PAHs could be transported to Tibetan Plateau in accompany with atmospheric circulation. The forest regions were found be an important sink for PAHs, while their distributions and migrations in forest are still uncertain. In this study, soil profile samples were collected in southeastern Tibet and the concentrations, distributions, and migration of PAHs in forest region were investigated. The PAHs levels in the forest soils were at the low end of remote sites, ranged from 27.4 to 120.3 ng g?1 on a dry weight based. Due to low ambient temperature and high organic carbon content, enrichment of PAHs was found in higher altitude on north side. According to the soil profiles, the vertical distributions of PAHs in organic layers were mainly influenced by pedogenesis, while the vertical distributions in mineral layers were dominated by downward leaching effect. Enrich factor (EF) of PAHs was estimated, and the values in organic layers were positively correlated with the octanol–air partition coefficients (KOA), but EFs in mineral layers decreased with the KOA values. PAHs in the surface soils on the north side of forest were relatively stable, while the migration of PAHs on the south sides and other clearing sites was more active. The leaching rates of PAHs in clearing site ranged between 1.42 and 29.3%. The results from this study are valuable on the characterization of PAHs in Tibetan Plateau. 相似文献
To understand how extraction of different energy sources impacts water resources requires assessment of how water chemistry has changed in comparison with the background values of pristine streams. With such understanding, we can develop better water quality standards and ecological interpretations. However, determination of pristine background chemistry is difficult in areas with heavy human impact. To learn to do this, we compiled a master dataset of sulfate and barium concentrations ([SO4], [Ba]) in Pennsylvania (PA, USA) streams from publically available sources. These elements were chosen because they can represent contamination related to oil/gas and coal, respectively. We applied changepoint analysis (i.e., likelihood ratio test) to identify pristine streams, which we defined as streams with a low variability in concentrations as measured over years. From these pristine streams, we estimated the baseline concentrations for major bedrock types in PA. Overall, we found that 48,471 data values are available for [SO4] from 1904 to 2014 and 3243 data for [Ba] from 1963 to 2014. Statewide [SO4] baseline was estimated to be 15.8 ± 9.6 mg/L, but values range from 12.4 to 26.7 mg/L for different bedrock types. The statewide [Ba] baseline is 27.7 ± 10.6 µg/L and values range from 25.8 to 38.7 µg/L. Results show that most increases in [SO4] from the baseline occurred in areas with intensive coal mining activities, confirming previous studies. Sulfate inputs from acid rain were also documented. Slight increases in [Ba] since 2007 and higher [Ba] in areas with higher densities of gas wells when compared to other areas could document impacts from shale gas development, the prevalence of basin brines, or decreases in acid rain and its coupled effects on [Ba] related to barite solubility. The largest impacts on PA stream [Ba] and [SO4] are related to releases from coal mining or burning rather than oil and gas development.
Environmental Geochemistry and Health - Urban street dust samples from 49 sampling sites in Xuzhou (China) were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs) using gas... 相似文献
在黑龙江省梧桐河,调查了13个点位的着生硅藻群落结构和水环境特征,应用8种硅藻指数对该河流水生生态系统进行健康评价,并在此基础上应用主成分分析、相关分析、冗余分析、箱型图分析等统计分析方法研究了影响梧桐河着生藻类群落的主要环境因子和8种硅藻指数在梧桐河的适用情况。结果显示:梧桐河存在一定程度的环境污染,优势种以小型异极藻(Gomphonema parvulum)等耐污种为主。8个硅藻指数中,硅藻属指数(Generic Index of Diatom,GI)、澳大利亚河流硅藻生物评价指数(Diatom Index for Australian Rivers,DIAR;Diatom Species Index for Bioassessment of Australian Rivers,DSIAR)评价结果偏差较大,在梧桐河不适用;相似度指数(Jaccard Index,JI)与富营养化硅藻指数(Trophic Diatom Index,TDI)评价结果较为严格,评分明显偏低;硅藻污染耐受指数(Pollution Tolerance Index,PTI)、硅藻生物评价指数(Diatom Bioassessment Index,DBI)和生物硅藻指数(Biological Diatom Index,BDI)在梧桐河流域适用性最好。根据冗余分析(RDA),将梧桐河流域点位分为3组,第一组点位为中-重度污染,主要影响因子为流速和总磷;第二组点位为轻-中度污染,主要影响因子为磷酸盐、氨氮和溶解氧;第三组点位为轻污染-清洁,主要影响因子为p H和电导率。 相似文献
Green source Ep was extracted from marine alga waste.The molecule model structure of Ep was studied and constructed.PAC-Ep coagulation system improves the efficiency of removal efficiency.Synergistic effects between NPs and HA make a big difference to enhance efficiency.Mechanism is charge neutralization, hydrogen bonding and adsorbing-complexing Enteromorpha polysaccharide (Ep) extracted from alga a novel green coagulant aid for nanoparticles (NPs) and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride (PAC-Ep) coagulants exhibited higher coagulation performance than that of the polyaluminum chloride (PAC) because of the negatively charged NPs suspension and humic aid (HA) solution. Significant high removal efficiencies of dissolved organic matter (94.1%), turbidity (99.3%) and Zn ions (69.3%) were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including (i) Al3+ charge neutralization; (ii) hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; (iii) adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment. 相似文献
This paper analyses the contents and species distributions of rare earth elements (REEs) in the water-suspended particulate-sediment
system of the Baotou section of the Yellow River, China, with known anthropogenic REE input from industrial discharges. The
major forms of REEs were suspended and dissolved in the mainstream and the tributaries of the Baotou section, respectively.
The concentrations of the dissolved and suspended REEs had the same trends in the overlying water along the mainstream, which
increased from the Seqi section (site A) to the mouth of the Sidaosha River (site D), reaching a maximum value at site D,
and tending to decrease thereafter. The contents of REEs in sediment cores showed enrichment with light rare earth elements
(LREEs). The bound to carbonates and to Fe–Mn oxides are the major forms of REE in the secondary phase and the REE exhibited
LREE enrichment pattern and moderate Eu depletion in suspended particulates and surface sediments. The contents and species
distributions of REEs in the water-suspended particulate-sediment system of the Baotou section suggest that the anthropogenic
source of REEs from Baotou city have enhanced REE accumulation to the Baotou section. This information is important for predicting
possible pollution resulting from anthropogenic REE input into rivers. 相似文献