Evaluating seasonal variations of fecal coliform colonization in Magallana hongkongensis and Crassostrea rhizophorae: A preliminary study of oyster quality grown in Hong Kong aquacultural farms

The objective of this research is to investigate the spatial and temporal patterns of bacteriological quality in raw oysters sampled from different aquacultural farms located in Aberdeen Typhoon Shelter, Carp Gates, Lau Fau Shan, Ma Wan, and Mui Wo in Hong Kong. Magallana hongkongensis and Crassostrea rhizophorae were collected and analyzed for fecal coliforms. Throughout the 13-month monitoring period, all samples had generally high bacterial loads, ranging from 1.4 × 10⁷ cfu/g to 8.9 × 10⁷ cfu/g and exceeded the guideline suggested by the HKSAR government (i.e. 700 MPN/100 g). Besides, a linear regression analysis showed that the amount of fecal coliforms in raw oysters had strong correlations (p < 0.05) to the monthly rainfall records throughout the monitoring period. Such findings illustrate the high loading of pathogenic microorganisms in the tissue of oysters which represent a potential threat of people contracting foodborne diseases.

Comparative assessment of soil quality parameters after implementing afforestation programme in forest areas of Hong Kong

The objective of this research is to investigate and compare the alteration of soil parameters with and without afforestation programme in a Hong Kong forest, analysed by Principal Component Analysis (PCA). One hundred soil samples were collected from the following sites: Pak Ngau Shek (PNS), Shing Mun (SM), Tai Po Kau (TPK), Tai Tong (TT) (forest with afforestation programme) and Lantau Peak (LP) (control site). A significant difference was found in only two out of 16 parameters: pH (8.34-8.87) and PAHs (4.35-6.32 μg/kg) by comparing the soils taken in the forest with and without an afforestation programme implemented. Three principle components are responsible for soil quality variations in the studied sites. The first, second and third components included pH (0.167) and EC (0.176), PAHs (0.331) and PAHs (0.207), respectively. This framework provides information on the least disturbance of soil properties for the afforestation programme. To conclude, a rigorous monitoring of soil quality is necessary to assess forest health after an afforestation programme. Besides, in the long term, an appropriate forest preservation programme should be implemented to achieve rural area sustainability.

An assessment of heavy metal contamination in the marine soil/sediment of Coles Bay Area, Svalbard, and Greater Bay Area, China: a baseline survey from a rapidly developing bay

The objective of this research is to investigate the pollution levels of tin (Sn), arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), and zinc (Zn) of soil/sediment taken in Coles Bay Area (CBA), Svalbard, and Great Bay Area (GBA), China, in an attempt to evaluate the pollution potential related to recent development in the areas. A total of 150 soil/sediment samples were collected in each location. Heavy metal concentrations were detectable levels at all sites and the values of Cd of all soil/sediment samples were higher than Dutch Target and Intervention Values. Heavy metal concentration in soil/sediment was further analyzed by principal component analysis (PCA). It was revealed that three components were found in two studying sites and contributed 60.2% and 75.9% of variations to reflect soil/sediment quality in CBA and GBA, respectively. Based on the results of KMO (0.52) and Bartlett's test (p < 0.000), there are 32.1%, 15.6%, and 11.1% and 39.45%, 19.01%, and 17.52% of the variance in the first, second, and third component explained that the metal concentration of Pb, Cd, and Sn was highly correlated with the soil/sediment quality in CBA and GBA, respectively. Among these three heavy metals, Cd concentration was the common dominant factor to affect soil/sediment quality in these two study sites. It is recommended that investigation of the sources of pollution (either point or non-point source) during CBA or GBA development and management together with consideration of abiotic (soil)-biotic (organisms) interactions should be taken into account when choosing suitable remediation strategies in the future.

Feasibility of Sijunzi Tang (Chinese medicine) to enhance protein disulfide isomerase activities for reactivating malate dehydrogenase deactivated by polycyclic aromatic hydrocarbons

The objective of this research is to investigate the enzymatic activities between protein disulfide isomerase (PDI) found in animals and plants and the properties found in a commonly used Chinese medicine called Sijunzi Tang. During the investigation, PDI, which is a monomer with a molecular mass of 57.0 kDa, was used to reactivate malate dehydrogenase (MDH). However, with the interference of polycyclic aromatic hydrocarbons (PAHs), evidence indicates that such chemicals are carcinogenic, mutagenic, and toxic to humans. The enzymatic activity of PDI found in animal's liver and plant was 1657 folds of purification; 0.284 unit/mg of enzyme activity, and 5694.4 folds of purification; 1.00 unit/mg of enzyme activity, respectively. PDI extracted in treated animal and plant tissue revealed 2.40% and 80.44% of regaining MDH enzymatic activity, respectively. Although in its initial phase of investigation, it is assumed that the properties found in Sijunzi Tang can help regain enzymatic activity in those affected by xenobiotic substances, thus, making it a potential ingredient in assisting with PDI functions.

Behavioural toxicity studies of Cyclope neritea and Nassarius mutabilis exposed to polycyclic aromatic hydrocarbons

The objective of the work was to study behavioural change of Cyclope neritea (sea snail) and Nassarius mutabilis (land snail) upon exposure to different levels of PAHs. Snail's behaviour was translated and expressed in Behavioural State Score (BSS) where the score ranged from "0" to "5" points refers to the ascending level of locomotion of a snail. A significant difference was found in snail's behaviour in 25.0 mg/L than in 0.5 mg/L with p value smaller than 0.01. BSS scores appear most frequent on the treatment and control group were 5 (61.5-64.5%) and 2 (41.0-45.0%), respectively. Intersex behaviour was found in all species (i.e. the same sex was grouped together) regardless of PAH concentrations. This is the first reported to study the behavioural change of snail sampled in Hong Kong area when exposed to PAHs. Further studies should be carried on the impact of snail's behaviour exposure on each congener in the family of PAHs.

The potential of Mikania micrantha (Chinese creeper) to hyperaccumulate heavy metals in soil contaminated by electronic waste

The objective of this study is to investigate the contributions of Mikania micrantha (chinese creeper) to remediate heavy metal pollutants present in an e-waste-contaminated soil. Different proportions of e-waste soil (0%, 25%, 50%, 75%, and 100% w/w) planted with Cynodon dactylon together with the test species were prepared for testing relative seed germination (RSG), relative root growth (RRG), and germination index (GI) tests. A significant higher value of GI (77.8%) was found in M. micrantha than that of the other species when planting in 100% e-waste-contaminated soil. A significant correlation (< 0.05) was found between heavy metal concentration and germination assays in M. micrantha. A significant decrease in heavy metal concentration of the polluted soil after the experiment indicated that biomolecule development studies to determine the aggregate benefit of M. micrantha for phytoremediation remain to be studied in future.

Enhancement of Chlorella vulgaris harvesting via the electro-coagulation-flotation (ECF) method

This article explores the potential of using an electro-coagulation-flotation (ECF) harvester to allow flotation of microalgae cells for surface harvesting. A response surface methodology (RSM) model was used to optimize ECF harvesting by adjusting electrode plate material, electrode plate number, charge of the electrodes, electrolyte concentration, and pH value of the culture solution. The result revealed that three aluminum electrode plates (one anode and two cathodes), brine solution (8 g/L), and acidity (pH = 4) of culture solution (optimized ECF harvester) The highest flocculant concentration was measured at 2966 mg/L after 60 min and showed a 79.8 % increase of flocculation concentration. Such results can provide a basis for designing a large-scale microalgae harvester for commercial use in the future.

Monitoring and assessment of heavy metal contamination in a constructed wetland in Shaoguan (Guangdong Province, China): bioaccumulation of Pb, Zn, Cu and Cd in aquatic and terrestrial components

The objective of this study is to evaluate the current status of heavy metal concentrations in constructed wetland, Shaoguan (Guangdong, China). Sediments, three wetland plants (Typha latifolia, Phragmites australis, and Cyperus malaccensis), and six freshwater fish species [Carassius auratus (Goldfish), Cirrhinus molitorella (Mud carp), Ctenopharyngodon idellus (Grass carp), Cyprinus carpio (Wild common carp), Nicholsicypris normalis (Mandarin fish), Sarcocheilichthys kiangsiensis (Minnows)] in a constructed wetland in Shaoguan were collected and analyzed for their heavy metal compositions. Levels of Pb, Zn, Cu, and Cd in sediments exceeded approximately 532, 285, 11, and 66 times of the Dutch Intervention value. From the current study, the concentrations of Pb and Zn in three plants were generally high, especially in root tissues. For fish, concentrations of all studied metals in whole body of N. mormalis were the highest among all the fishes investigated (Pb 113.4 mg/kg, dw; Zn 183.1 mg/kg, dw; Cu 19.41 mg/kg, dw; 0.846 mg/kg, dw). Heavy metal accumulation in different ecological compartments was analyzed by principle component analysis (PCA), and there is one majority of grouped heavy metals concentration as similar in composition of ecological compartment, with the Cd concentration quite dissimilar. In relation to future prospect, phytoremediation technology for enhanced heavy metal accumulation by constructed wetland is still in early stage and needs more attention in gene manipulation area.

Application of veterinary antibiotics in China's aquaculture industry and their potential human health risks

China contributes to more than 60 % of the global aquaculture production, and its aquaculture industry has become one of the main players in food security. A large amount of antibiotics is believed to be used in fish cultivation for ensuring adequate production. The use of antibiotics as disease control agents and growth promoter in aquaculture in China has raised significant concerns recently because of the potential threats to human health. The extensive use of antibiotics in aquaculture may result in water and sediment contamination and the development of antibiotic resistance genes. In this review, the role of aquaculture in antibiotic contamination of the environment as well as the emerging concern of antibiotic resistance genes in China is discussed. Based on this review, it has been concluded that more information regarding the types and quantities of antibiotics used by Chinese fish farmers is required. Studies about the contribution of antibiotic usage in aquaculture to environmental levels in surface water, their potential risks on environment and human health, and the existence and spread of antibiotic resistance genes in aquaculture are needed.

Maximization of cell growth and lipid production of freshwater microalga Chlorella vulgaris by enrichment technique for biodiesel production

Chlorella vulgaris was cultivated under limitation and starvation and under controlled conditions using different concentrations of nitrate (NaNO₃) and phosphate (K₂HPO₄ and KH₂PO₄) chemicals in modified Bold basal medium (BBM). The biomass and lipid production responses to different media were examined in terms of optical density, cell density, dry biomass, and lipid productivity. In the 12-day batch culture period, the highest biomass productivity obtained was 72.083 mg L^-1 day^-1 under BBM - N_controlP_limited condition. The highest lipid content, lipid concentration, and lipid productivity obtained were 53.202 %, 287.291 mg/L, and 23.449 mg L^-1 day^-1 under BBM - N_ControlP_Deprivation condition, respectively. Nitrogen had a major effect in the biomass concentration of C. vulgaris, while no significant effect was found for phosphorus. Nitrogen and phosphorus starvation was found to be the strategy affecting the lipid accumulation and affected the lipid composition of C. vulgaris cultures.

Angiosuppressive properties of marine-derived compounds-a mini review

Angiogenesis, formation of new blood vessels from preexisting one, is a critical step of tumorgenesis of solid tumors. Therefore, antiangiogenic therapy is one of the promising approaches to control tumor growth. In the past 20 years, a lot of compounds have been tested for their antiangiogenic properties. Bevacizumab, Avastin^®, the first antiangiogenic drug approved by the US FDA, has been widely used in clinic for treating cancer. Indeed, many synthetic compounds are highly toxic and exert side effects even though they are effective in inhibiting neovessel formation and cancer cell growth. Using natural compounds or their derivatives is one of the ways to solve these problems. Sinomenine and ginsenosides are common antiangiogenic and anticancer compounds that are extracted from herbal medicines. Recent findings suggested that marine algae-derived natural pigments also possess similar activities. It has been reported that fucoxanthin from Undaria pinnatifida, Siphonaxanthin from Codium fragile, can inhibit angiogenesis and cancer growth effectively. In conclusion, natural compounds derived from marine algae could provide a novel and safe source for new drug development in anticancer and antiangiogenic properties in the future.

Combined effects of land reclamation, channel dredging upon the bioavailable concentration of polycyclic aromatic hydrocarbons (PAHs) in Victoria Harbour sediment, Hong Kong

The up-to-date concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment materials of Victoria Harbour was investigated so as to evaluate the pollution potential associated with the reclamation projects in Hong Kong. A total of 100 sediment samples were collected at 20 locations. Except the control point in reservoir, the PAHs concentrations were detectable levels all sites (131-628.3ng/g, dw) and such values were higher than Dutch Target and Intervention Values (the New Dutch standard in 2016). The PAHs concentration indicating that construction waste and wastewater discharges were the main pollutant sources. Results of correlation in single cell gel electrophoresis assay (comet assay) studies also revealed that the PAHs concentration was highly correlated (<0.01) with DNA migration (i.e. the length of tail moment of fish cells) in 5mg/ml of PAHs. The above observation indicates that the PAHs present in the sediment may substantially effect the marine ecosystem. Although the dredged sediment can be a useful sea-filling material for land reclamation; however, the continuing leaching of PAHs and its impact on the aquatic environment need to be studied further.

Comparative assessment of water quality parameters of mariculture for fish production in Hong Kong Waters

The objective of the study is to evaluate the effect of fish cultivation on water quality in fish culture zone (FCZ) and analysed by Principle Component Analysis (PCA). 120 surface water samples were collected from Hong Kong Waters (60 samples in Victoria Harbour and another 60 in Ma Wan FCZ). Significant difference was found in dissolved oxygen (MW: 59.6%; VH: 81.3%), and Escherichia coli (MW: 465 CFU/100 ml; VH: 162.5 CFU/100 ml). Three principle components are responsible for water quality variations in the studying sites. The first component included E. coli (0.625) and dissolved oxygen (0.701). The second included E. coli (0.387) and ammonical-nitrogen (0.571). The third included E. coli (0.194) and ammonical-nitrogen (0.287). This framework provides information to assess the relative contribution of eco-aquaculture to nutrient loads and the subsequent risk of eutrophication. To conclude, a rigorous monitoring of water quality is necessary to assess point and nonpoint source pollution. Besides, appropriate remediation techniques should be used to combat water pollution and achieve sustainability.

Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China

The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication.

Arbuscular mycorrhizal fungi enhance both absorption and stabilization of Cd by Alfred stonecrop (Sedum alfredii Hance) and perennial ryegrass (Lolium perenne L.) in a Cd-contaminated acidic soil

A greenhouse pot experiment was conducted to compare the phytoextraction efficiencies of Cd by hyper-accumulating Alfred stonecrop (Sedum alfredii Hance) and fast-growing perennial ryegrass (Lolium perenne L.) from a Cd-contaminated (1.6 mg kg(-1)) acidic soil, and their responses to the inoculations of two arbuscular mycorrhizal (AM) fungal strains, Glomus caledonium 90036 (Gc) and Glomus mosseae M47V (Gm). Ryegrass and stonecrop were harvested after growing for 9 and 27 wk, respectively. Without AM fungal inoculation, the weekly Cd extraction by stonecrop (8.0 μg pot(-1)) was 4.3 times higher than that by ryegrass (1.5 μg pot(-1)). Both Gc and Gm significantly increased (P < 0.05) root mycorrhizal colonization rates, soil acid phosphatase activities, and available P concentrations, and thereby plant P absorptions (except for Gm-inoculated ryegrass), shoot biomasses, and Cd absorptions (except for Gm-inoculated stonecrop), while only Gc-inoculated stonecrop significantly accelerated (P < 0.05) the phytoextraction efficiency of Cd by 78%. In addition, both Gc and Gm significantly decreased (P < 0.05) phytoavailable Cd concentrations by 21-38% via elevating soil pH. The results suggested the potential application of hyper-accumulating Alfred stonecrop associated with AM fungi (notably Gc) for both extraction and stabilization of Cd in the in situ treatment of Cd-contaminated acidic soil.

Mixed arbuscular mycorrhizal (AM) fungal application to improve growth and arsenic accumulation of Pteris vittata (As hyperaccumulator) grown in As-contaminated soil

A greenhouse pot experiment was conducted to study the effects of three types of single inoculum [indigenous mycorrhizas (IM) isolated from As mine, Glomus mosseae (GM) and Glomus intraradices (GI)] and two types of mixed inoculum (mixed with IM and either GM or GI) on the growth response of Pteris vittata (hyperaccumulator) and Cynodon dactylon (non-hyperaccumulator) at three levels of As concentrations (0, 100 and 200mgkg(-1)). Both mycorrhizal plants exhibited significantly higher biomass, and N and P accumulation in its tissue than the control. Among the mycorrhizal inoculum, the mixed inoculum IM/GM promoted substantially higher mycorrhizal colonization and arsenate reductase activity in P. vittata than C. dactylon, among all As levels. The portion of Paris arbuscular mycorrhizal structure (observed in colonized roots) together with the highest As translocation factor of 10.2 in P. vittata inoculated with IM/GM was also noted. It was deduced that IM/GM inoculum may be the best choice for field inoculation at any contaminated lands as the inoculum exhibited better adaptation to variable environmental conditions and hence benefited the host plants.

Synergistic effects of arbuscular mycorrhizal fungi and phosphate rock on heavy metal uptake and accumulation by an arsenic hyperaccumulator

The effects of arbuscular mycorrhizal (AM) fungi and phosphate rock on the phytorextraction efficiency of a hyperaccumulator (Pteris vittata) and a non-hyperaccumulator (Cynodon dactylon) plant were studied. Both seedlings were planted in As contaminated soil under different treatments [(1) control (contaminated soil only), (2) indigenous mycorrhizas (IM), (3) mixed AM inoculum [indigenous mycorrhiza + Glomus mosseae (IM/Gm)] and (4) IM/Gm + phosphate rock (P rock)] with varying intensities (40%, 70% and 100%) of water moisture content (WMC). Significant As reduction in soil (23.8% of soil As reduction), increase in plant biomass (17.8 g/pot) and As accumulation (2054 mg/kg DW) were observed for P. vittata treated with IM/Gm + PR at 100% WMC level. The overall results indicated that the synergistic effect of mycorrhiza and P rock affected As subcellular distribution of the hyperaccumulator and thereby altered its As removal efficiency under well-watered conditions.

The effect of arbuscular mycorrhizal fungi and phosphate amendement on arsenic uptake, accumulation and growth of Pteris vittata in As-contaminated soil

This study investigated the contributions of mixed arbuscular mycorrhizal fungi (AMF) inoculum-i.e., mixed populations of indigenous mycorrhiza (Glomus intraradices, Glomus geosporum, Glomus mosseae) (IM) isolated from arsenic (As) contaminated soil and non-indigenous mycorrhiza such as G. mosseae (GM), which possess metal tolerance characteristics-and the addition of phosphate rock (PR) towards the uptake and accumulation of As by Pteris vittata (As hyperaccumlator) grown in As-contaminated soil. Regardless of As levels added to soil, plant growth was substantially improved in amended treatments when compared with the control. In addition, root surface area (0 mg/kg As: 15.2 cm2; 150 mg/kg As: 16.9 cm2; 300 mg/kg As: 20.7 cm2), chlorophyll contents (0 mg/kg As: 1.16 mg/g; 150 mg/kg As: 1.46 mg/g; 300 mg/kg As: 1.81 mg/g) and As translocation factor (0 mg/kg As: 0; 150 mg/kg As: 4.29; 300 mg/kg As: 5.22) in P. vittata of PR+IM/GM were also increased. Such combination could further enhance plant growth (indicated by higher N, P and chlorophyll contents) and As uptake by P. vittata.

Variation in arsenic, lead and zinc tolerance and accumulation in six populations of Pteris vittata L. from China

Arsenic, Pb and Zn tolerance and accumulation were investigated in six populations of Pteris vittata collected from As-contaminated and uncontaminated sites in southeast China compared with Pteris semipinnata (a non-As hyperaccumulator) in hydroponics and on As-contaminated soils. The results showed that both metallicolous and nonmetallicolous population of P. vittata possessed high-level As tolerance, and that the former exhibited higher As tolerance (but not Pb and Zn tolerance) than the latter. In hydroponic culture, nonmetallicolous population clearly showed significantly higher As concentrations in fronds than those in metallicolous populations. In pot trials, As concentrations in fronds of nonmetallicolous population ranged from 1060 to 1639 mg kg(-1), about 2.6- to 5.4-folds as those in metallicolous populations. It was concluded that As tolerance in P. vittata resulted from both constitutive and adaptive traits, Pb and Zn tolerances were constitutive properties, and that nonmetallicolous population possesses more effective As hyperaccumulation than metallicolous populations.

A liquid-filled tunable double-focus microlens

A novel microlens design with tunable double-focus is presented. It is fabricated by adding only one SU-8 photolithography step to the well-developed liquid-filled microlens fabrication process. The thickness of this layer determines the thickness difference between the central and peripheral region of the membrane, the deformation of which is used to define the surface profile of the microlens. The stepped thickness variation is finally manifested as the difference in deformation contour at two different regions of the membrane when subjected to uniform applied pressure, thereby causing two focal lengths to appear. Experimental and simulation results are presented, from which the tunability of the focal lengths of the double-focus microlens is demonstrated to be effective over a wide range through combining the structural design with pressure control. The successful demonstration of this unconventional microlens design concept will potentially extend t application of liquid-filled microlens technology.

Interaction of higher plant (jute), electrofused bacteria and mycorrhiza on anthracene biodegradation

The interaction of bacteria, mycorrhiza and jute (Corchotus capsulari, a higher plant) to reduce anthracene in different concentrations of spiked soils was investigated. Dominant indigenous bacterium (Pseudomonas sp.) isolated in the rhizosphere of jute was electrofused with anthracene degraders (Sphingomonas paucimobilis and Pseudomonas aeruginosa) which were able to produce different types of biosurfactants. The highest population (56 x 10(5)CFU/g) was found in the planted soil with the inoculation of mixtures of electrofused anthracene degraders after 7 days. The growth of anthracene degraders in the spiked soil was improved by gene transfer from indigenous bacteria. After 35 days, enhanced anthracene removals were observed in inoculated soils planted with jute (65.5-75.2%) compared with unplanted soil without inoculation (12.5%). The interaction of jute and electrofused S. paucimobilis enabled the greatest reduction of soil anthracene with or without the addition of P. aeruginosa. Mycorrhizal colonization was not significantly inhibited by anthracene in soils up to 150 mg/kg. Inoculation of jute with Glomus mosseae and Glomus intraradices improved plant growth and enhanced anthracene removal in the presence of electrofused S. paucimobilis.

Metal concentrations of common freshwater and marine fish from the Pearl River Delta, south China

Sediments and fish, including tilapia (Oreochromis mossambicus), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idellus), and mandarin fish (Siniperca chuatsi) were collected from different fish ponds in the Pearl River Delta (Tanzhou, Sanjiao, Guangzhou, Shipai, Changan, and Mai Po) for the analysis of metalloids and heavy metals [arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb)]. The pollution of As in pond sediments was great; however, As in the edible parts of pond fish were within the international permissible safety levels for human consumption. Axial muscles from 10 species each of freshwater and marine fish purchased from markets in Hong Kong were also analyzed for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. Freshwater fish contained 0.24 to 2.13 mg/kg As, 0.10 to 0.17 mg/kg Cd, 0.09 to 0.36 mg/kg Cr, 0.06 to 0.35 mg/kg Cu, 0.07 to 0.34 mg/kg Hg, 0.04 to 0.36 mg/kg Ni, 0.11 to 0.52 mg/kg Pb, and 2.67 to 19.1 mg/kg Zn (wet weight). Marine fish had higher Hg and lower Pb concentrations than freshwater fish. A few fish species had average concentrations greater than the international standards for Cd and Pb established by the European Union and the China National Standard Management Department. Total Hg concentrations in 10 of 20 market fish species were generally greater than those of the World Health Organization's recommended limit of 0.2 mg/kg for at-risk groups, such as children and pregnant women. Daily intake through fish consumption of these metals were compared with the Provisional Tolerable Weekly Intake proposed by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives. There appears to be potential threat to local people from Hg contamination because of the high marine fish consumption rate (142 g/d/person).

Exposure to polybrominated diphenyl ethers associated with consumption of marine and freshwater fish in Hong Kong

Concentrations of polybrominated diphenyl ethers (PBDEs) in market fish have not previously been reported in Hong Kong. Axial and ventral muscles from 10 each common species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for 22 PBDEs. Among the 10 freshwater fish species, spotted snakehead (Channa maculate) contained the highest level of PBDEs in ventral muscle (130 ng g(-1) wet wt.). For marine fish, bigeye (Priacanthus macracanthus) showed significantly higher levels of PBDEs (60.7 ng g(-1)wet wt. in ventral tissue) than all other marine species. The levels of PBDEs in fish samples ranged from 0.53 to 130 ng g(-1)wetwt. The tetrabrominated congener BDE-47 and pentabrominated BDE-99 were the predominant congeners, which accounted for 27% and 30%, respectively, of the total PBDEs. Daily PBDE intake was calculated according to the different fish consumption rate for Hong Kong consumers, and the results ranged from 222 to 1198 ng day(-1) for marine fish and 403-2170 ng day(-1) for freshwater fish. The daily PBDE intake from fish reported here were higher than those reported from the United States (8.94-15.7 ng day(-1)) and Europe (14-23.1 ng day(-1)).

Residual levels of DDTs and PAHs in freshwater and marine fish from Hong Kong markets and their health risk assessment

Axial and ventral muscle from 10 each species of freshwater and marine fish purchased from markets in Hong Kong were analyzed for dichlorodiphenyltrichloroethane (total DDTs including DDE, DDD and DDT) and polycyclic aromatic hydrocarbons (PAHs). Among the 10 freshwater fish species, rice field eel (Monopterus albus) showed significantly higher levels of DDTs in both ventral (125 ng/g wet wt) and axial muscle (127 ng/g wet wt) than the other species. The highest concentration of PAHs was detected in catfish (Clarias fuscus), with 24.8 ng/g in ventral muscle and 9.1 ng/g in axial muscle. As to marine fish, snubnose pompano (Trachinotus blochii) showed significantly higher levels of DDT and its metabolites (1018 ng/g in ventral and 409 ng/g wet wt in axial tissues) than all other marine fish species. The overall concentrations of PAHs in marine fish species were 15.5-57.0 ng/g (axial muscle) and 18.1-118 ng/g wet wt (ventral muscle) where yellow seafin (Acanthopeyrus latus) and golden threadfin bream (Nemipterus virgatus) exhibited the highest concentrations of PAHs in the axial and ventral muscles, respectively. In general, results showed that levels of PAHs in Hong Kong market fish was low and do not expect to cause any concern for human consumption. However, the levels of DDTs in fish samples ranged from 1.10 to 1018 ng/g wet wt, and based on a fish consumption rate of 142.2g/day to calculate the screening value of 14.4 ng/g wet wt for human consumption (USEPA, 2000. Guidance for assessing chemical contaminant, data for use in fish advisories, vol. 1: fish sampling and analysis, third ed. EPA 823-R-95-007. Office of Water, Washington, DC), there were 9 out of 20 (45%) muscle samples of freshwater fish species and 14 out of 20 (70%) muscle samples of marine fish species had elevated levels of DDTs exceeded the screening value. It was also suggested to use ventral muscle for detecting concentrations of persistent organic pollutants in fish.

Survival strategies of plants associated with arbuscular mycorrhizal fungi on toxic mine tailings

A field survey of metal concentrations and arbuscular mycorrhizal (AM) components of plants growing on five mining sites was conducted in Chenzhou City, Hunan Province, Southern China and a control site in Hong Kong. Significant differences were observed in the average concentrations of total heavy metals (Pb, Zn, Cu, Cd) and one metalloid (As) in contaminated soils compared with the control site. Gramineae and Compositae were the dominant plant families growing on mine tailings, with Chrysanthemum moritolium (common chrysanthemum), Cynodon dactylon (Bermuda grass), Miscanthus florodulus (Sword grass) and Pteris vittata (Ladder brake fern) commonly found at all sites. AM fungal colonization was detected in most of the plants. Comparing the four common plant species, three components of mycorrhizal colonization (arbuscules, vesicles and coiled hyphae) were found in the roots of C. dactylon and P. vittata growing at Do Shun Long (DSL) mine site. Concentrations of As in fronds were 24-fold higher than in roots of P. vittata with the highest mycorrhizal colonization rate (73%) among all sampling sites. Extensive mycorrhizal colonization (85%) was also recorded in the roots of C. dactylon with As accumulation 57 times higher than in shoots. The four common plants found in metal contaminated sites had developed different strategies for survival in the contaminated sites with the aid of indigenous AM fungi.

Interactions of mycorrhizal fungi with Pteris vittata (As hyperaccumulator) in As-contaminated soils

A greenhouse trial was conducted to investigate the role of arbuscular mycorrhizas (AM) in aiding arsenic (As) uptake and tolerance by Pteris vittata (As hyperaccumulator) and Cynodon dactylon (a multi-metal root accumulator). Plants inoculated with lived and killed native mycorrhizas isolated from an As mine site were grown in a sterile and slightly acidic soil. The infectious percentage of mycorrhizas (0 mg/kg As: 26.4%, 50 mg/kg As: 30.3%, 100 mg/kg As: 40.6%) and the average biomass of shoots in infected P. vittata increased (0 mg/kg As: 2.45 g/pot, 50 mg/kg As: 2.48 g/pot, 100 mg/kg As: 10.9 g/pot) according to the increase of As levels when compared to control. The indigenous mycorrhizas enhanced As accumulation (0 mg/kg As: 3.70 mg/kg, 50 mg/kg As: 58.3 mg/kg; 100 mg/kg As: 88.1 mg/kg) in the As mine populations of P. vittata and also sustained its growth by aiding P absorption. For C. dactylon, As was mainly accumulated in mycorrhizal roots and translocation to shoots was inhibited.

Biopharmaceutical statistics in a pharmaceutical regulated environment: past, present, and future

The practice of statistics in the pharmaceutical industry has changed markedly over the last 25 years. This paper examines the evolution of clinical trial statistics in relationship to advances in statistical methodology and computational power as well as the changing regulatory environment. The current role of the biopharmaceutical statistician is assessed along with the drivers for future change.

Comparisons of confidence intervals for attributable risk

Confidence intervals for the attributable risk in various epidemiologic study designs are obtained, via a transformation, from the confidence interval for the natural logarithm of the product of the probability of being exposed to the risk factor, and the risk ratio minus one. When the estimated attributable risk is between .21 and .79, the width of the logarithmic transformation (LT)-based interval is less than that for a maximum likelihood (ML)-based interval. This simple sufficient condition applies to all three well-known epidemiologic study designs. Computer simulation results further demonstrate the superiority of the LT-based interval to the ML-based one when the sufficient condition is satisfied.