Mixing Zone Characterization of Two Transition Terrain Streams With Tracers1

Abstract: For most wastewater discharges to streams, the effluent creates a plume that becomes less distinct as it mixes with the receiving water. Constant‐discharge tracer studies were used to characterize the plume or physical mixing zone (PMZ) at two similar transition terrain streams. At both sites, the laterally unmixed PMZs did not extend across the entire stream and mixing occurred relatively quickly. The observed plumes were significantly smaller than the regulatory mixing zone (RMZ) allowed by the State of Colorado. At Site 1 mixing occurred within a much shorter distance due to the presence of a riffle zone located a few meters downstream of the discharge point. Interpretation of field data with an analytical model suggests that the effective transverse dispersion coefficient (k_z) for the riffle zone at Site 1 (～1 m²/s) was significantly higher than the average value over the longer nonriffle section at Site 2 (～0.01 m²/s). These results imply that to achieve the fastest mixing in transition terrain streams, thereby minimizing the size of the PMZ, discharge outfalls should be located upstream and close to riffle zones.     

基于测点环境浓度影响的点源应急强化减排分析

基于预报气象条件、广州及周边城市的重点企业排放清单,采用CALPUFF模型模拟2010年亚运会开幕式期间重点企业对广州市内空气质量监测点的相对环境浓度影响,据此筛选得出预报不利气象条件下工业点源应急强化减排名单,并利用GIS可视化技术分析点源强化减排效果,为空气质量保障的专家会商提供依据.广州亚运会期间点源应急强化减排实施效果表明,有针对性地对测点环境浓度影响大的企业实施强化减排措施,可有效缓解个别点位的一定范围内超标问题.本文提出的研究方法和配套的GIS软件可为不利气象条件下工业点源的应急强化减排提供辅助决策服务和数据支持.     

Determining short chain fatty acids in sewage sludge hydrolysate：A comparison of three analytical methods and investigation of sample storage effects

In anaerobic digestion, the production of short-chain fatty acids （SCFAs） can be beneficial or harmful to the overall process, depending on the concentration of accumulated acids. Therefore, the accurate determination of the SCFA concentration in both fresh and stored sludge hydrolysates is important. To select a suitable method for monitoring SCFAs during the anaerobic digestion of sewage sludge, the accuracy of three available analytical methods, including 5 pH point acid titration （TITRA5）, gas chromatography （GC）, and spectrophotometry, were compared in the present study. The results revealed that TITRA5 and GC displayed better agreement in the achieved measurements and higher precision and accuracy than the spectrophotometric assay, as supported by the application of different statistical models. TITRA5 excelled in titrating unfiltered hydrolysate while simultaneously measuring the alkalinity, whereas the GC method provided detailed information on the contribution of different fatty acids to the total acidity. In contrast, the spectrophotometric assay suffered from many forms of interference, depending on the sample＇s matrix. SCFA production followed the pattern of enzymatic reactions and fitted the Michaelis-Menten model. In addition to promoting TITRA5 as an accurate and robust analytical tool for routine SCFA analyses, this comparative study also demonstrated the possibility of storing hydrolysate samples at different temperatures and durations without altering the SCFA measurements.     

钢结构防腐涂层面漆可剥离现象的原因分析及处理措施

目的分析钢结构防腐涂层面漆出现可剥离现象的原因。方法利用质谱仪、环境扫描电镜、ICS 1100型离子色谱仪对涂料和漆膜进行测试分析。结果聚氨酯涂料和漆膜样品含有高沸点溶剂三甲苯和四甲苯,通过微观形貌分析发现漆膜固化不充分,在漆膜样品的萃取溶液中检测出了铵基盐类物质。结论聚氨酯涂料中的高沸点溶剂、低温环境下的小分子胺析出和湿热海洋环境是导致涂层面漆出现大面积可剥离现象的主要原因。     

关于在丹东市新城区建设环境空气自动监测点位的阐述

根据丹东市环境空气自动监测点位现状,结合环境空气质量监测规范及创建环境保护模范城的要求。考虑在新城区建设环境空气自动监测点位。这样可以保证丹东市各行政区环境空气监测点位分布的均匀性,反映新城区主要功能区和主要空气污染源的污染状况及变化趋势。     

关于确保大气自动监测网点正常运转的探讨——以日本电气化学计器株式会社产品为例

文章探讨和分析了日本DKK（日本电气化学计器株式会社）产品SO2（二氧化硫,英文Sulfur Dioxide的缩写）、NOx（氮氧化物,英文Nitrogen Oxides的缩写）、SPM（空气中的飘尘,英文Suspended Particulate Matter的缩写）监测仪器安全有效运转的途径。     

钢铁产业政策导向及在环评中应注意的问题

在介绍中国钢铁产业发展现状及其面临形势、中国对钢铁产业进行结构调整的政策导向的基础上,分析了钢铁产业环境影响评价中应注意的若干评价技术要点及评价难点。经分析,因钢铁产业政策的变化,环评的评价技术要点及难点主要为钢铁产业与国家政策的相符性。     

Characteristics and influence factors of NO2 exchange flux between the atmosphere and P. nigra

Nitrogen dioxide(NO_2)is an important substance in atmospheric photochemical processes and can also be absorbed by plants.N02 fluxes between the atmosphere and P.nigrc seedlings were investigated by a double dynamic chambers method in Beijing from June 15to September 3,2017.The range of N02 exchange fluxes between P.nigra seedlings and the atmosphere was from-14.6 to 0.8 nmol/(m~2.sec)(the positive data represent N02 emissior from trees,while the negative values indicate absorption).Under ambient concentrations the mean NO_2 flux during the fast-growing stage(Jun.15-Aug.4)was-3.0 nmol/(m2·sec)greater than the flux of-1.5 nmol/(m2-sec)during the later growth stage(Aug.8-Sept.3)The daily exchange fluxes of NO_2 obviously fluctuated.The fluxes were largest in the morning and decreased gradually over time.Additionally,the N02 fluxes were larger undei high light intensities than under low light intensities during the whole growth period.The effects of temperature on N02 fluxes were different under two growth periods.The NO_2exchange fluxes were larger in a range of temperatures close to 44℃in the fast-growing stage,whereas there were no evident differences in N02 exchange fluxes under widel differing temperatures in the later growth stage.Under polluted conditions,the uptake ability of N02 was weakened.Additionally,the compensation point of N02 was 5.6 ppb ir the fast-growing stage,whereas it was 1.4 ppb in the later growth stage.The depositior velocities of NO_2 were between 0.3 and 2.4 mm/sec.     

美国工业点源排放控制经验对中国的借鉴研究

文章分析了以排放限值为主要手段的美国工业水污染控制体系.美国工业水污染控制体系包括基于水质的排放限值和基于技术的排放限值,两者相辅相成,互为补充,不仅促使工业点源排放量不断降低,而且按照水质标准维护自然水体健康.在此基础上,文章提出了美国经验对中国水污染控制政策的三点启示:一是基于水质的排放限值与基于技术的排放限值分开设置,二是基于技术的排放限值始终保持先进性,三是重视统计学方法在排放限值制定中的应用.     

流域尺度污染溯源模拟-优化防控方法:以铜陵市顺安河流域为例

长江经济带发展是我国重要国家战略,但面临着水环境保护难度大、污染来源不清和措施集成度低等问题.针对流域尺度多源污染协同治理面临的方法瓶颈,结合资料调研分析、机制模型模拟和智能算法优化,构建了"污染精准溯源-措施效果评价-措施整体优化"为主体的流域水环境保护框架,并以安徽省铜陵市顺安河流域为例进行了方案应用.结果表明,新框架可精准量化流域内种植业、农村生活、畜禽养殖、水产养殖、工业废水和生活污水的贡献,并评价多种防控措施及其集成的总体效果;多目标优化蛙跳算法通过系统对比多种方案的成本效益,提供了性价比高的流域多源污染协同治理方案,如通过合理投资可使顺安河流域总氮在丰、平和枯水年分别削减1274.24、855.24和381.96 t ·a^-1,总磷削减321.42、159.80和42.93 t ·a^-1,保障水质达到地表Ⅲ类水质标准.新框架可推广到其他流域,为流域高质量发展背景下的水环境保护提供模式参考.