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Exotic species especially Asteraceae plants severely invade wetlands in Shenzhen Bay, an important part of the coast wetland in Guangdong-Hong Kong-Macau Bay Area, China. However, the reasons causing their expansion are unclear. The leaf traits and expansion indices of six invasive Asteraceae plants from the Overseas Chinese Town (OCT) wetland were studied and the results showed that nearly 45% of the total plant species (31 out of 69 species) in the OCT wetland, belonging to 15 families and 27 genera, were exotic invasive species. The expansion indices of six Asteraceae species negatively correlated with their leaf construction cost based on mass (CCM), caloric values and carbon concentration, but their relations with ash content were positive. Multiple linear regression analysis revealed that CCM was the most important factor affecting the expansion of an exotic species, indicating CCM may be an important reason causing the expansion of exotic species in coastal wetlands., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Microplastic (MP) pollution is an emerging problem in the marine environment and the assessment of the presence and abundance of microplastics in wild organisms is essential for risk assessment. The occurrence of microplastics in four species of barnacles at 30 sites in Hong Kong waters was investigated. The median number of microplastics ranged between 0 and 8.63 particles g -1 wet weight, or 0 and 1.9 particles individual -1 , with fibers being the most abundant type of microplastics. The chemical composition of 152 pieces out of 606 potential microplastics was analyzed using micro-Fourier Transform Infrared Spectroscopy (μ-FTIR). Fifty-two of them were synthetic polymers, 95 natural cotton fibers and five unknowns. Eight types of polymer were identified with cellophane being the most abundant (58%). Correlation analysis was conducted between the abundance of MPs in sediments obtained in our previous study and that in individual barnacle species in this study, and a positive correlation was established for the barnacle Amphibalanus amphitrite, highlighting the potential of using this species as a bioindicator of microplastics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Effects of wastewater discharge on radial oxygen loss (ROL), formation of iron (Fe) plaque on root surface, and their correlations in Bruguiera gymnorrhiza (L.) Poir and Excoecaria agallocha L. were investigated. ROL along a lateral root increased more rapidly in control than that in strong wastewater (with pollutant concentrations ten times of that in municipal sewage, 10NW) treatment, but less Fe plaque was formed in control for both plants. For B. gymnorrhiza receiving 10NW, Fe plaque formation was more at basal and mature zones than at root tip, while opposite trend was shown in E. agallocha. At day 0, the correlation between ROL and Fe plaque was insignificant, but negative and positive correlations were found in 10NW and control, respectively, at day 105, suggesting that more ROL was induced leading to more Fe plaque. However, excess Fe plaque also served as a 'barrier' to prevent excessive ROL in 10NW plants., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

To investigate the relationship between personality, club-drug use and high-risk drug-related behaviour, 360 club-drug users and 303 non-drug users in Hong Kong were assessed on measures of two impulsivity dimensions, reward drive and rash impulsivity, and a related trait of punishment sensitivity. The most frequently used drugs were ketamine, ecstasy, and cannabis, with the majority of participants using two or more drugs on any one occasion. Club-drug users were more rash-impulsive and reward-driven, and less punishment-sensitive than non-drug users (p<0.001). Rash impulsivity, but not reward drive or punishment sensitivity, was significantly (p<0.001) associated with risky drug-related behaviour. There was no association between any personality traits and preferred drug. These findings suggest that, while those who use club drugs are generally more impulsive and less punishment-sensitive, some discrete facets of impulsivity are associated with differing patterns of drug-use behaviour.

The concentrations of polychlorinated biphenyls (PCBs) in surface sediments of ten mangrove sites in Hong Kong were determined by Congener-specific and Arcolor methods. Spatial variations were found between mangrove sites and within the same site, indicating that the sediment samples were heterogeneous and total PCBs concentrations in mangrove sediments should be normalised to compensate for natural variability and for identifying serious anthropogenic contamination. In addition to total organic carbon, Al, Fe and Mn were possible normalisers. Based on PCB/normaliser ratio and 95% prediction limits of scatter plots between total PCB and normaliser, all mangrove sites were not seriously contaminated by human activities. The estimated total PCBs concentrations (quantified by Congener-specific method) for most sediment ranged from 0.5 to 5.8 ng g(-1) (dry weight, n = 92). However, very high concentrations of PCB were found in sub-samples from Yi O, Tolo Pond and Lai Chi Wo, suggesting that these samples represented the PCB contaminated "hot spots".

Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) have been found in mangrove sediments due to anthropogenic pollution, and microbial degradation has been suggested as the best way to remove PAHs from contaminated sediments. The degradation of phenanthrene, a model PAH compound by bacteria, either the enriched mixed culture or individual isolate isolated from surface mangrove sediments was examined. The effects of salinity, initial phenanthrene concentrations and the addition of glucose on biodegradation potential were also investigated. Results show that surface sediments collected from four mangrove swamps in Hong Kong had different degree of PAH contamination and had different indigenous phenanthrene-degrading bacterial consortia. The enriched bacteria could use phenanthrene as the sole carbon source for growth and degrade this PAH compound accordingly. A significant positive relationship was found between bacterial growth and percentages of phenanthrene degradation. The phenanthrene biodegradation ability of the enriched mixed bacterial culture was not related to the degree of PAH contamination in surface sediments. The growth and biodegradation percentages of the enriched mixed culture were not higher than that of the individual isolate especially at low salinity (0 and 10 ppt). High salinity (35 ppt) inhibited growth and biodegradation of phenanthrene of a bacterial isolate but less inhibitory effect was found on the mixed culture. The inhibitory effects of salinity could be reduced with the addition of glucose.

The total suspended dust levels, particle shape and size distributions and metal concentrations (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of wood dust in the breathing zone of 3 small wood-working establishments were monitored. In vitro culture assay indicated that the mortality of alveolar macrophage was related to the metal content of dust collected from these 3 workplaces.

Airborne particles were collected in two small urban gardens along the roads with heavy traffic in Hong Kong. The chemical and physical properties of the particles of a diameter about 1 micron were analysed by a scanning electron microscope incorporated with a x-ray energy dispersive microanalyzer and an atomic absorption spectrophotometer. The cytotoxicities of particles were compared using an in vitro alveolar macrophage culture assay. It was found that both particles significantly increase (p less than 0.05) the release of lactate dehydrogenase and acid phosphatase into the medium in addition to damage the surface morphology and intracellular structures of the macrophages to a variable extent after exposure to the particles.

An ecological survey was conducted on metal contamination (including Cd, Pb, Ni, Zn, Cu, Mn and Fe) of vegetation (leaf of Bauhina variegata), surface soil (0-1 cm) and dust (from road curbs) collected at 13 urban parks near busy roads (with heavy traffic volume) in Hong Kong. Samples from roadside parks had significantly higher metal contents than the control site (away from automobile traffic). A close correlation was found between traffic volume and metal contents of leaf, soil and dust. Washing of leaf samples reduced the levels of Cu, Mn, Zn and Fe contamination and suggested that the source of heavy metal pollution was mainly due to aerial deposition from motor vehicles.