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Sulfate concentrations in eutrophic waters continue to increase; however, the transformations of arsenic (As) in sediments under these conditions are unclear. In this study, we constructed a series of microcosms to investigate the effect of algal degradation on As transformations in sediments with high sulfate concentrations. The results showed that both the elevated sulfate levels and algal degradation enhanced the release of As from sediments to the overlying water, and degradation of algal in the presence of elevated sulfate levels could further contribute to As release. Sulfate competed with arsenate for adsorption in the sediments, leading to As desorption, while algal degradation created a strongly anaerobic environment, leading to the loss of the redox layer in the surface sediments. With high sulfate, algal degradation enhanced sulfate reduction, and sulfur caused the formation of thioarsenates, which may cause re-dissolution of the arsenides, enhancing As mobility by changing the As speciation. The results of sedimentary As speciation analysis indicated that elevated sulfur levels and algal degradation led to a shift of As from FeO/oxyhydroxide-bound state to specifically adsorbed state at the sediment water interface. This study indicated that algal degradation increases the risk of As pollution in sulfate-enriched eutrophic waters.
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http://dx.doi.org/10.1016/j.envpol.2023.123154 | DOI Listing |
Photosynth Res
September 2025
College of Life Sciences, Shanghai Normal University, Shanghai, 200235, China.
Euglena sanguinea (Ehrenberg 1831) is one of the earliest reported species within the genus Euglena. Its prolific proliferation leading to red algal bloom has garnered significant scientific attention due to its ecological and environmental impacts. Despite this, research on E.
View Article and Find Full Text PDFMar Life Sci Technol
August 2025
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200241 China.
Unlabelled: CO concentration mechanisms (CCMs) are important in maintaining the high efficiency of photosynthesis of marine algae. Aquatic photoautotrophs have two types of CCMs: biophysical CCMs, based on the conversion of inorganic carbon, and biochemical CCMs, based on the formation of C acid intermediates. However, the contribution of biophysical and biochemical CCMs to algal carbon fixation remains unclear.
View Article and Find Full Text PDFSci Total Environ
September 2025
Sichuan Academy of Eco-Environmental Sciences, Chengdu 610041, China.
This study investigates the bioavailability of humic nitrogen (humic-N) to algae through controlled bioassay experiments. Algae were able to utilize dissolved organic nitrogen (DON) from both humic acid (HA) and fulvic acid (FA), with bacterial co-culture enhancing uptake. Bioavailable nitrogen (BAN) from HA accounted for ~20 % of total nitrogen, whereas FA reached ~45 %, with bacterial presence further increasing FA utilization by about 6-7 %.
View Article and Find Full Text PDFWater Res
September 2025
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China. Electronic address:
The differentiation of the nitrate reduction pathway is of great significance in the ecosystem, as it determines the occurrence form of ecosystem N. In order to explore the impact and mechanism of different algal dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) on differentiation of nitrate (NO-N) reduction pathway, small-scale enclosure experiment was conducted to analyze the DON and DOP composition, nutrient level, microbial community composition and NO-N reduction pathway in ponds with Microcystis and Dolichospermum blooms. The main DON produced by Microcystis included lipids and proteins as well as carbohydrate which were readily degradable, whereas the DOP produced by Dolichospermum predominantly consists of readily degradable forms such as carbohydrate and protein.
View Article and Find Full Text PDFEnviron Monit Assess
September 2025
State Key Laboratory of Lake and Watershed Science for Water Security, Institute of Geography and Limnology, Chinese Academy of Sciences, Beijing East Road 73, Nanjing, 210008, China.
Dissolved carbon is a crucial component of freshwater ecosystems and plays an important role in the Earth's carbon cycle. This paper delivers a groundbreaking exploration of dissolved carbon (DOC and DIC) variations spanning 12 years in a eutrophic lake where nutrient levels are gradually declining to reveal their spatial and temporal distribution patterns and the key drivers behind this variation. Our findings indicate that both DIC and DOC concentrations in Lake Chaohu exhibit a westward spatial gradient, with an overall upward trend in DIC levels from 2012 to 2023, contrasting with a downward trend in DOC.
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