Lead Isotopic Compositions of Selected Coals, Pb/Zn Ores and Fuels in China and the Application for Source Tracing.

Lead (Pb) pollution emission from China is becoming a potential worldwide threat. Pb isotopic composition analysis is a useful tool to accurately trace the Pb sources of aerosols in atmosphere. In this study, a comprehensive data set of Pb isotopes for coals, Pb/Zn ores, and fuels from China was presented. The ratios of 206Pb/207Pb and 208Pb/206Pb in the coals were in the range of 1.114-1.383 and 1.791-2.317, similar to those from Europe, Oceania, and South Asia, but different from those from America (p < 0.01). The Pb/Zn ores had 206Pb/207Pb and 208Pb/206Pb in 1.020-1.183 and 2.088-2.309, less radiogenic than the coals. Leaded gasolines showed similar Pb isotopic compositions to Pb/Zn ores, with unleaded gasolines and diesels being mixed sources. The average Pb isotopic ratios of gasolines and diesels were significantly different (p < 0.01) from those of coals in China, leading to the possibility to discriminate Pb in fuels from in coals. Urban aerosols demonstrated similar Pb isotopic compositions to coals, Pb/Zn ores, and fuels in China. After removing the leaded gasoline, the Pb in aerosols is more radiogenic, supporting the heavy contribution of coal combustion to the atmospheric Pb pollution.

Towards quantum communications in free-space seawater.

Long-distance quantum channels capable of transferring quantum states faithfully for unconditionally secure quantum communication have been so far confirmed to be feasible in both fiber and free-space air. However, it remains unclear whether seawater, which covers more than 70% of the earth, can also be utilized, leaving global quantum communication incomplete. Here we experimentally demonstrate that polarization quantum states including general qubits of single photon and entangled states can survive well after travelling through seawater. We perform experiments with seawater collected over a range of 36 kilometers in the Yellow Sea. For single photons at 405 nm in a blue-green window, we obtain an average process fidelity above 98%. For entangled photons at 810nm, albeit very high loss, we observe the violation of Bell inequality with 33 standard deviations. Our results confirm the feasibility of a seawater quantum channel, representing the first step towards underwater quantum communication.

[Distributions, Sources and Pollution Assessment of Hg in Sediment of Douhe Reservoir in Tangshan City].

Sediment cores from Douhe reservoir in Tangshan City were sampled in August 2013, in order to evaluate the mercury (Hg) pollution degree and its possible sources. Agriculture soils surrounding the Douhe reservoir and sediments from an upstream reservoir (Daheiting) were also collected. Total mercury (THg), methylmercury (MeHg), dissolved mercury in pore water (DHg) and organic matter (OM) in sediment of Douhe reservoir were analyzed, while, only THg in the agriculture soils and upstream reservoir sediments was determined. Finally, the geoaccumulation index method was applied to evaluate the Hg pollution status in soils and reservoir sediments. The results showed that THg content in sediment of Douhe reservoir ranged from 19 to 97 ng·g-1. dw, MeHg (dw) from 0.02 to 1.27 ng·g-1, and the contents of both THg and MeHg were higher in the upper layers than the deeper layers, indicating that Hg in sediments was increasing in recent years by the exogenetic loadings. THg (dw) in soils offshore the Douhe reservoir, which is close to a large coal-fired power plant, averaged at 22 ng·g-1. Among the three sediment cores of Douhe reservoir, the central point had the highest THg, followed by the western site, and the eastern site had the lowest THg. While, THg content (dw) in sediments of Daheiting reservoir was much higher, with a mean of 176 ng·g-1. Combining all the above information, we concluded that Hg in Douhe reservoir was mainly derived from the Daheiting reservoir and the mercury atmospheric deposition from the nearby coal-fired power plant contributed a less content. THg and MeHg in the sediments of Douhe reservoir were positively correlated with OM, indicating that OM in sediments had good ability of adsorbing THg and MeHg, and also played an important role in Hg methylation. The geoaccumulation index (Igeo) showed that the Hg pollution status deceased in this order:central of Daheting, Daba of Daheting, central of Douhe, western of Douhe, eastern of Douhe, soils surrounding Douhe. Central and western sites in Douhe belonged to moderate pollution and the eastern site belonged to slight pollution. While, sediments of Daheiting reservoir, affected by the iron ore mining activities, were in the moderate and strong pollution status.

[Distribution characteristic and bioaccessibility of lead in kindergarten dust of Wuhan City].

The characteristics of lead pollution and the associated health risk of children for the dust samples from 69 representative kindergartens in different type districts of Wuhan were investigated. Total lead concentration and bioaccessibility according to physiologically based extraction test (PBET) were determined. Results showed that the levels of lead concentration in dust ranged from 36.3 to 1 523 mg x kg(-1) with an average value of 169 mg x kg(-1), lower than published data from other areas. The great spatial variation of Pb in dust indicated that specific sites have been seriously contaminated by Pb. The bioaccessibilities of Pb in dusts were 35% +/- 15% at gastric phases and 7.6% +/- 5.8% at intestinal phases. According to the predicted model with the Integration Exposure Uptake Biokinetic Model (IEUBK), the geometric mean blood lead of children (0-6 years) was 2.73 microg x dL(-1), of which over 10 microg x dL(-1) was less than 0.001% and exceeded 5 microg x dL(-1) was 3.32%.

Assessing heavy-metal contamination and sources by GIS-based approach and multivariate analysis of urban-rural topsoils in Wuhan, central China.

Nine potentially harmful heavy metals (Cd, Co, Cr, Cu, Hg, Mn, Pb, Ni, and Zn) were measured in 477 topsoil samples collected from urban-rural areas in the city of Wuhan in order to identify their concentrations and possible sources, and characterize their spatial variability for risk assessment. Results showed that in most rural areas heavy-metal concentrations in soil were similar to their natural background values, but Cd, Cu, Hg, Pb, and Zn concentrations were relatively higher in densely populated districts and around industrial facilities. Multivariate analyses (correlation matrix, principal component analysis, and cluster analysis) indicated that Cd, Cu, Hg, Pb, and Zn were mainly derived from anthropogenic inputs, and Co, Cr, and Mn were controlled by natural source, whereas Ni appeared to be affected by both anthropogenic and natural sources. The result of risk assessment indicated that nearly 48% of the study area suffered from moderate to severe contamination.

[Geochemical cycling of mercury in the sediment of Hongfeng Reservior].

Spatial and temporal distributions of total and methyl mercury and controlling factors were investigated based on cold vapor atomic fluorescence detection. Total mercury levels in the whole sediments are (0.392 +/- 0.070) microg/g, without significant variations between different seasons, but generally increase toward the sediment-water interface. Total mercury levels are higher compared to data reported in other uncontaminated reservoirs and Wujiangdu Reservoir. This indicates there are mercury contaminations in Hongfeng Reservoir. Methyl mercury concentrations are highest in spring, without significant variations in other seasons. The peak values of methyl mercury typically appear in the upper 8 cm of the sediment profiles which are also the zones of sulfate-reducing bacteria activities. The seasonal variation and maximum peak value distributions of methyl mercury in sediment are mainly controlled by seasonally migration of oxic/anoxic boundary layer. Total mercury concentrations in the pore water and partition coefficients for THg in solid phase and water phase are mainly controlled by temperature or redox potential. Total mercury concentrations in the pore water have no relationship with total mercury concentrations in solid phase. However, the methyl mercury concentrations in the pore water have a strong relationship with those in solid phase (r = 0.70, p < 0.001). The methyl mercury concentrations in solid phase and pore water are controlled by solid/water partition coefficient, as well as methyl mercury production.

[Pathways of mercury emissions to atmosphere from closed municipal landfills].

Using the automated mercury vapor analyzer and dynamic flux chamber (DFC) method, the pathways of mercury emissions to atmosphere were measured at a closed landfill in Wuhan, China. The results show that the mainly pathway is by the surface cover, and emissions from vent pipes is negligible. Average Hg fluxes during the observation period was (192.5 +/- 245.3) ng x (m2 x h)(-1), which was 1 - 2 orders of magnitude greater than that from background zone. Hg flux exhibited a clearly diurnal pattern, reaching the maximum near midday and the lowest during night. Solar radiation was the environmental factor that has highest relationship with Hg flux, with coefficient of 0.77, this indicated that photo-reduction of Hg(II) being a prominent process in the production of volatile elemental mercury (Hg(0)). Mercury concentrations in landfill gas (LFG) at different vent pipes averaged from 7.0 - 68.9 ng x m(-3), which was much lower than that of operational landfills, and the flow rate of landfill gas was very slow.