Qualitative estimates of soil disturbance in the vicinity of CANDU stations, utilizing measurements of 137Cs and 210Pb in soil cores

Anthropogenically derived 14C has been used to trace recent carbon input in a study of carbon accumulation and turnover in Canadian soils. In order to do so, documentation of the undisturbed nature of the soil horizons sampled was of prime concern. Although all the sites chosen for coring were currently uncultivated, detailed information on long-term land usage was not available. To overcome this problem, 137Cs profiles were measured in all the cores used in the study. 210Pb measurements were also made in cases where total 137Cs deposition was lower than predicted. For some sample sites, the data obtained showed correlated losses of both radionuclides, indicating that land disturbance and/or erosion had indeed occurred in these areas over the past 50 years, hence invalidating the use of those cores for carbon cycling studies. In a few cases a marked lack of correlation between these two radionuclides has made it necessary to hypothesize that chemical, rather than physical, processes have been partially responsible for the observed anomalies. Since results of this nature raise doubts about the reliability of the 137Cs method for identification of land disturbance, further investigation is warranted.     

Transformation of [14C] trichloroethylene by poplar suspension cells

Trichloroethylene (TCE) is one of the most prevalent environmental contaminants, and it poses an expensive remediation problem. Phytoremediation has been investigated as a potential tool for the removal of TCE from ground water and soil, and has shown promise in preliminary trials. However, the fate of TCE in plants is largely unknown. Radiolabel studies showed that once taken up and transformed, most of the TCE is incorporated into plant tissue as a non-volatile, un-extractable residue. We describe here an assay for TCE transformation by poplar suspension cells. Using this assay, it was shown that two different activities contribute to the fixation of TCE by poplar cells, one associated with cell walls and insoluble residues, the other associated with a high molecular weight, heat labile fraction of the cell extract. It appears that plant enzymes catalyze some of the transformations.     

Issues and approaches in assessing cumulative impacts on waterbird habitat in wetlands

Wetlands are attractive to vertebrates because of their abundant nutrient resources and habitat diversity. Because they are conspicuous, vertebrates commonly are used as indicators of changes in wetlands produced by environmental impacts. Such impacts take place at the landscape level where extensive areas are lost; at the wetland complex level where some (usually small) units of a closely spaced group of wetlands are drained or modified; or at the level of the individual wetland through modification or fragmentation that impacts its habitat value. Vertebrates utilize habitats differently according to age, sex, geographic location, and season, and habitat evaluations based on isolated observations can be biased. Current wetland evaluation systems incorporate wildlife habitat as a major feature, and the habitat evaluation procedure focuses only on habitat. Several approaches for estimating bird habitat losses are derived from population curves based on natural and experimentally induced population fluctuations. Additional research needs and experimental approaches are identified for addressing cumulative impacts on wildlife habitat values.     

MATERIALS INPUT OF LAKE CHAMPLAIN: A SYNOPTIC APPRAISAL1

ABSTRACT: The complex morphometry of Lake Champlain requires that detailed, regional studies be made, and the results integrated, to yield total lake conditions. Using specific conductance measurements, and values of total dissolved solids calculated from them, we present an approach to assessing the materials budget of the lake. The sampling program involved inventorying all 319 tributaries, determining the watershed area for each, and dividing the Champlain basin into appropriate hydrographic regions. Data were obtained from samples collected from 41 selected streams (representing 97.5% of the annual water input), sampling occurring in all seasons of the year since 1970. Results indicate that over one million metric tonnes of total dissolved solids enter Lake Champlain annually, about two-thirds (63%) from the eastern (Vermont) portion and almost one-fourth (22%) from the western (New York) part of the drainage basin, the remainder (15%) entering from the south end. Of the total quantity added annually, 17.4% is retained in the lake, indicating that a solids build-up is occurring, at a significant rate. We suggest that specific conductance, and therefore total dissolved solids, be utilized as a convenient indicator of water quality conditions, and results applied to permit more efficient watershed management.     

Biomonitoring of contaminated mine tailings through age accumulation of trace metals in the bank vole (Clethrionomys glareolus)

Lead, zinc and cadmium were determined in a range of tissues from laboratory-bred bank voles (Clethrionomys glareolus) exposed to elevated levels of dietary zinc (124 micrograms g-1). The pelletised diet was derived from vegetation harvested from the surface of a revegetated tailings dam at a modern Zn-Pb mine. Exposure regimes to the contaminated diet were 16, 32, 64, 128 or 256 days. Elevated levels of dietary zinc were not reflected in the individual tissue or total body concentrations. Marginal age accumulation of lead and cadmium was evident in the liver (Pb) and kidney (Pb and Cd). Tissue residues did not attain toxicologically significant concentrations. Animals inhabiting the grassland are considered to be at low ecotoxicological risk with respect to trace metals.     

Effects of low concentrations of herbicides on full-season, field-grown potatoes

Current phytotoxicity plant test protocols for US pesticide registration require testing for effects on seedling emergence and early growth without regard to other important factors, such as plant reproduction. Yield and quality reduction can have significant economic and ecological effects. Therefore, field trials were conducted to determine if potato (Solanum tubersum L.) vegetative growth and tuber yield and quality were affected by herbicides at below recommended field rates. Potatoes were grown in fields at the Oregon State University Horticulture Farm with herbicides applied at below recommended field application rates 14 d after emergence (DAE) or at 28 DAE. Plant height was measured before and 14 d after application. Visual foliar injury was rated 14 d after application, and tuber yield and quality parameters were measured at harvest (120 DAE). Some tubers were grown in the greenhouse the following year to determine if there were carry-over effects. Potato vegetation and tuber yield quality were generally more affected by herbicides applied at 14 DAE than at 28 DAE. Tuber yield and quality parameters were more affected by lower herbicide rates than were plant height or injury. There were significant yield losses caused by low rates of sulfometuron methyl and imazapyr and, to a lesser extent, with glyphosate and cloransulam-methyl. Bromoxynil and MCPA ((4-chloro-2-methylphenoxy)acetic) acid had little effect on the plants. Vegetative responses did not accurately predict yield and quality responses of tubers; therefore, reproductive responses should be considered in phytotoxicity test protocols for pesticide registration in the USA.     

Natural concentrations and reference values of heavy metals in sedimentary soils in the Brazilian Amazon

The soils of the Brazilian Amazon exhibit large geochemical diversity reflecting the different soil formation processes in an area covering 49% of the Brazilian territory. Soil contamination by heavy metals is one of the threats to the sustainability of this Biome but establishing quality reference values (QRVs) for the region is a challenging owing to the immense territorial area of the Amazon. This study aimed to determine the natural background of heavy metals in soils from the southwestern Brazilian Amazon in order to propose QRVs for Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, and Zn for alluvial sedimentary soils. One hundred and twenty-eight soil samples were collected at a depth of 0.0–0.2 m in sites with minimal anthropogenic interference. Soil sample digestion was based on the EPA 3051A method and metal concentrations were determined by ICP-OES. QRVs calculated for the southwestern Brazilian Amazon are among the lowest recorded in Brazil (mg kg^?1): Ba (16.5), Cd (0.1), Cr (6.9), Cu (2.8), Fe (15.4), Mn (13.4), Ni (1.7), Pb (4.4), Sb (0.9), and Zn (5.7). The low metal concentration is likely a result of the sedimentary origin of the soils. The results of this study can serve as a basis for defining public policies to investigate the environmental impacts resulting from changes in land use in areas of the Brazilian Amazon.     

The impact of the Gulf crisis on Qatar's humanitarian sector

The 2017 Gulf crisis is one of the most challenging episodes faced by Qatar since its independence in 1971, with major economic, social, and political impacts on the Arab Gulf nation. Its economic prognosis has been brought into doubt, the map of regional alliances has been redrawn, and any prospects of deeper regional integration have been dashed. This paper analyses the little-documented impact of the crisis on Qatar's humanitarian sector, which has unfolded as the small, gas-rich emirate has striven to become a major humanitarian donor. It concludes that while there have been disruptions to humanitarian operations and regional coordination, the Gulf crisis has triggered and in some cases accelerated already intended reforms across the Qatari humanitarian sector. In the long term, the reorganisation and adaptation implemented to weather the storm of the crisis may help Qatar to emerge from the crisis with a more sustainable and resilient humanitarian sector.     

Comments on the NAS Report: Odors From Stationary and Mobile Sources

ABSTRACT

Solid phase microextraction (SPME) presents many advantages over conventional analytical methods by combining sampling, preconcentration, and direct transfer of the analytes into a standard gas chromatograph (GC). Since its commercial introduction in the early 1990s, SPME has been successfully applied to the sampling and analysis of environmental samples. This paper presents an overview of the current methods for air sampling and analysis with SPME using both grab and time-weighted average (TWA) modes. Methods include total volatile organic compounds (TVOCs), formaldehyde, and several target volatile organic compounds (VOCs). Field sampling data obtained with these methods in indoor air were validated with conventional methods based on sorbent tubes. The advantages and challenges associated with SPME for air sampling are also discussed. SPME is accurate, fast, sensitive, versatile, and cost-efficient, and could serve as a powerful alternative to conventional methods used by the research, industrial, regulatory, and academic communities.