Effects of inoculation of plant growth-promoting rhizobacteria on metal uptake by Brassica juncea

A greenhouse study was carried out with Brassica juncea to critically evaluate effects of bacterial inoculation on the uptake of heavy metals from Pb-Zn mine tailings by plants. Application of plant growth-promoting rhizobacteria, including nitrogen-fixing bacteria and phosphate and potassium solubilizers, might play an important role in the further development of phytoremediation techniques. The presence of these beneficial bacteria stimulated plant growth and protected the plant from metal toxicity. Inoculation with rhizobacteria had little influence on the metal concentrations in plant tissues, but produced a much larger above-ground biomass and altered metal bioavailability in the soil. As a consequence, higher efficiency of phytoextraction was obtained compared with control treatments.     

Heavy metals in oysters,mussels and clams collected from coastal sites along the Pearl River Delta,South China

Concentrations of 8 heavy metals:cadmium(Cd),copper (Cu),zinc(Zn),lead(Pb),nickel(Ni),chromium (Cr),antimony (Sb) and tin(Sn)were examined in 3 species of bivalves (Perna viridis,Crassostrea rivularis and Ruditapes philippinarum)collected from 25 sites along the Pearl River Delta coastal waters in the South China Sea from July to August 1996.In general,Cd,Cu,Zn and Sn concentrations in the three bivalve species collected from the Estuarine Zone were significantly higher than those collected from the Western and Eastern Zones of the Pearl River Delta,which are related to the existence of various anthropogenic activities in the catchment of the Pearl River Delta.The Western Estuarine Zone is mainly impacted by Cr,Ni and Cu contamination.In Victoria Harbor,heavy metal contamination is mainly due to Cu and Pb.Cd,Cu and Zn concentrations in oysters were significantly higher than those in mussels and clams.This could be explained by the fact that oysters live mainly in the Estuarine Zone of the Pearl River Delta which receives most of the polluting discharges from the catchment of the Delta.During turbid condition,heavy metals(soluble or adsorbed on suspended particulates)discharged from the Delta are filtered from the water column and subsequently accumulated into the soft body tissues of oysters.Heavy metal concentrations in the three bivalve species were compared with the maximum permissible levels of heavy metals in seafood regulated by the Public Health and Municipal Services Ordinance,Laws of Hong Kong, and it was revealed that Cd and Cr concentrations in the three bivalve species exceeded the upper limits.At certain hotspots in the Delta, the maximum acceptable daily load for Cd was also exceeded.     

Chromosome mosaicism and maternal cell contamination in chorionic villi

While chorionic villus sampling allows both early and rapid prenatal diagnosis of chromosome disorders, the accuracy of this technique has not been fully established. Maternal cell contamination and pseudomosaicism represent two major sources of diagnostic error. Combined use of both direct chromosome preparations and villus cultures is important in overcoming these problems. Direct preparations of villus tissue allow recognition of maternal cell contamination of villus cultures. Conversely, villus cultures yield higher resolution chromosomes and may be helpful in differentiating between true versus pseudomosaicism when two or more cell lines are identified in direct chromosome preparations. Preliminary data suggest that analysis of direct preparations from multiple individually processed villus fragments may also be of value in this regard. Until more experience is gained, mid-trimester amniocentesis should be offered to CVS patients when mosaicism is encountered.     

VOCs 组分监测数据在改进香港PATH 模型中的作用

 利用香港2 个监测站的VOCs 组分监测数据对香港PATH 模型进行了验证分析.结果明,PATH 模型在模拟VOCs 组分浓度上存在较大的误差.实际观测的VOCs 组分AOD、OLE、TOL 和XYL 浓度是模型模拟的2~3 倍;而模型模拟的PAR 和ETH 浓度是实际观测的 2~4倍.这些误差可能是由于当前使用的VOCs 排放清单低估了实际的VOCs 排放量,以及在估算来自不同排放源的排放量及组分分布上有较大的不确定性.使用高质量的VOCs 组分监测数据验证PATH 模型有助于指导改进VOCs 排放清单和理解复杂的光化学烟雾污染问题,从而改进和提高PATH 模型.     

Identification of a new Irgarol-1051 related s-triazine species in coastal waters

A previously unknown s-triazine species present in commercially available Irgarol-1051, a booster biocide additive in copper-based antifouling paints for the replacement of organotin-based antifoulants, has been identified in the coastal aquatic environment. After careful isolation, purification and characterization by high resolution MS-MS and (1)H NMR, the molecular structure of that unknown species is found to be N,N'-di-tert-butyl-6-methylthiol-s-triazine-2,4-diamine (designated as M3). Levels of Irgarol-1051, its major degradation product (M1) and the newly identified M3 in the coastal waters of Hong Kong, one of the world's busiest ports located in the southern coast of China, were monitored by SPME-GC-MS and SPME-GC-FID. Water samples from five locations within Hong Kong waters were analysed and the levels of Irgarol-1051, M1 and M3 were found to be 0.1-1.6 microg l(-1), 36.8-259.0 microg l(-1) and 0.03-0.39 microg l(-1), respectively. Our results indicate that M3 is relatively stable against photo- and bio-degradation and may pose considerable risk to primary producer communities in the coastal marine environment.     

Polychlorinated camphenes (toxaphenes), polybrominated diphenylethers and other halogenated organic pollutants in glaucous gull (Larus hyperboreus) from Svalbard and Bjørnøya (Bear Island)

The levels of polychlorinated camphenes (toxaphenes) were investigated in liver samples from 18 glaucous gulls (Larus hyperboreus) from Bj?rn?ya (74 degrees N, 19 degrees E) and four individuals from Longyearbyen (78 degrees N, 15 degrees E). Additionally brominated flame retardants (BFRs), PCBs and chlorinated pesticides were investigated in liver and intestinal contents of 15 of the glaucous gulls from Bj?rn?ya. Of the analysed BFRs only 2,2',4,4'-tetra- and 2,2',4,4',5-pentabrominated diphenylethers (PBDE 47 and 99) could be detected. The concentrations ranged between 2 and 25 ng/g ww. In addition, high resolution measurements with GC/HRMS revealed the existence of several, not quantified, PBDEs and polybrominated biphenyls (PBBs) congeners in the samples. B9-1679 and B8-1413 were the dominating toxaphenes with median concentrations of 8 and 15 ng/g ww. Concentrations of toxaphenes and PBDEs were up to 100-times lower than the concentrations of PCB and some of the pesticides. PCB and p,p/-DDE constituted 90% of the contaminants found.     

Determination and analysis of sorption of 137Cs to soils in Hong Kong reservoir

Soils from a local reservoir had been analyzed for their physical and chemical properties, distribution coefficients Kd and sorption rates for 137Cs. It was found that soils in Hong Kong were relatively low in organic matter and more acidic than those in some other countries. In sorption experiments, the rates of decrease in water activity concentration were initially very high, higher for larger mass of soils added, and then slowed down. The larger the mass, the shorter was the time for equilibrium. Three isotherms had been obtained by varying one of the three parameters (initial water activity concentration, slurry ratio and particle size) at a time. For constant initial water activity concentration and random sizes, percent sorption increased with slurry ratio. For soils of constant mass and random sizes. percent sorption decreased with increasing initial water activity concentration. For constant initial water activity concentration and slurry ratio, percent sorption increased with decreasing size of soil particles. A simple logistic model was developed to explain some of the findings.     

Correlation between phenotypic expression of de novo marker chromosomes and genomic organization using replicational banding

It has been suggested that actively expressed genes are primarily located in early replicating bands. This hypothesis is supported by cytogenetic and pregnancy outcome data from four consecutive cases of prenatally detected de novo marker chromosomes. Two fetuses with major anomalies had large early replicating bands, while the marker in a third phenotypically normal fetus was late replicating. In the fourth case, a ring marker chromosome had only a small early replicating region. Pregnancy termination was elected. While no structural malformations were apparent, potential intellectual function in this case remains unresolved. An understanding of the relationship between genomic organization and chromosome banding is critical in counseling for prenatally detected de novo marker chromosomes. Replicational banding is particularly helpful in recognizing genes that may be actively expressed and result in developmental abnormality.     

Compensation effect during the pyrolysis of tyres and bamboo

Pyrolysis parameters (e.g. pre-exponential factor A, and activation energy E) of two waste materials, namely, tyre rubber and bamboo scaffolding, based on the Arrhenius equation were obtained from weight loss data via thermogravimetry at different heating rates. The compensation effect, which suggests that the linear variation in the pre-exponential factor and the activation energy, was observed for these materials. This can be attributed to the variety of active sites over the reactant surface in the course of decomposition. The calculated data from several revised, first-order models were compared with similar models in the literature. It has been shown that both literature and our calculated data exhibit high linearity in terms of ln A and E, revealing that the latter agree well with other researchers’ work.