Post-rehabilitation environmental hazard of Cu, Zn, As and Pb at the derelict Conrad Mine, eastern Australia

A post-rehabilitation audit of the derelict Conrad base metal mine, eastern Australia, indicates ongoing environmental hazard regarding acid mine drainage and concentrations of arsenic and lead to 3 wt% in the soil and sediment. In order to rehabilitate remote contaminated sites effectively, on-site analyses should be carried out to ensure that the materials used to rehabilitate the site are not contaminant-bearing. Understanding the geomorphic setting of the rehabilitated areas is also important in understanding where, and for what period, contaminated materials might be stored in fluvial systems downstream of mine workings. Chemical and geomorphic audits should form a fundamental part of all rehabilitation works to ensure favourable environmental outcomes.     

Experimental measurements and numerical simulations of the transport and retention of nanocrystal CdSe/ZnS quantum dots in saturated porous media: effects of pH,organic ligand,and natural organic matter

Environmental Science and Pollution Research - The risks of environmental exposures of quantum dot (QD) nanoparticles are increasing, but these risks are difficult to assess because fundamental...     

Identifying source correlation parameters for hydrocarbon wastes using compound-specific isotope analysis

A preliminary evaluation of compound-specific isotope analysis (CSIA) as a novel, alternative method for identifying source correlation compounds in soils contaminated with residual heavy or weathered petroleum wastes is presented. Oil-contaminated soil microcosms were established using soil (sandy-loam, non-carbonaceous cley) amended with ballast-, crude- or No.6 fuel oil. Microcosms were periodically sampled over 256 days and delta(13)C values (which express the ratio of (13)C to (12)C) determined at each time point for five n-alkanes and the isoprenoid norpristane using gas chromatography-isotope ratio mass spectrometry (GC-IRMS). Although some temporal variation was observed, no significant temporal shifts in the delta(13)C values for the five n-alkanes were measured in all three oils. Isoprenoid isotope ratios (delta(13)C) appeared to be least affected by biotransformation, especially in the No.6 fuel oil. The research suggests that the delta(13)C of isoprenoids such as norpristane, may be of use as source correlation parameters.     

Concentrations of iron-55 in commercial fish species from the North Atlantic

Concentrations of the weapon-test, fallout radionuclide iron-55 have been reported for migratory species, such as the Pacific salmon, which suggest a marked decrease in concentration with decrease in latitude of the point of capture. This situation has been examined for North Atlantic cod stocks in order to provide data for a species representative of a large geographical area, but divided into more or less distinct stocks each with a restricted territory, in order to provide further data on the importance of latitude in determining iron-55 concentrations. The data obtained show that there is a marked dependence upon latitude, Arctic cod averaging 90 pCi ⁵⁵Fe/mg Fe compared with 15 pCi ⁵⁵Fe/mg Fe for cod from middle latitudes. The mechanisms that could lead to such distribution are examined, and it is concluded that deposition of this radionuclide was exceptionally high over the sea in northern latitudes compared with its deposition on land, and that this pattern of deposition, taken together with the very high biological availability of the material at the time of deposition, has led to the very high specific activities found in northern latitudes and recorded for Arctic cod stocks in particular.     

Gas/particle partitioning behaviour of azaarenes in an urban atmosphere

The gas/particle partitioning of azaarenes in the Liverpool urban atmosphere was measured from May 1995 to April 1996. This period included one of the hottest summers and coldest winters recorded in the UK. The changes of the relative proportions of particulate and vapour phases showed a strong seasonal variation in which over 80% of azaarene compounds are associated with the particles in the winter and over 60% of azaarene compounds exist as vapour phase during the summer. The results are fitted into a gas/particle partitioning equation. Calculated vapour pressures, vaporization and desorption enthalpies are also given. Azaarene partitioning behaviour is modelled at a variety of aerosol concentrations and over a temperature range which includes normal ambient temperatures. It is hypothesised that three ring azaarene species are more likely to undergo changes in the relative proportions of particle and vapour phase material than either two or four ring compounds.     

The associations of linear alkyl benzenes with the bulk properties of sediments from the River Mersey Estuary

The concentration distributions of linear alkyl benzenes (LAB) are reported as a function of sediment grain size and organic-carbon and lipid concentration for samples from three sites from the River Mersey Estuary, UK. There is not a simple relationship between contaminant concentration and grain size because the contaminant burden is much more strongly related to the organic-carbon and lipid content. This association between LAB, lipid, and organic carbon can be understood in terms of a simple model in which a proportion of LAB is introduced to the bulk material at source, with the remainder being adsorbed into particle surfaces after discharge. LAB concentrations in the Mersey Estuary are relatively high, and the compounds show evidence of degradation that arises from the high level of bacterial activity within the system.     

A hydrologic network supporting spatially referenced regression modeling in the Chesapeake Bay Watershed

The U.S. Geological Survey has developed a methodology for statistically relating nutrient sources and land-surface characteristics to nutrient loads of streams. The methodology is referred to as SPAtially Referenced Regressions On Watershed attributes (SPARROW), and relates measured stream nutrient loads to nutrient sources using nonlinear statistical regression models. A spatially detailed digital hydrologic network of stream reaches, stream-reach characteristics such as mean streamflow, water velocity, reach length, and travel time, and their associated watersheds supports the regression models. This network serves as the primary framework for spatially referencing potential nutrient source information such as atmospheric deposition, septic systems, point-sources, land use, land cover, and agricultural sources and land-surface characteristics such as land use, land cover, average-annual precipitation and temperature, slope, and soil permeability. In the Chesapeake Bay watershed that covers parts of Delaware, Maryland, Pennsylvania, New York, Virginia, West Virginia, and Washington D.C., SPARROW was used to generate models estimating loads of total nitrogen and total phosphorus representing 1987 and 1992 land-surface conditions. The 1987 models used a hydrologic network derived from an enhanced version of the U.S. Environmental Protection Agency's digital River Reach File, and course resolution Digital Elevation Models (DEMs). A new hydrologic network was created to support the 1992 models by generating stream reaches representing surface-water pathways defined by flow direction and flow accumulation algorithms from higher resolution DEMs. On a reach-by-reach basis, stream reach characteristics essential to the modeling were transferred to the newly generated pathways or reaches from the enhanced River Reach File used to support the 1987 models. To complete the new network, watersheds for each reach were generated using the direction of surface-water flow derived from the DEMs. This network improves upon existing digital stream data by increasing the level of spatial detail and providing consistency between the reach locations and topography. The hydrologic network also aids in illustrating the spatial patterns of predicted nutrient loads and sources contributed locally to each stream, and the percentages of nutrient load that reach Chesapeake Bay.     

Biodegradation of low aqueous concentration pentachlorophenol (PCP) contaminated groundwater

Bioremedial treatment to remove low level organic contamination to regulatory standards has met with limited success. In this study source water from a contaminated surficial aquifer at a former wood treatment facility was used to evaluate the potential for indigenous microorganisms to degrade low level (< 1.0 mg) pentachlorophenol (PCP) to a regulatory drinking water standard of 0.001 mg/L. PCP degradation was evaluated in series of batch reactors in a two phase study to (a) determine the rate and extent of PCP removal and (b) evaluate the impact of nutrient amendment (N and P) on removal rate. All reactors with the exception of the abiotic control demonstrated PCP removal to a level < 0.002 mg/L within a maximum period of 32 d with and without nutrient amendment. A regression analysis of reactive phosphate (ortho-P) concentration versus removal rate produced an R2 of 0.94 (p = 0.006) indicating a significant correlation between the level of available phosphate and PCP degradation rate. Selective bacterial enumeration (for PCP degrading bacteria) revealed PCP-degrading bacteria increased in abundance prior to and in conjunction with the degradation phase to a density of between 10(3) to 10(4) CFU/ml. Isolates were also analyzed for total fatty acids using Fatty Acid Methyl Ester (FAME) methodology and the results indicated that PCP degrading bacteria were present in the aquifer and consisted of predominately fluorescent, oxidase positive Pseudomonas species. Overall, data indicate that autochthonous microbes are capable of removing low level PCP (< 1.0 mg/L) to approach if not reach the regulatory standard of 0.001 mg/L with the addition of oxygen, with or without nutrient amendment. Results of this research can be applied to full-scale implementation of in-situ or ex-situ bioremediation of groundwater at former wood treatment facilities.     

Intraplacental sonolucent spaces: Incidences and relevance to chorionic villus sampling

Detailed ultrasound examination of the placentae from 293 consecutive women requesting first-trimester chorionic villus sampling (CVS) showed evidence of intraplacental sonolucent spaces with varying density in 42.3 per cent of these placentae. Their presence, however, did not complicate the subsequent course of these women's pregnancies. Their prime significance relates to CVS, where inadvertent entry into these areas can lead to bleeding and contamination of the villus specimens with blood. A search for these spaces should be made before sampling, and when present, they should be avoided wherever possible.     

Lead in a residential environment in Jamaica

The background levels of lead in Jamaica in soils and sediments, estimated at 37 mg kg^–1, are relatively high compared with world averages. Several areas have values in excess of this due to mineralisation and pollution. One such is the residential Hope Flats/Kintyre area in which levels of lead up to 2.5% are found in the soils and up to 8 g kg^–1 in the water of the nearby Hope River. The blood lead levels of a sample of children were in the range 5.7–57 g dl^–1. The high lead levels suggest a potential health risk, particularly for the children. This can be minimised by programmes which include community education, case management and abatement to reduce the lead exposure.