Inle: A large Myanmar lake in transition

An integrated biosphere model (IBIS) and a hydrological routing algorithm (HYDRA) are used in conjunction with long time‐series climate data to investigate the response of the Lake Chad drainage basin of northern Africa to climate variability and water use practices over the last 43 years. The simulated discharge, lake level, and lake area of the drainage basin for the period 1953–1979 are in good agreement with the observations. For example, the correlation coefficient (r2) between the simulated and the observed level of Lake Chad for the 288 months of available observations is 0.93. Although irrigation is only a modest portion of the hydrology in the period 1953–1979; representing only 5 of the 30% decrease in simulated lake area for the decade 1966–1975, the simulated lake level and area are in better agreement with the observations when irrigation is included. For the period 1983–1994 the observed water use for irrigation increased fourfold compared to 1953–1979. A comparison of the simulated surface water area, with and without irrigation, suggests that climate variability still controls the interannual fluctuations of the water inflow but that human water use accounts for roughly 50% of the observed decrease in lake area since the 1960s and 1970s.

Lake area changes in the middle Yangtze region of China over the 20th century

The Ebinur Lake is a closed inland lake located within the arid region of the Xinjiang Autonomous Region in the northwestern part of China, near the Kazakhstan border. The shrinkage of the lake area is believed to be caused by ecological environmental deterioration and has become an important restraining factor for the social development of the local population. Of all the lakes in the Xinjiang Autonomous Region, the Ebinur Lake is the most severely impacted water body. The lake has undergone change in size naturally for over thousands of years due to natural causes. However, the authors observed the dramatic changes in the freshwater resources of this region from the aerial images from 1972 to 2013. Thus, this paper traces and analyzes the change in the Ebinur Lake surface area in the past 41 years. A set of six satellite images acquired between 1972 and 2013 was employed to map the change in the surface area of the Ebinur Lake using the water index approach. The authors applied the traditional normalized difference water index (NDWI) and the modified normalized difference water index (MNDWI) to quantify the change in the water body area of the Ebinur Lake during the study period. The results indicate that the lake area has experienced a dramatic decrease of 31.4% from 1972 to 2013. The paper also examines the natural processes and human activities that may have contributed to the decrease in the lake area. The results show that the decrease in total lake area appears to coincide with periods of rapid land reclamation in the study area. Moreover, the uncontrolled land reclamation activities, such as irrigation, can increase the sedimentation in the Ebinur Lake thereby reducing the lake size. Reduction of the lake area has a negative ecological impact on the environment and on human life and property. The lake area is the most important factor to ensure the environment of the watershed and the key index to measure the environment balance.

Land use intensification destabilizes stream microbial biodiversity and decreases metabolic efficiency

Water chemistry has been shown experimentally to affect the stability of water films and the sorption of organic oil components on mineral surfaces. When oil is displaced by water, water chemistry has been shown to impact oil recovery. At least two mechanisms could account for these effects, the water chemistry could change the charge on the rock surface and affect the rock wettability, and/or changes in the water chemistry could dissolve rock minerals and affect the rock wettability. The explanations need not be the same for oil displacement of water as for water imbibition and displacement of oil. This article investigates how water chemistry affects surface charge and rock dissolution in a pure calcium carbonate rock similar to the Stevns Klint chalk by constructing and applying a chemical model that couples bulk aqueous and surface chemistry and also addresses mineral precipitation and dissolution. We perform calculations for seawater and formation water for temperatures between 70 and 130°C. The model we construct accurately predicts the surface potential of calcite and the adsorption of sulfate ions from the pore water. The surface potential changes are not able to explain the observed changes in oil recovery caused by changes in pore water chemistry or temperature. On the other hand, chemical dissolution of calcite has the experimentally observed chemical and temperature dependence and could account for the experimental recovery systematics. Based on this preliminary analysis, we conclude that although surface potential may explain some aspects of the existing spontaneous imbibitions data set, mineral dissolution appears to be the controlling factor.

Adverse conditions in the acid mine drainage (AMD) system at the Green Valley mine, Indiana, limit diatom diversity to one species, Nitzschia tubicola. It is present in three distinct microbial consortia: Euglena mutabilis-dominated biofilm, diatomdominated biofilm, and diatom-exclusive biofilm. E. mutabilis dominates the most extensive biofilm, with lesser numbers of N. tubicola, other eukaryotes, and bacteria. Diatom-dominated biofilm occurs as isolated patches containing N. tubicola with minor fungal hyphae, filamentous algae, E. mutabilis, and bacteria. Diatom-exclusive biofilm is rare, composed entirely of N. tubicola. Diatom distribution is influenced by seasonal and intraseasonal changes in water temperature and chemistry. Diatoms are absent in winter due to cool water temperatures. In summer, isolated patchy communities are present due to warmer water temperatures. In 2001, the diatom community expanded its distribution following a major rainfall that temporarily diluted the effluent, creating hospitable conditions for diatom growth. After several weeks when effluent returned to preexisting conditions, the diatom biofilm retreated to isolated patches, and E. mutabilis biofilm flourished. Iron-rich stromatolites underlie the biofilms and consist of distinct laminae, recording spatial and temporal oscillations in physicochemical conditions and microbial activity. The stromatolites are composed of thin, wavy laminae with partially decayed E. mutabilis biofilm, representing microbial activity and iron precipitation under normal AMD conditions. Alternating with the wavy layers are thicker, porous, spongelike laminae composed of iron precipitated on and incorporated into radiating colonies of diatoms. These layers indicate episodic changes in water chemistry, allowing diatoms to temporarily dominate the system.

Changes in water chemistry along the High Arctic fluvial–lacustrine system located in Wedel Jarlsberg Land in the SW Spitsbergen (Svalbard) were investigated during the summer season of 2010 and 2011. The newly formed river–lake system consists of three lakes connected with the Brattegg River. The first bathymetric measurements of these lakes were made by the authors in 2010. The Brattegg River catchment represents a partly glaciered Arctic water system. The studied lakes are characterized by low mineralization and temperature of water. The value of the electrolytic conductivity (EC) ranges from 30.2 to 50.5 μS cm−1 and the temperature of surface water from 1.5 to 7.8 °C. The temperature increase takes place downstream starting from Upper Lake to the outflow from Myrktjørna Lake. The waters of lakes have higher temperatures than the stream. The predominant ions are HCO3− (up to 16.5 mg L−1), Cl− (6.66–8.53 mg L−1), Ca2+ (2.40–4.45 mg L−1) and Na+ (2.65–3.36 mg L−1). The highest values of ammonium and DOC found in the lowest Myrktjørna Lake seem to be related to the presence of aquatic organisms and also birds. From the group of 10 analyzed microelements, increased concentrations of aluminum, up to almost 500 μg L−1, are present in the lakes’ water. Water isotopic composition ranges for δ18O and δ2H, from −10.6 to −10.9‰ and from −70.8 to −72.3‰, respectively. The vertical zonality of lake waters is manifested in a decrease in the temperature and increase in EC and chemical elements concentrations.

PFOS fate and transport in the subsurface are significantly impacted by the spatially and temporally variable hydrochemical conditions found in natural environments, which often exhibit strong ionic strength gradients and pH fluctuations [1,2]. Batch and flow-through column experiments are standard methods for characterizing PFOS adsorption and transport behaviors, and their outcomes are often quantitatively interpreted by defining empirically derived solid-water distribution coefficients (e.g., Langmuir and Freundlich equations) [3]. The limitation of these models is that they are strictly system-dependent and cannot precisely assess PFOS removal under varying water chemistry conditions. Thus, there is a need for mechanistic sorption prediction models able to account for varying electrostatic properties of the surface-solution interface in response to changes in pore water chemistry, and that could be implemented in reactive transport simulators for precisely assessing PFOS migration under dynamic hydrochemical conditions in multicomponent systems [4].In this work, we initially conducted a comprehensive set of adsorption experiments and IR spectroscopy analyses with varying pH and ionic strength conditions to elucidate PFOS binding behavior on goethite surfaces as a function of solution chemistry. The experimental outcomes were quantitatively interpreted by developing a surface complexation model (CD-MUSIC) built on the results of the adsorption experiments and on the molecular-level understanding acquired through IR spectroscopy. Subsequently, a series of one-dimensional flow-through experiments were conducted in fully saturated goethite-coated silica sand columns by injecting a 2 mg/L PFOS pulse with varying NaCl background electrolyte concentrations and collecting PFOS and pH breakthrough curves at the outlet of the domain. PFOS uptake exhibited a complex behavior that was strongly dependent on solution pH and electrolyte concentration and that originated from the co-existence and speciation of two distinct PFOS-goethite surface complexation mechanisms: (i) a hydrogen-bonded complex (HB) and (ii) a weaker outer-sphere complex involving Na+ co-adsorption (OS-Na+). The non-trivial dependency of PFOS uptake on solution chemistry significantly impacted its transport behavior. Dynamic ionic strength gradients established during the flow-through experiments led to distinct retardation and transport behaviors which were not observed in the experiments performed with constant ionic strengths [5]. PFOS and pH breakthrough curves were quantitatively described by implementing the developed surface complexation model within the reactive transport simulator PHREEQC-3 coupled with MATLAB through the IPhreeqc module [6,7]. The simulations illuminated the key role of multicomponent transport effects on PFOS mobility and the importance of explicitly accounting for mineral surface charge adjustments in response to changes in water chemistry.[1] Zhu et al. (2017) Chemosphere 168, 390-398. [2] Blowes et al. (2014) In Treatise on Geochemistry 2nd Edition Vol. 11, pp 131-190. [3] Johnson et al. (2007) J. Chem. Eng. Data 52, 1165-1170. [4] Cogorno and Rolle (2024) Env. Sci. Technol. https://doi.org/10.1021/acs.est.3c09501. [5] Cogorno and Rolle (2024) In prep. [6] Charlton and Parkhurst (2011) Comput. Geosci. 37, 1653-1663. [7] Muniruzzaman and Rolle (2016) Adv. Water Resour. 98, 1-15.

Jianghan Plain is one of the most important lake regions in the middle reaches of the Yangtze River in China. Over thousands of years, there has been a dynamic relationship between human impacts and the lake-river system, especially in the second half 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> century. Here, we analyze lake evolution in Jianghan Plain in the last fifty years with lake size large than 0.1 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> by using drainage network and relief maps, historical maps and gazette, and remote sensing images of different periods. Historical changes of lakes were evaluated by total area, total number, annual variation rate in the whole regions and the area and number in four scale levels (0.1-lkm2, 1-5 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 5-10 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and >10 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) using a time series of lake maps. Lake landscape pattern dynamics were assessed by the landscape index of FRA_CAM which can reveal the change processes and features of lake shape by human impacts. The results show that during the second half of the 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> century there has been a general trend of significantly decreasing in lake area and number and the elimination of the large size lakes was the key to the rapid reduction of total area. The value of FRA_CAM was gradually increasing with the lake scale levels in every period except 1995. In the past fifty years, the FRA_CAM of large scale lakes decreased to minimum and that of other scale lakes did not have the law. The study indicates that the decrease in lake area in Jianghan Plain is caused by land reclamation and excessive soil erosion and sedimentation while the human impacts are likely the main factor. The reproduce of lake change process will benefit the ecological restoration and rehabilitation of lake area in the middle reaches of the Yangtze.

The Ramsar Convention on Wetlands designates over 2,000 sites of international importance, providing crucial habitats for diverse species. Uluabat Lake faces anthropogenic pressures such as urbanization, agriculture, and industrialization, affecting its ecological integrity. The land use/land cover (LULC) changes in the lake's catchment area were assessed using multi-temporal Landsat 7 and Landsat 9 satellite images from 2002 and 2022, along with 2019 management plans. Data were pre-processed with ENVI and stored in ERDAS Imagine program. Then, pixel-based image analysis with maximum likelihood classification (MLC) was employed to generate LULC maps and evaluated classification accuracy using ground truth data and the kappa coefficient. The results revealed a 15.8% reduction in lake area, from 136.1 km² in 2002 to 114.5 km² in 2022, primarily due to sediment transport from surrounding agricultural land and tributary streams. Urban-agricultural and reed-swamp areas increased by 74.7% and 59.6%, respectively, while shrubs and forests declined by 35.64%, largely from reed conversion to agriculture in the Mustafakemalpaşa River delta. Overall classification accuracy ranged from 88.2% to 91% with a kappa coefficient of 0.81 to 0.82, respectively. These transformations highlight the increase in reed and swamp areas and the decrease in lake area, emphasizing the need for effective conservation and management practices.

Abstract. Size fluctuations in endorheic lakes in northwestern Argentina (NWA) and southwestern Bolivia (SWB) are very sensitive to basin hydrological balances, and consequently, very vulnerable to deleterious effects from climatic changes. The management of these water resources and their biodiversity requires a comprehensive knowledge of their natural variability over multiple timescales. In this study, we present a multi-century reconstruction of past lake-area fluctuations in NWA and SWB. The evidence used to develop and validate this reconstruction includes satellite images and a century-long tree-ring record from P. tarapacana. Inter-annual fluctuations in lake area of nine lakes were quantified based on Landsat satellite images over the period 1975 to 2009. A regional P. tarapacana tree-ring chronology, composite from two sampling sites, was used as predictors in a regression model to reconstruct the mean annual (January–December) lake area from the nine lakes. The reconstruction model captures 62 % of the total variance in lake-area fluctuations and shows adequate levels of cross-validation. This high-resolution reconstruction covers the past 601 years and characterizes the occurrence of annual to multi-decadal lake area fluctuations and its main oscillation modes of variability. Our reconstruction points out that the late 20th century decrease in lake area was exceptional over the period 1407–2007; a persistent negative trend in lake area is clear in the reconstruction and consistent with glacier retreat and other climate proxies from the Altiplano and the tropical Andes. Since the mid 1970s, the Vilama-Coruto lake system recorded an accelerated decrease in area consistent with an increasing recurrence of extremely small lake-area events. Throughout the 601 years, the reconstruction provides valuable information about spatial and temporal stabilities of the relationships between changes in lake area, ENSO, and PDO, highlighting the Pacific influence over most modes of lake area variability. Global and regional climate models for the Altiplano project a marked reduction in precipitation to the end of the 21st century, exacerbating presently dry conditions. These results provide a baseline for the historical range of variability in lake fluctuations and thus should be considered for the management of biodiversity and water resources in the Central Andes during the next decades.

Environmental chemistry changed greatly with climate change, thereby influencing chemical processes in the atmosphere, hydrosphere and lithosphere. This review assessed this by examining changes in atmospheric chemistry, water chemistry, soil chemistry and biogeochemical cycles. Rising global temperatures and increased greenhouse gas emissions have changed atmospheric chemical reactions leading to alterations in air quality and the formation of secondary pollutants. Water temperature shifts and changes in water chemistry caused by climate change impacted marine biogeochemistry through ocean acidification. Nutrient cycling, soil organic matter and metal mobility were also altered as a result of soil chemistry effects. Additionally, the review focused on mitigation and adaptation strategies that involved the development of green technologies and sustainable practices for managing climate change impacts. In this analysis, environmental chemistry was emphasized as having a significant role in understanding climate change challenges through synthesis of present research works. The end also recommended further studies to be conducted while suggesting interdisciplinary approaches along with long-term monitoring needed to improve our knowledge about climate change impacts and enable policy makers take sound decisions.

This study presents a unique data set from a laboratory experiment where we explored changes in the chemical composition of deionized water samples exposed to smoke. Inside a laboratory hood, water samples placed into a chamber were exposed to smoke for up to 60 min. The pattern of variations in hydrochemistry observed over time with increasing smoke exposure was similar in response to two different smoke treatments generated from burning tree litter. To estimate the smoke dosage and assess the consistency of replicate smoke treatments, we conducted additional experiments to evaluate changes in light transmission. Smoke inputs to the deionized water samples drove changes in hydrochemistry, with increases in acidity (with decreasing pH values), the content of organic matter (with increasing concentrations of dissolved organic carbon and dissolved organic nitrogen), and the content of inorganic N species (with increasing concentrations of ammonium, nitrate, and nitrite). The study was conducted on deionized water samples, and the results may not be directly transferrable to natural waters. Stream or lake waters that are low in ionic strength, poorly buffered, or low in acid‐neutralizing capacity might respond the most similar to the results of this study. In contrast, well‐buffered surface waters having higher acid‐neutralizing capacity would be more likely to neutralize acidic inputs from the smoke without significant effects on water quality. The publicly available dataset associated with this study will contribute to further consideration of the relative importance of short‐term changes in hydrochemistry driven by in‐stream inputs (e.g., changes in water chemistry from direct smoke deposition to the water surface) in contrast to terrestrial inputs (e.g., changes in water chemistry stemming from altered flow paths and source areas of the burned watershed landscape).

In recent decades, many aquatic ecosystems in Europe and North America have experienced reduced inputs of nutrients and acidifying substances because of improved sewage treatment and reduced emission of sulphur oxides. We evaluated the consequences of these efforts to changes in water chemistry, species richness and community composition of aquatic macrophytes in 56 lakes in Denmark around 1990 and again around 2010. Reductions in lake water concentrations of phosphorus and nitrogen were strongest in eutrophic and hypertrophic lakes, for example, lakes which had been heavily affected by domestic sewage. These changes translated into decreased algal biomass in the most eutrophied lakes. Oligo‐ and mesotrophic lakes did not change significantly in terms of nutrients or algal biomass. Water clarity increased across all lakes but not significantly in specific trophic lake groups. Alkalinity and pH increased significantly (up to 2 pH‐units) in low‐alkaline lakes, while well‐buffered high‐alkaline lakes (&gt;0.5 meq/L) did not show any change. Macrophyte species richness per lake increased, on average, by 13% during the 20‐year study period. The increase was strongest in species preferring nutrient‐rich conditions and could be directly attributed to reductions in phytoplankton biomass in lakes of medium water clarity. The similarity among all lakes in terms of species composition increased over the study period. This development was closely related to higher average species richness and was mainly caused by recolonisation of lakes, recovering from past eutrophication, by relatively common species (e.g., Lemna trisulca, Sparganium emersum and Potamogeton berchtoldii). Higher pH in low‐alkaline lakes was accompanied by a shift from acid‐tolerant to more acid‐sensitive species. Our results demonstrate that investment in pollution control has been successful in terms of markedly improving water quality of lakes and, with a time lag, macrophyte species richness. Although relatively common species have spread across lakes and resulted in homogenised macrophyte communities, continued efforts to reduce pollution could ensure the survival of rare specialist species and perhaps even increase their abundance in the future.

Changes in water chemistry, water clarity, and planktonic chlorophyll a were measured as hydrilla (Hydrilla verticillata) abundance increased and then decreased in Lake Baldwin, Florida. Grass carp (Ctenopharyngodon idella) were used to eliminate submersed macrophytes. No major trends in lake pH, conductivity, or total nitrogen concentrations occurred in association with changes in hydrilla levels. Increased Secchi disc transparency and reductions in total alkalinity, calcium, magnesium, potassium, total phosphorus, and chlorophyll a concentrations occurred as hydrilla abundance increased. Large increases in the chemical parameters and a reduction in Secchi disc transparency occurred as hydrilla decreased and was eliminated from the lake by grass carp. The effects of hydrilla on lake water chemistry are related to the percentage of the lake's volume infested with hydrilla and macrophyte standing crop.