Three-dimensional hydrodynamic and water quality model for TMDL development of Lake Fuxian, China

Lake Fuxian is the largest deep freshwater lake in China. Although its average water quality meets Class I of the China National Water Quality Standard (CNWQS), i.e., GB3838-2002, monitoring data indicate that the water quality approaches the Class II threshold in some areas. Thus it is urgent to reduce the watershed load through the total maximum daily load (TMDL) program. A three-dimensional hydrodynamic and water quality model was developed for Lake Fuxian, simulating flow circulation and pollutant fate and transport. The model development process consists of several steps, including grid generation, initial and boundary condition configurations, and model calibration processes. The model accurately reproduced the observed water surface elevation, spatiotemporal variations in temperature, and total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) concentrations, suggesting a reasonable numerical representation of the prototype system for further TMDL analyses. The TMDL was calculated using two interpretations of the water quality standards for Class I of the CNWQS based on the maximum instantaneous surface and annual average surface water concentrations. Analysis of the first scenario indicated that the TN, TP and COD loads should be reduced by 66%, 68% and 57%, respectively. Water quality was the highest priority; however, local economic development and cost feasibility for load reduction can pose significant issues. In the second interpretation, the model results showed that, under the existing conditions, the average water quality meets the Class I standard and therefore load reduction is unnecessary. Future studies are needed to conduct risk and cost assessments for realistic decision-making.     

某工业园区VOCs臭氧生成潜势及优控物种

臭氧(O3)污染日趋严重,控制光化学反应前体物之一的挥发性有机污染物(volatile organic compounds,VOCs)对减少臭氧生成有重要意义.为研究天津某工业园区VOCs臭氧生成潜势,采集了园区6个代表企业厂界气体样品,使用质子转移反应飞行时间质谱仪(PTR-TOF-MS)对VOCs进行了定量分析,估算了各企业臭氧生成潜势,运用VOCs/NO_x研究了臭氧生成控制敏感性因素,并在熵值法基础上筛选出了减少臭氧生成优先控制VOCs物种.结果表明,通过PEC法估算臭氧生成F企业最高为0.423 3 mg·m~(-3),MIR法估算结果 C企业最高为1.573 3 mg·m~(-3);PEC法估算结果与臭氧浓度更接近,适用于园区对臭氧生成的估算;VOCs和NOx均为工业园区臭氧生成敏感性因素,需同时控制;园区内VOCs物种臭氧生成贡献大小为烷烃烯炔烃醇类芳香烃,优先控制物种为正庚烷及其同分异构体、正壬烷、正辛烷及其同分异构体、正十一烷、戊烷、正癸烷、甲醇.     

Dissipation of Endosulfan and Dichlorvos Residues In/On Cauliflower Curds

Dissipation behaviour of endosulfan and dichlorvos in/on cauliflower, variety Snowball-16, was studied during rabi season (Sep.–March) 2003–2004. Endosulfan and dichlorvos were sprayed @ 350 and 110g a.i. with 115 g a.i., respectively, 80 days after transplanting. Samples were taken at the interval of 0 (1h after spray), 3, 5, 7, and 10 days after spray (DAS) in triplicate and residues were estimated on GC-ECD system equipped with capillary column. The initial deposits of 3.452 and 0.295μgg⁻¹ of endosulfan and dichlorvos dissipated to 0.084 (97.56%) and 0.009 (96.95%), respectively after 10 DAS. Residues of endosulfan reached below maximum residue limit of 2μgg⁻¹ one day after spray and of dichlorvos were below MRL value of 0.5μgg⁻¹ even on 0 day. Dissipation pattern followed first order kinetics for both the insecticides with half life periods of 1.81 and 2.08 days for endosulfan and dichlorvos, respectively.     

降水量时间序列变化的小波特征

利用小波变换对降水量时间序列的多时间尺度变化及突变特征进行了探讨。小波变换不仅能将降水量时间序列的频率特征在时间域上展现出来，清晰地给出各种时间尺度的强弱和分布情况以及早涝变化趋势和突变点，而且还能分析出其主要周期。以新安江流域黄山地区主汛期(5—7月)和年降水量为例，计算表明，其年际及年代际时间尺度在时域中分布不均匀，具有明显的局部化特征；同时分析出主汛期降水具有8年、19年左右的周期，年降水存在6年、19年左右的周期；研究还表明，主汛期降水与年降水的时间尺度变化比较接近。     

ADSORPTION IN MULTICOMPONENT SOLUTION BY ACTIVATED CARBON

It was found that the total adsorptive capacity of activated carbon was enhanced by using a multicomponent solution with glucose, peptone and phenylphosphonic acid. A maximum use of the carbon adsorptive capacity is possible if the carbon is used for tertiary treatment followed by treating a stronger waste.     

长三角和珠三角土壤中汞的化学形态、转化和吸附特性

为了解长江三角洲和珠江三角洲农业土壤中汞的积累可能产生的环境影响,选择10个代表性农业土壤样品,研究了土壤中汞的化学形态、积累过程中形态的转化及吸附-解吸行为.研究表明,当无外源汞加入时,长江三角洲和珠江三角洲农业土壤中,汞主要以稳定的残余态形式存在.但随着汞加入量的增加,土壤中可交换态汞显著增加,增加程度与土壤性质有关.土壤pH是影响土壤汞有效性最重要的因素,其对土壤汞的吸附、解吸、形态转化和存在形态均有很大影响.土壤酸化可促进土壤汞的释放,加剧对环境的危害,防治土壤酸化也可有效降低土壤中汞对环境的危害.     

Pipeline leakage detection and isolation: An integrated approach of statistical and wavelet feature extraction with multi-layer perceptron neural network (MLPNN)

Leakage diagnosis of hydrocarbon pipelines can prevent environmental and financial losses. This work proposes a novel method that not only detects the occurrence of a leakage fault, but also suggests its location and severity. The OLGA software is employed to provide the pipeline inlet pressure and outlet flow rates as the training data for the Fault Detection and Isolation (FDI) system. The FDI system is comprised of a Multi-Layer Perceptron Neural Network (MLPNN) classifier with various feature extraction methods including the statistical techniques, wavelet transform, and a fusion of both methods. Once different leakage scenarios are considered and the preprocessing methods are done, the proposed FDI system is applied to a 20-km pipeline in southern Iran (Goldkari-Binak pipeline) and a promising severity and location detectability (a correct classification rate of 92%) and a low False Alarm Rate (FAR) were achieved.     

某二高线通风改造实践研究

根据自然通风原理,对某二高线厂房进行了通风改造,主要从以下三方面人手：在进风窗下增设百页进风口、用通风栅栏代替封闭平台以及扩大天窗喉口。改造前后气流及温度分布的实测结果表明,改造后工作区的热环境得到了较大的改善,气流分布均匀,温度下降明显,提高了人体舒适性。     

TA-FTIR/MS用于硝酸铵及其混合物的热化学行为研究

为评价物料混合对危险化学品热化学行为的影响,采用热分析-红外/质谱联用技术(TA-FTIR/MS)研究硝酸铵、柠檬酸和蔗糖的混合物的热化学行为。通过对硝酸铵及其混合物的分解温度和分解过程中逸出气体的分析,发现硝酸铵、柠檬酸和蔗糖的混合物热分解温度分别降低至135℃和153℃,而硝酸铵与甲基纤维素的混合物分解温度与硝酸铵基本相同为201℃,且各混合体系的气相分解产物均有氮氧化物(NOX),H2O和CO2。结果表明,混合物受热后其中的硝酸铵首先分解为硝酸和氨气;酸性物质和还原性物质由于对硝酸的分解反应有催化作用,使得混合物的热稳定性下降。     

纵向风对隧道火灾拱顶最高温度及其位置的影响

研究了燃烧风洞内不同纵向风速、不同火源功率条件下,隧道近火源区顶部温度沿纵向分布情况。结果表明,纵向风对不同尺寸火源条件下的顶部温度的影响呈不同特征。对较小尺寸火源,隧道顶部温升随风速增加而减小至稳定值;而对较大尺寸火源,顶部温升随风速增加先增加后减小。对于矩形火源,当纵向风较小(0.5~1.5m/s)时,长边平行于纵向风时顶部最高温升大于长边垂直于纵向风的情况;而当纵向风较大(≥2 m/s)时,两种油盘放置方式的顶部最高温升一致。纵向风作用下,顶部最高温升位置向下游呈现"两次移动"特征,即随着纵向风速增加该位置先向下游移动,当风速达到某一值时,隧道拱顶的加热机制由对流和辐射共同主控转变为辐射单独主控,最高温升位置突变回到上游后再次逐渐向下游移动。