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Endogenous phosphorus (P) release from lake sediments is an important factor in the eutrophication of overlying waters, as P is the limiting nutrient salt affecting cyanobacterial growth. Microorganisms are also key to the evolution of cyanobacterial growth and disappearance, as they can influence the release of endogenous P. Meanwhile, endogenous phosphorus can also have an impact on microbial structure. However, there is a lack of studies on the response mechanisms between endogenous P release and microorganisms, as well as the exploration of endogenous P release on the whole cyanobacterial growth and disappearance evolution process. In this study, metagenome sequencing was used to characterize the microbial community structure at different times and to explain the P cycle from the perspective of functional genes. The results showed that the number of sediment microorganisms (genes) gradually increased with the P release capacity, and the outbreak with the strongest P release capacity possessed the most abundant microorganisms (genes). Proteobacteria with P solubilizing functions were consistently the most abundant phylum in all four periods and were positively correlated with P release potential assessment factors EPC 0 , EPC 0F , and NAP. Functional genes affect the P cycle by acting primarily on inorganic P solubilization, organic P mineralization, and P transport. These P-functional genes are mainly found in Proteobacteria, Acidobacteria, Chloroflexi, and Actinobacteria microorganisms. In addition, the P form in the sediments was dominated by IP, with the highest concentration (704.86 mg/kg) occurring during the dormant period. Sediments from this period acted as a strong P "sink", creating a precondition for cyanobacterial recovery and outbreaks to provide a source of P. The results of this study can provide a theoretical basis for controlling endogenous P release at the microscopic level of cyanobacterial growth and disappearance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

The arsenic (As) release from sediments in great lakes is affected by various factors. In this study, the characteristics of As release from sediments was investigated, and the As sources and sinks with the strengths in sediments from different areas (grass-type, algae-type, and grass-algae alternation areas) in great shallow lakes (Taihu Lake, China) were analyzed, and the influence of P competition in the process of As release was also studied. The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes (0 to 28.12 µg/L), and the sediments from algae-type areas had the higher values. The sediments from western lake and northwest lake bay were a strong As and a weak P source, and the north lake bay had the opposite trend of these two regions. Intense P source competition with As from the sediments occurred in algae-type areas. The grass-type areas had strong As and P retention capacities, indicating a sink role of sediment with high As and P sorption capacities. The degree of As and P saturation had similar trend in sediments, and the grass-type areas had the higher values, 18.3%-21.4% and 15.31%-20.34%, respectively. Contribution analysis results showed that most of As release contribution was from the bottom (30-50 cm) sediments, and the surface (0-10 cm) sediments from algae-type areas contributed more to the overlying water than other region., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Attapulgite co-modified by lanthanum-iron (MT-LHMT) was used to study its effectiveness and mechanism in controlling phosphorus release from sediments. MT-LHMT has high adsorption capacity for phosphate and the maximum adsorption capacity of MT-LHMT to phosphate can reach 75.79 mg/g. The mechanism mainly involved electrostatic action, surface precipitation and ligand exchange between MT-LHMT bonded hydroxyl and phosphate to form La-O-P and Fe-O-P inner-sphere complexes. MT-LHMT has excellent adsorption performance in the pH range of 3-8. In addition to HCO 3 - , CO 3 had a negative effect on the phosphorus removal of MT-LHMT, while NO 2- and HA - had a negative effect on the phosphorus removal of MT-LHMT, while NO 3 - , Cl - , SO 4 had a positive or no effect on phosphorus removal. MT-LHMT significantly reduced the risk of phosphorus release from overlying water in different dose effects and covering methods, as well as the unstable inactivation of flowing phosphorus, sediment dissolved reactive phosphorus (DRP) and available phosphorus with medium diffusion gradient in thin film in the sediment-water interface (Labile-P 2- ). The MT-LHMT capping wrapped with fabric can reduce the risk of nitrogen release from sediment to overlying water more than only MT-LHMT capping. The results of this study showed that the MT-LHMT capping wrapped with fabric has high potential and can be used as an active capping material to manage the nitrogen and phosphorus load in surface water.+ , Ca 2+ and Mg 2+ had a positive or no effect on phosphorus removal. MT-LHMT significantly reduced the risk of phosphorus release from overlying water in different dose effects and covering methods, as well as the unstable inactivation of flowing phosphorus, sediment dissolved reactive phosphorus (DRP) and available phosphorus with medium diffusion gradient in thin film in the sediment-water interface (Labile-P DGT ). The MT-LHMT capping wrapped with fabric can reduce the risk of nitrogen release from sediment to overlying water more than only MT-LHMT capping. The results of this study showed that the MT-LHMT capping wrapped with fabric has high potential and can be used as an active capping material to manage the nitrogen and phosphorus load in surface water., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The arsenate (As(V)) biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen (N) and phosphorus (P) has been studied under laboratory conditions. When 15 μg/L As(V) was added, N and P in the medium showed effective regulation on arsenic (As) metabolism in M. aeruginosa , resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration (4–20 mg/L) significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid (DMA), the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa , leading to higher contents of DMA per cell. However, As(V) uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment, resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As(V) transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As(V) biotransformation processes. [ABSTRACT FROM AUTHOR]

The release of endogenous phosphorus from lacustrine sediment is a key element of freshwater eutrophication. The microbes in sediments may affect phosphorus migration and transformation during the growth of cyanobacteria, which may lead to the release of phosphorus from sediments and contribute to water eutrophication. To study phosphorus sorption and the microbial community structure in the overlying water and the vertical depth of sediments, samples in Meiliang Bay were collected during the dormancy and resuscitation phases of cyanobacteria. The results showed that there were high total phosphorus (TP) concentrations in the overlying water and sediment, with maximum values reached 0.24 mg L−1 and 1059 mg kg−1, respectively. Fitting by modified Langmuir model indicated that the partitioning coefficients (K P) was, from greatest to least: bottom sediment (maximum of 0.923 L g−1) > middle sediment (0.571 L g−1) > surface sediment (0.262 L g−1). During the cyanobacteria resuscitation stage, the relative abundance of Proteobacteria (18.37%–33.56%), Chloroflexi (9.57%–17.76%), Cyanobacteria (0.38%–2.62%), and the Nitrospirota phylum Thermodesulfovibrionia (4.61%–10.14%) were higher than the dormant period of cyanobacteria, and bacteria with phosphorus-solubilizing (27.27%–52.01%) accounted for the majority. The redundancy analysis (RDA) found that the structure of the microbial communities in sediments was significant correlation with organic phosphorus (OP) (P = 0.002) during recruitment period of cyanobacteria, which would accelerate the conversion of OP into soluble inorganic phosphorus and then gets released from sediment to water. The most predominant phylum among phosphorus-solubilizing bacteria (PSB) is Proteobacteria, followed by Actinobacteriota, which were positively correlated with equilibrium phosphorus concentration (EPC 0) (P < 0.05) during the cyanobacterial resuscitation phase. The sediments from the cyanobacteria resuscitation phase had phosphorus release risk and highlighted the significant role of the bacterial community. [Display omitted] • IP concentration mainly consisted of NaOH–P was highest. • The modified Langmuir parameters were significantly correlated with some PSB. • Risk of phosphorus release during the cyanobacteria resuscitation stage. [ABSTRACT FROM AUTHOR]

The release of phosphorus from sediment and the high concentration of phosphorus in the water environment make the water body continuously eutrophic, so it is very important to develop new phosphorus removal materials to reverse the eutrophication of river and lake. In this study, the effect and mechanism of magnetic lanthanum carbonate modified attapulgite (MT-LCMT) prepared by co-precipitation in fixed water and prime phosphorus were studied. The results showed that MT-LCMT had excellent magnetic hysteresis performance and its maximum model adsorption of phosphate could reach 51.69 mg/g. The phosphate adsorption process mainly followed the co-kinetics of intraparticle diffusion and membrane diffusion and conformed to the Redlich-Peterson model and Sips model. After five adsorption-desorption cycle experiments, MT-LCMT exhibited stable adsorption and regeneration properties, which may also be used for the removal of phosphate from actual water bodies. The experiment of exploring the factors affecting the adsorption of phosphate by MT-LCMT shows that the adsorption capacity of phosphate is the highest when the pH is between 3 and 8, and the existence of HCO 3 -, CO 3 2- and humic acid reduce the adsorption capacity of phosphate. The binding mechanism of MT-LCMT to orthophosphate involves coordination exchange, precipitation and electrostatic attraction. MT-LCMT capping can significantly reduce the risk of sediment releasing mobile phosphorus (Mobile-P), bioavailable phosphorus (BAP), overlying water dissolve reactive phosphorus (DRP) and available phosphorus with medium diffusion gradient in thin film (DGT-P) to the overlying water, and the unstable phosphorus (NH 4 Cl-P and BD-P) of surface sediment are converted into stable phosphorus (HCl-P and NaOH 85 -P). The above results indicated that MT-LCMT had a high potential to be used as an active capping material for managing phosphorus loads inside surface water bodies and substrates. [Display omitted] • The adsorption mechanism of MT-LCMT involves coordination complexation, precipitation and electrostatic attraction. • MT-LCMT can intercept phosphorus release from anoxic sediment. • MT-LCMT reduces the leakage of F-La in water environment. [ABSTRACT FROM AUTHOR]