Research was conducted in the Kura, Araz, Ganikh, and Okchuchay transboundary rivers. Seasonal monitoring was carried out in order to study the physico-chemical and microbiological condition of water in the studied rivers. River water temperature, pH, dissolved oxygen, nitrate, nitrite, ammonium, phosphorus concentration, and physico-chemical indicators of heavy metals, as well as the quantitative variability of microorganisms, saprotrophic, pathogenic, oil-phenol-absorbing bacteria and those involved in the nitrogen cycle bacteria, have been studied.
Kura and Ganikh rivers are transboundary rivers that pass from the territory of Georgia to Azerbaijan. During the microbiological monitoring of rivers, it was determined that the amount of saprotrophic bacteria in river water corresponds to the classification of highly polluted waters from an ecological point of view. Thus, the results of chemical and microbiological analysis of water were higher than the TLV.
Starting from Armenia, Okchuchay flows through the territory of Azerbaijan and joins the Araz River, which is the natural border between Iran and Azerbaijan, before flowing into the Caspian Sea. On the Armenian side, there are two large mining plants: Gajaran-Zangazur copper-molybdenum and Gafan iron ore processing plant. The waste water of these plants is regularly discharged into the river without treatment. As a result of our research, it became clear that the amount of saprotrophic bacteria, biogenic elements, and heavy metals in river water is extremely high; in particular, the amount of nickel is 5-7 times higher than normal, iron is 3-4 times higher, and copper-molybdenum is 2 times higher. Environmental pollution of river waters has a negative effect on biodiversity in the river, mainly causing mass destruction of trout and other fish in the river. From the research conducted in all four rivers, it can be concluded that the chemical and microbiological pollution in these rivers is at a high level.

Continuous monitoring of water extent at inland water surfaces is necessary during any season. However, it is not often possible due to the unavailability of flood gauges, inaccessible locations, and other hazardous situations in flooded areas. Despite this, advanced satellite radar altimetry-derived water surface elevations may be utilized to supplement in-situ data. Synthetic Aperture Radar (SAR) high-resolution mode has replaced pulse-limited low-resolution mode (LRM) in satellite radar altimetry in recent years. In Pakistan, radar altimetry satellite data is used to find and compare the level of the water surfaces of the River Indus near the Sukkur barrages and analyzed that altimetry performed better in flat areas as compared to mountain areas. In this study Sentinel 3 L2 datasets on inland water surfaces were evaluated and applying pulse masking using the global water surface explorer facilitated isolating the pulses in the waveform over water and land in Sindh near Sukkur Barrage for a rainy year August 25, 2022 (Inundation Period). Echoes were found highly specular during inundation while quasi-specular during dry months. Waveform shapes were separated in different months. Time series of the water level of these months were also evaluated and compared with In-Situ gauge data taken from the Sindh Irrigation Department (SID). The accuracy evaluation uses variate differences, pass-to-pass repeatability, and comparison to gauge measurements. We have proposed a straightforward rule to separate Specular, Quasi-Specular, and non-Specular echoes for floodplains. Furthermore, radar altimetry may provide information about flood water depth. This study will help to map inundation extent and depth at inaccessible locations during all weather conditions.

Plastic pollution presents a critical environmental challenge, with plastic waste infiltrating natural ecosystems and posing severe threats to biodiversity and human health. The issue is further amplified by the leaching of plastic additives (PAs) into rivers from inadequately managed terrestrial plastic waste. This study examines the occurrence and bioaccumulation potential of selected PAs in two freshwater macroinvertebrates inhabiting the habitat of the endangered Gangetic Dolphin, within a densely populated, agriculturally intensive, and tourism-driven landscape.
This study focuses on the Lamellidens marginalis (bivalve) and Filopaludina bengalensis (gastropod) to assess their suitability as biological monitors of PA contamination in an effluent-impacted stretch of the Ganga River. Samples were collected along a 25 km stretch of the Middle Ganga Reach, and seven PAs, including Dimethyl phthalate (DMP), Diethyl phthalate (DEP), Di-n-butyl phthalate (DnBP), Butyl benzyl phthalate (BBP), Bis(2-ethylhexyl) phthalate (DEHP), Di-n-octyl phthalate (DnOP), and Bisphenol A, were quantified using UHPLC–MS/MS and GC-MS-MS.
The bioaccumulation patterns observed in both the macroinvertebrate species were DnBP > DEHP > DEP > DMP > BPA, with BBP and DnOP concentrations observed below detection limits. L. marginalis showed particular promise for site-specific assessments due to its sedentary nature, limited mobility, ease of sampling, and longer lifespan, which are advantageous for reflecting localized contamination and understanding long-term trends. Using L. marginalis as biomonitors for PA contamination can provide critical insights into pollutant levels and sources in the Ganga River, enabling targeted remediation efforts, assessing habitat quality, identifying pollution hotspots, and informing conservation strategies.
This study is the first to investigate PAs in wild macroinvertebrates of the Ganga River, providing critical insights that can inform targeted remediation efforts and support conservation strategies for the endangered Gangetic Dolphin by improving habitat quality and reducing pollutant exposure.

A cascade of four preliminary small lowland reservoir was created in the course of the Cybina River in Poznan (Western Poland) in the end of the XXth century in order to improve the water quality before it reaches to the Maltanski Reservoir, where international rowing and canoeing competitions are held each year. The deposition of suspended solids together with planktonic cells as well as the uptake of dissolved nutrients by phytoplankton proliferating in the shallow reservoirs were supposed to aim at water transparency improvement and nutrient concentrations decrease. Unfortunately, thirty years after the cascade was formed, reservoirs became a highly eutrophic, with severe blooms during summer. The chlorophyll-a content reached over 300 mg m^-3 in 2023, severely affecting the primary production in the reservoir situated below the cascade. At the same time, nutrient loads increased in the river downstream the cascade, as the ponds periodically supplied the river with additional 1,5 kgP per day and over 13 kgN per day. Climate changes, influencing the shortage of water in the Cybina River during warm months, also affect the water quality by increasing the water retention time and thus extending the blooms period. These results indicated an urgent need to undertake additional actions to improve the water purification in the system in order to maintain good water quality in the Maltanski Reservoir. Nature-based solutions shall be considered e.g. increasing the role of macrophytes in nutrient assimilation in the shallow reservoirs.

The Bari Doab region in Pakistan, an important agricultural area, is increasingly threatened by climate change, leading to severe water scarcity. This study employs sophisticated hydrological modeling techniques, including the Soil and Water Assessment Tool (SWAT), to predict the impacts of changing precipitation patterns, rising temperatures, and extreme weather events on water availability. By incorporating statistical downscaling of General Circulation Models (GCMs), the research provides localized manageable climate projections for enhancing the accuracy of forecasts for this specific region. The study assesses changes in water resources and evaluates risks of floods and droughts which offers a comprehensive view of future challenges. Socioeconomic vulnerability indices are developed to gauge the region’s resilience to water-related hazards, considering factors such as economic stability, infrastructure, and social support systems. Based on these analyses, the study proposes several adaptation strategies which includes the adoption of advanced water use efficiency techniques, the implementation of early warning systems for extreme weather events, and the diversification of livelihoods to reduce reliance on agriculture alone. These strategies aim to improve sustainable water management and ensure food security in Bari Doab by providing actionable, evidence-based insights for climate change adaptation planning, thus enhancing the region’s overall resilience to environmental stresses.

Surface water monitoring using remote sensing images is important for understanding the impact of water on global ecosystems and climate change. Environmental changes and human interventions lead to significant environmental impacts that must be considered. Today, remote sensing satellite images have helped to monitor changes in various issues, including environmental issues. Using Landsat-5 and Landsat-8 images and the NDWI index, this research has investigated the changes in Bakhtegan Lake over two decades. The results show that the lake has dried up and, according to the "from-to" maps, a large percentage of the water has turned into salt, so the calculated lake's water surface area has decreased from 505 square kilometres in 2000 to almost 0 square kilometres by 2022. Therefore, the potential factors affecting lake changes were investigated using MODIS, GPM, FLDAS, and GRACE data. The results indicate that the changes in temperature, evaporation, and transpiration did not play an important role in the drying of the lake, but the reduction in the underground water level due to the digging of deep wells is known as the main cause of the drying of the lake. In order to restore the lake and prevent the transformation of salts into dust, it is suggested to prevent the extraction of water through well pumping in the catchment area of ​​the lake and to limit its use for agricultural purposes.

Introduction: Macao, a densely populated region in China's southern coast, has experienced rapid urbanization, leading to significant fragmentation of wetland ecosystems. This transformation threatens local biodiversity and ecosystem services. Despite their diminished size, urban wetlands provide ecological benefits in the city. However, traditional biodiversity assessment methods are often impractical in these urban settings due to limitations. This study employs environmental DNA (eDNA) analysis to explore biodiversity in Macao's urban wetlands, aiming to provide comprehensive insights for conservation strategies in developed urban areas.

Methods: Water samples were collected from urban wetlands in Macao, sampling was conducted across multiple sites to account for the diversity of microhabitats and ensure comprehensive coverage. eDNA was extracted from the water samples and analyzed using metabarcoding techniques. Multiple genetic markers were to identify various aquatic and terrestrial species. Bioinformatics pipelines were employed to process the sequencing data and match DNA sequences to taxonomic databases. Biodiversity indices were calculated to assess the complexity and structure of the biological communities in these urban wetlands.

Results: While specific results are pending, we hypothesize that eDNA analysis will reveal diverse species, including some previously unrecorded in traditional surveys. We expect to find native and non-native species, reflecting the complex dynamics of urban ecosystems. In addition, it integrates eDNA analysis with water quality assessments, focusing on key nutrient indicators. By abundance with water nutrient levels, this multi-faceted approach allows us to explore potential relationships between nutrient concentrations and biodiversity patterns.

Conclusions: This research demonstrates the potential of eDNA as a powerful tool for biodiversity assessment in urban wetlands. The findings will contribute to understanding biodiversity patterns in highly urbanized environments and targeted conservation efforts. By providing a comprehensive snapshot of Macao's wetland biodiversity, this study supports sustainable urban planning and water resource management in the face of ongoing development pressures.

The disposal of low-level radioactive waste at uranium ore mining and processing sites is currently considered unsafe due to complex pollution near uranium sludge storage facilities. The relevance of this study is related to the need to search for possible ways to remove uranium from migration in water flows to minimize the harm from the release of nuclear fuel to the environment. One of the ways to study the radionuclide species in water is the use of the cascade filtration method, whereby a water sample issequentially filtered through a set of membranes with decreasing pore size.

In this work, we collected samples of surface and groundwater in the area near the sludge storage of the Novosibirsk Chemical Concentrates Plant. The concentrations of HCO₃^- and Cl^- were determined using the titrimetric method, while the concentration of SO₄^2- was measured using the turbidimetric method. To determine the concentration of cations and trace elements, the ICP MS method was used. The uranium species were determined using the method of cascade fractionation using Sartorius vacuum filter systems and membranes with pore sizes of 1.2, 0.45, 0.2, 0.1, and 0.05 microns.

As a result of the experiments, it was established that when uranium enters water flows, the leading form of migration is suspensions (1.2-0.45 µm) and large colloids (0.22-0.45 µm). At a sufficiently high concentration of bicarbonate in waters, uranyl-carbonate complexes are formed. With increasing distance from the sludge storage site, as a result of water dilution, sorption and sedimentation processes, the uranium concentration decreases, the pH value increases, while the Eh decreases, and the geochemical situation is reduced. As a result, carbonate complexes with uranium break down; part of the uranium passes into sediment, forming uranium oxide; and suspensions and large colloids again become the leading form of transport.

The Mekong Delta, a vital agricultural and ecological region in Vietnam, experiences serious challenges from flooding, saltwater intrusion, and freshwater shortages. These issues, worsened by climate change and upstream developments, are endangering the region's sustainable development and are causing great concern for the local population and authorities. This study examines traditional strategies for addressing challenges to freshwater availability, tidal flooding, and saltwater intrusion in this area. The disadvantages of different strategies are highlighted, and a novel approach involving the construction of large multi-functional barriers in the main estuaries of the Mekong Delta is presented. The idea has been preliminarily considered for the Ham Luong estuary region in Ben Tre province, which is among the most vulnerable to the abovementioned threats. The large barrier at the main estuaries can be integrated with river and sea dikes to form new coastal reservoirs, offer flexible operational capabilities to manage saltwater intrusion, and protect the landside from tidal inundation as well as storm surges. Moreover, a schematized model of the Ham Luong estuary was developed using Delft3D to assess the hydrodynamic impact of the proposed barriers. The numerical results indicate that strategically positioning the opening and closing gates in alignment with flood and ebb flow patterns and increasing the structure's opening can considerably mitigate the adverse effects of the estuarine barriers. This research highlights the potential of an innovative multi-functional flood defense system at the main entrance of the estuary to ensure water security and support sustainable development in the Mekong Delta.

Globally, stream ecosystems draining mining landscapes experience alarming metal(loid) pollution, threatening the attainment of “2030 UN-SDGs 6 and 14”. This study was conducted monthly in the north-western Zambian Copperbelt between May 2022 and April 2023 to investigate the spatiotemporal distribution and ecotoxicological risks of As, Cr, Cu, Ni, Pb, and Zn in stream sediments. Pb (12.7), Cu (2073), and Zn (126.6) mg/kg were highest in the dry season. Generally, metal concentrations (mg/kg) followed the order Pb (5.98) <As (6.98) <Zn (49.6) <Ni (99.7) <Cr (109.2) <Cu (418.3). Streams with anthropogenic inputs were most impacted by Cu (1691-2073 mg/kg), up to 28% above the local background value. Cu, Ni, and Cr exhibited “moderately–severe” enrichment and “moderate” and “low-to-medium” contamination. The contamination factor (CF) ranged from “low-to-moderate” to “very high” [Pb (0.63) >As (0.81) >Zn (1.33) >Ni (2.39) >Cr (6.16)>Cu (46.01)]. KSC sediments were enriched from “none-to-minor” to “very severe”, with increasing enrichment (EF) [Pb (0.64) >Zn (0.89) >As (1.48) >Ni (1.82) >Cr (2.59) >Cu (30.45)]. Ecological risk assessment indicated a “low risk” (mPERI 41.7-47.4), while the toxicity risk index (TRI, 13.1-19.3) depicted “moderate-to-considerable” ecotoxicological risk to benthic biota. Based on the sediment quality guidelines, As and Cr concentrations were “potentially hazardous”; Cu and Ni were “hazardous”, while Pb and Zn were “non-toxic”. While the overall ecotoxicological risk was considerably low, proactive interventions must be instituted to mitigate anthropogenic metal pollution for the effective and sustainable management of CACB aquatic ecosystems.