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991.
992.
Jiang Y Xu H Zhang W Zhu M Al-Rasheid KA 《Environmental science and pollution research international》2012,19(5):1747-1754
Introduction
In order to reveal the potential relationships between body-size patterns of microzooplankton and environmental status, the spatial patterns in body-size spectra of ciliated zooplanktons were studied based on an annual dataset in a bay of the Yellow Sea, northern China.Materials and methods
A total of 120 samples were collected at a depth of 1?m from each of five sampling sites with a spatial gradient of environmental stress from June 2007 to May 2008. A range of physico-chemical variables were measured synchronously for comparison with biotic parameters.Results
The spatial body-size patterns of ciliated zooplankton represented significant differences among the five sites, and were significantly correlated with the changes of physico-chemical parameters, especially salinity, dissolved oxygen and nutrients. Two paired indices, the average body-size distinctness (AvBSD) and the variation in body-size distinctness (VarBSD), were proposed based on the trait resemblances among ciliate species in body-size pattern. The paired measures showed a clear decreasing trend of departure from the expected body-size spectra in response to water quality status.Conclusion
These results suggest that the body-size pattern of ciliated zooplankton might be used as a potential indicator of marine water quality. 相似文献993.
Cosorption of organic chemicals with different properties: their shared and different sorption sites
Zhang D Pan B Wu M Zhang H Peng H Ning P Xing B 《Environmental pollution (Barking, Essex : 1987)》2012,160(1):178-184
Complementary sorption of different chemicals was expected and investigating the relationship between the sorption inhibition of primary sorbate (ΔQ(pri)) and sorption of secondary sorbate (Q(sec)) could provide a new angle to understand coadsorption of different chemicals. This study used bisphenol A (BPA) as the primary adsorbate, sulfamethoxazole (SMX) as the competitor, and carbon nanotubes as model adsorbents to study their complementary and competitive adsorption. At low BPA concentrations, the sorption of SMX (Q(sec)) exceeded BPA sorption inhibition (ΔQ(pri)), indicating that these two chemicals complementarily adsorbed on their respectively preferred sorption sites. At high BPA concentrations, higher ΔQ(pri) was observed in comparison to Q(sec), which may be resulted from different packing efficiencies of the adsorbed SMX and BPA. This study emphasized that both competitive and complementary sorption should be discussed in binary sorption system. 相似文献
994.
Chaosheng Zhang Ya Tang Lin Luo Weilin Xu 《Environmental pollution (Barking, Essex : 1987)》2009,157(11):3083-3090
Outliers in urban soil geochemical databases may imply potential contaminated land. Different methodologies which can be easily implemented for the identification of global and spatial outliers were applied for Pb concentrations in urban soils of Galway City in Ireland. Due to its strongly skewed probability feature, a Box–Cox transformation was performed prior to further analyses. The graphic methods of histogram and box-and-whisker plot were effective in identification of global outliers at the original scale of the dataset. Spatial outliers could be identified by a local indicator of spatial association of local Moran's I, cross-validation of kriging, and a geographically weighted regression. The spatial locations of outliers were visualised using a geographical information system. Different methods showed generally consistent results, but differences existed. It is suggested that outliers identified by statistical methods should be confirmed and justified using scientific knowledge before they are properly dealt with. 相似文献
995.
Polycyclic aromatic hydrocarbon (PAH) deposition to and exchange at the air-water interface of Luhu, an urban lake in Guangzhou, China 总被引:3,自引:0,他引:3
Urban lakes are vulnerable to the accumulation of semivolatile organic compounds, such as PAHs from wet and dry atmospheric deposition. Little was reported on the seasonal patterns of atmospheric deposition of PAHs under Asian monsoon climate. Bulk (dry + wet) particle deposition, air-water diffusion exchange, and vapour wet deposition of PAHs in a small urban lake in Guangzhou were estimated based on a year-round monitoring. The total PAH particle deposition fluxes observed were 0.44-3.46 μg m−2 day−1. The mean air-water diffusive exchange flux was 20.7 μg m−2 day−1. The vapour deposition fluxes of PAHs ranged 0.15-8.26 μg m−2 day−1. Remarkable seasonal variations of particulate PAH deposition, air-water exchange fluxes and vapour wet deposition were influenced by seasonal changes in meteorological parameters. The deposition fluxes were predominantly controlled by the precipitation intensity in wet season whereas by atmospheric concentration in dry season. 相似文献
996.
Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China 总被引:37,自引:0,他引:37
We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products. 相似文献
997.
氧化沟反应器流体力学特性的数值模拟与实验研究 总被引:4,自引:1,他引:4
采用CFD数值计算和体视PIV测试相结合的方法研究卡鲁塞尔氧化沟反应器流场特性。探索复杂边界条件下反应器流场的模拟方法,采用体视PIV技术分别测量了反应器直道、弯道处三维全场流速;研究不同位置处纵、横、垂三向的流动结构和沿程分布特点。结果表明,模拟与实验结果较吻合;纵、垂两向的流动分布是决定沟内水力特性的主要因素;横、垂两向的流动是决定污泥沉积位置的主要因数;外沟靠近曝气叶轮直道段的流速分布上大下小,在低速区底部易发生污泥沉积;外沟远离曝气叶轮直道段流速分布上小下大,利于防止泥水分离;弯道段受横比降和横向环流的影响,内侧容易形成低速区或停滞区而发生污泥沉积。 相似文献
998.
Monitoring of organochlorine pesticides using PFU systems in Yunnan lakes and rivers, China 总被引:3,自引:0,他引:3
Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GC-ECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 microgl-1 (mean 0.27 microgl-1), undetectable to 0.72 microgl-1 (mean 0.11 microgl-1), and 0.24-21.95 microgl-1 (mean 7.39 microgl-1) respectively in lakes; and those in rivers were undetectable to 0.23 microgl-1 (mean 0.08 microgl-1), 0.68-2.93 microgl-1 (mean 1.70 microgl-1), and 2.71-37.56 microgl-1 (mean 17.01 microgl-1) respectively. Notably, some residue levels of OCPs exceeded the US National Recommended Water Quality Criteria, implying Yunnan has levels of OCPs potentially harmful to human health. Further, the contamination by OCPs showed an obvious spatial distribution pattern. Amongst the lakes, Dianchi, Xingyun, Lugu and Yangzonghai had the highest OCP levels dominated by beta-HCH, whereas among rivers, Nujiang and Lancang Rivers had the highest contents of OCPs dominated by alpha-HCH. This demonstrates that HCHs are the predominant contaminants and some point sources of HCHs may still exist in Yunnan. The pollution levels in Yunnan were compared with other studies, suggesting the PFU method is suitable for long-term on-line monitoring of trace OCPs in aquatic ecosystems. Therefore, continuous studies monitoring OCPs in lakes and rivers are needed to further understand the future trend of contamination. 相似文献
999.
Deng DM Shu WS Zhang J Zou HL Lin Z Ye ZH Wong MH 《Environmental pollution (Barking, Essex : 1987)》2007,147(2):381-386
To investigate the variation of Zn and Cd accumulation and tolerance of Sedum alfredii (a newly reported Zn/Cd hyperaccumulator), field surveys and hydroponic experiments were conducted among three populations of this species: two originating from old Pb/Zn mines in Zhejiang (ZJ) and Hunan (HN) Provinces and one from a "clean" site in Guangdong (GD) Province, China. Under field conditions, up to 12,524 and 12,253 mg kg(-1) Zn, and 1400 and 97 mg kg(-1) Cd in shoots of ZJ and HN plants were recorded respectively. Under hydroponic conditions, ZJ and HN plants accumulated significantly higher Zn and Cd in their leaves and stems, and possessed significantly higher Zn and Cd tolerance than GD plants. Among the two contaminated populations, ZJ plants showed higher Cd tolerance and accumulation (in leaves) than HN plants. The present results indicate that significant differences in Zn and Cd accumulation and tolerance exist in populations of S. alfredii. 相似文献
1000.
In this paper, we addressed the utilization of photochemical method as an innovative technology for the destruction and removal of two potent greenhouse gases, SF(6) and SF(5)CF(3). The destruction and removal efficiency (DRE) of the process was determined as a function of excitation wavelength, irradiation time, initial ratio of acetone to SF(5)X (X represented F or CF(3)), initial SF(5)X concentration, additive oxygen and water vapor concentration. A complete removal was achieved by a radiation period of 55min and 120min for SF(6)-CH(3)COCH(3) system and SF(5)CF(3)-CH(3)COCH(3) system respectively under 184.9nm irradiation. Extra addition of water vapor can enhance DRE by approximately 6% points in both systems. Further studies with GC/MS and FT-IR proved that no hazardous products such as S(2)F(10), SO(2)F(2), SOF(2), SOF(4) were generated in this process. 相似文献