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471.
IntroductionAnatmospheredispersionfieldexperimentwasdoneonthecoastalsiteofnuclearpowerplant (NPP)intheeastpartofChinaduring 1995— 1996 Thecontentofthisexperimentincludes:hourlyobservationofwindandtemperatureonthetowerof10 0m ;Observationofsurfacewindandseeandl…  相似文献   
472.
从安全工程师应具备的知识结构出发,主要讨论了安全工程专业学历教育中的课程设置及办学过程中存在的一些的问题。  相似文献   
473.
塑料企业周边水体中多溴联苯醚的污染特征   总被引:1,自引:0,他引:1  
多溴联苯醚(PBDEs)是一种新型的持久性有机污染物(POPs)。采用固相萃取-气相色谱法测定了某塑料企业周边及当地自然水体中的PBDEs浓度,主要针对BDE~(-1)7、28、47、66、85、99、100、138、153、154、183、203及BDE-209共13个PBDE同系物的浓度水平、组成分布和污染特征进行分析。结果显示,使用企业周边水体中除BDE-203在水体中未检出外,其余12种PBDE同系物均有不同程度的检出。Σ13PBDEs质量范围处于未检出~363 ng·L~(-1),各同系物的平均质量浓度为未检出~42.6ng·L~(-1)。其中BDE-209为最大检出质量丰度同系物,但其检出率仅为25.0%,检出率较高的同系物是BDE~(-1)7、BDE-28和BDE~(-1)00,检出率分别为75.0%、75.0%、58.3%,低溴代联苯醚的检出率显著高于高溴代联苯醚。当地自然水体中13种PBDEs均有不同程度的检出,检出浓度在0.161~1.83 ng·L~(-1)。企业周边水体中PBDEs的污染水平显著高于自然水体,是自然水体浓度的5~100倍。因此,企业周边区域水体中PBDEs的污染情况应引起相关部门关注。  相似文献   
474.
The UV/Ag-TiO2/O3 process was investigated for ballast water treatment using Dunaliella salina as an indicator. Inactivation curves were obtained, and the toxicity of e uent was determined. Compared with individual unit processes using ozone or UV/Ag-TiO2, the inactivation e ciency of D. salina by the combined UV/Ag-TiO2/O3 process was enhanced. The presence of ozone caused an immediate decrease in chlorophyll a (chl-a) concentration. Inactivation e ciency and chl-a removal e ciency were positively correlated with ozone dose and ultraviolet intensity. The initial total residual oxidant (TRO) concentration of e uent increased with increasing ozone dose, and persistence of TRO resulted in an extended period of toxicity. The results suggest that UV/Ag-TiO2/O3 has potential for ballast water treatment.  相似文献   
475.
为明确4种烟嘧磺隆复配除草剂对意大利蜜蜂和玉米螟赤眼蜂的急性毒性影响并评估其初级风险。采用饲喂法、点滴法和玻璃管药膜法,分别测定了8%烟嘧·氯吡嘧磺隆、16%烟嘧·硝磺·氯吡嘧磺隆、36%烟嘧·莠去津和22%烟嘧·氯吡·氯氟吡氧乙酸异辛酯对意大利蜜蜂成年工蜂和玉米螟赤眼蜂的急性毒性,并分别采用危害商值和安全系数进行初级风险评估。结果表明,上述4种制剂对意大利蜜蜂成年工蜂的经口毒性48 h-LD_(50)(半致死剂量,median lethal dose)分别为68.03、1.60×10~2、1.40×10~2和100μg a.i.·蜂-1,接触毒性48 h-LD_(50)分别为18.53、53.01、89.98和100μg a.i.·蜂-1,危害商值均小于50,对意大利蜜蜂均为低毒且低风险。4种制剂对玉米螟赤眼蜂的急性毒性24 h-LR50(半致死用量,median lethal rate)分别为1.88×10~(-4)、5.46×10~(-4)、2.12×10~(-3)和1.68×10~(-3)mg a.i.·cm~(-2),安全系数分别为0.16、0.23、0.59和0.51,其中8%烟嘧·氯吡嘧磺隆和16%烟嘧·硝磺·氯吡嘧磺隆对玉米螟赤眼蜂为高风险性,36%烟嘧·莠去津和22%烟嘧·氯吡·氯氟吡氧乙酸异辛酯为中等风险性。因此,这4种复配制剂对蜜蜂成年工蜂的风险性较低,但对赤眼蜂的风险性较高,所以在喷洒防除期间应与赤眼蜂释放期错开。  相似文献   
476.
The physical properties of gas and water are important in usage of gas reservoirs with water and water-soluble gas reservoirs. According to the Petroleum and Natural Gas Industry Standards SY/T5542-2009 of the People's Republic of China, by applying the crude oil multistage degassing method from the “Test Method for Reservoir fluid Physical Properties” and the formation water high-pressure property testing method described in the “Theory and Application of Reservoir Fluid Phase”, this investigation employed a Ruska 2370–601A phase analyzer to obtain data regarding gas–water ratios, water volume factors, compressibility coefficients, and densities. The results showed curve trends with changes in the temperature and pressure. The gas–water ratio was compared to the gas content of subsurface samples from the X water-soluble gas reservoir, suggesting that these findings might help in the analysis of water-soluble gas reservoirs.  相似文献   
477.
Polybrominated diphenyl ethers(PBDEs) are new kinds of persistent organic pollutants(POPs) and their potential threats to the equilibrium and sustainability of marine ecosystems have raised worldwide concerns. Here, two kinds of PBDEs, tetra-BDE(BDE-47)and deca-BDE(BDE-209) were applied, and their toxic effects on the swimming behavior,population growth and reproduction of Brachionus plicatilis were investigated. The results showed that:(1) The actual concentrations of BDE-47 and-209 in the seawater phase measured by GC–MS(Gas Chromatography-Mass Spectrometer) were much lower than their nominal concentrations.(2) In accordance with the 24-hr acute tests, BDE-209 did not show any obvious swimming inhibition to rotifers, but a good correlation did exist between the swimming inhibition rate and BDE-47 concentration suggesting that BDE-47 is more toxic than BDE-209.(3) Both BDE-47 and-209 had a significant influence on the population growth and reproduction parameters of B. plicatilis including the population growth rate, the ratio of ovigerous females/non-ovigerous females(OF/NOF), the ratio of mictic females/amictic females(MF/AF), resting egg production and the mictic rate, which indicate that these parameters in B. plicatilis population were suitable for monitoring and assessing PBDEs. Our results suggest that BDE-47 and-209 are not acute lethal toxicants and may pose a low risk to marine rotifers at environmental concentrations for short-term exposure. They also accumulate differently into rotifers. Further research data are needed to understand the mechanisms responsible for the effects caused by PBDEs and to assess their risks accurately.  相似文献   
478.
The integrated terrestrial ecosystem C-budget model (InTEC) developed by Chen and co-workers has been used successfully to predict carbon dynamics of forests in Canada. It was tested here for forest soil organic carbon (SOC) density of China's northern temperate zone and southern subtropical zone. The results show that the simulated SOC density is highly correlated and in broad agreement with observations in Liping and in Changbaishan, representing the southern subtropical zone and the northern temperate zone in China, respectively. SOC density ranged from 2.2 to 11.2 kg/m(2) in Liping and from 3.4 to 14.8 kg/m(2) in Changbaishan. The correlation coefficients (r(2)) are 0.63 (N=16) and 0.76 (N=14) between the simulated and measured data in Liping and Changbaishan, respectively. The SOC densities under different vegetation types in Liping decrease in the order of mixed forest, broadleaf forest, Chinese fir, couch grass, and Chinese redpine, and in Changbaishan in the order of mixed forest, silver fir, larch forest, and birch forest.  相似文献   
479.
LAI inversion algorithm based on directional reflectance kernels   总被引:3,自引:0,他引:3  
Leaf area index (LAI) is an important ecological and environmental parameter. A new LAI algorithm is developed using the principles of ground LAI measurements based on canopy gap fraction. First, the relationship between LAI and gap fraction at various zenith angles is derived from the definition of LAI. Then, the directional gap fraction is acquired from a remote sensing bidirectional reflectance distribution function (BRDF) product. This acquisition is obtained by using a kernel driven model and a large-scale directional gap fraction algorithm. The algorithm has been applied to estimate a LAI distribution in China in mid-July 2002. The ground data acquired from two field experiments in Changbai Mountain and Qilian Mountain were used to validate the algorithm. To resolve the scale discrepancy between high resolution ground observations and low resolution remote sensing data, two TM images with a resolution approaching the size of ground plots were used to relate the coarse resolution LAI map to ground measurements. First, an empirical relationship between the measured LAI and a vegetation index was established. Next, a high resolution LAI map was generated using the relationship. The LAI value of a low resolution pixel was calculated from the area-weighted sum of high resolution LAIs composing the low resolution pixel. The results of this comparison showed that the inversion algorithm has an accuracy of 82%. Factors that may influence the accuracy are also discussed in this paper.  相似文献   
480.
The aim of this study was to assess the total concentration and health risk to infants of breast milk mercury in urban mothers and mothers married to fishermen in relation to fish intake in Taiwan. A total of sixty-eight healthy mothers were recruited for the study. The breast milk mercury geometric mean concentration was 2.02 microgl(-1) (n=56, range: 0.24-9.45 microgl(-1)) for the city group and 2.04 microgl(-1) (n=12, range: 0.26-8.62 microgl(-1)) for the fishermen's group. Of the three sources of mercury exposure (i.e., ingestion (breast milk), inhalation (ambient air), and dermal exposure (shower)), breast-feeding was found to be the largest (96.3-99.6% of the total). From a Monte Carlo simulation, in which methyl mercury accounted for about 50% of total mercury, the hazard quotient (exposure estimate/oral minimal risk level or target organ toxicity dose) exceeded 1.0 for 12.9% of urban babies and 18.8% of fishermen's babies (chronic oral minimal risk level and target organ toxicity dose: 3 x 10(-4)mgkg(-1)d(-1)). The calculated mercury exposure was 3.02 x 10(-1) microgkg(-1)d(-1) for a 3.49 kg urban baby boy and 3.06 x 10(-1) microgkg(-1)d(-1) for a 3.44 kg urban baby girl. These results suggest the life style of mothers (eating raw fish and shellfish such as used in "Sashimi" and "Sushi," and vitamin supplementation) may influence the mercury concentration in breast milk.  相似文献   
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