Experiments on mixing and dissipation in internal solitary waves over two triangular obstacles

A series of laboratory experiments was undertaken in a stratified two-layer fluid to investigate the energetics of the interaction between an internal solitary wave (ISW) and triangular obstacles, as well as to determine the partitioning of ISW energy and its subsequent dynamics. The ISW energy was dissipated as a result of internal breaking and turbulent mixing induced by wave instability. Tests involving different combinations of triangular obstacles in various heights and intervals and ISW of different amplitudes were performed. The wave features resulting from the interaction of an ISW and double obstacles were found to differ from those of single obstacle. The incident energy of an ISW was either reflecting back from the obstacles, dissipated through turbulent mixing, or transmitted over the double obstacles. Reduction in wave energy increased as the intervals between obstacles reduced. For two obstacles in different heights, energy dissipation was greater in the case with a higher obstacle ahead of a lower one. However, the overall performance was dependent on the relative height of the obstacles, relative water depth of the upper and bottom layer, in addition to the intervals between the obstacles.     

城市空气悬浮颗粒物的理化性质及其健康效应

城市空气悬浮颗粒物的理化性质是其他相关研究的理论基础,目前的研究主要集中在分析空气颗粒物的成分组成、来源解析上.空气悬浮颗粒物主要由金属元素、有机化学成分和无机盐类等组成,城市交通、工业等各种源的排放是其主要来源,按照粒径大小不同一般可将其分为总悬浮颗粒物(TSP)、可吸入颗粒物(PM10)、细颗粒物(PM2.5)等.空气悬浮颗粒物达到一定浓度后,会对环境和人体产生一定的危害,而且颗粒物粒径大小不同,来源和成分组成就有别,其产生的危害程度也不一样.文章从粒径大小、来源、成份以及三者间的相互关系等几个方面详细阐述了城市空气悬浮颗粒物的理化性质,并从其对人体、其他动植物和环境等方面造成的影响综述了空气颗粒物的健康效应及影响因素,最后又提出了今后的研究方向和发展途径.     

三峡库区不同植被覆盖对土壤碳的影响

植被覆盖变化对三峡库区生态环境产生重要影响.土壤有机碳在陆地生态系统的发育和运行等方面均起着极其重要的作用,所以本课题研究宜昌点军区柏树地,橘树地以及菜地的土壤性质状况.结果表明:土壤含水量是柏树林最大.菜地的最小,而土壤容重的大小顺序是:柑橘树地>柏树地>菜地.土壤有机碳、易氧化碳和二者的比值都是柏树地的最大,柑橘地的最小,菜地的处于中间状态.而微生物碳和微生物墒含量大小顺序是柏树地>柑橘树>菜地;微生物代谢墒的大小顺序是:柑橘地>菜地>柏树地.由此说明柏树生长有利于土壤活性碳源含量的提高和土壤质量的改善.     

Simulation analysis of environmental risk accident and management of high-sulfur gas field development in complex terrain

Environmental risk of high sulfur gas field exploitation has become one of the hot spots of environmental management studies. Severe gas H₂S blowout accidents in recent years have shown that poor understanding and estimates of the poisonous gas movement could lead to dangerous evacuation delays. It is important to evaluate the real concentration of H₂S, especially in complex terrain. Traditional experiential models are not valid in the case of rough terrain, especially in low-lying areas where the gas accumulates. This study, using high sulfur content gas field of Sichuan “Pu Guang gas field” as study object and adopting objective diagnosis of wind field of land following coordinate three dimensions, applied Lagrangian Puff Model and breaking up technique of puffs to simulate the H₂S diffusion condition of blowout accidents produced in the high sulfur content gas field of complex terrain area. The results showed that the H₂S distribution did not occur mainly in low wind direction, and due to the obstruction of the mountain’s body, it accumulated in front of mountain on produced turn over, flowed around submitted jumping type distribution. The mountain waist near the hilltop and low hollow river valley site rapture points simulating contrast showed that the higher the rapture point, the better the diffusing condition of pollutant, the distribution of risk sensitive point decided piping rupture environmental risk size combining the H₂S diffusion result and residential area dispersing in the study area, synthetic judge located in the high rapture point environmental risk was smaller than the low hollow point, thus it was suggested to carryout laying of lining build of equal high line of higher terrain. According to simulation results, the environmental risk management measures aimed at putting down adverse effects were worked out.     

On-line controlling system for nitrogen and phosphorus removal of municipal wastewater in a sequencing batch reactor (SBR)

The objectives of this study were to establish an on-line controlling system for nitrogen and phosphorus removal synchronously of municipal wastewater in a sequencing batch reactor (SBR). The SBR for municipal wastewater treatment was operated in sequences: filling, anaerobic, oxic, anoxic, oxic, settling and discharge. The reactor was equipped with on-line monitoring sensors for dissolved oxygen (DO), oxidation-reduction potential (ORP) and pH. The variation of DO, ORP and pH is relevant to each phase of biological process for nitrogen and phosphorus removal in this SBR. The characteristic points of DO, ORP and pH can be used to judge and control the stages of process that include: phosphate release by the turning points of ORP and pH; nitrification by the ammonia valley of pH and ammonia elbows of DO and ORP; denitrification by the nitrate knee of ORP and nitrate apex of pH; phosphate uptake by the turning point of pH; and residual organic carbon oxidation by the carbon elbows of DO and ORP. The controlling system can operate automatically for nitrogen and phosphorus efficiently removal.     

开都河灌区灌溉引水对博斯腾湖面积影响的定量分析

开都河是注入博斯腾湖的最大河流,1958～2002年间平均入湖水量达23.62×10⁸m³,占博斯腾湖总补给量的80%以上。1958年以来开都河灌区灌溉引水量维持在8.17×10⁸m³～13.18×10⁸m³之间,其中20世纪60年代灌溉引水量平均为10.14×10⁸m³/a,占开都河径流量的31.1%;70年代引水量上升到12.15×10⁸m³/a,为开都河径流量的36.5%;80年代引水量下降到11.29×10⁸m³/a,但引水量仍占开都河径流量的36.5%;90年代灌溉引水量进一步降至9.85×10⁸m³/a,仅占径流量的27.1%。通过水量平衡分析和相关回归计算,得出开都河灌区灌溉引水对博斯腾湖面积影响的数值:20世纪60年代平均值为62.4km²;70年代平均值为80.8km²;80年代、90年代分别为90.4km²、76.7km²,2000年以来平均仅为41.3km²。由此可见,45年来开都河灌区灌溉引水对博斯腾湖面积的影响经历了弱→强→弱的变化过程。     

添加乙醇碳源对驯化菌种降解油制气废水的影响

进行了添加乙醇作为碳源强化油制气废水生物降解的研究,并利用GC／MS分析对油制气废水中芳烃类化合物的降解进行了初步研究。研究表明,共代谢基质乙醇的加入,可使菌种S-2、Y-3、XH-3、M-3对COD、氨氮、可萃取有机物等指标的去除率分别提高17．6％～25．6％、34．9％～42．8％、10．4％～14．2％;但在所采用的时间范围内,酚类化合物的去除率降低;芳烃类化合物的去除率提高15．4％～21．2％。除了维持无共代谢条件下对芳环数≤3的芳烃类化合物的良好降解能力外,对芳环数为4～6的化合物降解能力也有所提高。     

日本畜禽产业排泄物处理与循环利用的现状与技术

20世纪40年代后,日本畜禽产业结构向大型集约化方向发展,年畜禽粪便排放总量7600万t左右。同时,由于畜禽产业等中小规模企业排出含有高氮磷等污染物的废水,致使湖泊、海域的富营养化问题日益严重。日本《水质污浊防止法》规定:饲养规模在50m2以上的养猪场和200m2以上的养牛场的排泄物排放标准为:总氮<120mg/L,总磷<16mg/L。牲畜粪便处理技术的研究和开发,一方面着重于高效脱氮除磷技术,另一方面,从资源的有效利用角度考虑,建立各种排水与废弃物处置的自立型循环共生系统。本文介绍了当前日本畜产业排泄物的处理与循环利用的现状与技术,特别是复合回收型处理系统及远程自动控制等技术的应用,推进了生物量循环的循环型社会的形成,同时,实现环境改善与资源的再利用。     

TiO2薄膜光催化降解双酚A的研究

采用sol-gel法制备TiO2薄膜.以该薄膜为催化剂,研究了在H2O2存在的条件下,对内分泌干扰物质双酚A的光催化降解反应.分别讨论了pH值、H2O2的加入量、双酚A的初始浓度以及光照时间对降解反应的影响.结果表明,在pH=4,30 mg/L的H2O2中对初始浓度为50 mg/L的双酚A溶液光照180 min有较好的降解效果.     

Three-dimensional simulation of reservoir temperature and pollutant transport by the lattice Boltzmann method

Predicting the three-dimensional (3D) transport processes of reservoir temperature and pollutants is essential for water environmental protection and restoration, and introducing the lattice Boltzmann (LB) method into this prediction is necessary because of its simple algorithm, straightforward implementation of boundary conditions, and high computation efficiency. In this paper, a triple-distribution function (TDF) LB model for flow-temperature-concentration coupling simulations is introduced. Some essential techniques for implementing this method in 3D reservoirs are also described, including the treatment of water surface fluctuation, the consideration of surface heat exchange, and the hardware acceleration using the graphics processing unit (GPU). Two cases verified the proposed model, and then, the temporal-spatial variations of flow, temperature, and pollutants in the upper reservoir of a pumped-storage power station during both pumping and generating modes were analyzed to demonstrate its applicability. In the reservoir, the water forms several circulations, the cold water from the inlet flows as an undercurrent firstly, and then spread laterally, and the spreading of pollutants directly relates to the flow velocity. The results of flow, temperature, and concentration fields in different working conditions are consistent with model tests and physical laws, which shows good prospects of the proposed LB model.