Assessment of risk of PCDD/Fs and dioxin-like PCBs in marine and freshwater fish in Pearl River Delta, China

Fish consumption is known to be beneficial to human health. However since the age of industrialization, the released/disposed chemical pollutants into water systems make fish a source of various environmental toxicants to humans. In oceanic cities with heavy industrial activities, fish products contribute the greatest proportion of exposure to pollutants. In this study, risks and potential effects of dioxins to health of coastal populations in the Pearl River Delta were assessed. Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) were measured in common fish species purchased at local markets. Concentrations of total dioxins in fish ranged from 0.481 to 9.05 pg TEQ/g wet weight were similar to the lesser concentrations reported for fish from other countries. The greatest concentrations of dioxins were measured in mandarin fish, a carnivorous freshwater fish. Exposure of murine primary leydig and ovarian cells to 2,3,7,8-tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TCDD) reduced the synthesis of progesterone, testosterone and/or estrogen. The reductions were probably via inhibitory effects on the expression of the steroidogenic enzymes, steroidogenic acute regulatory protein (StAR) and cytochrome P450 side-chain cleavage enzyme (P450scc). Based on these reproductive parameters, the concentrations of dioxins and dioxin-like residues represent a moderate health risk due to consumption of fish.     

Predicting tsunami arrivals: Estimates and policy implications

Tsunami is one of a few kinds of natural disasters that leave people some time for escape. This escape time, which is essentially the time for the giant wave to propagate from the epicentre to a coast, has to be estimated without delay upon the occurrence of the incident. With the advancement of water wave theories, much work has been done to model the propagation of tsunamis from deep oceans to shallow water. The authors argue that while much emphasis has been put on the expansion of the high-tech early warning system and the development of complicated tsunami models, a simple-to-use yet accurate predictive model is still wanting. This paper presents a handy linear wave model, which is capable of estimating the arrival time of a tsunami with very good accuracy, as has been verified by comparison with past incidents. With the availability of such a simple model, even local communities without access to a high-tech warning system can readily estimate the time left for emergency evacuation.     

Linear and nonlinear vibration of non-uniform beams on two-parameter foundations using p-elements

A hierarchical finite element is presented for the geometrically nonlinear free and forced vibration of a non-uniform Timoshenko beam resting on a two-parameter foundation. Legendre orthogonal polynomials are used as enriching shape functions to avoid the shear-locking problem. With the enriching degrees of freedom, the accuracy of the computed results and the computational efficiency are greatly improved. The arc-length iterative method is used to solve the nonlinear eigenvalue equation. The computed results of linear and nonlinear vibration analyses show that the convergence of the proposed element is very fast with respect to the number of Legendre orthogonal polynomials used. Since the elastic foundation and the axial load applied at both ends of the beam affect the ratios of linear frequencies associated with the internal resonance, they influence the nonlinear vibration characteristics of the beam. The axial tensile stress of the beam in nonlinear vibration is investigated in this paper, and attention should be paid to the geometrically nonlinear vibration resulting in considerably large axial tensile stress in the beam.     

Some characteristics of ozone profiles above Hong Kong

Summary Analysis of ozonesonde data shows that in the lower troposphere above Hong Kong, there is a relative maximum with respect to height in all seasons except winter. In the upper troposphere, there is with respect to height a relative minimum in the seasonally averaged ozone mixing ratio in winter. Ozone mixing ratios in the upper troposphere in winter and spring can be significantly enhanced by stratospheric intrusions associated with the passage of cold fronts and upper cut-off lows.For Hong Kong, the seasonally averaged total ozone has the highest value in spring, and the lowest in winter. The seasonally averaged total tropospheric ozone also has the highest value in spring, but the lowest in summer. In a relative sense, total tropospheric ozone contributes most to the total ozone in spring and the least in summer.The phase of the total ozone anomaly above Hong Kong is influenced by the Quasi-Biennial Oscillation (QBO), with the positive anomaly associated with the easterly phase of QBO, and the negative anomaly the westerly phase.     

Trematode parasites of Otago Harbour (New Zealand) soft‐sediment intertidal ecosystems: Life cycles,ecological roles and DNA barcodes

Parasites, in particular trematodes (Platyhelminthes: Digenea), play major roles in the population dynamics and community structure of invertebrates on soft‐sediment mudflats. Here, we provide a list of the 20 trematode species currently known to infect molluscs, crustaceans and polychaetes from Otago Harbour (New Zealand) soft‐sediment intertidal areas, as well as information on their transmission modes, life cycles, andknown ecological impacts. Several of the host‐parasite species combinations recorded here are reported for the first time. We also provide DNA barcodes, based on sequences of the cytochrome oxidase subunit l (CO1) gene, for 19 of the 20 trematode species, to facilitate future identification of these parasites in marine ecological studies.     

The Wild Life of Pesticides: urban agriculture,institutional responsibility,and the future of biodiversity in Sydney's Hawkesbury-Nepean River

Agricultural chemicals are a notoriously intractable source of environmental pollution. Offering enhanced agricultural productivity, they simultaneously risk degrading the ecological basis upon which agriculture depends. This paper considers chemicalisation as a cause of the erosion of aquatic biodiversity and ecosystem resilience, focusing on the Hawkesbury-Nepean River and the small-scale horticulturalists who supply the city's fresh vegetable markets, working under the pressure of urbanisation, retail monopolies, indifferent land-use planning, and often without access to information about pesticide use in the languages they understand. Arguing that standard practices of ‘risk management’ are unable to adequately control chemical contamination, the paper presents findings from interviews with actors within the ‘assemblage’ of institutions with responsibility for agriculture, water quality, and environmental protection, in order to assess the effectiveness of pesticide governance in the Greater Sydney Basin. It appears that pesticide pollution is far from being tamed: it is rarely measured nor monitored, neither is it a priority of any particular agency. Arguing that public health, the long-term viability of local farming and the ecological well-being of the Hawkesbury-Nepean River are mutually consistent goals, we conclude that these vital elements of the common-weal are currently subject to a system of ‘organised irresponsibility’. The paper concludes by proposing several ways forward.     

LOCATIONAL CHARACTERISTICS OF FOREIGN EQUITY JOINT VENTURE INVESTMENT IN CHINA, 1979–1985

An examination of the locational characteristics of intended foreign equity joint venture (EJV) investment in China during the period 1979 to 1985 indicates that foreign EJV investment was highly concentrated in the coastal region, in the more developed areas of the provinces, and in large cities. The locational characteristics, however, differed between economic sectors and between countries of origin of investment. Although foreign EJV investment became spatially more dispersed through time, the impacts on the development of inland regions and backward areas in China remained limited.     

Using spatial analysis and Bayesian network to model the vulnerability and make insurance pricing of catastrophic risk

Vulnerability refers to the degree of an individual subject to the damage arising from a catastrophic disaster. It is affected by multiple indicators that include hazard intensity, environment, and individual characteristics. The traditional area aggregate approach does not differentiate the individuals exposed to the disaster. In this article, we propose a new solution of modeling vulnerability. Our strategy is to use spatial analysis and Bayesian network (BN) to model vulnerability and make insurance pricing in a spatially explicit manner. Spatial analysis is employed to preprocess the data, for example kernel density analysis (KDA) is employed to quantify the influence of geo-features on catastrophic risk and relate such influence to spatial distance. BN provides a consistent platform to integrate a variety of indicators including those extracted by spatial analysis techniques to model uncertainty of vulnerability. Our approach can differentiate attributes of different individuals at a finer scale, integrate quantitative indicators from multiple-sources, and evaluate the vulnerability even with missing data. In the pilot study case of seismic risk, our approach obtains a spatially located result of vulnerability and makes an insurance price at a finer scale for the insured buildings. The result obtained with our method is informative for decision-makers to make a spatially located planning of buildings and allocation of resources before, during, and after the disasters.     

Copper toxicity in the marine copepod Tigropus japonicus: Low variability and high reproducibility of repeated acute and life-cycle tests

The intertidal copeopod Tigriopus japonicus, which is abundant and widely distributed along the coasts of Western Pacific, has been suggested to be a good marine ecotoxicity testing organism. In this study, a series of experiments were conducted to investigate the reproducibility and variability of copper (Cu) sensitivity of T. japonicus so as to evaluate its potential to serve as an appropriate test species. To understand the seasonal variation of Cu sensitivity, individuals of T. japonicus were collected from the field in summer and winter, and subjected to standard 96 h acute (static renewal) toxicity tests. 96 h-LC50 values of T. japonicus collected from the two seasons were marginally different (p = 0.05), with an overall coefficient of variation (CV) of 33%. Most importantly, our results indicated that chronic Cu sensitivity of T. japonicus was highly reproducible. The CVs of intrinsic rates of increase in the population of the control and Cu treatment (10 μg Cu l⁻¹) groups were only 10–11% between 10 runs of a standardised complete life-cycle test. Moreover, different Cu(II) salts generally resulted in a similar 96 h-LC50 value while Cu(I) chloride was consistently slightly less toxic than Cu(II) salts. Given such a high reproducibility of toxic responses, it is advocated to use T. japonicus as a routine testing organism.