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Lockhart Ulriksen posted an update 5 days, 9 hours ago
The integrated control of multiple pollutants is a promising approach for efficient and economical pollution reduction. Inspired by the simultaneous removal of SO2 and NOx by the spray-and-scattered-bubble (SSB) technology, this paper further explores gas phase arsenic and selenium removal ability of this new technology. Ammonia concentration, SO2 concentration, liquid/gas ratio and immersion depth, which are the key operating parameters of SSB technology, are evaluated to determine their effect on arsenic and selenium removal. The experimental results indicate that ammonia concentration and SO2 will facilitate the simultaneous removal of arsenic and selenium by SSB technology. learn more However, the excess ammonia concentration and SO2 should avoided to prevent the decrease in removal efficiency caused by the ammonia escape, increased mass transfer resistance, and mechanical carry-over. The maximum removal efficiency for arsenic can be obtained at the liquid-gas ratio of 10 L/m3, and for selenium, the maximum removal efficiency will be reached at 14 L/m3. For the technology of spray-and-scattered-bubble, chemical reaction and mass transfer jointly play the role in contaminant removal. By changing the immersion depth and measuring the corresponding pressure drop, the weight assigned to the effect of chemical reaction and mass transfer effect could be ascertained to a certain degree. It is speculated that chemical reaction will play a more important role for selenium removal in the bubble zone than the mass transfer. Moreover, for arsenic, mass transfer effect will play a more important role than chemical reaction. The sensitivity analysis for simultaneous removal of arsenic and selenium by SSB technology indicating that the variation of operating conditions will lead to a greater change in arsenic removal as compared with selenium.Identifying the eco-hydrological processes associated with water-salt dynamics is important for the sustainable management of water resources and eco-environmental systems in groundwater-dependent ecosystems, especially across different land use types in salt-affected oasis-desert ecosystems. In this study, a typical cropland-shelterbelt-desert site at the oasis-desert system in the Sangong River watershed of northwestern China was selected to investigate the spatio-temporal variations of water-salt dynamics using the Spearman rank correlation analysis and water/mass balance analysis, and to identify the response of vegetation dynamics to water-salt variations based on a model framework for vegetation-salinity-groundwater interactions, within and among these land uses during crop growth period (CGP April 1-June 28, 2018) and non-crop-growth period (Non-CGP June 29-October 31, 2018). Results showed that the soil water content (SWC) and soil electrical conductivity (SEC) had clear vertical stratification, horizhropogenic processes, especially the development of modern water-saving irrigation agriculture with groundwater-fed, are dominating the vegetation-salinity-groundwater interactions and its ecohydrological consequences in this ecosystem. Adaptive management of water and salt migration in soil and groundwater is essential for maintaining the coexistence of oasis-desert ecosystems in arid areas.Biological nitrogen fixation (BNF) in sediments is an important source of bioavailable nitrogen in aquatic systems. However, the effect of habitat change caused by eutrophication on nitrogen fixation within sediments is still unclear. In this study, nitrogen fixation rates and diazotroph diversities in sediments with heterogeneous ecological status in one eutrophic lake were investigated by using an isotope tracer method and sequencing of nitrogen-fixing (nif) genes. The results showed that both nitrogenase activity (NA) and nifH abundance in sediments of blooms area were higher than those in vegetation-dominated habitats. Correlation analysis showed that NA was correlated closely to nifH abundance, dissolved sulfide, and iron. The diazotrophic assemblage contained mainly Proteobacterial sequences belonging to Cluster I and III, and the variations of diazotrophic community could be explained by total nitrogen content, total phosphorus content, organic matters, sulfides, ammonium and iron content. Moreover, the co-occurrence network analysis showed the Alphaproteobacteria shaped the major interactions in diazotrophic community, and sediment properties had stronger effect on diazotrophic community in cyanobacteria-dominated habitat. This study revealed that habitat heterogeneity in eutrophic lakes shaped different succession of BNF in sediments and cyanobacterial blooms significantly improved the nitrogen-fixing activity in sediments, which broadened our understanding of nitrogen cycle and nutrient management in eutrophic freshwater lakes.Trophic transfer of metals has been well researched in aquatic food webs; however, most studies have examined the presence of metal residuals in the entire body of marine organisms and but not in specific tissues. In this study, we determined the concentrations of Cu, Cr, Pb, Zn, Cd, and Ni in various organs of 17 marine species, including crustaceans, gastropods, bivalves, and fishes, with different trophic levels (TLs), which were collected from the Liaodong Bay, China, in July 2019. Results showed that the liver, gill, and muscle tissues of marine species are ideal indicators for analyzing Cu, Cr, Pb, Zn, Cd, and Ni contamination in marine environments. When the entire bodies of these marine species were considered, a bio-dilution in Cu, Cr, Pb, Zn, Cd, and Ni was observed in the studied food web. In contrast, the metal tissue-specific bio-magnification in the entire studied food web showed different results. In the liver and gill tissues, negative correlations were found between the concentrations of cadmium and TLs, while copper bio-dilution was also observed in gill tissue. In the muscle tissues, Cu, Pb, and Ni showed bio-dilution and trophic magnification factors of Cu, Pb, and Ni ranged from 0.44 to 0.73. This study highlights the importance of tissue-specific considerations to obtain further accurate information on metal trophodynamics and trophic transfers in marine food webs, thereby enhancing the risk assessment of many elements in wildlife and human health.