Low Water Quality Research Articles

Effect of biofloc technology at varies biological factors on the growth performance and water quality in cultivation of red hybrid tilapia

Aquaculture is one of the important food-producing sectors. However, the effluent of the aquaculture system consists of pollutants such as nitrogenous compounds and the ample usage of water for traditional aquaculture systems. Therefore, biofloc technology was developed in the aquaculture industry in the 1980s to improve the water quality of the system and increase the fish production. The purpose of this experimental work is to investigate the effect of biological factors on the growth performance of fish and the water quality of the biofloc technology (BFT) aquaculture system for red hybrid tilapia cultivation. In this study, 3 biological factors such as the carbon-to-nitrogen ratio, stocking density and the feeding rate were studied under BFT. Parallel experiments in thirteen suspended growth tanks were carried out within (10:1-20:1) C/N ratio, (1%-5%) feeding rate and (20-80 fish m-3) stocking density for 10 weeks. Growth rate of fish and water quality data such as ammonia, nitrite and nitrate concentrations were collected weekly during the study. The results revealed that the 20:1 C/N ratio gave the best water quality. Feeding rate at 4% of body weight produced good growth performance of the tilapia species and the higher stocking densities lead to lower water quality and survival rate.

Enhancing slaughterhouse wastewater treatment through the integration of microbial fuel cell and Electro-Fenton systems: A comprehensive comparative analysis

This research examined the viability of combining the Microbial Fuel Cell (MFC) and Electro-Fenton (EF) system to treat slaughterhouse wastewater. The study compared three different setups: the first utilizing only the MFC, the second employing solely EF, and the third integrating both systems for wastewater treatment (MFC and EF). In the case of Microbial Fuel Cell treatment, notable removal efficiencies were observed, including 58.8 % for turbidity, 41.2 % for color, 69.9 % for chemical oxygen demand, 72.2 % for biochemical oxygen demand, and 69.9 % for total coliform bacteria. EF treatment demonstrated substantial Removal efficiencies of 72.5 % for turbidity, 81.6 % for Chemical Oxygen Demand (COD), 86.5 % for biochemical oxygen demand, and 84.3 % for Escherichia coli (E. coli) bacteria. Integrated treatment yielded exceptional Removal efficiencies of 98.9 % for turbidity, 95.5 % for chemical oxygen demand, 95.4 % for biochemical oxygen demand, and 100 % for E. coli bacteria. After computing water quality indices, it was found that raw wastewater had an extremely high water quality index (1.087 × 1012), indicating severe pollution. Despite lower water quality indices from MFC and EF treatments, the water remained unsuitable for drinking. Integrated treatment significantly reduced the water quality index (1.67 × 104), indicating enhanced water quality, though it remained non-potable.

On conservation of world heritage Beijing-Hangzhou grand canal for enhancing cultural ecosystem services

The Beijing-Hangzhou Grand Canal carries unique social and cultural significance as a world cultural heritage, but with the acceleration of global urbanization, it has potentially severe environmental risks under continuous anthropogenic disturbances. Therefore, to protect the ecological and cultural values of the Grand Canal, it is necessary to assess the corresponding relationship of water quality to land use and the perception of ecosystem services that focus on cultural ecosystem services (CES). This study aims to analyze the water quality response to land use in the Beijing-Hangzhou Grand Canal, describe the land use types closely related to water quality, and propose corresponding management strategies for enhancing CES. This study investigated the impacts of land use structure and landscape pattern on water quality by calculating the correlation between land use structure and landscape pattern indices and water quality in buffer zones of different distances on both sides of the canal. The results show that green land dominates the land use structure and can effectively reduce water pollution in the canal. On the other hand, urban impervious surfaces showed a significant positive correlation with pollution contributing to low water quality. We accessed the impact of water quality on the perception of CES in the Beijing-Hangzhou Grand Canal and proposed optimization strategies for promoting CES. Both content analysis and thematic analysis were applied to analyze the impact of the water environment quality of the Beijing-Hangzhou Grand Canal on the perception of CES. We found that the perceptions of CES along the Beijing-Hangzhou Grand Canal are associated with the public’s opinions on its cultural heritage services and artistic inspiration services. The perceptions of CES are closely related to the quality of the water environment and riparian greenness, which affect the values of cultural heritage and conservation of the Beijing-Hangzhou Grand Canal.

Assessment of Water Quality During 2018-2022 in the Vam Co River Basin, Vietnam

Water pollution in the Vam Co River basin is becoming more complicated due to untreated wastewater being directly discharged into rivers and canals from agricultural, industrial, and domestic activities. To assess the water quality in this area, this study conducted monitoring at ten sampling locations (S1-S10) from 2018 to 2022, calculated the Water Quality Index (WQI) for each parameter, and simulated water quality in 2022 using the 1D- MIKE 11 model developed by DHI with two main modules including HD and AD. The findings showed that most parameters did not surpass the allowable limits per QCVN 08-MT:2015/BTNMT on Vietnam National Technical Regulation on Surface Water Quality. However, organic and microbial pollution led to certain parameters, such as BOD5, COD, and Coliform, exceeding the limits. The lowest water quality was recorded in Long An province, especially at sampling locations S3, S4, and S6, with the average WQI for nine water quality parameters from February to July 2022 being 58.4, 67.8, and 21.1, respectively. Additionally, the simulation outcomes of the MIKE 11 model salinity, BOD5, DO, and NH4 aligned with the real measurements taken. It has been observed that the southern area of the Vam Co River Basin possesses poorer water quality than the northern part, with Long An province located downstream of the Vam Co River basin being the primary source of pollution. The development of this hydraulic model signifies a crucial milestone in comprehending and regulating the effects of pollution in monitoring and managing water management systems, controlling saline intrusion, and ensuring water supply for agricultural production and daily use in the Vam Co River basin.

Effect of sufficient and deficit irrigation with different salt inputs on the yield of cucumber

Soil salinisation is considered one of the major environmental hazards threatening agricultural productivity and can be accentuated by climate change as well as the use of low-quality water in irrigation. This is the case in our study area which is affected by secondary salinisation due to the use of saline irrigation water for horticultural production. Deficit irrigation technique is implemented especially in arid and semiarid regions due to its potential to optimise water productivity while maintaining or increasing crop yield. The main objective of this study was to compare the effect of irrigation with sufficient (SD) and deficit (DD) doses. This research was carried out in Karcag in 2020. Cucumber was grown on a meadow chernozem soil and was irrigated with SD and DD of two irrigation water qualities. Soil moisture was monitored and crop yields were recorded. Despite the differences in quality and quantity of water, the application of less water by DD maintained the same yield as SD. We found a non-significant difference between the average soil moisture contents under the treatments (15.5 v/v% for SD and 13.5 v/v% for DD). Deficit irrigation can be an efficient technique due to its potential for improving water use efficiency, maintaining sufficient soil moisture content favourable for proper crop development and yield.

Evaluation of Treated Wastewater Quality for Reuse in the Northern Region of Minas Gerais

Objective: This study aims to analyze the quality of effluents treated at three Wastewater Treatment Plants (WWTPs) in the northern region of Minas Gerais, evaluating reuse potential and proposals. Theoretical framework: The practice of reusing sanitary effluents holds significant economic and environmental importance. It conserves water resources allocated for higher priority uses. When assessed and compliant with regulations, effluents become potential water sources for agriculture and urban squares. The trend towards reusing treated effluents presents an alternative to meet water demands that could be satisfied with lower-quality water. Method: The study conducted laboratory analyses of three COPASA MG sewage treatment plants, referred to as WWTPs I, II, and III, between January 2021 and September 2022. Parameters crucial for effluent reuse, including Biochemical Oxygen Demand (BOD), Electrical Conductivity (EC), Hydrogen Potential (pH), Escherichia coli, Sodium Adsorption Ratio (SAR), and viable helminth eggs, were monitored and evaluated. The feasibility of proposed water reuse methods was assessed by analyzing the quality of treated effluents from the three WWTPs, considering that the treatments adhered to the conditions and effluent discharge standards outlined in Joint Normative Decision COPAM and CERH-MG No. 01 of May 5, 2008 (Minas Gerais, 2008), as well as the reuse parameters defined in Normative Decision CERH-MG No. 65/2020 of June 18, 2020 (CERH-MG, 2020). Results and Conclusion: The findings indicate that the effluents treated in the studied WWTPs are suitable for reuse, with potential corrective measures for non-compliant parameters. This allows for irrigation of urban squares, subject to approval by local authorities, and internal irrigation within interested businesses. Research Implications: This approach is highly relevant for fostering discussions on expanding reuse practices and shaping regulations through legislation, norms, and deliberations. Originality: This study stands out due to its in-depth investigation, ensuring a viable water reuse source for localities facing water scarcity, particularly in the northern region of Minas Gerais. This innovative topic, though less explored in literature, is gaining momentum in environmental discourse, thanks to the potential of effluents for agricultural purposes.

Evaluating groundwater contamination: An examination of a municipal solid waste dump yard in southern India's Manchester City

Groundwater is a critical resource that is utilized for a variety of reasons, but over-extraction can lead to a number of environmental and socioeconomic issues such as diminished water supply, land subsidence, and pollution. To manage groundwater resources in a sustainable manner, proper monitoring, regulation, and conservation strategies are required. Groundwater contamination in India is growing as a result of population increase and industrialisation, which can have serious health and environmental consequences. To avoid groundwater pollution, it is critical to monitor and control possible sources of contamination, as well as to promote sustainable farming practices and the use of less hazardous pesticides and fertilizers. To get a better knowledge of groundwater pollution, the current study attempted to analyse the quality of groundwater in the neighbourhood of the Vellalore dump yard (located in Coimbatore, India), encompassing an area of 161.87 hectares. To examine the quality of groundwater in the contaminated region, several physical and chemical properties such as pH, dissolved oxygen, total dissolved solids, and water quality index were measured. The majority of the water samples from the region are classed as low quality and unsafe for drinking. The plume appears to be migrating northerly and northwest from the landfill location, most likely due to the natural slope of the dump site towards the northwestern direction. The bulk of the gathered samples have low water quality, making the water unfit for even basic residential use. These findings highlight the need of local governments taking proactive efforts to protect the groundwater in this area, pushing for a comprehensive approach to prevent additional pollution. The report emphasizes the critical need for local governments to take prompt action to prevent additional groundwater pollution by establishing a comprehensive strategy.

For Want of a Cup: The Rise of Tea in England and the Impact of Water Quality on Mortality

Abstract This paper explores the impact of water quality on mortality by exploiting a natural experiment: the rise of tea consumption in eighteenth century England. This resulted in an unintentional increase in consumption of boiled water, thereby reducing mortality rates. The methodology uses two identification strategies tying areas with lower initial water quality to larger declines in mortality rates after tea drinking became widespread and following larger volumes of tea imports. Results are robust to the inclusion of controls for income and access to trade. The hypothesis is further bolstered by suggestive evidence from cause specific deaths and early childhood mortality.

Quality Characterization of Groundwater for Human Consumption using Water Quality Index for Gandhinagar District, Gujarat

As we know, Water is an important parameter for survival of biotic component. Current analysis deals with ground water characteristic of Gandhinagar District, Gujarat. The properties of water and the water quality index are closely related. It is a number between 1 and 100 that represents the overall water quality at a specific location and time based on different water quality attributes. Better water quality is demonstrated by a lower water quality index. The land use pattern and waste disposal system have the most impacts on groundwater quality. The word "water quality" refers to the physical, chemical, or biological properties of the water. This was discovered by the collection of 50 groundwater samples from various locations across Gandhinagar and the comprehensive physicochemical examination of each sample. The following 10 factors have been taken into account when calculating the WQI.: PH, Sodium (Na+) , Total Hardness(CaCO3), Calcium, Magnesium, Chloride, Fluorides, Iron, Nitrate and Sulphate(SO4). The Bureau of Indian Standards (BIS, 2012) has been taken into account when determining whether groundwater is fit for drinking and for calculating WQI. Understanding the structure and operation of a specific water body may be aided by the physicochemical investigation. For the Gandhinagar District, the WQI was determined to be within the advised ranges, and all significant villages have values that fall into the Good category for water quality (B grade).

Growth Performance, Feed Utilization, Hematological Parameters, and Histological Features of Nile Tilapia (Oreochromis niloticus) Fed Diets with Supplementary Herbal Extracts Under Prolonged Water Exchange

Abstract Nile tilapia is known for its relative tolerance to some biotic and abiotic stressors. However, long-period water exchange may impair the health status and, thereby, the growth performance and feed utilization. In this regard, using herbal extracts may help to relieve the adverse impacts of low water quality on the productivity of this fish species. A 100-day feeding trial was designed to examine the effects of dietary supplements of Aloe vera leaves (AVE), and chamomile flowers, Matricaria chamomilla (CFE) extracts on water quality, growth performance, and well-being of Nile tilapia. Fish (3.95±0.05 g, n=1200) were distributed into five groups (15 fiberglass tanks, 2 m3) under a water exchange rate of 20% every two days for standard control (T0) without herbal supplements. Groups (T1, T2, T3, and T4) were exposed to a long water exchange period of 50% every month, wherein T1 (stressed control), T2, T3, and T4 groups were fed a diet supplemented with 0% herbal extract, 1% AVE, 1% CFE and 0.5% AVE +0.5% CFE, respectively. Results showed that feeding on a T2 diet exhibited a clear improvement under a long period of water exchange stress, and it is almost similar to their counterparts under normal conditions (T0) in terms of specific growth rate, survival rate, feed intake, feed conversion ratio, and protein efficiency ratio. Moreover, the lowest levels of aspartate aminotransferase were obtained with T2 and T0. In addition, the highest white blood cell count and hemoglobin values were recorded with group T0, followed by T2, and T4, while there was no significant difference between T3 and T1. Fish under stressed conditions without herbal extracts (T1) showed the lowest performance and survival rate compared to T0 and T2 groups. In conclusion, feeding diet supplied with 1% A. vera extract to stressed fish restored their performance and well-being to the level of their counterparts under normal conditions.

Measuring biodiversity vulnerability in French lakes – The IVCLA index

Assessing the vulnerability of ecosystems to biodiversity loss has become increasingly crucial in conservation and ecology research. This study proposed a methodology for measuring lake vulnerability to biodiversity loss employing an established framework that combines three components. For this, we measured the resilience (functional redundancy) and sensitivity (an index considering three characteristics of rarity) components for fish and phytoplankton communities. We also measured the exposure component of the main stressors in lakes. We then combined the three components and calculated the vulnerability index (IVCLA) using data from 255 French lakes. We found that all lakes exhibited low levels of resilience, elevated sensitivity regarding average values for fish and phytoplankton groups, and medium exposure to stressors associated with human activities. In addition, there were some discrepancies in resilience and sensitivity patterns between fish and phytoplankton groups, emphasizing the importance of considering information from multiple biological groups when assessing ecosystem vulnerability. Hydrological alterations and low water quality were key stressors related to higher lake vulnerability. Most French lakes have been classified as exhibiting moderate vulnerability. It is crucial to emphasize the potential increase in exposure risks, which could lead to even higher vulnerability levels and, subsequently, biodiversity loss in the future. The IVCLA index offers several advantages, including integrating multiple taxa groups and stressors. We recommend incorporating additional data, such as the resilience and sensitivity of the entire food web, and considering temporal responses to stressors to improve accuracy and predictive power. The IVCLA was developed with the purpose of serving as an effective tool for guiding environmental managers in designing conservation strategies and making informed decisions for lake ecosystems.

Improving industrial wastewater irrigation: the effects on Indian baby pumpkin (Praecitrullus fistulous) cultivation

Increasing insufficiency of freshwater resources is driving many countries in arid and semi-arid regions to use low-quality water for agriculture and related activities. This wastewater may have some useful as well adverse effects on various parameters. In this regard, we design an experimental setup to investigate the impact of irrigation with industrial wastewater on the Praecitrullus fistulosus (Indian baby pumpkin) plant. For this purpose, Praecitrullus fistulous was cultivated in soil irrigated with different concentrations (i.e. 25, 50, 75, 100%) of industrial wastewater, while control contain 0% of wastewater. Before the treatment, physicochemical parameters (pH, TDS, EC, etc.) of industrial wastewater were analysed. It was observed that lower concentration/s of wastewater positively affects various morphological (no. of leaves, fruits etc.) and biochemical (Total protein, Flavonoids, Sugar/s content etc.) attributes in treated plants, whereas elevated concentration may hurt these parameters.

How sustainable and profitable are large-scale hydrogen production plants from CH4 and H2S?

The large-scale production of hydrogen through mature technologies such as steam methane reforming (SMR) has set a benchmark for emerging hydrogen production processes to gauge their economic viability for the hydrogen economy. In this work, we use detailed process modeling to perform a techno-economic and environmental assessments on the potential of alternative emerging hydrogen production processes based on H2S utilization including H2S-methane reforming (H2SMR), and H2S pyrolysis (H2SPyrol) compared to steam methane reforming (SMR), SMR with CO2 capture, storage, and utilization (CCUS), and CH4 pyrolysis (CH4Pyrol). Technically, the energy intensity of these processes in terms of electrical and thermal energy consumption was ranked as CH4Pyrol < SMR < SMR + CCUS < H2SMR < H2SPyrol. However, lower CH4 feedstock and absence of direct CO2 emissions were seen for H2SMR for the same target hydrogen production. Economically, both H2S-based hydrogen production technologies were competitive with levelized cost of hydrogen (LCOH) of $-1.000 and $3.537 per kg for H2SMR and H2SPyrol, respectively, compared to LCOH of $2.400, $2.410, and $1.930 per kg for SMR, SMR + CCUS, and CH4Pyrol, respectively, with consideration for by-product sales, and sensitivity analysis to their market prices and effect of carbon taxes. Environmentally, H2SMR and H2SPyrol revealed their lower contribution to global warming, with the absence of direct CO2 emissions, qualifying as low carbon hydrogen production processes. Although direct CO2 emissions are missing from CH4Pyrol, its qualification as low carbon hydrogen producer hinges on the level of decarbonization for the electricity grid. Conversely, the water footprint of H2S-based hydrogen production process remains to be the largest due to the indirect consumption of cooling water required for product recovery, although not necessarily impacting water stress, due to the lower quality of water required for cooling. In summary, transitioning from SMR wo/w CCUS to H2SMR or CH4Pyrol seems to be potentially attractive for competing with current processes for H2 production within the existing policies for decarbonization.

Coastal aquifer water quality for domestic supply of small communities in the semiarid Potiguar - Brazilian Northeast

This study analyzed groundwater quality used to supply small communities in the coastal zone of the Brazilian Northeast, identifying the risks from domestic use of water, and potential contaminants from domestic effluents. We realized analyses of 24 chemical and physical parameters in 15 samples of water from shallow wells. The data was processed through quality modeling, descriptive statistics, principal component analysis, and geoespacialization through kriging. The groundwater used by communities showed some limitations to domestic use. Parameters of Br, hardness, Na+, NO3−, Cl−, SO4−, and turbidity exceed the allowed for Brazilian Health Minister (Ministerial Order n. 888/2021). Furthermore, TDS values present low water quality, predominantly brackish and saltwater, most salinity waters are related to depth and sea proximity. Depth of saturated zone probably is a determinant in nitrate concentrations, comparing the study areas. Water self-supply is considered a risk by health because inferior natural quality of water used and contaminations from domestic sewage determine concentrations of some parameters above of legislation.

Land use and rainfall influences on bacterial levels and sources in stormwater ponds.

Urban stormwater runoff is a known source of microbial contamination of stormwater ponds. However, less is known about the influences of land use and rainfall on microbial quality over time in these receiving waters. In this study, two fecal indicator bacteria (FIB), namely Escherichia coli and thermotolerant coliforms, were monitored in three stormwater ponds in Calgary, Alberta, Canada. The stormwater ponds were selected due to their potential as water sources for beneficial uses such as irrigation, which requires lower water quality than drinking water, thereby alleviating the pressure on the city's potable water demands. The selected stormwater ponds vary in size and shape, contribution catchment size, and percentages of several primary land use types. Microbial source tracking for human, dog, seagull, Canada goose, ruminant, and muskrat was also conducted to determine sources of bacterial contamination in the stormwater ponds. Sampling was conducted near the pond surface and adjacent to the shoreline, specifically near the outfalls that discharge stormwater runoff into the ponds and the inlets that convey water out of the ponds. Overall, the FIB concentrations in the vicinity of pond outfalls were significantly or relatively higher than those near pond inlets. The contamination in the McCall Lake and the Country Hills stormwater ponds showed higher amounts of human markers (40 to 60%) compared to the Inverness stormwater pond (< 20%), which coincided with their higher FIB concentration medians. The results revealed that stormwater drained from catchments with a higher percentage of commercial land use was more contaminated than those with primary residential land use, while the impacts of residential development on the FIB levels in the Inverness stormwater pond were not obvious. Furthermore, FIB concentrations in the ponds increased in response to both rain events and inter-event dry periods, with human-specific markers being predominant despite the high levels of animal markers during inter-event dry periods. Human-origin sources might be among the main microbial loading contributors in the pond catchments in general. All these findings can inform the development or improvement of measures for mitigating microbial pollution, strategies for reusing stormwater, and maintenance programs.

Utilizing Local Resources Of Ijuk Aren To Produce Clear Water In Gegerung Village, Lingsar District, Lombok Barat District, NTB

Clean water is one of the main human needs in everyday life is very important to pay attention to its quality. Unfortunately there are still many areas that cannot enjoy clean water as it should. One of the villages that has low water quality is Gegerung Village, Lingsar District, West Lombok Regency. With a variety of natural resources owned by Gegerung Village, the Mataram&#x0D; University Community Service Team took the initiative to make a water filter made from natural palm fiber to overcome existing water problems. Natural materials used include river stone, gravel, palm fiber, and fine river sand. The material is stacked until it fills the tub, then the water is flowed to get clear water.&#x0D; &#x0D; Keywords : Water quality, local resources, palm fiber

Calculation of ecological water replenishment in small coastal watersheds based on environmental capacity constraints: A case study of eastern Xiamen, China

In response to the issues of severe coastal pollution and exacerbated eutrophication, it is crucial to consider characteristics such as small flow in small coastal urban watersheds and water of low quality when implementing water replenishment measures. The selection of appropriate constraints and methods for calculating the ecological water replenishment (EWR) is the top priority. Here we present a calculation model appropriate for pin down the range of EWR in small coastal watersheds. Taking four of the eastern regions of Xiamen City as examples, the minimum and maximum EWR are independently computed based on the envelope curve and the restriction of the estuarine area's environmental capacity. Rational results are achieved with the approaches of Tennant as well as landscape water requirement, and it shows that the range of EWR for the four watersheds is 1.77×106 – 12.41×106 m3. The calculation model proposed in this paper has greater environmental feasibility from the perspective of the river channel demand and coastal environmental protection. Additionally, it also can provide a reference for EWR plans for urban rivers in coastal regions.

Assessment of groundwater vulnerability for seawater intrusion using DRASTIC model in coastal area at Patuakhali District, Bangladesh.

Seawater intrusion is a growing concern for coastal regions in Bangladesh. Overexploitation of groundwater, low rainfall, a high rate of evaporation, rising sea level, cyclones, storm surges, and shrimp cultivation are the causes of seawater intrusion that polluted the groundwater near the coastal area. High values of EC, TDS, Na+, and Cl- ions in groundwater indicate the seawater intrusion. Piper's Trilinear and Durov diagrams of groundwater indicated that most gathered groundwater show predominantly Na-Cl-type of water. Based on the USSL diagram, it is observed that the salinity of the study area is medium to high and the alkalinity is medium to very high. Also, in view of the Wilcox outline, most of the samples in the area of interest are permissible to doubtful, and doubtful to unsuitable. Chloride is moderately correlated with Na+ (R2 = 0.590) and poorly correlated with (HCO3- + CO32-) (R2 = 0.128), which indicates seawater intrusion. According to a comparison of the levels of Fe and Mn in the groundwater of the study area with those recommended by the World Health Organization (WHO) and Department of the Environment (DOE), twenty-two out of thirty-one samples exceed the acceptable limit for Fe and thirty out of thirty-one samples fall within the acceptable limit for Mn. The calculated water quality index reveals that most samples are of low drinking water quality. The research area's poor water type is found in the north-central and southern parts. The WQI geographic variation map reveals that the study's water has a WQI of more than 100, making it unsuitable for consumption. The final seawater intrusion vulnerability map clearly identifies the moderate to highly vulnerable zone of the study area using DRASTIC index parameters. DRASTIC index parameters revealed that some portions of the northwestern part of the sample area show a moderately vulnerable zone. And the rest of the sampling area indicates the highly vulnerable zone.

Remote sensing inversion of water quality parameters in the Yellow River Delta

In recent years, with the rapid socio-economic development of the Yellow River Delta (YRD), the pressure on the supply of water resources has continued to rise. The development of oil-based industries has also led to a series of ecological and environmental problems, such as wetland degradation and water quality deterioration. As an increasing number of rivers are getting polluted, resulting in the deterioration of their water quality, monitoring, managing, and protecting water resources in the YRD is particularly important. In this study, water quality monitoring data and simultaneous Sentinel-2 image data from April 30, 2020, to October 26, 2021, were used to construct an experimental sample in the YRD. Water quality parameters (WQPs) concentrations were correlated with Sentinel-2 image element spectral reflectance and sensitive bands were selected. An empirical method based on the characteristic bands was used to invert a total of six water quality indicators, namely dissolved oxygen (DO), permanganate index (CODMn), ammonia nitrogen (NH3-H), total phosphorus (TP), total nitrogen (TN) and turbidity. The results show: (1) A total of five water quality inversion models for DO, TN, CODMn, TP and TN were effective in the areas of the Guangli River, the Tiaohe and the Branch River. The inversion accuracies of the five inversion models (R2of 0.6099, 0.9271, 0.9581, 0.8784 and 0.7387; RMSE of 1.2723, 0.3413, 0.9923, 0.0118 and 1.8476; RPD of 1.53, 2.08, 3.56, 2.76 and 1.53) indicated the feasibility of the water quality inversion method based on Sentinel-2 data using statistical theory for monitoring water quality concentration in the YRD. (2) The spatial distribution of water quality in the YRD was generally characterized by high water quality in the upper reaches and low water quality in the middle and lower reaches (except for some seasonal variations). Among them, the water quality of the upper reaches of the Guangli River was poor, with opposite trends in DO and TN concentrations. In the Tiaohe, CODMn and TP concentrations were not strongly correlated. However, CODMn and TP concentrations were high in the middle reaches where water quality was the worst. The TN concentrations in the Branch River decreased between 2020 and 2021, but the water quality is still in Category V. Therefore, continued attention and appropriate water quality management measures in the YRD are required. Further, by measuring water quality indicators at monitoring stations, regression-fitting equations for WQPs were established to obtain complementary multi-platform observations. Thus, the water quality conditions in the YRD region can be evaluated more accurately and quickly. The research results not only provide an important reference basis for the identification and monitoring of pollution sources, prevention and treatment of water environment pollution in the YRD, but also provide water security for socio-economic and ecological environment security.

ON-REEF CYCLONIC WAVE CLIMATE THROUGHOUT THE GREAT BARRIER REEF

The Great Barrier Reef is an iconic ecosystem that is collapsing under low lagoon water quality from terrestrial runoff and resulting overly productive crown-of-thorns starfish, coral bleaching from thermal stress and physical destruction from tropical cyclones, to name the top four stresses. This collapsing is mostly seen in coral coverage declining over time from water quality and starfish stresses combined with episodic large scale drops from thermal stress and tropical cyclones. Action on improved land use would decrease the impact from water quality and starfish and action on climate change would reduce thermal stresses and hence, the frequency of bleaching events. Tropical cyclone impacts, while they may be getting more intense or larger under climate change, their destructive power is significant either way (i.e., before and after climate changes). These stresses have led to the administrative body, the Great Barrier Reef Marine Park Authority, to shift from passive management to active interventions, which are generally extremely costly compared to the income generated by the Great Barrier Reef. Consequently, to ensure the limited resources are deployed to obtained maximum benefit, interventions are being tested across all stresses including cyclonic stresses. This requires fine scale determination of cyclonic wave climates across the entire Great Barrier Reef.