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101.
苏州河纵向离散系数的分析研究 总被引:2,自引:0,他引:2
通过对苏州河水文水质资料的分析,并进行了水槽因子影响试验、非定常潮汐水流的模拟试验以及环境水力学理论分析和相似律推算,得到了比较符合实际的纵向离散系数取值范围:苏州河为单向流时K≈(5-35)m^2/s;苏州河在潮流往复作用下,k=(2-12)m^2/s。运用水质数学模型和苏州河实测的水文水质同步资料对纵向离散系数进行了验证。 相似文献
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Water quality modeling has been shown to be a useful tool in strategic water quality management. The present study combines the Qual2K model with the HEC-RAS model to assess the water quality of a tidal river in northern Taiwan. The contaminant loadings of biochemical oxygen demand (BOD), ammonia nitrogen (NH3-N), total phosphorus (TP), and sediment oxygen demand (SOD) are utilized in the Qual2K simulation. The HEC-RAS model is used to: (i) estimate the hydraulic constants for atmospheric re-aeration constant calculation; and (ii) calculate the water level profile variation to account for concentration changes as a result of tidal effect. The results show that HEC-RAS-assisted Qual2K simulations taking tidal effect into consideration produce water quality indices that, in general, agree with the monitoring data of the river. Comparisons of simulations with different combinations of contaminant loadings demonstrate that BOD is the most import contaminant. Streeter-Phelps simulation (in combination with HEC-RAS) is also performed for comparison, and the results show excellent agreement with the observed data. This paper is the first report of the innovative use of a combination of the HEC-RAS model and the Qual2K model (or Streeter-Phelps equation) to simulate water quality in a tidal river. The combination is shown to provide an alternative for water quality simulation of a tidal river when available dynamic-monitoring data are insufficient to assess the tidal effect of the river. 相似文献
105.
Su Mei Liu Xiao Na Li Jing Zhang Hao Wei Jing Ling Ren Gui Ling Zhang 《Water, Air, & Soil Pollution: Focus》2007,7(6):625-643
Three cruises were carried out in Jiaozhou Bay (JZB) in the neap tide in October 2002 (fall) and in both neap and spring tides
in May 2003 (spring) to understand the relative importance of external nutrient inputs versus physical transport and internal
biogeochemical processes. Nutrients (, , , , silicic acid, total dissolved nitrogen (TDN) and phosphorus (TDP), dissolved organic nitrogen (DON) and phosphorus (DOP))
were measured. The concentrations of nutrients were higher in the northern part than in the southern part. High concentrations
of and DON in JZB demonstrated the anthropogenic input. Ambient nutrient ratios indicated that the potential limiting nutrients
for phytoplankton growth were silicon, and then phosphorus. Nutrients showed an obvious tidal effect with low values at flood
tide and high values at ebb tide. Nutrient elements were transported into JZB in the north and output in the south (i.e.,
into the Yellow Sea), which varied with season, tidal cycle and investigation sites. Water exchange between JZB and the Yellow
Sea exports , and DON out of JZB, while it inputs , silicic acid and DOP into JZB. Nutrient budgets demonstrate that riverine input and wastewater discharge are major sources
of nutrients, while residual flow is of minor importance in JZB ecosystem. JZB is a sink for the nutrient elements we studied
except for DON. Stoichiometric calculations demonstrate that JZB is a net autotrophic system. 相似文献
106.
Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions.Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples.The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts.Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks.Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5 mg d−1 kg−1 pig at swine finishing barns and from 2.3 to 45.2 g d−1 m−2 at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates.Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors. 相似文献
107.
电除尘器进气烟箱参数对气流分布影响的仿真研究 总被引:2,自引:1,他引:1
电除尘器进气烟箱结构参数不仅对除尘器内部气流分布的均匀性产生重要影响,而且还会影响除尘效率和排放指标。针对电除尘器进气烟箱结构参数选取与气流分布均匀性问题,采用欧拉-拉格朗日多相流模型,对进气烟箱扩散角,气流分布板孔形、开孔率和导流板角度等参数,进行了三维流场模拟仿真计算,获得各参数对气流均匀性的影响关系规律。仿真结果表明:方形孔的气流分布板能获得较佳的气流分布均匀性;合理调节进气烟箱扩散角、开孔率和导流板角度可有效地改善电场内气流分布状况。研究结果可为电除尘器进气烟箱的设计与改进提供依据。 相似文献
108.
餐厨垃圾和绿化废弃物换向通风好氧堆肥 总被引:2,自引:0,他引:2
以某高校餐厨垃圾和绿化废弃物为原料,利用一种换向通风的堆肥降解装置对其进行好氧堆肥处理,研究了2个进气温度(35℃、45℃)和3个通风速率(1.5、2.5和4 m3/h)6个处理组对堆肥原料理化性质(堆体温度、含水率、pH值、有机质含量、C/N、种子发芽指数)的影响。餐厨垃圾和绿化废弃物进行15 d好氧堆肥后,pH值上升到7左右,有机质含量达到20%~80%,C/N都降到20以下,种子发芽指数均大于50%。经过1个月腐熟,其含水率≤30%。上述指标符合有机肥料标准(NY525-2011)的要求,该堆肥产物可用于园林绿地,具有显著的经济效益和生态效益。本研究结果表明,将城市餐厨垃圾和绿化废弃物混合后进行好氧堆肥是废弃物处理的高效工程,具有良好的发展前景。 相似文献
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感潮河网地区的污染物质混合输移的机制十分复杂,本文结合广州河段1987年枯水期的水文水质同步实测资料,利用理论分析,室内实验及计算机模拟识别等方法,对感潮河网地带的纵向离散系数进行了全面的研究。对天然河流的振荡剪切离散提出了一个实用的解析分析方法;通过实验研究分析了等效离散系数D*与振荡剪切离散系数D-的关系;利用实测数据分析了典型断面的D*/D-的基本特征,并通过计算机模拟,为广州河段提供了D*的预测公式。 相似文献