Cobalt and secondary poisoning in the terrestrial food chain: data review and research gaps to support risk assessment

Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals and has diverse industrial importance. It is cycled in surface environments through many natural processes (e.g. volcanic eruptions, weathering) and can be introduced through numerous anthropogenic activities (e.g. burning of coal or oil, or the production of cobalt alloys). The environmental behaviour of cobalt in terrestrial environment is relatively poorly studied and in particular where Co is used in industrial processes, the baseline information to support wider and long-term environmental impacts is widely dispersed. To support the adoption of new EU regulations on the risk assessment of chemicals, we review here the various aspects of the environmental chemistry, fate and transport of Co across environmental interfaces and discuss the toxicology and potential for bio magnification and food chain accumulation. The soil-to-plant transfer of Co appears to be viable route to expose lower trophic levels to biologically significant concentrations and Co is potentially accumulated in biomass and top soil. Evidence for further accumulation through soil-invertebrate transfer and to higher trophic levels is suggested by some studies but this is obscured by the relatively high variability of published transfer data. This variation is not due to one particular aspect of the transfer of Co in terrestrial environments. Influences are from the variability of geological sources within soil systems; the sensitivity of Co mobility to environmental factors (e.g. pH) and the variety of life strategies for metal elimination/use within biological species. Toxic effects of Co have been suggested for some soil-plant animal studies however, uncertainty in the extrapolation from laboratory to field is a major limitation.     

Radiation-induced adaptive response in fish cell lines

There is considerable interest at present in low-dose radiation effects in non-human species. In this study gamma radiation-induced adaptive response, a low-dose radiation effect, was examined in three fish cell lines, (CHSE-214 (Chinook salmon), RTG-2 (rainbow trout) and ZEB-2J (zebrafish)). Cell survival after exposure to direct radiation with or without a 0.1 Gy priming dose, was determined using the colony forming assay for each cell line. Additionally, the occurrence of a bystander effect was examined by measuring the effect of irradiated cell culture medium from the fish cell lines on unexposed reporter cells. A non-linear dose response was observed for all cell lines. ZEB-2J cells were very sensitive to low doses and a hyper-radiosensitive (HRS) response was observed for doses <0.5 Gy. A typical protective adaptive response was not detected in any of the three fish cell lines tested. Rather, it was found that pre-exposure of these cells to 0.1 Gy radiation sensitized the cells to subsequent high doses. In CHSE-214 cells, increased sensitivity to subsequent high doses of radiation was observed when the priming and challenge doses were separated by 4 h; however, this sensitizing effect was no longer present when the interval between doses was greater than 8 h. Additionally, a "protective" bystander response was observed in these cell lines; exposure to irradiated medium from fish cells caused increased cloning efficiency in unirradiated reporter cells. The data confirm previous conclusions for mammalian cells that the adaptive response and bystander effect are inversely correlated and contrary to expectations probably have different underlying mechanisms.     

Salmonella typhimurium survival and viability is unaltered by suspended particles in freshwater

Rolling microcosm experiments were conducted to determine whether suspended particles affect the survival and viability of a model pathogen, Salmonella choleraesuis, serotype typhimurium (American Type Culture Collection no. 23567), in a freshwater microbial community. Water from the Duluth, MN harbor of Lake Superior (including native microorganisms) was inoculated with clay, silt, or flocculent organic particles in a range of concentrations and a streptomycin-resistant strain of S. typhimurium. Microcosms (incubated at 20 degrees C) were rolled horizontally (3 rpm) and sampled periodically for total bacteria and total, viable, and culturable S. typhimurium. Total S. typhimurium abundance decreased rapidly in all experiments (8.5-73.1% d-1). Total bacteria did not decrease as rapidly as the S. typhimurium population in any experiment, suggesting that a microcosm effect was not responsible for the decline in S. typhimurium populations. Loss rates of attached and free cells were similar, indicating that attachment to particles did not enhance the persistence of Salmonella cells beyond our minimum detectable differences. After eight days, only 0.1 to 11.9% of the initial S. typhimurium inocula were detected by direct counts. Suspended particles had a minimal effect on the survival and viability of S. typhimurium; the losses of total, viable, or culturable Salmonella were generally the same across particle treatments and concentrations. Silt and flocculent particles affected loss rates of total and viable S. typhimurium similarly to inorganic particles (clay). It appears unlikely that suspended particles would provide a means for S. typhimurium to persist at hazardous levels in freshwater.     

Conceptualizing and communicating management effects on forest water quality

We present a framework for evaluating and communicating effects of human activity on water quality in managed forests. The framework is based on the following processes: atmospheric deposition, weathering, accumulation, recirculation and flux. Impairments to water quality are characterized in terms of their extent, longevity and frequency. Impacts are communicated using a “traffic lights” metaphor for characterizing severity of water quality impairments arising from forestry and other anthropogenic pressures. The most serious impairments to water quality in managed boreal forests include (i) forestry activities causing excessive sediment mobilization and extirpation of aquatic species and (ii) other anthropogenic pressures caused by long-range transport of mercury and acidifying pollutants. The framework and tool presented here can help evaluate, summarize and communicate the most important issues in circumstances where land management and other anthropogenic pressures combine to impair water quality and may also assist in implementing the “polluter pays” principle.     

Wetland Flowpaths Mediate Nitrogen and Phosphorus Concentrations across the Upper Mississippi River Basin

Eutrophication, harmful algal blooms, and human health impacts are critical environmental challenges resulting from excess nitrogen and phosphorus in surface waters. Yet we have limited information regarding how wetland characteristics mediate water quality across watershed scales. We developed a large, novel set of spatial variables characterizing hydrological flowpaths from wetlands to streams, that is, “wetland hydrological transport variables,” to explore how wetlands statistically explain the variability in total nitrogen (TN) and total phosphorus (TP) concentrations across the Upper Mississippi River Basin (UMRB) in the United States. We found that wetland flowpath variables improved landscape-to-aquatic nutrient multilinear regression models (from R² = 0.89 to 0.91 for TN; R² = 0.53 to 0.84 for TP) and provided insights into potential processes governing how wetlands influence watershed-scale TN and TP concentrations. Specifically, flowpath variables describing flow-attenuating environments, for example, subsurface transport compared to overland flowpaths, were related to lower TN and TP concentrations. Frequent hydrological connections from wetlands to streams were also linked to low TP concentrations, which likely suggests a nutrient source limitation in some areas of the UMRB. Consideration of wetland flowpaths could inform management and conservation activities designed to reduce nutrient export to downstream waters.     

Low‐concentration hydrogen peroxide decontamination for Bacillus spore contamination in buildings

Remediation and recovery efforts after a release of Bacillus anthracis (anthrax) spores may be difficult and costly. In addition, response and recovery technologies may be focused on critical resources, leaving the small business or homeowner without remediation options. This study evaluates the efficacy of relatively low levels of hydrogen peroxide vapor (HPV) delivered from off‐the‐shelf equipment for the inactivation of Bacillus spores within an indoor environment. Decontamination evaluations were conducted in a house using both Bacillus atrophaeus var. globigii (Bg; as surrogates for B. anthracis) inoculated on the carpet and galvanized metal as coupons and Geobacillus stearothermophilus (Gs) as biological indicators on steel. The total decontamination time ranged from 4 to 7 days. Using the longer exposure times, low concentrations of HPV (average levels below 20 parts per million) effectively inactivated Bg and Gs spores on the materials tested. The HPV was generated with commercial humidifiers and household‐strength hydrogen peroxide solutions. The presence of home furnishings did not have a significant impact on HPV efficacy. This simple, inexpensive, and effective decontamination method could have significant utility for remediation following a B. anthracis spore release, such as following a terrorist attack.     

Defining the Diurnal Pattern of Snowmelt Using a Beta Distribution Function

Snow is an important component of the hydrologic cycle for many regions worldwide. In addition to vital water resources, snowmelt can be important for forest ecosystem dynamics and flood risk. However, standard design events in the United States lack a design snowmelt event, including only precipitation events, though snowmelt has been shown to be larger than rainfall. In this article, we present a method using hourly snow water equivalent data to develop and test a function for representing the diurnal pattern of snowmelt. A two‐parameter beta distribution function is modified for the purposes of this study and found to fit the pattern of snowmelt well with a root mean squared error of 0.008. Soil moisture sensors were additionally utilized to assess the timing of the snowmelt water outflow from the base of the snowpack that supports the shape of the function, but suggests that the timing of losses recorded on snow pillows lag as much as 3 h. Further testing of the function showed the shape of the function to be accurate. The methods developed and tested in this paper can be applied for design purposes comparing snowmelt and rainfall events or to improve hydrological models investigating processes such as streamflow or groundwater recharge.     

弘文重教十余年的《文教资料简报》

创刊于1972年12月的《文教资料简报》是由南京师范学院(1984年易名为南京师范大学)内部编印的资料性月刊,主要目的是为文科教研服务。本文回顾该刊从创办至拥有统一刊号、从非正式出版物至成为正式出版物的历史沿革,具体观照该刊的编辑理念,总结该刊的内容特色、文献价值及经验启示。