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BACKGROUND The eutrophication level in water is related to the phosphorus species in porewater and sediment closely. At present, as the one of the eutrophic elements, the vertical distribution characteristics of phosphorus species, the transfer and transformation behavior among phosphorus species and its influencing factors have made clear research progress. OBJECTIVES In order to further reveal the temporal and spatial characteristics of the transfer and transformation of different forms of phosphorus in porewaters and sediments, and assess the ecological restoration in the area by analyzing the soluble reactive phosphorus (SRP), soluble unreactive phosphorus (SUP) and total dissolved phosphorus (TDP) in porewaters, and by analyzing total inorganic phosphorus (TIP), total phosphorus (TP), residual phosphorus (Res-P), exchangeable phosphorus (Exc-P), Fe-bound phosphorus(Fe-P), Al-bound phosphorus (Al-P) and Ca-bound phosphorus (Ca-P) in sediments in Jianyang section of Tuojiang River. And the results were compared with the records of phosphorus species in the same place ten years ago to discuss the change trend and influencing factors of phosphorus occurrence. METHODS SRP, SUP and TDP in porewaters were determined by phosphomolybdate blue spectrophotometry. TIP, TP, Res-P, Exc-P, Fe-P, Al-P and Ca-P in sediments were extracted by SMT method and the improved sequential extraction method. The concentration of the phosphorus species were determined by phosphomolybdate blue spectrophotometry. RESULTS The content of SRP, SUP and TDP in porewaters ranged from 0.004 to 0.36mg/L, 0.080 to 3.19mg/L and 0.056 to 3.28mg/L, respectively. The content of TP, TIP, Res-P, Exc-P, Al-P and Ca-P in sediment ranged from 1235.40 to 1646.94mg/kg, 860.00 to 1318.59mg/kg, 130.31 to 537.13mg/kg, 1.35 to 14.10mg/kg, 0.007 to 0.12mg/kg and 743.13 to 1109.91mg/kg, respectively. However, Fe-P in the sediment samples were not detected. Compared with the results of phosphorus species in sediment-water system ten years ago, it was found that although the content of SRP, SUP and TDP in porewaters were not significantly changed above -10cm, but they increased below -10cm due to the influence of exogenous phosphorus input, which also led to the increase of TP and TIP in sediments. The weak alkaline environment resulted in the release of Al-P, and the decrease of Exc-P was related to its transformation into stable forms of Ca-P or Res-P. CONCLUSIONS The sediment in Jianyang section of Tuojiang River presents the comprehensive pollution of exogenous input and endogenous release. Generally speaking, because most of the input phosphorus exist in the forms of stable Ca-P and Res-P in sediments finally, the part of phosphorus which can be directly used by organisms in the sediment-water interface has little changed. So the eutrophication degree in this area has not increased with the change of time and space. To maintain the weak alkalinity of the sedimentary environment is conducive to the effective conversion of Al-P and Exc-P to Ca-P, and to inhibit the river eutrophication.

BACKGROUND The serious water pollution accident that occurred in the Tuo River in February 2004 caused serious harm to the ecological environment. In recent years, the ecological environment of the Tuo River has suffered from some degrees of pollution through industrial, agricultural and the life of coastal residents, but the geochemical study of nitrogen in the Tuo River is scarce. BAOBJECTIVES To reveal the vertical distribution and temporal and spatial variation characteristics of nitrogen in river sediments and assess the ecological restoration in the area by analyzing the total nitrogen (TN), exchangeable ammonia nitrogen (AN) and organic nitrogen (ON) in the winter sediments of the Jintang Section of the Tuo River and to compare the results with the records of nitrogen species in the same sediments 10 years ago. METHODS Based on the method of Mackin's extraction method of adsorbed ammonia nitrogen in sediments and Smart's method for total nitrogen extraction in sediments, spectrophotometry is used to analyze the occurrence of TN, AN and ON in winter sediments in the Jintang area of the Lancang River Basin. RESULTS [JP3]The concentrations of TN range from 518.913 to 4386.899 mg/kg, whereas ON range from 101.531 to 3793.683 mg/kg. The concentrations of TN and ON were above -3 cm, and ON was the main form of TN. With the increased depth, the concentrations of TN and ON decreased rapidly, and the concentrations of AN decreased slightly. A comparison between the results of nitrogen species in sediments and the records of 10 years ago shows that the concentration of AN increased significantly and the concentrations of ON and TN increased significantly above -3 cm. CONCLUSIONS The nitrogen in the sediments of the Tuo River had been released upward to the porewaters and even overlying waters as endogenous nitrogen. Combined with external pollution in this area, the concentrations of ON and TN in the surface of the sediment have increased significantly.

Abstract To investigate the usefulness of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in discriminating the pathological complete response (pCR) to neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC), 42 patients underwent preoperative IVIM-DWI before (pre-nCRT) and after nCRT (post-nCRT). The values of pre-nCRT and post-nCRT IVIM-DWI parameters (ADC, D, D* and f), together with the percentage changes (∆% parametric value) induced by nCRT, were compared between the pCR (tumour regression grade [TRG] 4) and non-pCR (TRG 0, 1, 2 or 3) groups and between the GR (TRG 3 or 4) and PR (TRG 0, 1 or 2) groups based on the Dworak TRG system. After nCRT, the ADC and D values for LARC increased significantly (all P

Methylmercury is the most toxic form among mercury compounds in the aquatic ecosystem, and poses health risks to organisms through the food chain.The effective control of methylation processes of mercury is an active research field in environmental chemistry and toxicology.Selenium(Se) has a significant suppression effect on the methylation processes of mercury(Hg).Therefore, it will be beneficial to the prevention and control of mercury contamination to clarify the speciation characteristic of mercury and the interaction mechanisms between mercury and selenium in the aquatic ecosystem.Mercury toxicity is closely associated with the levels of selenium in organisms, the interaction between Hg and Se are mainly embodied in the formation of insoluble compounds to contribute mercury demethylation or methylmercury directly ruled out by inhibition of biological a selenium related enzyme, which inhibits the toxic effect of mercury.In this paper, the speciation and distribution characteristics of mercury and selenium in the aquatic ecosystem and their interaction mechanisms were reviewed.Meanwhile, the reasonable addition of selenium compounds into water will be an effective way to inhibit the methylation processes of mercury in organisms.The development direction for the studies of interaction mechanisms between mercury and selenium and its physical effects in organisms were also reviewed.

Predation is one of the most important extrinsic factors acting upon animal populations and is a strong selective force in the evolution of form and function. Understanding the impact of predation on bird population dynamics is crucial for understanding the predation pressure of bird populations and implementing conservation strategies, especially for threatened or endemic bird species. In this paper, we sorted the predation events in the wild Crested Ibis population in Yangxian County, Shaanxi Province, from 1981 to 2021 and in the reintroduced Crested Ibis population in Ningshan from 2008 to 2021. With the use of age‐classified Leslie matrix models to simulate Crested Ibis populations under different predation pressures, the random population growth rate was estimated, and the impact of predation on population dynamics was evaluated. The results showed that snakes and raptors were the main predators of Crested Ibis in the wild and reintroduced populations, and the number of dead individuals was unevenly distributed within the three age classes in both the wild population (df = 2, χ2 = 13.236, p < 0.05) and reintroduced population (df = 2, χ2 = 49.273, p < 0.01). Predation caused a reduction in the potential annual population growth rate of 2.37% (confidence interval [CI]: 2.29–2.45) in the wild population and 2.88% (CI: 2.82–2.94) in the reintroduced population. The overall average growth rates of the wild and reintroduced populations derived from population model simulations were 12.84 and 18.13%, respectively, which suggested that the wild and reintroduced populations was increasing under the current predation pressure and that the impact of predation on the population was acceptable and sustainable. [ABSTRACT FROM AUTHOR]