Modeling the fate of benzo[a]pyrene in the wastewater-irrigated areas of Tianjin with a fugacity model

A Level III fugacity model was applied to characterize the transfer processes and environmental fate of benzo[a]pyrene in wastewater-irrigated areas of Tianjin, China. The physical-chemical properties and transfer parameters of benzo[a]pyrene were used in the model and the concentration distribution of benzo[a]pyrene in sediment, soil, water, air, fish, and crop compartments, as well as transfer fluxes across the compartments, were then derived under steady-state assumptions. The calculated results were compared with monitoring data for air, soil, water, and sediment collected from the literature. The results indicate that there was generally good agreement and the differences were within an order of magnitude for air, soil, and sediment. The concentration of benzo[a]pyrene in the ambient air in the area was very low with a majority present sorbed to aerosol. In the water compartment, approximately 70% of benzo[a]pyrene dissolved in water phase. Relatively high concentrations of the compound were found in the soil and sediment, with the soil serving as the dominant sink in the area. Benzo[a]pyrene, with a slow metabolic rate, was found to accumulate in fish in the area.     

Landscape metrics and estuarine sediment contamination in the mid-Atlantic and southern New England regions

In a previously published study, quantitative relationships were developed between landscape metrics and sediment contamination for 25 small estuarine systems within Chesapeake Bay. These analyses have been extended to include 75 small estuarine systems across the mid-Atlantic and southern New England regions of the USA. Because of the different characteristics and dynamics of the estuaries across these regions, adjustment for differing hydrology, sediment characteristics, and sediment origins were included in the analysis. Multiple linear regression with stepwise selection was used to develop statistical models for sediment metals, organics, and total polycyclic aromatic hydrocarbons (PAHs). The landscape metrics important for explaining the variation in sediment metals levels (R2 = 0.72) were the percent area of nonforested wetlands (negative contribution), percent area of urban land, and point source effluent volume and metals input (positive contributions). The metrics important for sediment organics levels (R2 = 0.5) and total PAHs (R2 = 0.46) were percent area of urban land (positive contribution) and percent area of nonforested wetlands (negative contribution). These models included silt-clay content (metals) or total organic C (organics, total PAHs) of sediments and grouping by estuarine hydrology, suggesting the importance of sediment characteristics and hydrology in mitigating the influence of the landscape metrics on sediment contamination levels. The overall results from this study are indicative of how statistical models can be developed relating landscape metrics to estuarine sediment contamination for distributions of land cover and point source discharges.     

Use of pyrolysis molecular beam mass spectrometry (py-MBMS) to characterize forest soil carbon: method and preliminary results

The components of soil organic matter (SOM) and their degradation dynamics in forest soils are difficult to study and thus poorly understood, due to time-consuming sample collection, preparation, and difficulty of analyzing and identifying major components. As a result, changes in soil organic matter chemical composition as a function of age, forest type, or disturbance have not been examined. We applied pyrolysis molecular beam mass spectrometry (py-MBMS), which provides rapid characterization of SOM of whole soil samples. to the Tionesta soil samples described by Hoover, C.M., Magrini, K.A., Evans, R.J., 2002. Soil carbon content and character in an old growth forest in northwestern Pennsylvania: a case study introducing molecular beam mass spectrometry (PY-MBMS). Environmental Pollution 116 (Supp. 1), S269-S278. Our goals in this work were to: (1) develop and demonstrate an advanced, rapid analytical method for characterizing SOM components in whole soils, and (2) provide data-based models to predict soil carbon content and residence time from py-MBMS analysis. Using py-MBMS and pattern recognition techniques we were able to statistically distinguish among four Tionesta sites and show an increase in pyrolysis products of more highly decomposed plant materials at increasing sample depth. For example, all four sites showed increasing amounts of older carbon (phenolic and aromatic species) at deeper depths and higher amounts of more recent carbon (carbohydrates and lignin products) at shallower depths. These results indicate that this type of analysis could be used to rapidly characterize SOM for the purpose of developing a model, which could be used in monitoring the effect of forest management practices on carbon uptake and storage.     

Bioavailability of calcium from sweetpotato and soy flour supplemented diets in hamsters

The bioavailability of calcium from two varieties of sweetpotatoes and supplementation of sweetpotatoes with soy flour was investigated in hamsters using plasma calcium concentration and femur calcium content as indicators. Five different diets were fed to five groups of animals for 28 days. There was no significant difference in plasma calcium concentrations of hamsters in all the diet groups. However, the femur calcium content of hamsters with transgenic sweetpotato flour (TSPF) and parent nontransgenic (from which transgenic was produced) sweetpotato flour (NTSPF) diets was significantly higher than that of the transgenic sweetotato flour supplemented with soy flour (TSPF + SF) and parent nontransgenic sweetpotato flour supplemented with soy flour (NTSPF + SF) diets. The relative bioavailability of calcium from the control (100%), TSPF+SF (30%), NTSPF+SF (23%), TSPF (57%) and NTSPF (46%) indicated that sweetpotatoes could be the better source of calcium, however, supplementation with soy flour might reduce the bioavailability of calcium.     

Transfer of 137Cs and 60Co from irrigation water to a soil-tomato plant system

An experiment has been performed at the nuclear power plant of Garigliano (Caserta, Italy), aiming at the measurement of transfer factors of 137Cs and 60Co radionuclides from the irrigation water to a soil-plant system, with particular attention to the influence on such transfers of the irrigation technique (ground or aerial). Tomato plants were irrigated weekly with water contaminated with 137Cs and 60Co (about 375 Bq/m2 week), using both irrigation techniques. After 13 weeks, fruits, leaves, stems, roots and soil were sampled, and radionuclide concentrations were measured by high-resolution gamma spectroscopy. It was found that the activity allocated to the plant organs is significantly dependent upon the irrigation technique, amounting to 2.1% and 1.6% of the activity given in the cultivation for aerial treatment and 0.4% and 0.3% for the ground treatment, for 137Cs and 60Co respectively. The activity absorbed by plants is allocated mainly in leaves (> 55%), while less then 10% is stored in the fruits, for both irrigation techniques. Transfer factors (soil-plant and irrigation water-plant) of tomato plants and of weeds have been determined for 137Cs and 60Co, as well as for natural 40K in the soil.     

Modelling the long-term dynamics of radiocaesium in closed lakes

During the years after the Chernobyl accident the radioceasium activity concentration in most contaminated aquatic ecosystems decreased markedly. Lakes with no permanent inflows and outflows (closed lakes), however, still present a radioecological problem which is expected to continue for some time. In this paper, a mechanistic model for the long-term prediction of radiocaesium behaviour in closed lakes is developed. The model of Prokhorov (Radiokhimiya (Radiochemistry) 11 (1969) 317) was modified to describe the effects of bottom sediment bioturbation, surface runoff from the catchment and suspended solids formation and sedimentation. The model input parameters are the effective diffusion coefficient in bottom sediments, depth of the completely mixed layer, the distribution coefficient in the sediment-water system, the runoff coefficient, sedimentation rate, and deposition density. Values of all these parameters can be independently estimated or measured in a short-term experiment. Given negligible runoff and sedimentation, the dynamics of radiocaesium in lake water is described by a simple equation with only one unknown parameter. This allows us to make long-term predictions on the basis of a series of measurements carried out during the relatively short period. The model was tested against 137Cs activity concentrations measured between 1993 and 1999 in Svyatoe lake in the Bryansk region of Russia. Calculated and measured activity concentrations are in good agreement.     

Use of 129I and 137Cs in soils for the estimation of 131I deposition in Belarus as a result of the Chernobyl accident

Using radioactivity measurements for 131I and 137Cs and nuclear activation analysis (NAA) or accelerator mass spectrometry (AMS) for 129I, ratios of 131I/137Cs and 129I/137Cs have been determined in soils from Belarus. We find that the pre-Chernobyl ratio of 129I/137Cs in Belarus is significantly larger than expected from nuclear weapons fallout. For the Chernobyl accident, our results support the hypothesis that there was relatively little fractionation of iodine and caesium during migration and deposition of the radioactive cloud. For sites having 137Cs > 300 Bq/kg, 129I can potentially give more reliable retroactive estimates of Chernobyl 131I deposition. However, our results suggest that 137Cs can also give reasonably good (+/-50%) estimates for 131I in Belarus.     

Distribution of long-lived radionuclides of the 238U series in the sediments of a small river in a uranium mineralized region of Spain

A study is presented on the distribution and mobilization of the natural U isotopes (238U and 234U), 230Th, and 226Ra in the sediments of a small river crossing an uranium mineralized zone where a disused uranium mine is located. Due to the preferential directions for surface run-off waters and to the mine's situation, one sampling point along the river bed was identified as a point of accumulation of radionuclides. The average values of the activity concentrations (Bq/kg) in this sediment sample were 5,025, 5,055, 5,915 and 1,694 for 238U, 234U, 230Th and 226Ra, respectively, while the respective average values of the activity concentrations (Bq/kg) for the sediment sample considered to give the background level were 125, 124, 131 and 370. Isotopic ratios between the descendants of 238U served to clarify some paths of distribution, involving the soils nearest to the sampling points and the location of these points with respect to the disused mine. The differences in behaviour found between the uranium, thorium and radium isotopes were associated to the mobility of these radionuclides in the fluvial system studied. Correlations between the radionuclide activity concentration ratios and stable element concentrations in the sediment samples were also investigated.     

Ultra-structural changes in the reproductive system of overwintering females of Acartia longiremis

As the only member of its genus, and along with only a few other marine copepod species, Acartia longiremis Lilljeborg overwinters as adult females in "active diapause" in the plankton. This study describes the changes in ultra-structure of the resting reproductive system from August to January, and evidence for fertilization in overwintering North Norwegian A. longiremis. Gonads in overwintering individuals remain in an undifferentiated state from September to January, i.e. without oocyte development or oocyte migration into the oviduct and its diverticulae. Lipid stores in close association with the reproductive system appear to be utilized for the development of primary oocytes after the overwintering period.     

Optimisation and use of tandem-in-time mass spectrometry in comparison with immunoassay and HRGC/HRMS for PCDD/F screening

Rapid screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans using quadrupole ion storage tandem-in-time mass spectrometry (QISTMS) conjointly with polyclonal antibody immunoassay has been considered. The optimisation of the fragmentation of the parent ion in the trap has been completed. The analysis of fly ashes from a municipal waste incinerator contaminated at different levels has then been realised. Results obtained using QISTMS, HRMS and immunoassay are compared.