Distribution of polychlorinated biphenyls in the water, sediment and fish from the Pearl River estuary, China

The concentrations and distribution of polychlorinated biphenyls were determined in water, surface sediments and fishes from the estuaries of Pearl River, PR China. The results showed that the concentrations ranged from 2.47 ng l-1 to 6.75 ng l-1 in water, from 11.13 ng g-1 to 23.23 ng g-1 in sediments (dry weight) and from 68.64 ng g-1 to 316.85 ng-1 in fish (lipid weight). It was found that the feeding habits of fish were very significant in the accumulation of polychlorinated biphenyls and pattern of congeners. Carnivorous and benthic fishes such as eel (Anguilla japonica) and Chinese sea catfish (Arius sinensis) were found to have high concentrations of polychlorinated biphenyls and of high-chlorinated congeners, while herbivores such as shad (Clupanodon punctatus) and mullet (Mugil cephalus) exhibited an opposite trend. Congeners IUPAC Nos. 153, 138, 118, 87/81, 170 and 52 were found frequently in most samples (both sediment and fish). In comparison with other places in the world, the concentration of polychlorinated biphenyls in sediment and fish from the estuary of Pearl River were low.     

Delineating alluvial aquifer heterogeneity using resistivity and GPR data

Conceptual geological models based on geophysical data can elucidate aquifer architecture and heterogeneity at meter and smaller scales, which can lead to better predictions of preferential flow pathways. The macrodispersion experiment (MADE) site, with >2000 measurements of hydraulic conductivity obtained and three tracer tests conducted, serves as an ideal natural laboratory for examining relationships between subsurface flow characteristics and geophysical attributes in fluvial aquifers. The spatial variation of hydraulic conductivity measurements indicates a large degree of site heterogeneity. To evaluate the usefulness of geophysical methods for better delineating fluvial aquifer heterogeneities and distribution of preferential flow paths, a surface grid of two-dimensional ground penetrating radar (GPR) and direct current (DC) resistivity data were collected. A geological model was developed from these data that delineate four stratigraphic units with distinct electrical and radar properties including (from top to bottom) (1) a meandering fluvial system (MFS); (2) a braided fluvial system (BFS); (3) fine-grained sands; and (4) a clay-rich interval. A paleochannel, inferred by other authors to affect flow, was mapped in the MFS with both DC resistivity and GPR data. The channel is 2 to 4 m deep and, based on resistivity values, is predominantly filled with clay and silt. Comparing previously collected hydraulic conductivity measurements and tracer-plume migration patterns to the geological model indicates that flow primarily occurs in the BFS and that the channel mapped in the MFS has no influence on plume migration patterns.     

Organochlorine and heavy metal concentrations in blubber and liver tissue collected from Queensland (Australia) dugong (Dugong dugon)

Tissue samples of liver and blubber were salvaged from fifty-three dugong (Dugong dugon) carcasses stranded along the Queensland coast between 1996 and 2000. Liver tissue was analysed for a range of heavy metals and blubber samples were analysed for organochlorine compounds. Metal concentrations were similar in male and female animals and were generally highest in mature animals. Liver concentrations of arsenic, chromium, iron, lead, manganese, mercury and nickel in a number of individual animals were elevated in comparison to concentrations previously reported in Australian dugong. Dieldrin, DDT (and its breakdown products) and/or heptachlor epoxide were detected in 59% of dugong blubber samples. In general, concentrations of organochlorines were similar to those reported in dugong 20 years earlier, and were low in comparison to concentrations recorded from marine mammal tissue collected elsewhere in the world. With the exception of lead, the extent of carcass decomposition, the presence of disease or evidence of animal starvation prior to death did not significantly affect dugong tissue concentrations of metals or organochlorines. The results of the study suggest that bioaccumulation of metals and organochlorine compounds (other than dioxins) does not represent a significant risk to Great Barrier Reef dugong populations, particularly in the context of other pressures associated with coastal development and other anthropogenic activities.     

Mercury distribution in Douro estuary (Portugal)

Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically <20 mg dm(-3), and concentrations of DOC in the range <1.0-1.8 mg dm(-3). The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm(-3), whereas for the more saline bottom waters it was about 65 ng dm(-3). The surface waters had maximum concentrations of total suspended particulate mercury of approximately 7 microg g(-1) and the bottom waters were always <1 microg g(-1). Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 microg g(-1). The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters.     

COMPUTER DEMODULATION TECHNIQUE FOR A DUAL-CHANNEL MICROWAVE RADIOMETER

The three stairstep output of the video amplifier has now been designed for the NOAA/WPL dual-channel radiometer in order to provide an analog input to one A/D converter instead of to two phase-detectors, and the synchronous detection for data and AGC is done in software. We put the new system into the dual-channel radiometer which was set in Boulder Atmospheric Observatory (BAO) to make experiments for three weeks and found the processor reliable and flexible.     

An assessment of the pollutant status of surficial sediment in Cork Harbour in the South East of Ireland with particular reference to polycyclic aromatic hydrocarbons

Surface sediment from three polluted sites within Cork Harbour, Ireland, and from a relatively clean reference site were collected and analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), organotins (OTs), and heavy metals. PAHs were determined to be the most abundant class of contaminant. Concentrations of the sum (Sigma) of the 21 PAHs measured from the Harbour sites (2877.70 ng g(-1), 1000.7 ng g(-1) and 924.40 ng g(-1) dry weight respectively) were significantly higher than that of the sediment from the reference site (528.30 ng g(-1) dry weight). An inner harbour site, Douglas being the more contaminated of the three harbour sites. A similar pattern was observed with the other contaminants however, these compounds, with the exception of the heavy metals, all tended to be detected at concentrations on or below detection limits.     

On the Age of the Protolepidodendron-and Bothriolepis-Bearing Formations in Southwestern China

正 For many years,there has been considerable difference of opinion in regard to the age of the horizons bearing both Protolepidodendron and Bothriolepis in Central Hunan and Eastern Yunnan.I am in full accord with the view recently put forward by. H. C. Wang that the plant- and fish-bearing series o     

A Detailed Section of the Gigantopteris Coal-bearing Formation near Shuicheng,Western Kneichow

正 With 1 Text-figure. The Gigantopteris coal-bearing formation is widely distributed in western Kueichow. In the Tahopien~1 coal-field of Shuicheng~2, this formation has been observed by different investigators like S. S. Yoh, C. J. Peng and T. P. Chai. An almost complete section of it, from the top     

The Origin of the Luipo Iron Ore in Western Szechuan

正 Ⅰ. INTRODUCTION Close to the grand canyon of the Chingshakiang near Luipo~1 in western Szechuan (Plate I, Fig. 1), there occurs a more or less.flat-topped mountain, which, stretching from the city of Luipo northeastward to Wenshuicheng~2, is