An Assessment of the Spatial Distribution of Polychlorinated Biphenyl Contamination in Turkey

This study summarizes the relevant information regarding the spatial distribution of polychlorinated biphenyls (PCBs) in various environmental (e. g., soil, sediment, air, water) and biological (e. g., fish, mussel, adipose tissue, milk) media in Turkey. The information sources used for this purpose, in addition to the scientific literature, were; official import records, governmental reports on monitoring of organochlorines, and reports prepared by international organizations. PCBs were never produced in Turkey; however they were imported and used within equipment or otherwise. The number of studies conducted on the topic is increasing significantly throughout the years and especially in the last decade. Evidence of PCB pollution was compared with the available background monitoring results from the region and other parts of the world, as well as relevant legislative standards. Overall, the presence of a number of important local PCB contamination sources is indicated as a result of this assessment.     

Fate and Behavior of Organochlorine Pesticides in the Indonesian Tropical Climate: A Study in the Segara Anakan Estuarine Ecosystem

The fate and behavior of organochlorine pesticides (OCPs) in the Segara Anakan Estuarine ecosystem was studied in the Indonesian tropical climate, which is characterized by heavy rainfall in the rainy season and low rainfall in the dry season. Since OCPs have high affinity for soil, a field study on the dissipation and degradation pattern of soil‐applied 1,1,1‐trichloro‐2,2‐bis (4‐chlorophenyl) ethane (p,p′‐DDT) and 1,1‐dichloro‐2,2‐bis (4‐chlorophenyl) ethylene (p,p′‐DDE) as model OCPs was carried out. They occurred at a faster rate in the biphasic mode in wet conditions and at a slower rate in dry conditions. In wet conditions, the conversion from p,p′‐DDT to p,p′‐DDE and p,p′‐DDD (1,1‐dichloro‐2,2‐bis (4‐chlorophenyl) ethane) was governed by a parallel reaction. In dry conditions, only p,p′‐DDE was formed. The fate and behavior of OCPs in sediment estuary are similar to those in soil under wet conditions, except that their sorption‐desorption constants are influenced by estuarine surface water salinity. In the dry season, due to high salinity, the sediment acts as an OCP sink and a secondary source for the ecosystem, causes higher OCP concentration of local bio‐monitors, i. e., Geloina spp. and Mugil spp. In the rainy season, high water inflow washed the desorbed OCP pesticides out of the estuarine ecosystem, and caused lower concentrations of bio‐monitors. A risk evaluation for the uptake of OCP pesticides during the dry season suggests that adult fish meal consumers are safe, but risk management is required for pregnant woman.     

Distribution of persistent organic pollutants in bivalves from the northeast coast of China

To assess the levels of organochlorine compounds (OCs) in the Chinese coastal environment, monitoring study using bivalves was conducted in 2005. A total of 21 bivalve samples covering the northeastern coast of China were collected and analyzed. Organochlorine compounds were widely distributed in the Chinese coastal environment, with dichlorodiphenyltrichloroethane (DDT) contamination being particularly prevalent. The overall concentrations of PCBs, DDTs, HCHs, chlordane compounds (CHLs), dieldrin, and endosulfans in bivalves were in the ranges of 3.27-25.4, 54.8-2680, 1.42-25.5, n.d. (not detected)-2.28, n.d.-4.02, and n.d.-9.55 ng g(-1) on a dry weight basis, respectively. The concentrations of DDT and HCH compounds are relatively higher than those from the coastal areas of other Asian countries. DDT metabolites were predominant, suggesting that the degradation of DDT is in progress in the Chinese coastal environment. Still, however, DDTs of high concentration exceeding 1000 ng g(-1) were observed at 19% of the stations surveyed. Among HCH compounds, beta-HCH, which is an isomer with strong persistency, was observed predominantly. Compositions of DDT and HCH compounds imply that fresh input of the two compounds into the Chinese coasts is possibly low.     

PCDD/Fs and PCBs in seafood species from Moreton Bay, Queensland, Australia

Previous studies have identified elevated levels of polychlorinated dibenzo-p-dioxins (PCDDs) in sediments and megafauna (dugongs and green turtles) in the marine environment of southeast Queensland, Australia. Little information exists, however, regarding the levels of PCDDs, polychlorinated dibenzofurans (PCDFs) and related polychlorinated biphenyls (PCBs) in seafood from this area. This study aims to establish baseline information on PCDD/F and PCB contamination in a range of seafood species from Moreton Bay and to investigate contaminant variability due to harvesting season, size, habitat location and trophic level. In addition, different seafood extraction methods were tested to evaluate their impact on lipid yields and contaminant concentration. Overall, the median TEQ(DF&PCB) levels in seafood from Moreton Bay were elevated compared to background levels in Australian marine/estuarine and retail fish. However, TEQ(DF&PCB) levels of most seafood analysed were below the respective EU maximum limits. High inter- and intraspecies variability was observed, which could be partially attributed to differences in trophic level, season harvested and habitat location.     

A study of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in the livestock waste compost of Hong Kong, PR China

Composting is one of the waste disposal methods adopted for disposal of livestock waste in Hong Kong. The composting livestock waste normally undergoes 6–8 weeks fermentation, followed by 16–20 weeks maturation. The matured compost is sold as soil conditioner in the local market. In 2006, feedstock material and a time-series of compost samples were collected throughout the fermentation and maturation process from the Sha Ling Composting Plant in the New Territories. The feedstock material and compost samples were analyzed for contents of three unintentional persistent organic pollutants (POPs), i.e. dioxins/furans, dioxin-like PCBs and total PCBs. These POPs are unintentionally produced by-products of chemical industrial processes and combustion processes. Selected heavy metals were also analyzed, which served as conservative tracers to determine potential mass loss during the composting process. Levels of contamination by these POPs were found to be low in the matured compost for sale. The mean concentrations (lower–upper bound) of total dioxins/furans, total dioxin-like PCBs and total PCBs were 2.01–2.05 ng I-TEQ/kg dw, 0.04–0.05 ng WHO-TEQ/kg dw and 1.55–1.55 μg/kg dw, respectively. Progressively elevated levels of these POPs were observed in the compost samples during the fermentation process. Analysis of the congener profiles revealed that the heptaCDD and octaCDD were the main contributors to the observed increase in dioxin/furan content. The possible sources of dioxins/furans in the compost were discussed. The study results established a local dioxins/furans emission factor specific to the trade and provided a better estimate of the annual dioxins/furans emission for the livestock waste composting activity in Hong Kong.     

声衍射层析成像中吸收型散射体的Rytov二阶近似重建

文中详细讨论了Rytov二阶近似下的声逆散射微扰论公式，并考察了它的适用范围. 介 绍了吸收型散射体的Rytov二阶近似重建算法，重建了散射体内部的波数和吸收系数. 这种 散射体的重建与纯位相型散射体的重建一样，不同的只是在计算正散射时考虑了吸收的影响 . 数值模拟给出了Born一阶、二阶和Rytov一阶、二阶近似重建的例子，说明Rytov二阶近似 在一定范围内比其他三种近似算法好.     

山东半岛一次持续性强冷流降雪过程的成因分析

利用NCEP/NCAR逐日6 h再分析资料和观测资料,诊断分析了2005年12月3～21日山东半岛北部沿海地区发生的罕见持续性强降雪过程.结果表明: 降雪以西北气流下的冷流降雪为主,具有典型冷流降雪分布特征;有利的大气环流形势造成强冷空气频繁,经过渤海暖海面时产生较大海气温差,是降雪持续时间长、强度大的直接原因;一定的海气温差是冷流降雪的重要指标,产生冷流降雪时山东北部近海海域的海气温差常在22K以上;冷流暴雪产生在高能舌、对流层低层辐合、中层辐散的上升运动区,上升运动层浅薄;水汽来源于渤海,水汽辐合层位于超低层(925 hPa高度以下);对流层中低层的垂直速度、散度场、涡度场的动力耦合结构配置有利于暴雪的形成和维持;特殊的低山丘陵地形强迫抬升是冷流降雪的触发机制,对暴雪的产生起到增幅作用.     

2003年与2005年淮河流域强降水过程环流特征的对比分析

利用淮河流域气象中心提供的淮河流域降水量资料和NCEP资料对2003年与2005年夏季强降水过程进行了对比分析.结果表明2003年与2005年强降水过程无论是降水分布还是环流形势都十分相似:(1)强降水中心都位于安徽省西北部(2)2003年与2005年南海夏季风建立时间均偏晚;(3)110~125 °E之间的西南风气流前沿均位于32.5 °N附近(4)在500 hPa高度场上,两个年份强降水过程中,副高脊线、588线北界和584线北界位置基本一致,并且在库页岛附近有阻高存在,日本岛附近均有一较强的低槽维持;(5)120 °E副高脊线与105 °E附近越赤道气流均存在着30 d左右的低频振荡,并且越赤道气流的变化要超前于副高脊线的变化.(6)冷空气活动对副高脊线的变化有着重要的影响(7)高低空耦合情况相似.     

夏季500hPa候平均高度场的多年持续性异常与我国北方持续干旱

本文对北半球夏季500hPa 候平均高度场,在进行旋转主分量分析的基础上,应用Mann-Kendall 秩和检验,计算分析了出现多年持续异常的地区和突变年代.结果表明,夏季西大西洋(WA)型具有明显的10—20年时间尺度的持续性异常特点,近40年中出现突变的标志年代是1966年,先前于 Sahel 和我国北方近20年来持续干旱的发展.     

持续性强降水的区域模式动力中期预报研究

持续性强降水及其次生灾害给人民的生产和生活造成严重影响, 延伸其模式动力预报能力对防灾、减灾具有重要意义。随着对持续性强降水过程形成机理及模式动力中期预报认识的不断提高, 以减小模式初始条件误差、边界条件误差以及内场预报误差为目标提出了一系列动力中期预报技术方法, 主要包括:针对边界条件提出低通滤波技术方案, 改进了5 d以上的环流及降水预报; 针对模式预报内场进行谱逼近技术试验, 对提前3—7 d的小雨以上量级的降水预报改进明显; 针对初始条件进行多尺度混合更新初值技术预报试验, 融合全球预报的大尺度场及区域模式预报的中小尺度场进行15 d预报, 明显提高了50及100 mm以上的持续性累积降水预报时效。