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681.
石河子市绿化适生树种的防尘作用研究   总被引:8,自引:0,他引:8  
通过对石河子市适生树种的滞尘能力分析,得到绿化对该市主要污染物(TSP)的影响作用效果。  相似文献   
682.
本文重点介绍了日本对当前作业环境空气中有害物质测定的设计及测定结果的评价.阐述了单元作业场所的确定以及为了解有害物质浓度的分布状况的A测定点、评价高浓度对操作者产生危险性的B测定点和为求出粉尘相对浓度变换系数的平行测定点的布点位置和作业环境的评价方法.  相似文献   
683.
Beryllium concentrations in atmospheric particulate and soil samples in and around a Beryllium Processing Facility (BPF) have been measured. The mean air concentration level of beryllium in and around the fence line of the BPF is 0.48 ± 0.43 ng m-3 (n = 397) and is mostly influenced by diurnaland seasonal changes. The observed air concentration levelswere well below the prescribed ambient air quality (AAQ)standard of 10 ng m-3. The soil concentration levels ofberyllium in the study area were found to be in the range of 1.42–2.75 g g-1. The mass median aerodynamic diameter (MMAD)of beryllium aerosols in ambient air was found to be 6.9 m.Source identification using the Enrichment Factor (EF) approachindicates soil as the predominant contributory source for air concentrations at the site.  相似文献   
684.
The South Carolina Estuarine and Coastal Assessment Program (SCECAP) was initiated in 1999 to assess the condition of the state's coastal habitats using multiple measures of water quality, sediment quality, and biological condition. Sampling was subsequently expanded to include components required for the National Coastal Assessment (Coastal 2000) Program. Habitats are classified as either tidal creeks (<#60; 100 meters in width) or larger open water bodies. Approximately 30 sites are sampled within each habitat during the summer months using a probability-based random sampling design. Results obtained from the first two years of sampling documented significant differences in several water quality parameters (DO, salinity, pH, turbidity, fecal coliform bacteria, total nitrogen, TKN, total phosphorus) and biological measures (chlorophyll-a, finfish and crustacean abundance and biomass and a number of benthic species) between the tidal creek and open water habitats. These differences highlight the value of partitioning shallow water habitats separately from the larger open water bodies traditionally sampled in estuarine monitoring programs, especially since tidal creeks serve as critical nursery areas for many species. Based on the differences observed, there is a clear need to identify different physical and biological thresholds for evaluating the condition of each habitat type.  相似文献   
685.
Two boat-based and one in-water sampling method have been used to collect submerged aquatic vegetation (SAV) as part of a long-term monitoring program in Lake Okeechobee, Florida, USA. The boat-based methods consisted of collecting SAV with a ponar dredge, used only to collect Chara, and an oyster tongs-like rake apparatus, used to collect all SAV. The in-water method involved use of a 0.5 m2 PVC quadrat frame deployed by a diver. During summer 2002, SAV biomass samples were collected using all three methods at various sites in the lake to compare between-methods sampling precision. Sites used for these comparisons were selected based on plant type, plant density and sediment type. Statistical comparisons indicated that there were significant (p ≤ 0.05) biomass differences in 8 of 15 possible pairwise comparisons between sampling method biomass means. In four of the eight comparisons, significantly higher biomass mean values were obtained using the quadrat frame. In three of the remaining four comparisons, significantly higher biomass mean values were obtained with the rake apparatus. For the fourth comparison, a significantly higher biomass mean value was obtained with the ponar dredge. Three of the four relationships between SAV biomass collected by the rake and the quadrat and the rake and the quadrat/ponar dredge were statistically significant, linear and explained between 67 and 78% of the biomass variability. There were no significant differences between regression coefficients or elevations for these relationships, therefore these regressions estimated the same population regression. The population regression coefficient was 0.95, suggesting that the quadrat and ponar over-sampled relative to the rake, but the amount of this over-sampling was very small. Since there was no consistent pattern in the sampling method which yielded the significantly different biomass values and there were no significant differences in sampling precision across a range of plant species, plant densities and two sediment types, the boat-based rake method appears to be a suitable replacement for the previously used ponar dredge and quadrat methods, when in-lake measurements are not practical.  相似文献   
686.
Before-After Control Impact (BACI) sampling designsare commonly used in environmental impact assessmentand are considered the most effective for detectingchanges due to anthropogenic disturbances. Thesedesigns handle local spatial variability throughrandomized placement of samples into a treatmentstratum and a control stratum. When a contaminantdisperses with distance from a point source it issuggested that a gradient design will be moresensitive to change than randomized placement ofsamples. This requires allocating samples according todistance, rather than by random placement withinrandomly placed blocks. In this paper gradient versusrandom sampling designs were compared using data froman oil field in the North Sea. The gradient samplingdesign was more powerful than a randomized CI sampling design.  相似文献   
687.
固定污染源烟(粉)尘测试中,烟尘波动、误差大,数据整理存在一定的困难,本文根据实验结果提出了数据修约的范围,并根据监测规范的布点要求,结合实测结果,提出了优化断面布点的设想.在直管段长度满足规范要求的条件下,管道直径小于0.5米时,可选断面上距管壁近的一点作测试点,该点测值可代表断面上平均测值.  相似文献   
688.
为评估杭州市典型室内公共场所空气中多溴联苯醚(PBDEs)的污染现状,2016年5~8月和9~12月期间,采用空气被动采样技术(PUF-PAS)在17家室内公共场所总计采集54个空气样品,经样品预处理和GC-ECD分析后,结果表明,5类环境空气样品中∑14PBDEs浓度均值大小依次为网咖(2470.43pg/m3)>建材市场(1119.87pg/m3)>电子市场(660.84pg/m3)>商场(478.37pg/m3)>图书城(182.18pg/m3).最主要的特征单体均为BDE-209,占总量的36.79%~56.21%,BDE-47、BDE-99、BDE-153、BDE-183也是PBDEs在空气中较主要的同系物,其最高浓度分别占7.77%,7.56%,6.32%和7.73%.评估PBDEs人群暴露水平的结果表明,网咖内暴露水平最高,图书城则为最低,其浓度分别为570.10和44.79pg/(kg×d).室内空气中,对人群PBDEs总摄入量贡献最高的特征单体是BDE-209,平均水平为18.44~323.70pg/(kg×d),最低的则为BDE-183,平均水平为1.75~20.05pg/(kg×d),目前杭州市各典型室内公共场所PBDEs人群暴露水平相比美国环境保护署(EPA)提出的参考剂量较低.  相似文献   
689.
目前对北方农村地区燃煤采暖情况的调查研究主要集中在北京及其周边地区,尚缺少不同气候条件、不同经济水平下的更大范围的样本.为了系统掌握山西全省的农村燃煤采暖情况,并为北方同类地区提供参考,考虑不同地区冬季气温及年采暖期的差异,采用随机分层抽样方法,对山西省农村地区2015年燃煤采暖的情况进行了抽样调查,对全省燃煤采暖的燃煤量以及大气污染物排放量进行了估算.调查共在8市10县获得有效样本394个.结果显示:山西省燃煤采暖的农户约占89.3%,户均采暖燃煤量3.4 t/a;冬季气温对户均采暖燃煤量有显著影响,晋北严寒地区户均采暖燃煤量可达4.4 t/a,而在晋南等相对温暖地区户均采暖燃煤量仅是其57%.在同一地区,家庭经济条件会影响所选择的采暖器具,进而影响采暖燃煤量,经济条件较好的家庭选择土暖气,户均燃煤量是选择暖炕加小煤炉采暖家庭的2.3倍.估算2014—2015年采暖期山西省农村采暖燃煤约1 297.8×104 t,PM、PM2.5、SO2、NOx、BC、OC、CO约分别排放13.0×104、9.1×104、19.9×104、2.1×104、4.1×104、5.6×104、123.3×104 t.研究显示,山西省单位面积采暖燃煤量约是北京、河北等同类地区的1/3,考虑到山西省经济条件较差,建议对城中村、城边村采暖实施煤改气、煤改电,其他地区则主要通过增强建筑的保温性,使用低硫煤等措施减少农村采暖燃煤排污.   相似文献   
690.
ABSTRACT: A stratified, spatially balanced sample with unequal probability selection was used to design a multipurpose survey of headwater streams in the Mid‐Atlantic Coastal Plain. Objectives for the survey include unbiased estimates of regional stream conditions, and adequate coverage of unusual but significant environmental settings to support empirical modeling of the factors affecting those conditions. The design and field application of the survey are discussed in light of these multiple objectives. A probability (random) sample of 175 first‐order nontidal streams was selected for synoptic sampling of water chemistry and benthic and riparian ecology during late winter and spring 2000. Twenty‐five streams were selected within each of seven hydrogeologic subre‐gions (strata) that were delineated on the basis of physiography and surficial geology. In each subregion, unequal inclusion probabilities were used to provide an approximately even distribution of streams along a gradient of forested to developed (agricultural or urban) land in the contributing watershed. Alternate streams were also selected. Alternates were included in groups of five in each subregion when field reconnaissance demonstrated that primary streams were inaccessible or otherwise unusable. Despite the rejection and replacement of a considerable number of primary streams during reconnaissance (up to 40 percent in one subregion), the desired land use distribution was maintained within each hydrogeologic subregion without sacrificing the probabilistic design.  相似文献   
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