Altitude dependence of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in surface soil from Tibetan Plateau, China

Remote mountain areas besides high latitude regions are beginning to receive increased attention in studying the transport and behavior of persistent organic pollutants (POPs). In the present work, surface soil samples were collected from the Tibetan Plateau, the highest plateau in the world which includes the northern slope of Mt. Qomolangma, to investigate the levels and trends of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) along the altitudinal gradient. The average PCB and PBDE concentrations were 185.6 ng kg⁻¹ dry weight (dw) (range 47.1–422.6 ng kg⁻¹ dw) and 11.1 ng kg⁻¹ dw (range 4.3–34.9 ng kg⁻¹ dw), respectively. Regression analysis between the log-transformed TOC-normalized concentrations and the altitudes of the sampling sites showed two opposite trends with regard to altitude dependence: negative relationship with altitude below about 4500 m followed by a positive altitude dependence above this point. Considering minimum anthropogenic activities and very sparse precipitation in the north of Himalayas, the trends above 4500 m imply that the significant altitude dependence of these two groups of POPs were irrespective of pollution sources, but could be predicted by the global distillation effect involving cold condensation in high altitude mountain areas. Increasing levels of heavier congeners were found in higher altitude sites, although the lighter congeners were the main contributors to the total amount, suggesting that less volatile congeners seem to become enriched easier than those more volatile at higher altitudes in this region.     

韩国农村排水系统的建设和管理

农村排水系统是农村建设发展的重要基础设施.结合韩国农村排水系统建设和管理.介绍了韩国相关的政策措施的制定、排水系统的特点、污水处理工艺和设施管理等,同时对韩国农村排水系统目前存在的问题进行了分析.     

Spatial distribution and seasonal variation of char-EC and soot-EC in the atmosphere over China

A previous study on PM_2.5 carbonaceous aerosols measured with the thermal optical reflectance (TOR) method in fourteen Chinese cities is extended by subdividing total EC into char-EC and soot-EC. Average char-EC concentrations show great differences between the fourteen cities and between winter and summer periods, with concentrations of 8.67 and 2.41 μg m^?3 in winter and summer, respectively. Meanwhile spatial and seasonal soot-EC variations are small, with average concentrations of 1.26 and 1.21 μg m^?3 in winter and summer, respectively. Spatial and temporal distributions of char-EC, similar to EC, are mainly influenced by local fuel consumption, as well as the East Asian monsoon and some meteorological factors such as the mixing height and wet precipitation. The small spatial and seasonal variation of soot-EC is consistent with its regional-to-global dispersion, which may suggest that soot carbon is not local carbon, but regional carbon. Char-EC/soot-EC ratios show summer minimum and winter maximum in all cities, which is in good agreement with the difference in source contributions between the two periods. As OC/EC ratio is affected by the formation of the secondary organic aerosol (SOA), char-EC/soot-EC ratio is a more effective indicator for source identification of carbonaceous aerosol than previously used OC/EC ratio.     

Emissions of gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) in the Shing Mun Tunnel,Hong Kong

Real-world vehicle emission factors for seventeen gas and particulate polycyclic aromatic hydrocarbons (PAHs) were quantified in the Shing Mun Tunnel, Hong Kong during summer and winter 2003. Naphthalene, acenaphthylene, and acenaphthene were the most abundant gas PAHs while fluoranthene and pyrene were the most abundant in the particle phase. Most (98%) of the gas PAHs consisted of two- and three-aromatic rings whereas most of the particle-phase PAHs were in four- (～60%) and five-ring (～17%) for fresh exhaust emissions. Average emission factors for the gas- and particle PAHs were 950–2564 μg veh^?1 km^?1 and 22–354 μg veh^?1 km^?1, respectively. Good correlations were found between diesel markers (fluoranthene and pyrene; 0.85) and gasoline markers (benzo[ghi]perylene and indeno[1,2,3-cd]pyrene; 0.96). Higher PAH emission factors were associated with a higher fraction of diesel-fueled vehicles (DV) passing through the tunnel. Separate emission factors were determined from diesel and non-diesel exhaust by the regression intercept method. The average PAH emission factor (i.e., sum of gas and particle phases) from DV (3085 ± 1058 μg veh^?1 km^?1) was ～5 times higher than that from non-diesel-fueled vehicles (NDV, 566 ± 428 μg veh^?1 km^?1). Ratios of DV to NDV emission factors were high for diesel markers (>24); and low for gasoline markers (<0.4).     

Free amino acids and osmoregulation in the intertidal pulmonate Onchidium tumidium

The aim of this study is to elucidate the osmoregulatory capabilities of the intertidal pulmonate Onchidium tumidium. Our results indicate that O. tumidium could tolerate hyperosmotic stress more effectively than hypoosmotic stress. In 10% seawater (SW), it was capable of maintaining its plasma hyperosmotic and hyperionic to the external medium. However, it rapidly gained weight in 10% SW, and no restoration of body weight was observed. In contrast, in 90% SW it was able to recover its body weight partially. In a hyperosmotic medium, accumulation of intracellular free amino acids (FAA) was responsible for cell volume regulation. The accumulated FAA might originate from protein catabolism, which occurred in the internal organs (IO). In contrast, the relatively smaller amination:deamination ratio of glutamate dehydrogenase in the body wall (BW) and IO of specimens exposed to hypoosmotic stress might lead to a higher rate of amino acid catabolism. This was supported by the greater ammonia contents in the BW and IO of, and higher rate of ammonia excretion by, specimens exposed to 10% SW. Received: 11 March 1998 / Accepted: 2 May 1999     

Characterization of controlled-release KMnO4 (CRP) barrier system for groundwater remediation: a pilot-scale flow-tank study

Release and spreading of permanganate (MnO(4)(-)) in the well-based controlled-release potassium permanganate (KMnO(4)) barrier system (CRP system) was investigated by conducting column release tests, model simulations, soil oxidant demand (SOD) analyses, and pilot-scale flow-tank experiments. A large flow tank (L x W x D=8m x 4m x 3m) was constructed. Pilot-scale CRP pellets (OD x L=0.05 m x1.5m; n=110) were manufactured by mixing approximately 198 kg of KMnO(4) powders with paraffin wax and silica sands in cylindrical moulds. The CRP system (L x W x D=3m x 4m x 1.5m) comprising 110 delivery wells in three discrete barriers was constructed in the flow tank. Natural sands (organic carbon content=0.18%; SOD=3.7-11 g MnO(4)(-)kg(-1)) were used as porous media. Column release tests and model simulations indicated that the CRP system could continuously release MnO(4)(-) over several years, with slowly decreasing release rates of 2.5 kg d(-1) (day one), 109 g d(-1) (day 100), 58 g d(-1) (year one), 22 g d(-1) (year five), and 12 g d(-1) (year 10). Mean MnO(4)(-) concentrations within the CRP system ranged from 0.5 to 6 mg l(-1) during the 42 days of testing period. The continuously releasing MnO(4)(-) was gradually removed by SOD limiting the length of MnO(4)(-) zone in the porous media. These data suggested that the CRP system could create persistent and confined oxidation zone in the subsurface. Through development of advanced tools for describing agent transport and facilitating lateral agent spreading, the CRP system could provide new approach for long-term in situ treatment of contaminant plumes in groundwater.     

Characterization of hydrocarbons, halocarbons and carbonyls in the atmosphere of Hong Kong

Ambient air quality measurements of 156 species including 39 alkanes, 32 alkenes, 2 alkynes, 24 aromatic hydrocarbons, 43 halocarbons and 16 carbonyls, were carried out for 120 air samples collected at two sampling stations (CW and TW) in 2001 throughout Hong Kong. Spatial variations of volatile organic compounds (VOCs) in the atmosphere were investigated. Levels of most alkanes and alkenes at TW site were higher than that at the CW site, while the BTEX concentrations at the two sites were close. The BTEX ratios at CW and TW were 1.6:10.1:1.0:1.6 and 2.1:10.8:1.0:2.0, respectively. For major halogenated hydrocarbons, the mean concentrations of chloromethane, CFCs 12 and 22 did not show spatial variations at the two sites. However, site-specific differences were observed for trichloroethene and tetrachloroethene. Furthermore, there were no significant differences for carbonyls such as formaldehyde, acetaldehyde and acetone between the two sites. The levels of selected hydrocarbons in winter were 1-5 times that in summer. There were no common seasonal trends for carbonyls in Hong Kong. The ambient level of formaldehyde, the most abundant carbonyl, was higher in summer. However, levels of acetaldehyde, acetone and benzaldehyde in winter were 1.6-3.8 times that in summer. The levels of CFCs 11 and 12, and chloromethane in summer were higher than that in winter. Strong correlation of most hydrocarbons with propene and n-butane suggested that the primary contributors of hydrocarbons were vehicular emissions in Hong Kong. In addition, gasoline evaporation, use of solvents, leakage of liquefied petroleum gas (LPG), natural gas leakage and other industrial emissions, and even biogenic emissions affected the ambient levels of hydrocarbons. The sources of halocarbons were mainly materials used in industrial processes and as solvents. Correlation analysis suggested that photochemical reactions made significant contributions to the ambient levels of carbonyls in summer whereas in winter motor vehicle emissions would be the major sources of the carbonyls. The photochemical reactivity of selected VOCs was estimated in this study. The largest contributors to ozone formation were formaldehyde, toluene, propene, m,p-xylene, acetaldehyde, 1-butene/i-butene, isoprene and n-butane, suggesting that motor vehicles, gasoline evaporation, use of solvents, leakage of LPG, photochemical processes and biogenic emission are sources in the production of ozone. On the other hand, VOCs from vehicles and gasoline evaporation were predominant with respect to reactions with OH radical.     

香港及珠三角地区MODIS高分辨率气溶胶光学厚度的反演

为了有效解决地区性和城市范围内的气溶胶分布并反演陆地上气溶胶的性质,一种针对中分辨率成像光谱辐射计(MODIS)的气溶胶反演新算法应运而生.本文首先通过改良的最小反射率技术(MRT)来确定季节性的地表反射率和利用瑞利通道辐射率中解析出大气上气溶胶的反射率来估计气溶胶的反射系数.结果表明,MRT地表反射率的图像和MODIS地表反射系数的产品(MOD09)有很好的契合度.两者的相关系数高达0.9.此外,考虑到不同气溶胶的光学性质和太阳观测组合对计算辐射传输的影响,本研究还制定了全面广泛的差算表(LUT).由此产生的卫星500m分辨率的气溶胶光学厚度(AOT)和香港太阳光度计(AERONET)及MicrotopsⅡ观测资料的相关系数r分别为0.96和0.87(相伴概率值P<0.0001).该研究证明了城区高分辨率气溶胶反演的可行性,还能帮助研究气溶胶的分布和城区大气瞬态污染的影响.此外,MODIS 500m分辨率的气溶胶光学厚度图像还可用于研究跨境气溶胶,使定位珠江三角洲区域污染源变得可行.     

Novel mutation and prenatal sonographic findings of glutaric aciduria (type I) in two Taiwanese families

Glutaric aciduria type I (GA I) is an autosomal recessively inherited inborn error with a defect of the enzyme glutaryl-CoA dehydrogenase (GCDH), which has never been diagnosed prenatally in Taiwanese patients. We present the prenatal sonographic findings and mutational analysis data of three children in two Taiwanese families. One patient from each family was diagnosed postnatally due to macrocephaly and neurological deterioration at 4 months and 10 months, respectively. The third child, sister of the first patient, was diagnosed prenatally at 11 weeks' gestation through chorionic villus sampling (CVS). Molecular analysis revealed that the fetus and child in Family 1 were homozygous for a common mutation, IVS10 -2A>C, which has not been reported in the Caucasian population. The patient in Family 2 was a compound heterozygote for IVS10 -2A>C and a novel mutation 749T>C (L238P). After genetic counseling, the couple decided to continue the second pregnancy. However, dilatation of quadrigeminal cistern (QC) and suspicious macrocephaly were noted at 30 weeks. Progressive dilatation of the QC associated with macrocephaly, fronto-temporal atrophy and wide space of perisylvian fissure were found in the follow-up scans. The affected girl was delivered at 37 weeks' gestation by cesarean section. Postnatal magnetic resonance imaging (MRI) studies confirmed the prenatal sonographic findings. With prenatal sonographic findings and mutational analysis presented in the present cases, the feasibility of prenatal diagnosis of GA I in high-risk pregnancy can not be overlooked. Copyright © 2002 John Wiley & Sons, Ltd.