Estimates of synthetic fertilizer N-induced direct nitrous oxide emission from Chinese croplands during 1980-2000

There is increasing concern that agricultural intensification in China has greatly increased N₂O emissions due to rapidly increased fertilizer use. By linking a spatial database of precipitation, synthetic fertilizer N input, cropping rotation and area via GIS, a precipitation-rectified emission factor of N₂O for upland croplands and water regime-specific emission factors for irrigated rice paddies were adopted to estimate annual synthetic fertilizer N-induced direct N₂O emissions (FIE-N₂O) from Chinese croplands during 1980-2000. Annual FIE-N₂O was estimated to be 115.7 Gg N₂O-N year⁻¹ in the 1980s and 210.5 Gg N₂O-N year⁻¹ in the 1990s, with an annual increasing rate of 9.14 Gg N₂O-N year⁻¹ over the period 1980-2000. Upland croplands contributed most to the national total of FIE-N₂O, accounting for 79% in 1980 and 92% in 2000. Approximately 65% of the FIE-N₂O emitted in eastern and southern central China.     

A method of detecting carbonyl compounds in tree leaves in China

Background, aim, and scope  

Carbonyl compounds have been paid more and more attention because some carbonyl species have been proven to be carcinogenic or a risk for human health. Plant leaves are both an important emission source and an important sink of carbonyl compounds. But the research on carbonyl compounds from plant leaves is very scarce. In order to make an approach to the emission mechanism of plant leaves, a new method was established to extract carbonyl compounds from fresh plant leaves.     

小型燃油锅炉NOx的排放特征与管理控制

以68台燃油锅炉（≤10～MW）NOx排放实测数据为基础,通过统计分析方法,研究了NOx的排放特征;通过对比分析,探讨了我国燃油锅炉NOx排放控制与管理现状,讨论了进一步加强我国燃油锅炉NOx排放管理控制的可能性与可行性,并提出了相应的管理控制建议。结果表明,NOx平均排放浓度为318．2mg／m^3,基于燃料消耗量的平均排放因子为4．4kg／t,基于燃料发热量的平均排放因子为102．8ng／J,基于燃料氮含量的平均排放因子为2．1mg／mg;建议采取分阶段控制的方式,逐步提高NOx排放限制,从而实现控源减排目标。     

水解酸化-A2O污泥减量工艺的运行性能研究

生物处理单元采用水解酸化、多级串联接触曝气、连续流的除磷脱氮A2／O工艺,并辅以外排厌氧富磷污水侧流除磷,开发了一个新型的具有强化除磷脱氮功能的污泥减量HA—A／A—MCO工艺。用该工艺处理校园生活污水发现,在SRT60d、进水COD316～407mg／L、NH4＋-N30～40mg／L、TN35～53mg／L、TP8—12mg／L的条件下,出水COD≤18mg／L、NH4＋-N≤2．1mg／L、TN≤10．3mg／L、TP≤0．44mg／L。研究还发现,水解酸化池处理产生的VFA能有效促进生物除磷脱氮,导致厌氧释磷量达57mg／L,进入化学除磷池的侧流液量仅相当于进水量的13％;系统最主要的脱氮形式是SND和缺氧反硝化,SND脱氮占脱氮总量的50％,缺氧反硝化占26％;HA-A／A—MCO系统有效实现了生物相分离,并利用生物捕食作用获得较低的污泥产率,0．1gMLSS／gCOD。     

中小型工业窑炉NOx废气的净化技术与应用

介绍了中小型工业窑炉生产过程中排放NOx的现状,并针对NOx的治理问题,从工程应用角度,简述了湿法和干法净化NOx的原理和化学反应过程。讨论了NOx排放特性和NOx废气中NO2/NOx比例的问题。提出了影响NOx治理的主要因素,包括吸收剂、吸附剂、催化剂和设备的部分应用参数,并结合工程实例指出工程需要注意的问题。介绍了多项采用湿法和干法净化NOx的工程应用项目,丰富了中小工业窑炉NOx废气的治理的实践经验,为中小工业窑炉排放NOx治理奠定了基础。     

Carbon dioxide and methane fluxes in the littoral zones of two lakes,east Antarctica

During the summertime of 2007/2008, carbon dioxide (CO₂) and methane (CH₄) fluxes across air–water interface were investigated in the littoral zones of Lake Mochou and Lake Tuanjie, east Antarctica, using a static chamber technique. The mean fluxes of CO₂ and CH₄ were ?70.8 mgCO₂ m^?2 h^?1 and 144.6 μgCH₄ m^?2 h^?1, respectively, in the littoral zone of Lake Mochou; The mean fluxes were ?36.9 mgCO₂ m^?2 h^?1 and 109.8 μgCH₄ m^?2 h^?1, respectively, in the littoral zone of Lake Tuanjie. Their fluxes showed large temporal and spatial dynamics. The CO₂ fluxes showed a significantly negative correlation with daily total radiation (DTR) and a weakly negative correlation with air temperature and water temperature, indicating that sunlight intensity controlled the magnitude of CO₂ fluxes from the open lakes. The CH₄ fluxes significantly correlated with local air temperature, water table and total dissolved solids (TDS), indicating that they were the predominant factors influencing CH₄ fluxes. Summertime CO₂ budgets in the littoral zones of Lake Mochou and Lake Tuanjie were estimated to be ?152.9 gCO₂ m^?2 and ?79.7 gCO₂ m^?2, respectively, and net CH₄ emissions were estimated to be 312.3 mgCH₄ m^?2 and 237.2 mgCH₄ m^?2, respectively. Our results show that shallow, open, alga-rich lakes might be strong summertime CO₂ absorbers and small CH₄ emitters during the open water in coastal Antarctica.     

Impact of roadside noise barriers on particle size distributions and pollutants concentrations near freeways

Increasing epidemiological evidence has established an association between a host of adverse health effects and exposure to ambient particulate matter (PM) and co-pollutants, especially those emitted from motor vehicles. Although PM and their co-pollutants dispersion profiles near the open freeway have been extensively characterized by means of both experimental measurements and numerical simulations in recent years, such investigations near freeways with roadside barriers have not been well documented in the literature. A few previous studies suggested that the presence of roadside structures, such as noise barriers and vegetation, may impact the decay of pollutant concentrations downwind of the freeway by limiting the initial dispersion of traffic emissions and increasing their vertical mixing due to the upward deflection of airflow. Since the noise barriers are now common roadside features of the freeways, particularly those running through populated urban areas, it is pertinent to investigate the impact of their presence on the particles and co-pollutants concentrations in areas adjacent to busy roadways. This study investigated two highly trafficked freeways (I-710 and I-5) in Southern California, with two sampling sites for each freeway, one with and the other without the roadside noise barriers. Particle size distributions and co-pollutants concentrations were measured in the immediate proximity of freeways and at different distances downwind of the freeways. The results showed the formation of a “concentration deficit” zone in the immediate vicinity of the freeway with the presence of roadside noise barrier, followed by a surge of pollutant concentrations further downwind at 80–100 m away from freeway. The particle and co-pollutants concentrations reach background levels at farther distances of 250–400 m compared to 150–200 m at the sites without roadside noise barriers.     

Multi-objective, decision-based assessment of a water quality monitoring network in a river system

Water quality monitoring network design has historically tended to use experience, intuition and subjective judgement in locating monitoring stations. Better design procedures to optimize monitoring systems need to simultaneously identify significant planning objectives and consider a number of social, economic and environmental constraints. The consideration of multiple objectives may require further decision analysis to determine the preference weights associated with the objectives to aid in the decision-making process. This may require the application of an optimization study to extract such information from decision makers or experts and to evaluate the overall effectiveness of locating strategies. This paper assesses the optimal expansion and relocation strategies of a water quality monitoring network using a two-stage analysis. The first stage focuses on the information retrieval of preference weights with respect to the designated planning objectives. With the aid of a pre-emptive goal programming model, data analysis is applied to obtain the essential information from the questionnaire outputs. The second stage then utilizes a weighted multi-objective optimization approach to search for the optimal locating strategies of the monitoring stations in the river basin. Practical implementation is illustrated by a case study in the Kao-Ping River Basin, south Taiwan.     

河流沉积物中有机污染物的分析研究进展

总结了近年来河流沉积物中有机污染物的研究进展 ,集中评述了国内有关沉积物中多环芳烃、有机氯农药和多氯联苯的分析研究现状 ,包括样品采集、样品前处理和样品分析 ,并对今后河流、湖泊及水库沉积物中污染物的分析工作作了展望     

Influence of low molecular weight anionic ligands on the sorption of heavy metals by soil constituents: a review

Environmental Chemistry Letters - The sorption of heavy metals by soil constituents reduces the absorption of these pollutants by crops and vegetables, and thus limit food contamination. Low...