Multi-scale spatial structure of heavy metals in agricultural soils in Beijing

To effectively investigate the spatial variability of heavy metals in soil, produce a higher quality spatial distribution map, and identify the potential pollution sources of heavy metals, geostatistics was employed to evaluate the effect of scale on spatial variability of heavy metals in Beijing agricultural soils. The results revealed that spatial variability of Cr, Ni, Zn, and Hg was dependent on scale. Validation of the optimality of theoretical semivariance and comparative analysis of the estimation accuracy demonstrated that the multi-scale nested model can reveal the spatial structure of heavy metals effectively and improve the estimation accuracy better than the single-scale method, thereby enabling production a higher quality spatial interpolation map. Thus, the multi-scale kriging nested model is a useful tool for revealing spatial variability of heavy metals in soils, while the spatial distribution maps allow the identification of hot spots with high concentrations of heavy metals.     

Investigations on boron levels in drinking water sources in China

To evaluate boron contamination of public drinking water in China, both dissolved and total boron contents in 98 public drinking water sources from 49 cities, 42 brands of bottled water samples from supermarkets in several cities, and 58 water samples from boron industrial area were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Our experimental results showed that boron existed in public drinking water sources mainly in dissolved status with total concentrations ranging from 0.003 to 0.337 mg/L (mean = 0.046 mg/L). The mean boron concentrations in mineral and pure bottled water were 0.052 and 0.028 mg/L, respectively. The results obtained in this work showed that there was no health risk on view of boron in public drinking water sources and bottled water. In boron industrial area, boron concentrations in surface water and ground water were 1.28 mg/L (range = 0.007–3.8 mg/L) and 18.3 mg/L (range = 0.015–140 mg/L), respectively, which indicated that boron industry caused boron pollution in local water system.     

Investigation of heavy metals in sediments and Manila clams Ruditapes philippinarum from Jiaozhou Bay, China

Manila clams (Ruditapes philippinarum) and sediments were collected bimonthly during 2007 at five locations in Jiaozhou Bay near Qingdao, China, to determine heavy metal concentrations and to assess the validation of R. philippinarum as a metal biomonitor. Concentrations of heavy metals in clam soft tissues ranged between 0.75 and 3.31, 0.89 and 15.20, 5.70 and 26.03, 52.12 and 110.33, 10.30 and 72.34, 9.64 and 28.60, and 3.15 and 52.75 μg g^???1 dry weight for Cd, Pb, Cu, Zn, Mn, Cr, and Ni, respectively. Most of the highest values occurred at the northeast bay and the lowest values occurred at the western part. Regarding seasonal variation, relatively high tissue metal concentrations were observed during October or December. A similar pattern was also found in habitat sediments. There was a strong correlation between the concentrations of Cd, Pb, Zn, Mn, Cr, and Ni in soft tissues and surrounding sediments. It is indicated that R. philippinarum could be used as a biomonitor for heavy metal contamination in Jiaozhou Bay.     

Changes in the sorption and rate of 17β-estradiol biodegradation by dissolved organic matter collected from different water sources

The potential biodegradation and subsequent transformation of 17β-estradiol (E2) to estrone (E1) were examined in the presence of various dissolved organic matter (DOM) isolated from effluent, river and lake waters. In addition, estrogenicity was estimated in association with the removal of E2 via its sorption onto DOM and biodegradation. The more biodegradable lake-derived DOM promoted more extensive transformation of E2 into E1 than the effluent organic matter through a biodegradation process. Overall, under all conditions, biodegradation dominated the removal of E2 in water. The increased dissolved organic carbon (DOC) concentrations in river and lake-derived DOM (e.g. 6.5 mg C L(-1)) reduced the removal of E2 by decreasing its biodegradation due to the moderate sorption of E2 onto DOM. The effluent organic matter showed greater removal of E2 via biodegradation, as well as significantly high sorption. This was associated with a large amount of hydrophobic fulvic acid (FA)- and humic acid (HA)-like organic components, as shown by the small increase in the specific UV absorbance at 254 nm (SUVA(254)). An increase in the DOC concentration reduced the removal of E2, resulting in high estrogenicity. The present study suggests that both organic composition and DOC concentration influenced the removal of E2 and, therefore, should be fully considered when assessing estrogenicity and its impacts on the aquatic environment.     

Chlorinated and brominated dibenzo-p-dioxins and dibenzofurans in surface sediment from Taihu Lake, China

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in surface sediment samples from Taihu Lake--an important water supply of the Yangtze River Delta, China--were investigated in the present study. Concentrations of PCDD/Fs ranged from 0.91 to 4.8 pg TEQ g(-1) dw (mean: 2.9 pg TEQ g(-1) dw, TEQ: Toxic Equivalent), which were all higher than the threshold effect level established by interim sediment quality guidelines in Canada (0.85 pg TEQ g(-1) dw). The levels of PBDD/Fs ranged from 0.16 to 1.6 pg TEQ g(-1) dw (mean: 0.52 pg TEQ g(-1) dw) and accounted for 5-33% (mean: 14%) of the total PCDD/Fs and PBDD/Fs TEQ. Comparatively, the abundance of sedimentary PCDD/Fs in the three regions (Meiliang Bay, Gonghu Bay, and Xukou Bay) showed a decreasing trend from the inflow region to the outflow region, while no significant difference was observed among their 2,3,7,8-PBDD/Fs levels, which suggested that the sources of PCDD/Fs and PBDD/Fs differed in this area. Principal component analysis suggested that the historical production/usage of pentachlorophenol and sodium pentachlorophenate was the dominant source of PCDD/Fs in the sediment of these regions. Although the specific sources of PBDD/Fs in the sediment of Taihu Lake were unclear, it was suspected to be due to atmospheric deposition; however, an additional study is needed to confirm this.     

Even sampling designs generation by charges repulsion simulation

Evenly distributed sampling design is generally considered as an efficient sampling design. It is widely used in sampling for the environmental survey. In this paper, we present a novel method for generating N evenly distributed samples within a given irregular polygon via simulating the movements of some ideal homogeneous point charges. Initially, charges are randomly put into the sampling region; then, they are freed and held orderly; and after enough runs, the charges will finally reach a stable state with all of them having a zero resultant force and velocity; and so they distribute evenly within the region. Their layout can thus be considered as an evenly distributed sampling design. The main advantages of this method are: (1) it is easy to understand and implement; (2) it is efficient in both running and generating better designs. Analysis and experimental results indicate that this method is an efficient and robust method for generating even sampling designs for 2D polygonal sampling region.     

Occurrence and fate of steroid estrogens in the largest wastewater treatment plant in Beijing, China

Concern over steroid estrogens has increased rapidly in recent years due to their adverse health effects. Effluent discharge from wastewater treatment plants (WWTPs) is the main pollutant source for environmental water. To understand the pollutant level and fate of steroid estrogens in WWTPs, the occurrence of estrone (E1), 17-β-estradiol (E2), estriol (E3), and 17-β-ethinylestradiol (EE2) was investigated in the Gaobeidian WWTP in Beijing, China. Water samples from influent as well as effluent from second sedimentation tanks and advanced treatment processes were taken monthly during 2006 to 2007. In influent, steroid estrogen concentrations varied from 11.6 to 1.1?×?10(2)?ng/l, 3.7 to 1.4?×?10(2)?ng/l, no detection (nd) to 7.6×10(2)?ng/l and nd to 3.3?×?10(2)?ng/l for E1, E2, E3, and EE2, respectively. Compared with documented values, the higher steroid estrogen concentrations in the WWTP influent may be due to higher population density, higher birthrate, less dilution, and different sampling time. Results revealed that a municipal WWTP with an activated sludge system incorporating anaerobic, anoxic, and aerobic processes could eliminate natural and synthetic estrogens effectively. The mean elimination efficiencies were 83.2%, 96.4%, 98.8%, and 93.0% for E1, E2, E3, and EE2, respectively. The major removal mechanism for natural estrogens and synthetic estrogen EE2 were biodegradation and sorption on the basis of mass balance in water, suspension particles, and sludge. In the WWTP effluent, however, the highest concentrations of E1, E2, E3, and EE2 attained were 74.2, 3.9, 5.1, and 4.6?ng/l, respectively. This is concerning as residual steroid estrogens in WWTP effluent could lead to pollution of the receiving water. Advanced flocculation treatment was applied in the WWTP and transformed the residual estrogen conjugates to free species, which were reduced further by filtration with removal shifting from 32% to 57% for natural estrogen, although no EE2 was removed.     

铅冶炼区土壤重金属总量和有效态含量的函数分析

采集铅冶炼企业周边3 000 m范围内220个表层土壤样品,测定了有毒有害元素铅、镉、砷和汞的总量和有效态含量,探讨了它们之间的关系。结果表明:研究区土壤受到汞、砷、铅、镉的污染依次明显严重,土壤重金属的总量和有效态含量的变异系数均大于100%,土壤镉、铅、汞、砷的生物有效性系数平均值分别为25.9%、17.2%、0.58%、0.11%。土壤铅、镉和砷的总量与其有效态含量呈显著正相关(P0.001),而汞的总量与其有效态含量的相关性不显著(P0.05)。土壤铅和镉的总量和有效态含量可以用直线函数和幂函数表达,函数反推的有效态值和对应统计值的变异系数不大于10%。     

Quality assessment of groundwater from the south-eastern Arabian Peninsula

Assessment of groundwater quality plays a significant role in the utilization of the scarce water resources globally and especially in arid regions. The increasing abstraction together with man-made contamination and seawater intrusion have strongly affected groundwater quality in the Arabia Peninsula, exemplified by the investigation given here from the United Arab Emirates, where the groundwater is seldom reviewed and assessed. In the aim of assessing current groundwater quality, we here present a comparison of chemical data linked to aquifers types. The results reveal that most of the investigated groundwater is not suitable for drinking, household, and agricultural purposes following the WHO permissible limits. Aquifer composition and climate have vital control on the water quality, with the carbonate aquifers contain the least potable water compared to the ophiolites and Quaternary clastics. Seawater intrusion along coastal regions has deteriorated the water quality and the phenomenon may become more intensive with future warming climate and rising sea level.