Kinetics of trace metal accumulation and excretion in the polychaete <Emphasis Type="Italic">Nereis diversicolor</Emphasis>

The comparative kinetics of the accumulation of the trace metals copper, zinc and cadmium have been measured in the estuarine burrowing polychaete worm Nereis (Hediste) diversicolor from two sites: (a) a metal-rich site, Restronguet Creek, Cornwall, UK, which hosts a copper- and zinc-tolerant population of worms, and (b) the Blackwater estuary, Essex, UK as a control site. A sediment transfer experiment showed that the Blackwater worms responded to the increased copper bioavailability in Restronguet Creek sediment by accumulating significantly increasing copper concentrations over 50 days. The Restronguet Creek worms showed no significant change in copper concentration over 50 days in sediment from either site or in sand. Nevertheless, electron microscopy showed that some Restronguet Creek worms do appear to excrete accumulated copper, probably in association with renewal of the cuticle over a long time scale. The Blackwater worms did not accumulate extra zinc from the zinc-rich Restronguet Creek sediment, in probable reflection of the regulation of body zinc concentration by N. diversicolor. Radiolabelled zinc and cadmium were accumulated from labelled sediment and labelled solution by worms from both sites. The rate of uptake of labelled zinc from sediment was significantly greater in the Restronguet Creek worms, as was the rate of uptake of labelled cadmium from 10 μg l⁻¹ dissolved exposure; other rates of uptake did not differ between populations. Mucus, which is secreted by Restronguet Creek worms in response to enhanced copper exposure, adsorbed very small proportions of zinc and cadmium present in solution, indicating that the mucus does not act as an adsorption barrier against excessive metal uptake by these worms.     

Seasonal exposures to triazine and other pesticides in surface waters in the western Highveld corn-production region in South Africa

The objective of this study was to characterize concentrations of atrazine, terbuthylazine, and other pesticides in amphibian habitats in surface waters of a corn-production area of the western Highveld region (North-West Province) of South Africa. The study was conducted from November 2001 to June 2002, coinciding with the corn-production season. Pesticide residues were measured at regular intervals in surface water from eight ponds, three in a non-corn-growing area (NCGA) and five within the corn-growing area (CGA). Measured atrazine concentrations differed significantly among sites and between samples. In the five CGA sites, the maximum atrazine concentrations measured during the study ranged from 1.2 to 9.3 microg/L. Although no atrazine was recorded as being applied in the catchment of the three NCGA sites, maximum concentrations from 0.39 to 0.84 microg/L were measured during the study, possibly as a result of atmospheric transport. Maximum measured concentrations of terbuthylazine ranged from 1.22 to 2.1 microg/L in the NCGA sites and from 1.04 to 4.1 microg/L in the CGA sites. The source of terbuthylazine in the NCGA sites may have been in use other than in corn. The triazine degradation products, deisopropylatrazine (DIA) and deethylatrazine (DEA) and diaminochlorotriazine (DACT) were also found in water from both the CGA and NCGA sites. Concentrations of DIA were > or = 1 microg/L throughout the season, while DEA concentrations were mostly <0.5 microg/L before planting but increased after planting and application of herbicides to concentrations >2 microg/L in some locations. Concentrations of DACT were highly variable (LOD to 8 microg/L) both before and after planting and application, suggesting that they resulted from historical use of triazines in the area. Other herbicides such as simazine and acetochlor were only detected infrequently and pesticides such as S-metolachlor, cypermethrin, monocrotophos, and terbuphos, known to be used in the CGA, were not detected in any of the samples. Because of dilution by higher than normal rainfall in the study period, these concentrations may not be predictive of those in years of normal rainfall.     

Use of pattern recognition in the evaluation of PCDD and PCDF residue data from GC/MS analyses

We used the chemometric approach with SIMCA (soft independent modeling by class analogy) multivariate statistical programs, based on principal components modeling to examine complex PCDD and PCDF residues in environmental samples. This approach was employed to determine the acceptability of measured tetrachloro isotope ratios when three ion intensities, m^+., (m+2)^+., and (m+4)^+., were measured by monitoring multiple ions. Isotope labeled internal standards and native compounds were examined. Principal components contain information about similarity of samples and variability in measurement. The data for the observed ion ratios were merged with the theoretical ion ratios and a calculated set of data that deviated from the theoretical values over a range of +/− 10 % for each ion pair. Thus the plot of principal components sample scores contains the error boundaries for accepting data that meet this quality assurance criterion and identifies the samples and calibration data that are within the acceptable range. In addition, GC/MS peaks having more than one constituent with different degrees of chlorination were readily detected. Residues of PCDDs in eggs of herring gulls ( ) collected from colonies in the Great Lakes region in 1981 – 1984 were measured by GC/MS. Principal components modeling of the normalized residue data demonstrated that the sample residue profiles differed according to the sample's origin and that sample profiles remained remarkably similar over the 4-year period in which the samples were collected.     

Reversal of acidification in tributaries of the River Duddon (English Lake District) between 1970 and 1998

Long-term changes in stream water chemistry in the upper Duddon catchment (southwest Lake District, UK) were investigated. Ten streams were sampled and analysed weekly during 1998, and the results compared with data for the early 1970s and 1986. The waters exhibited a range of pH, average values for 1998 being 5.04-7.04. For all the streams, the average pH in 1998 was greater than that during 1971-73. Statistical analysis was carried out, using the 1970s data to estimate the magnitude of inter-annual variation, and taking discharge into account on the basis of antecedent rainfall. The results showed that for two of the streams the pH increase was significant at the 2.5% level, while for a further three it was significant at the 10% level. Comparison of the 1998 concentrations of nitrate and non-marine sulphate with data obtained for five streams in 1973-74 showed that average nitrate concentration had increased from 11 to 20 microeq dm(-3) while that of non-marine sulphate had decreased from 94 to 50 microeq dm(-3). For four of the streams, comparisons were also made between the 1998 data and those for 1986. In three cases, pH in 1998 was generally higher, and Al generally lower, than the values for 1986, but in the fourth case little difference was evident. The present results support observations for five nearby standing waters, strengthening the evidence for a general reversal of acidification in the southwest part of Lake District, due to a decline in the deposition of pollutant sulphur.     

Vapor-phase and fine particulate matter concentrations of polycyclic aromatic hydrocarbons measured during the winter months in a northern Rocky Mountain urban airshed

A fine particulate matter (PM2.5) sampling program was conducted in Missoula, MT, to investigate both the particle and vapor phases of PM2.5-associated polycyclic aromatic hydrocarbons (PAHs) found in a northern Rocky Mountain urban airshed. Twenty-four-hour samples were collected during the cold winter months of January through April 2002, when many of the more volatile organic components of PM2.5 were expected to be found in the condensed particle form. To meet analytical detection limits, each of the 12 individual sample days were aggregated into four total filter and polyurethane foam (PUF) samples, respectively, with each aggregate containing 3 sample days. Quartz filter (particle-phase PAHs) and PUF (vapor-phase PAHs) aggregates were analyzed separately for 18 individual PAHs and phenolics by gas chromatography/mass spectrometry. Results showed that 87% of the PM2.5-associated phenolics and PAHs measured in this study were found in the vapor phase. PM2.5-associated gas/particle partition coefficients (Kp,2.5) ranged from 0 for the lighter phenolics and PAHs to approximately 0.1 for some of the heavier PAHs, such as fluoranthene and pyrene. Calculating Kp,2.5 for the heaviest measured PAHs was not feasible because of low or undetectable concentrations in the vapor phases of these compounds. Phenolics and two-ringed and three-ringed PAHs were found almost exclusively in the vapor phase. Four-ringed PAHs were distributed between the particle and vapor phases, with more mass measured in the vapor phase. Very little five-ringed and higher PAHs were measured from either the filter or PUF sampling medium. These results provide information on both the concentrations and different phases of PM2.5-associated PAHs measured during the winter months in a northern Rocky Mountain urban airshed, when concentrations of PM2.5 are generally at their highest compared with the rest of the year.     

Studies on the acute toxicity of fluoride ion to stickleback,fathead minnow,and rainbow trout

We have studied the acute toxicity of fluoride ion to $\text{Gasterosteus aculeatus}$, $\text{Pimephales promelas}$, and juvenile $\text{Salmo gairdneri}$. LC50 values varied with species and (due to precipitation) initial water hardness. Exposure to elevated fluoride levels in water resulted in increased blood fluoride levels in $\text{Salmo gairdneri}$.     

Post-mortem findings in a fetus with 48,XXY, + 21

A fetus with 48,XXY, + 21 was detected on routine amniocentesis at 15 weeks for advanced maternal age. Fibroblast cultures from six different tissues were initiated after termination and each showed the same karyotype without any tissue limited mosaicism. The only pheno-typic abnormality detected at post-mortem examination was bilateral clinodactyly of the fifth finger which had been detected on ultrasound. The maternal serum alpha-fetoprotein and the femur length were normal. Maternal age remains an essential criterion for prenatal diagnosis.     

Evolution of habitat use by deep-sea mussels

Previous phylogenetic studies proposed that symbiont-bearing mussels of the subfamily Bathymodiolinae (Bivalvia: Mytilidae) invaded progressively deeper marine environments and evolved from lineages that decomposed wood and bone to specialized lineages that invaded cold-water hydrocarbon seeps and finally deep-sea hydrothermal vents. To assess the validity of the hypotheses, we examined two nuclear (18S and 28S rRNA) and two mitochondrial genes (COI and ND4) from a broad array of bathymodiolin species that included several recently discovered species from shallow hydrothermal seamounts. Bayesian phylogenetic analysis and maximum-likelihood estimates of ancestral character states revealed that vent species evolved multiple times, and that reversals in vent and seep habitat use occurred within the sampled taxa. Previous hypotheses regarding evolution from wood/bone-to-seeps/vents are supported in that mid-ocean hydrothermal vent species may represent a monophyletic group with one noticeable reversal. Earlier hypotheses about progressive evolution from shallow-to-deep habitats appear to hold with a few instances of habitat reversals.     

Dimethylsulfide,algal pigments and light in an Antarctic Phaeocystis sp. bloom

Dimethylsulfide (DMS) concentrations in sea water were found to be high (0.19 to 390 nM) in an Antarctic bloom of Phaeocystis sp. during October and November 1990. DMS concentrations were positively correlated with algal pigments, particularly 19-hexanoyloxyfucoxanthin, a prymnesiophyte pigment. Concentrations of DMS varied diurnally, possibly due to effects of sunlight, although the exact mechanism is unknown. Since oceanic DMS production has been linked to the global albedo through the formation of cloud condensation nuclei, light-mediated changes in DMS concentrations may affect the global climate. The flux of DMS from this bloom into the atmosphere is calculated to be 67±55 mol m^-2 d^-1.     

The effects of watercress growing on chalk headwater streams in Dorset and Hampshire

Chalk stream headwaters are of high value for water supply, amenity, game fishing and fish farming. The water quality implications of modern watercress growing watercress beds are reflected in increasing concentrations of phosphorus and potassium downstream of the beds. Zinc concentrations in both suspended solids emanating from the beds and in sediments downstream of the watercress farms reach high levels in some cases. Ranunculus plants downstream of the watercress farms show elevated levels of zinc. Large amounts of suspended solids enter the receiving streams from watercress beds and in many cases the stream bed directly downstream of the farms has a high proportion of fine organic sediments derived from the watercress farms.