was suggested that anthropogenic activities around the river may be responsible for the high concentration of some physiochemical parameters and bacterial loads observed in the river downstream. Moreover, it was concluded that microbial loads should be fully considered in WQI computation in terms of water quality. Our results are useful for water resource and waste management in terms of practices and policy guidance, especially for developing countries.

Toponyms: a neglected asset within the water framework and flood directives implementation process; the case study of Greece

Proxy data and qualitative information are important assets in water resources and floods management. In the research, the river water bodies with characteristic toponyms (hydronyms) in Greece that potentially reflect the water’s quality or the occurrence of floods are evaluated in comparison to the European Union’s (EU) Water Framework and Flood Directives implementation process outputs. For doing so, after identifying the river water bodies with characteristic toponyms which form the 10.2% of the Greek water bodies, the toponyms are cross correlated with the water bodies quality status as retrieved by the Directives’ databases to validate the existence of linkages between the names and the quality. Similarly, the significant floods, as derived from the Flood Directive, are spatially allied with the water bodies with characteristic toponyms to ground truth the connection between significant floods and water bodies whose toponyms imply flood prone areas. The research outputs indicate a high degree of correlation both in terms of water quality and floods, meaning that in almost all cases the water body toponym depicts the good or bad quality of the water body or the occurrence of flood events. Moreover, it is established that almost 90% of the water bodies with characteristic names are intermittent and ephemeral ones. The water bodies’ toponyms, hence, are proposed as an auxiliary criterion during the Directives implementation process that could foster increased water quality and flood-related knowledge, especially in intermittent and ephemeral water bodies which are generally lacking observations, and can be applied not only in all EU-Member States’ waters, but also in global scale.

Performance and sustainability of a multi-stage free water surface constructed wetland under seasonal change and shock loading

Multi-stage constructed wetlands (CWs) are widely used for water quality improvement, especially in the treatment of wastewater. Many studies focus on their treatment efficiency under steady loading, but fewer studies consider their sustainability under variable conditions. This study examines the multi-stage CWs in the Hong Kong Wetland Park for their long-term performance and sustainability in terms of water quality under seasonal changes, storm events, and shock loadings of pollutants. The results show that the multistage design performs well and is stable under these changing conditions. In such multistage CWs, the type of units and some changing conditions (e.g., inflow concentrations, seasonal changes of vegetation, and water levels) also affect the performance of the whole system. Compared to individual CW, a multi-stage CW system could recover more quickly on dissolved oxygen (DO), and ammonia nitrogen (NH4), but slowly on biochemical oxygen demand (BOD) and total phosphorus (TP). A pre-processing and buffering area is necessary to handle the shock loadings of BOD and TP in such a multistage CW system. Although water levels recover quickly in both, it is difficult to return to original water levels in multi-stage CWs compared to single ones. Besides, for sustainable operation, attention should be paid to the DO of the inlet, and aeration measures might be taken.

Drinking water management strategies for distribution networks: An integrated performance assessment framework

Due to rapid population growth, urbanization, water contamination, and climate change, global water resources are under increasing pressure. Water utilities apply drinking water management strategies (DWMS) to ensure that water is safe for drinking. However, in recent years, due to increased inclination towards climate change, environmental emissions, and sustainable development goals; the environmental and economic performance of DWMSs is getting attention. An integrated framework combining life cycle thinking and water quality assessment techniques was developed in this study to evaluate the DWMSs' performance in terms of water quality, environment, and economics. Six DWMSs were assessed using the integrated framework as a case study. The environmental impacts in terms of human health, ecosystem, and resource use ranged from 1.46E-06 to 4.01E-06 DALY, 9.35E-10 to 3.80E-09 species.yr, and 0.0025–0.0071 USD-$, respectively. Pollution water index (PWI) and cost-benefit analysis (CBA) were used as decision-making techniques to assess the overall performance and suitability of DWMSs under given settings. The DWMSs with surface water as a source or ones providing relatively more degree of treatment have a relatively high PWI score (i.e., ≈0.31), reflective of high environmental impacts and water pollution compared to other alternatives. The CBA scores of selected alternatives ranged between 0.22 and 1.0. Furthermore, it was identified that DWMSs applied on relatively bigger water distribution systems can outweigh their costs (i.e., environmental and economic impacts). The proposed framework and approaches are flexible as they can incorporate different criteria in evaluating the performance and applicability of DWMSs.

Membrane Separation Used as Treatment of Alkaline Wastewater from a Maritime Scrubber Unit.

Since 1 January 2020, the sulfur content allowed in exhaust gas plume generated by marine vessels decreased to 0.5% m/m. To be compliant, a hybrid scrubber was installed on-board, working in closed loop and generating a high volume of alkaline wastewater. The alkaline water suspension was treated by a silicon carbide multitubular membrane to remove pollutants, and to allow the water discharge into the natural environment. In this paper, membrane filtration behavior was analyzed for the maritime scrubber wastewater. A range of operating parameters were obtained for several feedwater quality-respecting industrial constraints. The objective was an improvement of (I) the water recovery rate, (II) the filtration duration, and (III) the permeate quality. Thus, in high-fouling water, a low permeate flow (60 L h−1 m−2) with frequent backflushing (every 20 min) was used to maintain membrane performance over time. In terms of water quality, the suspended solids and heavy metals were retained at more than 99% and 90%, respectively. Other seawater discharge criteria in terms of suspended solids concentration, pH, and polyaromatic hydrocarbons were validated. The recommended operating conditions from laboratory study at semi-industrial scale were then implemented on a vessel in real navigation conditions with results in agreement with expectations.

Hydrological assessment of the volume of water losses in Al-Habbaniyah Lake and its impact on the tourism activity of the tourist city h using modern geographical technologies

The research aims to study the estimation of the volume of water losses from surface streams in each of Lake Habbaniyah، and to achieve this goal the study adopted a descriptive approach to explain the reasons for the increase in the volume of water losses and study the factors affecting them. different، and it was found in general through the research that there are large amounts of surface water wasted through several processes، the most important of which are (leakage – evaporation. Where the latter worked to increase the amount of water losses from surface streams because the amount of evaporation from a water body during a specific period depends on two groups، the first includes climatic factors that carry between its folds، solar radiation، temperature، relative humidity ... etc.) and the second group includes factors related to The nature of water and its characteristics in terms of water quality، water depth، size and shape of water bodies. The results proved that both groups worked directly to increase the amount of water losses and thus led to a decrease in the amount of water in the study area، so this study came as an attempt to clarify the reality of the possibilities available to estimate the volume of water losses in Lake Habbaniyah، and its role in economic evaluation by working to reduce evaporation and shortage rates The occurrence of water، which leads to hitting the existing tourism in that region.

Observation of Water Quality Parameters on Induced Breeding of Bagrid Catfish in Bangladesh

Induced breeding of Bagrid catfish, Mystus tengara, is not widely practiced in Bangladesh, and seed is not readily available. The study was conducted to identify the optimum range of water quality parameters to best induced breeding results in a hatchery in Pabna district, Bangladesh. Fish breeding and other related work have been done in the hatchery. The (mean ± SD) temperature, dissolved oxygen, and pH were ranged from 29.75±1.22oC to 33.94±0.18oC; 4.40±0.57 to 5.35±1.06 mg/l; and 7.10±0.14 to 7.40±0.28 in brood pond and 26.50±0.71oC to 31.00±1.41oC; 3.80±0.14 to 5.50±0.42; and 7.00±0.00 to 7.30±0.42 in overhead tank, respectively. The highest fertilization rate (80%) was observed in brood pond water at the 7th and 8th weeks at temperatures of 33.94±0.18o C and 32.00±1.07oC, as well as oxygen concentrations of 5.20±1.41 mg/l, 4.60±0.14 mg/l, and pH values 7.20±0.14, 7.20±0.00, respectively. In the 9th week of the experiment, the temperature, dissolved oxygen, and pH values of 28.00±1.41oC, 5.50±0.42 mg/l and 7.00±0.00, respectively, were shown to have the highest hatching rates. A strong positive correlation was found among dissolved oxygen, temperature, fertilization rate, and hatching rate. Particularly, the brood raising pond's water quality parameters showed a strong positive correlation with fertilization rate. On the other hand, water quality parameters of the overhead tank showed a strong positive correlation with hatching rate. This study will help hatchery technicians in comprehending the requirements for M. tengara species induced breeding in terms of water quality.

Assessment of surface water quality in a drinking water supply reservoir in Vietnam: a combination of different indicators

Eutrophication and water pollution have become serious aquatic environmental problems worldwide. In this study, four different water quality indexing methods, the Canadian Council of Ministers of Environment Water Quality Index (CCME WQI), the revised Comprehensive Pollution Index (CPI), the Eutrophication Index (EI), and the Trophic State Index (TSI), were used to investigate water quality and trophic status in the Tri An Reservoir (TAR), Vietnam. Nineteen water variables were monitored bimonthly between February 2018 and December 2019 to calculate these four indices. Although different input data sets were used, all the indices showed similar results in terms of water quality and eutrophic state. The CCME WQI ranged from 32 to 68 (median 36–48), which indicated that the water quality was classified between poor and marginal and was insufficient for domestic purposes. Similarly, the water quality was ranked between slightly polluted and medium polluted based on the revised CPI index, with the median values ranging from 0.72 to 0.94. In the CCME WQI and the CPI, the major parameters that contributed to water pollution in the TAR were turbidity, dissolved oxygen (DO), total suspended solids (TSS), chemical and biological oxygen demand (BOD5), ammonium (NH4+), nitrite (NO2−), iron (Fe), lead (Pb), and coliforms. Regarding the trophic status of water, the EI ranged from 10 to 464, indicating that the reservoir was eutrophic, and the TSI values ranged from 53 to 89, indicating that the water quality was classified between light-eutrophic and hypereutrophic conditions. A temporal variation in water quality was found, with the highest levels of pollution recorded in June during the study period. Our results show that the combination of different water quality indices provides a comprehensive assessment of water quality in the TAR.

Plastic-Associated Microbial Communities in Aquaculture Areas

Microorganisms colonize plastics in the aquatic environment but their composition on plastics used in aquaculture remains poorly studied. Microorganisms play a significant role in aquaculture in terms of water quality and the health of cultivated species. In the current study, we explored the composition of microorganisms on floating plastics and their surrounding water collected from ponds and open aquaculture areas. Using scanning electron microscopy, the diversity of microbial communities, primarily diatoms, and bacteria were identified on the plastic surfaces. Additionally, epifluorescence microscopy revealed that prokaryotes were colonized on all plastic samples from 0.1 to 29.27×103 cells/cm2, with a high abundance found in open aquaculture areas compared to ponds. Bacterial communities were characterized by 16S rRNA sequencing which showed that bacterial communities on plastics were dominated by Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria. The level of these microbial communities on the plastics differed from those found in the surrounding seawater samples and the abundance of potentially pathogenic bacteria was higher in plastics than in seawater samples. Moreover, hydrocarbon-degrading bacteria were more abundant in the investigated plastic samples than in the water samples. This study contributes to the knowledge regarding the plastisphere community in aquaculture.