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The Debatable Function involving 24-S-Hydroxycholesterol throughout Alzheimer's.
In order to determine the distribution characteristics of Se in soil-crop systems, we carried out a study on the Se-rich soil threshold by collecting 8789 surface soils and 155 deep soils in the Qianjiang District of Chongqing City, China, and 141 corn seeds and 159 rice seeds (simultaneously collecting 141 and 159 corresponding root soil samples, respectively). We then analyzed the Se content, organic matter, S, Mn, TFe2O3, Al2O3, and K2O in soils and crops, and soil pH. We also analyzed the surface layer using geostatistical methods and the distribution characteristics of Se in deep soils using multiple regression analysis to study the factors influencing the bioavailability of Se. Based on the contents of each component of root soil and the Se contents of crops, the Se rich threshold was examined. The results showed that the high-Se soils in the study area account for 32.72% of the total area; the distribution of Se contents in the surface and deep soils is mainly controlled by the parent material, the source of soil Se is stable, and the surface enrichment is obvious. The Se-rich rates of corn and rice were 75.35% and 46.81%, respectively, and soil organic matter and S content will limit the bioavailability of Se. If the planted crop is corn, it is recommended to use 0.3 mg·kg-1 as the Se-rich soil threshold; if the planted crop is rice, when the soil pH is ≤ 7.5, it is recommended to use 0.3 mg·kg-1 as the Se-rich soil threshold, while at a soil pH>7.5, it is recommended to use 0.4 mg·kg-1 as the threshold. Similarly, if other large crops are planted in the study area, this method can also be used to carry out a study on the proposed Se-rich soil threshold.Classifying the quality of agricultural products is an important means of managing the arable land quality and guaranteeing the quality and safety of agricultural products. This work is planned to be completed in 2020. However, there is still no perfect method or technology for classifying the quality of arable lands. The species sensitivity distribution (SSD) has become commonly used for determining ecological safety thresholds since it takes into account differences in species sensitivity, the physical and chemical properties of soils, biological availability, and sources of pollutants. However, it has not yet been applied to the classification of arable land quality. Therefore, based on the routine monitoring data of rice production areas in southern China from the Agro-environmental Monitoring Center of China, this study proposes the use of species sensitivity distributions to classify the environmental quality of cadmium in rice production areas. The scientific rationale of this method was also discussed quality of cadmium in rice producing areas reflected good scientific rationale and operability. This study may provide a foundation for the construction and improvement of the arable land quality classification system in China.To study the condition of urban green space soils in the central parts of a city in North China, the spatial distribution, sources, and pollution levels of heavy metals (Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni) within green space soils in the central urban districts of the city were investigated. The results showed that the soil quality was high overall. The mean concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni were 0.172, 0.202, 9.02, 34.7, 57.0, 31.2, 85.7, and 26.3 mg·kg-1, respectively. The mean concentrations of Cd, Hg, Pb, and Zn in urban soils exceeded the background value of the Beijing-Tianjin-Tangshan region. All of the samples' heavy metal concentrations were lower than the risk screening values for soil contamination of development land in the national soil environment quality standards. With respect to the spatial distribution, the concentrations of As, Cr, and Ni were higher in the northwest of the study area, the concentrations of Cd and Zn were higher in the northeast, and the concentrations oft of pollution sources of elements over the standard. The contribution rates of sources were as followssource 2(46.1%), source 3(33.1%), source 1(17.7%), and others (3.1%) for Cd, source 1(93.0%) for Cu, source 1(52.4%), source 3(24.2%), source 2(20.0%), and others (3.4%) for Zn, source 1(56.3%), source 2(37.8%), and source 3(5.8%) for Ni. Sources 1 and 3 were anthropogenic, while source 2 was natural.Ferrous iron-activated calcium peroxide (Fe2+/CaO2) was innovatively put forward to improve the dewaterability of waste-activated sludge. The effects of initial pH, Fe2+, and CaO2dosages on sludge dewatering performance were investigated and its internal mechanism for achieving deep sludge dewatering was thoroughly explored. The results indicated that the best dewatering performance was obtained by dosing 3.31 mmol·g-1 Fe2+ and 3.68 mmol·g-1 CaO2 under neutral pH, in which specific resistance to filtration (SRF) and water content (WC) reduced from 20.99×1012 m·kg-1 and 86.61% to 3.91×1012 m·kg-1 and 76.15%, respectively. Selleck TL12-186 Fe2+/CaO2 oxidation caused sludge microbial cell lysis, release of intracellular organic matter, and degradation of extracellular polymeric substances (EPS). Meanwhile, the generated Fe3+ facilitated re-flocculation of sludge particles into rigid and porous structure flocs, which was beneficial to the release of EPS-bound water to achieve deep sludge dewatering. From the perspective of technology and economy, the Fe2+/CaO2 process is economical and practical, and has a promising application prospect in improving the dewatering performance of waste-activated sludge.To understand the changes in microbial community characteristics during the enrichment of anaerobic ammonium oxidation (ANAMMOX) bacteria, an ASBR reactor was used to culture the ANAMMOX bacteria. The composition, diversity, and species co-occurrence network of the microbial community were investigated under different cultivation times. The results showed that the ANAMMOX bacteria were enriched by gradually increasing the substrate concentration, with removal efficiencies for NH4+-N, NO2--N, and total nitrogen of 97.6%, 95.4%, and 84.9%, respectively. The high-throughput sequencing found that the dominant phyla (relative abundance>5%) were Proteobacteria, Bacteroidetes, Chloroflexi, Planctomycetes, Armatimonadetes, and Actinobacteria in the whole culture process. Candidatus Brocadia was the main ANAMMOX bacteria in the reactor, with its relative abundance increasing from 1.42% to 24.66%. During the cultivation process, the composition of the dominant microbial community did not change, while the relative abundance showed a significant difference (P less then 0.05). The alpha diversity of the microbial community significantly increased first and then decreased (P less then 0.05), and the beta diversity of the microbial community was significantly spatially differentiated (R=0.5672, P less then 0.01) during the culture process. Species network densities were 0.188, 0.068, 0.059, 0.18, and 0.0735 at different times during the culture process. Although the enrichment culture process resulted in weaker correlations between microorganisms, the related group of microorganisms in the phylum Aspergillus became the main node in the network. The enrichment process weakened the correlation between microorganisms; however, the microbial taxa related to the phylum Planctomycetes became the key node in the network.The performance and microbial characteristics of ammonium-limited and nitrite-limited ANAMMOX reactors were studied in two continuously stirred tank reactors. The influent TN concentrations were controlled below 50 mg·L-1. The hydraulic retention time and water temperature were maintained at 2.0 h and 20℃, respectively. Results showed that though both ANAMMOX reactors demonstrated similar TN removal loading rates[0.45-0.5 kg·(m3·d)-1] and TN removal efficiencies (around 70%), the ΔNO3-/ΔNH4+ ratio of the ammonium-limited ANAMMOX reactor showed a faster upward trend. Batch tests and high-throughput sequencing results indicated that the ammonium-limited ANAMMOX reactor had more significant functional and population heterogeneity than the nitrite-limited ANAMMOX reactor. Candidatus_Brocadia was the predominant ANAMMOX bacteria in both reactors. The relative abundance of Candidatus_Brocadia in large granules (53.9%) was significantly higher than that in flocs (19.1%) under the ammonium-limited conditions, whereas only a small difference in relative abundance of Candidatus_Brocadia was observed between the granules (28.1%) and flocs (21.3%) in the nitrite-limited ANAMMOX reactor. Nitrospira-like NOB were detected in both ANAMMOX reactors, which primarily inhabited flocs, seemingly driven by the availability of oxygen. Moreover, the ammonium-limited (i.e., excess nitrite) conditions seemingly favored the growth of Nitrospira. Building upon these results, a control strategy for optimal operation of the ammonium-limited ANAMMOX reactor was proposed based on selective floc discharge.In this study, to solve the problem of salinity enrichment in industrial wastewater recycling, a hydrolytic bioreactor was continuously operated to treat high-color printing and dyeing wastewater (PDWW) with salinity build-up. Nearly complete color removal was achieved even with salinity build-ups from 0.5 to 4 g·L-1 in the influent. Pyrosequencing of 16S rRNA genes showed that the salinity build-up results in the decrease of microbial species from 882 to 631; however, the biodiversity of the bacterial community remains stable. Metagenomic analysis indicated that salinity build-up caused no obvious effect on the overall function of the bacterial community, but altered the abundance of specific decoloring genes. Proteobacteria dominated in the bioreactor, and Methanothrix and Geobacter were the dominant genera under low salinity conditions. Proteobacteria increased in abundance with salinity build-up. Desulfovibrio and Desulfococcus were the two predominant genera in the bioreactor fed with sodium sulphate salinity build-up, demonstrating opposite responses to the sodium stress. PICRUSt functional analysis showed that the relative abundance of the decolorizing enzymes SOD1 and SOD2 decreased significantly, but the relative abundance of CAT and TYR increased, ensuring the stability of the decolorizing function of the hydrolysis biological system. From the perspective of the functional genes of hydrolysis decolorization, this study explored the effect of salinity build-up on the microbial community and function of hydrolysis, providing a theoretical basis for the study of decolorization and organic matter removal mechanism of PDWW under the condition of salinity build-up.There were significant differences in the working efficiency and mechanism of constructed wetlands between low temperature and suitable temperature conditions. This study designed a horizontal subsurface flow constructed wetland (HFCW) and a vertical subsurface flow constructed wetland (VFCW) to explore their performance differences in advanced treatment of sewage based on contaminant degradation analysis including the removal of organic matters, total nitrogen (TN), and total phosphorus (TP), as well as the analysis of microbial community structure. The results showed that when the COD concentration of influent was between 37.50 to 80.00 mg·L-1, the concentration of total nitrogen and total phosphorus were within the first level A criteria specified in the discharge standard of pollutants for municipal wastewater treatment plant at the continuous flow of 2 m3·d-1①Both HFCW and VFCW showed stable degradation ability of organic matter in influent and good resistance to high organic load. ②Supplementation of the carbon source significantly improved the nitrogen removal efficiency of two subsurface flow constructed wetlands.
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