Factors controlling seagrass growth in a gulf coastal system: Water and sediment quality and light

Effects of spatial variation in water quality and hydrological factors on environmental flows

Artificial neural networks exhibit significant advantages in terms of learning capability and generalizability, and have been increasingly applied in water quality prediction. Through learning a compressed representation of the input data, the Encoder-Decoder (ED) structure not only could remove noise and redundancies, but also could efficiently capture the complex nonlinear relationships of meteorological and water quality factors. The novelty of this study lies in proposing a multi-output Temporal Convolutional Network based ED model (TCN-ED) to make ammonia nitrogen forecasts for the first time. The contribution of our study is indebted to systematically assessing the significance of combining the ED structure with advanced neural networks for making accurate and reliable water quality forecasts. The water quality gauge station located at Haihong village of an island in Shanghai City of China constituted the case study. The model input contained one hourly water quality factor and hourly meteorological factors of 32 observed stations, where each factor was traced back to the previous 24 h and each meteorological factor of 32 gauge stations was aggregated into one areal average factor. A total of 13,128 hourly water quality and meteorological data were divided into two datasets corresponding to model training and testing stages. The Long Short-Term Memory based ED (LSTM-ED), LSTM and TCN models were constructed for comparison purposes. The results demonstrated that the developed TCN-ED model can succeed in mimicking the complex dependence between ammonia nitrogen and water quality and meteorological factors, and provide more accurate ammonia nitrogen forecasts (1- up to 6-h-ahead) than the LSTM-ED, LSTM and TCN models. The TCN-ED model, in general, achieved higher accuracy, stability and reliability compared with the other models. Consequently, the improvement can facilitate river water quality forecasting and early warning, as well as benefit water pollution prevention in the interest of river environmental restoration and sustainability.

Multivariate analyses link macrophyte and water quality indicators to seagrass die-off in Florida Bay

BackgroundChanging water quality was prevalent in the current water supply. The fluctuation of iron stability due to changing water quality followed four characteristics: objectivity, relativity, predictability, and controllability. Therefore, it was necessary to study the stability of iron in the pipe network by integrating different water quality factors.ResultsThe iron stability risk evaluation system was established according to the different water quality factors in the drinking water distribution systems (DWDSs). Meanwhile, an improved fuzzy comprehensive evaluation method was established to evaluate the risk of iron. Chloride, sulfate, dissolved organic matter (DOM) and pH were selected as the risk assessment index. The divisions of different evaluation levels were carried out through the values of water quality factor. On the basis of expert scoring, the weight and membership degree of water quality factors were analyzed by structural entropy method. In addition, risk analysis was established by using the optimized risk assessment system. According to the results of the comprehensive evaluation, DOM and pH were identified as two of the most important factors in the evaluation of the iron stability. In addition, compared with the traditional fuzzy comprehensive evaluation method, the optimized method had a higher degree of fit which could more clearly prove the relationship between the risk value and the iron concentration.ConclusionThe uncertainty between the factors was eliminated by establishment of the fuzzy evaluation method combined with the different effects of water factors on iron stability. The method could be used as a comprehensive evaluation and be beneficial to the analysis of iron risk in water supply network.

Response mechanisms of eukaryotic plankton community structure to complex environmental conditions in semi-arid river basins, China.

The Nile Delta is a dynamic ecosystem; its coastal area receives water from the two estuaries of the Nile River (Rosetta and Damietta), the outlets of the coastal lakes (Mariout, El-Manzala, El-Burullus, and Edku), and the drains. Water quality is a complex term that can indicate the state of the water compared to standard criteria for use in specific purposes. It contains many physical, chemical, and biological factors, but the critical water quality factors are water temperature, dissolved oxygen, nitrogen (ammonia/nitrate/nitrite), hydrogen ion concentration (pH), alkalinity, salinity and electrical conductivity, carbon dioxide, and turbidity. Estuaries are a mix between freshwater and marine water. Water and sediment quality were discussed for Rosetta and Damietta estuaries. Water quality of the Nile Delta coastal lakes is discussed for the four important lakes (Mariout, El-Manzala, El-Burullus, and Edku). Pollution, climate change, human activities, and fish farms are discussed as factors affecting water quality deterioration in the Nile River estuaries. The water quality index was introduced as single value representing water quality parameters. The spatial and temporal variations are presented in the Nile Delta estuaries. The pollution evaluation index is also discussed. Water management and environmental laws are briefly presented.

The biotic indices used in Rapid Bioassessment Protocol II (RBP II) developed by United States Environmental Protection Agency was used to assess the feasibility of using benthic macroinvertebates as bio-indicators for monitoring water and sediment quality in Ja-Ela stream, which is a lotic water body in the western coastal region of Sri Lanka. Five study sites to cover the entire length of the stream, which are in five different fringing land uses (undisturbed site, agricultural site, industrial discharge receiving site, densely populated urban site and a site close to the mouth of the stream) were sampled for water and sediment quality parameters and benthic macroinvertebrates from April to October 2015. Shannon-Weiner diversity index (H`), Hilsenhoff Family Biotic index (FBI), Taxa richness (TRI), and Ehemeroptera, Plecoptera and Trichoptera (EPT) index were calculated for each site. Results indicated significant spatial variations in BOD5, COD, visibility, nitrate concentration and total phosphorus concentrations in the water, and total organic carbon content and particle size distribution in sediments. The highest mean values for H' (2.38), TR (13.6) and EPT (6.2) were recorded from the undisturbed site. Significantly higher FBI values are recorded from the industrial discharge receiving site (6.97) and the urban site (6.81), indicating that they are the most polluted sites with higher degree of organic pollution than other sites. These biotic index values showed significant correlations with sediment and water quality characteristics of the study sites (R2 >0.5, p<0.05) The H', EPT, FBI and TR values for benthic macro-invertebrate community showed that the upstream portion of this stream is habitable to pollution sensitive taxa, while the downstream areas close to its opening to Negombo estuary are habitable by pollution tolerant taxa. Results of the present study identified the RBP II as a possible bio monitoring protocol to reflect the water and sediment quality in the Ja-Ela stream.

As a part of the monitoring practice of the lone natural habitat of the endemic and endangered Rucervus eldii eldii McClelland or Sangai, the paper reports sediment and water characteristics of Keibul Lamjao National Park-the only floating national park of the world in Manipur, Indo Burma hotspot. The water analysis showed low pH (5.69 ± 0.16), high electrical conductivity (342 ± 13.01 μS m-1), high turbidity (33.2 ± 9.407 NTU), and high phosphate concentrations (0.92 ± 0.11mg L-1) during the study period. The water quality index values calculated indicate that the park water during post-monsoon season is unfit for drinking. Thus, the degrading water quality poses a serious risk to the health of the deer and other species in the park. At present, Sangai in its natural habitat is threatened by pollution, encroachment, phoomdi thickness reduction, and inbreeding depression. To address the problem of inbreeding, Pumlen pat is considered as a second suitable natural habitat for the deer reintroduction program. During the study, water characteristics of the wetland showed similar characteristics as KLNP, i.e., low pH (5.86 ± 0.30), high electrical conductivity (377.6 ± 5.55 μS m-1), high turbidity (32.36 ± 4.91 NTU), and high phosphate concentrations (0.79 ± 0.14mg L-1). Likewise, sediments showed high TP accumulation that ranged from 197.03 ± 0.75 to 332.88 ± 0.99mgkg-1 for KLNP and 245.18 ± 0.85 to 351.48 ± 0.71mgkg-1 for Pumlen pat, respectively. Both, the lone natural habitat and the proposed habitat showed deteriorating water quality. As such, continuous monitoring of KLNP and Pumlen pat water and sediment quality should be a priority during the management practices to protect the endangered deer and health of the habitats for long-term conservation.

Conversion of forested lands to agriculture or urban/residential areas has been associated with declines in stream and lake water quality. Less attention has been paid to the effects of adjacent land-uses on wetland sediment and water quality and, perhaps more importantly, the spatial scales at which these effects occur. Here we address these issues by examining variation in water and sediment nutrient levels in 73 southeastern Ontario, Canada, wetlands. We modeled the relationship between water and sediment nutrient concentrations and various measures of adjacent land-use such as forest cover and road density, measured over increasing distances from the wetland edge. We found that water nitrogen and phosphorous levels were negatively correlated with forest cover at 2250 meters from the wetland edge, while sediment phosphorous levels were negatively correlated with wetland size and forest cover at 4000 meters and positively correlated with the proportion of land within 4000 meters that is itself wetland. These results suggest that the effects of adjacent land-use on wetland sediment and water quality can extend over comparatively large distances. As such, effective wetland conservation will not be achieved merely through the creation of narrow buffer zones between wetlands and more intensive land-uses. Rather, sustaining high wetland water quality will require maintaining a heterogeneous regional landscape containing relatively large areas of natural forest and wetlands.

Fundão dam (Minas Gerais, Brazil) breached on 5 November 2015, releasing 50 million m³ of Fe ore tailings and dam materials into the upper Doce River system. The tailings travelled 670 km along the river system to the ocean. Starting on 17 November 2015, 6 days before the tailings reached the Doce River mouth, a water quality monitoring program with a daily sampling schedule was implemented by Samarco Mineração S.A. (Samarco) to assess the impacts on marine water and sediment quality. Between November 2015 and August 2017 water and sediment quality were monitored at 28 locations offshore from the Doce River mouth. The sampling areas were grouped by hydrological and metocean season (i.e., rainy and dry seasons and wave and wind climates), distance from the river mouth (<5 km, >5 km and within a Marine Protected Area), and water depth. The data were compared to the Brazilian water quality standards and prebreach conditions. Statistical tests were conducted to evaluate temporal and spatial trends and patterns. For the water quality parameters of relevance (total suspended solids, turbidity, total and dissolved Fe, Al, and Mn), pulses of concentration increases were observed right after the arrival of the plume in the coastal zone and during the subsequent rainy seasons. Exceedances of prebreach conditions were more frequent closer to the Doce River mouth. During the dry season, concentrations tended to decrease, reaching prebreach levels for a number of parameters, with small short-term pulses associated with metocean factors. For sediment quality parameters of relevance (particle size, Fe, Al, and Mn), Fe was the only one that clearly resulted from the dam breach, which was mediated by river influence and oceanographic factors affecting particle size distribution. Results indicated that the Fundão dam failure did affect water and sediment quality in the Atlantic Ocean, with greater impacts closer to the river mouth and immediately after the arrival of the tailings plume, with concentrations gradually returning to preevent levels over time. Integr Environ Assess Manag 2020;16:643-654. © 2020 SETAC.

Simplistic thinking would have us believe that by eliminating the loading of a given pollutant, an aquatic system will revert to its previous pristine state. This premise is without scientific verification. Besides the fact that typically very little documentation exists defining what exactly that previous pristine state was, it should be noted tha

Shifting of phytoplankton assemblages in a regulated Chinese river basin after streamflow and water quality changes

In recent years, Cyber-Physical Systems (CPSs) have been applied to Water Distribution Systems (WDSs) to facilitate efficient operation and maintenance. Since data are transmitted through the network in such systems, a cyberattack can disrupt the operation of WDSs, for example, by causing water supply reduction, water pollution, and economic losses. In the past few years, cyberattack detection algorithms and various cyberattack scenarios have been proposed. These studies considered either hydraulic factors, such as pipe velocity, nodal pressure, or tank level, or water quality factors. However, an algorithm which considers only one factor cannot prevent the various problems that may arise, such as water quality issues, and the hydraulic and quality factors have a correlation. Therefore, in this study, a framework was developed by considering both hydraulic and water quality factors. The proposed approach was applied to an artificial neural network model. Performance indicators were used to examine the detection performance according to the parameters of the artificial neural network. By comparing the detection performance when only hydraulic factors were considered and the performance when both hydraulic and water quality factors were considered, the effectiveness of the algorithm that consider both hydraulic and water quality factors was demonstrated. A cyberattack detection algorithm that considers both hydraulic and water quality criteria can be applicable in more realistic scenarios and contribute to the establishment of safe infrastructure for the entire process of designing and operating WDSs with CPSs.

Site selection for shellfish aquaculture by means of GIS and farm-scale models, with an emphasis on data-poor environments

Controlling of water quality pollution and eutrophication of reservoirs has become a very important research topic in urban drinking water field. Xili reservoir is an important water source of drinking water in Shenzhen. And its water quality has played an important role to the city’s drinking water security. A fifteen-month’s field observation was conducted from April 2013 to June 2014 in Xili reservoir, in order to analyze the temporal and spatial distribution of water quality factors and seasonal variation of trophic states. Xili reservoir was seriously polluted by nitrogen. Judged by TN most of the samples were no better than grade VI. Other water quality factor including WT, SD, pH, DO, COD, TOC, TP, Fe, silicate, turbidity, chlorophyll-a were pretty good. One-way ANOVA showed that significant difference was found in water quality factors on month (p<0.005). The spatial heterogeneity of water quality was obvious (p<0.05). The successions of water quality factors y were similar and the mainly pattern was Pre-rainy period > Latter rainy period > High temperature and rain free period > Temperature jump period > Winter drought period. Two-way ANOVA showed that months rather than locations were the key influencing factors of water quality factors succession.TLI (Σ) were about 35~52, suggesting Xili reservoir was in mycotrophic trophic states. As a result of runoff pollution, water quality at sampling sites 1 and 10 was poor. In the rainy season, near sampling sites 1 and 10, water appeared to be Light-eutrophic. The phytoplankton biomass of Xili reservoir was low. Water temperature was the main driving factor of phytoplankton succession.The 14 water quality factors were divided into five groups by factor analysis. The total interpretation rate was about 70.82%. F1 represents the climatic change represented by water temperature and organic pollution. F2 represents the concentration of nitrogen. F3 represents the phytoplankton biomass. F4 represents the sensory indexes of water body, such as turbidity, transparency.