广州地区PBDEs长距离迁移潜力和总持久性模拟

运用TaPL3.0模型对7种PBDEs同系物在广州地区的长距离迁移潜力(LRTP)和总持久性(Pov)进行了模拟研究,并通过灵敏度分析得到了模型的关键参数.研究结果显示,PBDEs排放至大气中,特征迁移距离(CTD)为296~811km,均值为557km;Pov为19~279d,均值为184d;PBDEs平均约有73.8%分布在土壤中,16.9%分布在沉积物中,9.3%分布在其他三相中.PBDEs排放到水体时,CTD为3090~4291km,均值为3731km;Pov范围为228~854d,均值为731d;平均约92.1%分布在沉积物中,6.8%分布在水相中,1.1%在大气、土壤和植被相中.BDE47迁移潜力最大,BDE209易残留于源区形成点源性污染.PBDEs各同系物主要分布在沉积物和土壤中.随着溴代程度升高,CTD逐渐降低,Pov逐渐升高,与国外研究趋势一致.     

1980—2009年三峡库区空中水资源变化特征

利用1980—2009年三峡库区及周边15个气象探空站的高空资料,分析了三峡库区空中水资源的变化特征,结果表明:三峡库区上空整层水汽含量分布从东北到西南逐渐增加。三峡库区的水汽主要来自西南水汽输送,夏季西南风水汽输送强度最大。三峡库区上空水汽多以辐合为主,尤其在库区西北部和东南部的辐合特征更为明显。三峡库区的水汽主要从南边界流入,而主要从东边界流出。三峡库区各月的净水汽通量都为正值,呈单峰型变化,在7月达到最大值。近30 a,三峡库区净水汽通量经历了明显的先上升后下降的抛物线型年代际变化,春季和冬季的平均净水汽通量整体呈减少趋势,而夏季、 秋季和年平均的净水汽通量呈增加趋势。     

春运对广州火车站周边环境噪声的影响研究

在广州火车站及其周边不同功能区设8个监测点,利用AWA6291+A型噪声频谱分析仪测量了春运期间和非春运期间不同功能区的环境噪声水平.结果表明,春运对广州火车站及周边环境噪声影响较大;远离主要交通干道及火车站的小区和公园噪声比较低;测点的噪声值与其所处位置的交通流量和人为活动有关.     

Micro-analysis of nitrogen transport and conversion inside activated sludge flocs using microelectrodes

To investigate the nitrogen transport and conversion inside activated sludge flocs, micro-profiles of O₂, NH₄⁺, NO₂^–, NO₃^–, and pH were measured under different operating conditions. The flocs were obtained from a laboratory-scale sequencing batch reactor. Nitrification, as observed from interfacial ammonium and nitrate fluxes, was higher at pH 8.5, than at pH 6.5 and 7.5. At pH 8.5, heterotrophic bacteria used less oxygen than nitrifying bacteria, whereas at lower pH heterotrophic activity dominated. When the ratio of C to N was decreased from 20 to 10, the ammonium uptake increased. When dissolved oxygen (DO) concentration in the bulk liquid was decreased from 4 to 2 mg·L^-1, nitrification decreased, and only 25% of the DO influx into the flocs was used for nitrification. This study indicated that nitrifying bacteria became more competitive at a higher DO concentration, a higher pH value (approximately 8.5) and a lower C/N.     

Hierarchical modeling of the dilute transport of suspended sediment in open channels

We propose, discuss and validate a theoretical and numerical framework for sediment-laden, open-channel flows which is based on the two-fluid-model (TFM) equations of motion. The framework models involve mass and momentum equations for both phases (sediment and water) including the interactive forces of drag, lift, virtual mass and turbulent dispersion. The developed framework is composed by the complete two-fluid model (CTFM), a partial two-fluid model (PTFM), and a standard sediment-transport model (SSTM). Within the umbrella of the Reynolds-Averaged Navier-Stokes (RANS) equations, we apply K–ε type closures (standard and extended) to account for the turbulence in the carrier phase (water). We present the results of numerical computations undertaken by integrating the differential equations over control volumes. We address several issues of the theoretical models, especially those related to coupling between the two phases, interaction forces, turbulence closure and turbulent diffusivities. We compare simulation results with various recent experimental datasets for mean flow variables of the carrier as well as, for the first time, mean flow of the disperse phase and turbulence statistics. We show that most models analyzed in this paper predict the velocity of the carrier phase and that of the disperse phase within 10% of error. We also show that the PTFM provides better predictions of the distribution of sediment in the wall-normal direction as opposed to the standard Rousean profile, and that the CTFM is by no means superior to the PTFM for dilute mixtures. We additionally report and discuss the values of the Schmidt number found to improve the agreement between predictions of the distribution of suspended sediment and the experimental data.     

Cr~(6+)对活性污泥活性及有机物去除速率的影响

通过检测活性污泥系统的电子传递活性以及COD的去除速率,研究了Cr~(6+)对污泥活性以及有机物降解速率的影响,并探讨了两者之间的关系.研究结果表明:5 mg·L~(-1)的Cr~(6+)即会对系统产生明显影响,Cr~(6+)对污泥活性和COD去除率的抑制作用随其质量浓度的增大而增强;当Cr~(6+)质量浓度达到25 mg·L~(-1)时,污泥的INT和TTC-电子传递(TTC-ETS)活性以及有机物降解速率都表现为大幅的下降,下降比例分别为46.98%、54.18%以及64.47%.Cr~(6+)抑制污泥TTC-ETS活性的IC_(50)小于抑制INT-ETS活性的IC_(50),表明TTC-ETS活性反映Cr~(6+)毒性作用的灵敏性大于INT-ETS活性.此外,INT和TTC-ETS活性与有机物降解速率之间也均存在显著的正相关性,说明两者都是表征Cr~(6+)对有机物去除速率影响的灵敏参数.     

保守性离子在包气带层状土中运移规律研究

为研究溶质在多层层状包气带土中运移规律,选取5种颗粒配比不同的土样填装成由粗及细和由细及粗两分层顺序相反的土柱,通过室内试验研究保守性Br-在两种不同结构层状土中基本运移规律。研究得出:当土体表层遭受浓度为200 g/L Na Br一次性污染,在15 mm/12 h降雨强度下,Br-在第1、2层土体浓度经历快速上升段、峰值段、下降段3个阶段变化,第3、4、5层土体浓度经历上升段、平稳下降段。试验结束时,Br-在由粗及细的土柱中分布较均匀,在由细及粗的土柱中集中在表层;溶质穿透整个土柱的时间,由粗及细结构比由细及粗结构提前96 h。结果表明,在截污性能和延缓溶质向地下水补给方面,由细及粗结构均要优于由粗及细的结构。     

An opinion on the distribution and behavior of chemicals in response to climate change,with particular reference to the Asia-Pacific region

There is a general lack of knowledge as regards the effects of climate change on pollutant behavior. This is particularly true of the Asia-Pacific Region (APR). This region has major significance in terms of global pollutant emission and also displays a wide variety of environments. This review presents the authors’ opinions on possible implications of climate change for pollutant behavior in the APR. Although differing responses can be expected across the region, there are clear implications as regards the short- and long-term behavior of pollutants. Effects can be predicted through modeling, but further data are required for model calibration. Nevertheless, it can be predicted that climate change will affect processes including global distillation of persistent organic pollutants, airborne transport of heavy metals, half-life of readily degradable pollutants, and eutrophication in water bodies. Particulates are expected to play a central role in mediating the effects of climate change, and successful predictive models will need to be based on particulate-mediated transport and behavior. Climate change also has the potential to cause an increase in the intensity and frequency of harmful algal blooms in aquatic environments throughout the region, with significant implications for supply of both food and drinking water.