Nitrous oxide (N2O), a potent greenhouse gas, is emitted during nitrogen removal in wastewater treatment, significantly contributing to greenhouse effect. Nitrogen removal generally involves nitrification and denitrification catalyzed by specific enzymes. N2O production and consumption vary considerably in response to specific enzyme-catalyzed nitrogen imbalances, but the mechanisms are not yet completely understood. Studying the regulation of related enzymes’ activity is essential to minimize N2O emissions during wastewater treatment. This paper aims to review the poorly understood related enzymes that most commonly involved in producing and consuming N2O in terms of their nature, structure and catalytic mechanisms. The pathways of N2O emission during wastewater treatment are briefly introduced. The key environmental factors influencing N2O emission through regulatory enzymes are summarized and the enzyme-based mechanisms are revealed. Several enzymebased techniques for mitigating N2O emissions directly or indirectly are proposed. Finally, areas for further research on N2O release during wastewater treatment are discussed.
With the advent of new regulations concerning aircraft deicing and management of spent aircraft deicing fluids (ADFs), many airports now face the dual challenges of simultaneously maintaining public safety and protecting the environment. This paper provides a theoretical assessment of the potential environmental impact of stormwater runoff and offers detailed current information on alternative deicing fluid application methods and materials, collection and treatment practices. 相似文献
Much work has been done on gaseous emissions and leaching of nitrogenous compounds from whole soil profiles and also from soil surface measurements which are assumed to be mainly due to topsoil activity. In soils with an impervious clay subsoil, the boundary between the topsoil and subsoil may provide an interface for microbial activity, including N transformations. In this study, we investigated movement and transformations of two reactive N species (nitrate and urea) at the subsoil interface using a series of replicate, intact soil blocks, under two contrasting watering regimes. We measured fluxes in both liquid and gaseous phases and demonstrated that nitrate reaching the subsoil interface does not necessarily leach into water systems, but may denitrify immediately and could, therefore, add to atmospheric pollution through N2O production. On the other hand, ammonium reaching the subsoil interface either directly, or after mineralization, appears to be more mobile than expected and has the potential to pollute watercourses. 相似文献
ABSTRACT Firstly, on the basis of literature research, sort out and summarize the critical coupling relationship among the upstream, middle, and downstream enterprises in the wind power industry chain. Secondly, the evaluation index system of coupling coordination degree of China’s wind power industry chain was established. Based on entropy weight method and subsystem efficiency function, the capacity coupling (CC) coefficient model of wind power industry chain subsystem was established. The coupling coordination degree between the upstream subsystem and the midstream subsystem of the wind power industry chain, and between the midstream subsystem and the downstream subsystem is dynamically evaluated, and the coupling coordination degree evaluation model of the wind power industry chain in China is proposed. Thirdly, according to the relevant statistical data of China from 2010 to 2017, this paper conducts an empirical study on the coupling of the upstream, middle and downstream subsystems of the wind power industry chain. Finally, based on the collaborative coupling study of China’s wind power industry chain, this paper analyzes the key factors influencing the collaborative development of wind power industry chain, and puts forward Suggestions on the optimization of the collaborative development of China’s wind power industry chain. 相似文献