Spatiotemporal Variations in Water Flow and Quality in the Sanyang Wetland, China: Implications for Environmental Restoration

Water-Quality Assessment and Pollution-Risk Early-Warning System Based on Web Crawler Technology and LSTM

The openly released and measured data from automatic hydrological and water quality stations in China provide strong data support for water environmental protection management and scientific research. However, current public data on hydrology and water quality only provide real-time data through data tables in a shared page. To excavate the supporting effect of these data on water environmental protection, this paper designs a water-quality-prediction and pollution-risk early-warning system. In this system, crawler technology was used for data collection from public real-time data. Additionally, a modified long short-term memory (LSTM) was adopted to predict the water quality and provide an early warning for pollution risks. According to geographic information technology, this system can show the process of spatial and temporal variations of hydrology and water quality in China. At the same time, the current and future water quality of important monitoring sites can be quickly evaluated and predicted, together with the pollution-risk early warning. The data collected and the water-quality-prediction technique in the system can be shared and used for supporting hydrology and in water quality research and management.

Simulating the impact of piers on hydrodynamics and pollutant transport: A case study in the Middle Yangtze River

It is known that channel engineering, including the construction of piers, will change the river hydrodynamic characteristics, which is a significant factor affecting the transport process of pollutants. With this regard, this study uses the well-validated and tested hydrodynamic module and transport module of MIKE 21 to simulate the hydrodynamics and water quality under various pier densities in the Wuhan reach. Hydrodynamic changes around the piers show spatial differences, which are similar under different discharges. The range and amplitude of hydrodynamic spatial variations increase with the increase in pier density. However, there is a critical value of 1.25 to 2.5 units/km. When the pier density is less than this critical value, this type of cumulative effect is the most significant. Additionally, greater changes can be found in chemical oxygen demand concentrations, which also show spatial and temporal variations. The area with high chemical oxygen demand concentration upstream and downstream from the engineering area exhibits the distribution characteristics of “decrease in the downstream area and increase in the upstream area” and “increase in downstream the area and decrease in the upstream area” respectively. In the reach section of the engineering area, the area with high chemical oxygen demand concentration increases in the front area near the piers and decreases near the shoreline. Furthermore, the concentration shows attenuation actions with a longer residence time owing to the buffering effect of pier groups. These results have significant implications on shoreline planning and utilization. Moreover, they provide scientific guidelines for water management.

Assessment of Land Use/Land Cover Change and Morphometric Parameters in the Keta Lagoon Complex Ramsar Site, Ghana

The rapid urbanization, industrialization, agricultural activities, and increasing trend of some natural hazards, such as climate change, particularly in coastal areas, necessitate the continual assessment of critical but fragile ecosystems like that of the Keta Lagoon Complex Ramsar Site (KLCRS). This productive ecosystem in Ghana faces serious threats from intensive exploitation, physical modification, changes in water regime, and water pollution. The current study employed geospatial and intensity analysis to assess the pattern of land use/land cover (LULC) change for almost the past three decades and morphometric parameters of the KLCRS landscape. Landsat Satellite images for 1991, 2007, and 2020 were acquired to uncover the pattern of LULC change, while morphometric changes were assessed using global Advance Space Thermal Emission and Radiometer (ASTER) digital elevation model (DEM) data and the spatial analyst tools in GIS software. The result established that the acceleration of land transformation was intensive between 2007 and 2020, which could be linked to population growth and increased socio-economic activities. There was a net gross gain of built-up that originated largely from the conversion of marsh, dense vegetation, and cultivated land. Prior to this period, cultivated land recorded net gain (125.51 km2) between 1991 and 2007, whereas dense vegetation and marshland showed a net loss of 151.37 km2 and 2.44 km2, respectively. The gain of cultivated land largely targeted marshland in both time intervals. The construction of saltpans contributed largely to the small increase in water extent. The morphometric analysis revealed the groundwater potential of the KLCRS. The low-lying nature of the landscape makes the area susceptible to coastal flooding. The trend of the observed changes could invariably affect the ecological integrity of the landscape, hence suggesting the need for immediate preparation and implementation of marine and coastal spatial plans by relevant stakeholders.

A Fluorescence Method Based on N, S-Doped Carbon Dots for Detection of Ammonia in Aquaculture Water and Freshness of Fish

Excessive ammonia can cause the death of fish and the eutrophication of the water environment, so ammonia detection is essential for environmental monitoring. In this study, a highly selective sensing strategy for ammonia detection based on N, S co-doped carbon dots (N, S-CDs) was developed. The as-prepared N, S-CDs exhibited excellent photoluminescence properties and fluorescent stability. N, S-CDs demonstrated fluorescence quenched in the presence of ammonia in the wide linear range of 2–80 mmol/L, and were highly selective towards ammonia over metal ions. Furthermore, a possible fluorescence quenching mechanism is proposed. N, S-CDs were further applied to detection of ammonia in aquaculture water samples and river water samples, showing good practicability with recoveries from 0.93 to 1.27 and relative standard deviations (RSDs) of 0.54% to 17.3%. N, S-CDs were also successfully used to determine the freshness of bighead carps.