缺氧／厌氧／好氧工艺的脱氮除磷研究

通过实验研究缺氧环境倒置，来比较对Ａ／Ａ／Ｏ工艺脱氮除功能的影响。结果表明，与常规Ａ／Ａ／Ｏ（厌／缺／好）工艺相比，倒置后的工艺具有更好的脱氮除磷效果，在同等条件下，倒置系统的出水中ＰＯ４＾３－Ｐ明显降低，而比反硝化速率却可３０－５０％，该文还进一步揭示了聚磷微生物在各种环境下的释磷和吸磷规律及其相互关系。     

Significance of dredging on sediment denitrification in Meiliang Bay, China： A year long simulation study

An experiment for studying the effects of sediment dredging on denitrification in sediments was carried out through a one-year incubation of undredged (control) and dredged cores in laboratory. Dredging the upper 30 cm of sediment can significantly affect physico-chemical characteristics of sediments. Less degradation of organic matter in the dredged sediments was found during the experiment. Denitrification rates in the sediments were estimated by the acetylene blockage technique, and ranged from 21.6 to 102.7 nmol N2/(g dry weight (dw)·hr) for the undredged sediment and from 6.9 to 26.9 nmol N2/(g dw·hr) for dredged sediments. The denitrification rates in the undredged sediments were markedly higher (p0.05) than those in the dredged sediments throughout the incubation, with the exception of February 2006. The importance of various environmental factors on denitrification was assessed, which indicated that denitrification was regulated by temperature. Nitrate was probably the key factor limiting denitrification in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Sediment dredging influenced the mineralization of organic matter and denitrification in the sediment; and therefore changed the pattern of inherent cycling of nitrogen.     

Environmental factors and spatiotemporal distribution characteristics of the global outbreaks of the highly pathogenic avian influenza H5N1

The spread of highly pathogenic avian influenza H5N1 has posed a major threat to global public health. Understanding the spatiotemporal outbreak characteristics and environmental factors of H5N1 outbreaks is of great significance for the establishment of effective prevention and control systems. The time and location of H5N1 outbreaks in poultry and wild birds officially confirmed by the World Organization for Animal Health from 2005 to 2019 were collected. Spatial autocorrelation analysis and multidistance spatial agglomeration analysis methods were used to analyze the global outbreak sites of H5N1. Combined with remote sensing data, the correlation between H5N1 outbreaks and environmental factors was analyzed using binary logistic regression methods. We analyzed the correlation between the H5N1 outbreak and environmental factors and finally made a risk prediction for the global H5N1 outbreaks. The results show that the peak of the H5N1 outbreaks occurs in winter and spring. H5N1 outbreaks exhibit aggregation, and a weak aggregation phenomenon is noted on the scale close to 5000 km. Water distance, road distance, railway distance, wind speed, leaf area index (LAI), and specific humidity were protective factors for the outbreak of H5N1, and the odds ratio (OR) were 0.985, 0.989, 0.995, 0.717, 0.832, and 0.935, respectively. Temperature was a risk factor with an OR of 1.073. The significance of these ORs was greater than 95%. The global risk prediction map was obtained. Given that the novel coronavirus (COVID-19) is spreading globally, the methods and results of this study can provide a reference for studying the spread of COVID-19.

     

Spatiotemporal development of land use systems,influences and climate variability in Southwestern Ghana (1970–2020)

Environment, Development and Sustainability - This study assesses the spatiotemporal development of land use systems and climate variability in Southwestern Ghana over the past five decades using...     

High-expression and characterization of a novel serine protease from Ornithinibacillus caprae L9T with eco-friendly applications

Environmental Science and Pollution Research - In the current work, a novel thermophilic serine protease gene (P3862) from Ornithinibacillus caprae L9T was functionally expressed in Bacillus...     

Arbuscular mycorrhizal colonization increases plant above-belowground feedback in a northwest Chinese coal mining–degraded soil by increasing photosynthetic carbon assimilation and allocation to maize

Environmental Science and Pollution Research - A three-compartment culture system was used to study the mechanism by which the AM fungus Funneliformis mosseae influences host plant growth and soil...     

Patterns and drivers of CH4 concentration and diffusive flux from a temperate river–reservoir system in North China

Freshwater reservoirs are regarded as an important anthropogenic source of methane (CH₄) emissions. The temporal and spatial variability of CH₄ emissions from different reservoirs results in uncertainty in the estimation of the global CH₄ budget. In this study, surface water CH₄ concentrations were measured and diffusive CH₄ fluxes were estimated via a thin boundary layer model in a temperate river–reservoir system in North China, using spatial (33 sites) and temporal (four seasons) monitoring; the system has experienced intensive aquaculture disturbance. Our results indicated that the dissolved CH₄ concentration in the reservoir ranged from 0.07 to 0.58 µmol/L, with an annual average of 0.13 ± 0.10 µmol/L, and the diffusive CH₄ flux across the water–air interface ranged from 0.66 to 3.61 μmol/(m²•hr), with an annual average of 1.67 ± 0.75 μmol/(m²•hr). During the study period, the dissolved CH₄ concentration was supersaturated and was a net source of atmospheric CH₄. Notably, CH₄ concentration and diffusive flux portrayed large temporal and spatial heterogeneity. The river inflow zone was determined to be a hotspot for CH₄ emissions, and its flux was significantly higher than that of the tributary and main basin; the CH₄ flux in autumn was greater than that in other seasons. We also deduced that the CH₄ concentration/diffusive flux was co-regulated mainly by water temperature, water depth, and water productivity (Chla, trophic status). Our results highlight the importance of considering the spatiotemporal variability of diffusive CH₄ flux from temperate reservoirs to estimate the CH₄ budget at regional and global scales.