Influence of simulated tidal cycles on aromatic hydrocarbon uptake and elimination by the shore crab Hemigrapsus nudus

Specimens of the intertidal crab Hemigrapsus nudus (Dana, 1851) were collected near Sitka, Alaska, in 1983, and were used in laboratory experiments to determine the influence of periodic exposure to air on the toxicity, uptake, and elimination of two aromatic hydrocarbons, toluene and naphthalene. Three tidal cycles were simulated; i.e., crabs spent 0, 33, or 66% of the time in air and the remainder of the time in toxicant or seawater solutions. Naphthalene was 10 to 20 times more toxic than toluene: naphthalene caused locomotory impairment or killed the crabs more rapidly and at concentrations lower than those of toluene. In tissues, naphthalene was accumulated faster and to higher concentrations than was toluene. Exposure to air 66% of the time reduced mortality as well as the rate at which toluene and naphthalene were accumulated and lost. Crabs exposed to air had significantly higher respiration rates than those submerged in seawater; thus, reduced rates of accumulation and loss of hydrocarbons were not caused by general metabolic quiescence. Exposure to air reduced the time the crabs were in contact with water-borne hydrocarbons and, therefore, reduced toxicity of the hydrocarbons. Once crabs had accumulated the toxicants, however, elimination was hindered by exposure to air, even for the somewhat volatile compound toluene.     

Environmental contaminants in nonviable eggs of the endangered Mississippi sandhill crane (Grus canadensis pulla)

Our objectives were to determine if concentrations of environmental pollutants and microbial contamination in nonviable eggs of the endangered Mississippi sandhill crane (Grus canadensis pulla) contributed to egg failure. Six eggs collected in 1990 and four in 1991 contained only background levels of organochlorine pesticides and polychlorinated biphenyls (PCBs), and tests for microbial contamination were all negative. Two eggs contained late dead embryos, but neither revealed obvious abnormalities. Three eggs contained potentially harmful concentrations (23, 39, 146 pg/g, wet mass) of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), based on 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ) for combined compounds. Because of the scarcity of material suitable for laboratory examination and the endangered status of the crane, we recommend that nonviable eggs continue to be monitored for toxic pollutants.     

Host-plant green-leaf volatiles synergize the synthetic sex pheromones of the corn earworm and codling moth (Lepidoptera)

Summary The capture of adult male moths in female sex pheromone traps of two key agricultural pests, the corn earworm (Helicoverpa zea) and the codling moth (Cydia pomonella), is enhanced or synergized by a certain group of host-plant volatiles, the green-leaf volatiles (GLVs). Since female adults of both species call and release their sex pheromones while perched upon the leaves of their host-plants, the volatile constituents from the leaves of a number of host-plants were compared. Sex pheromone traps containing one of the prominent leaf volatiles of certainH. zea hosts, (Z)-3-hexenyl acetate, not only significantly increased the capture ofH. zea males but were preferred over traps baited only with sex pheromone. Similarly, traps baited with synthetic sex pheromome ofC. pomonella plus a blend of GLVs captured significantly more males than traps baited only with sex pheromone. Since male moths are not captured in traps baited only with these GLVs, it appears that these GLVs act as pheromone synergists which increase or enhance the attraction or arrestment of male moths in pheromone traps.     

Facilitation across stress gradients: the importance of local adaptation

While there is some information on genetic variation in response to competition in plants, we know nothing about intraspecific variation in facilitation. Previous studies suggest that facilitation should increase fitness in stressful environments. However, whether a plant experiences an environment as stressful may depend on prior adaptive responses to stressors at a site. Local adaptation to stress at a site may reduce the likelihood of facilitation. Seeds of Plantago erecta from stressful (serpentine soil) and non-stressful (non-serpentine soil) edaphic environments were reciprocally planted into these two soil types. Although competition did not differ significantly among seed sources, there was evidence for a local adaptation effect on facilitation. Non-serpentine seeds planted into serpentine soil exhibited greater individual plant biomass at higher densities. The interaction between population source and growth environment indicates a role for evolutionary processes such as local adaptation in the expression of facilitation in plants.     

Work—nonwork conflict and the perceived quality of life

From additive models of overall quality of life, two hypotheses were derived about the relationships among work—family conflict, work—leisure conflict, job satisfaction, family satisfaction, leisure satisfaction and global life satisfaction. In supporting these two hypotheses, path analyses of survey data from a national probability sample of United States workers (n = 823) showed: (1) the direct paths between work—nonwork conflict and global life satisfaction were nonsignificant; and (2) the indirect paths between work—nonwork conflict and global life satisfaction, which are mediated by job satisfaction and nonwork satisfaction, were all significant. Further analyses indicated that, in general, the magnitude of these path coefficients was not significantly moderated by sociodemographic variables. Discussion considered the role of additive models as conceptual frameworks for studies concerned with the effects of work experiences on the overall quality of life.     

Frequent but Accurate: A Closer Look at Uncertainty and Opinion Divergence in Climate Change Print News

The prevalence of uncertainty and opinion divergence frames in climate change news reporting has generated concerns about the misrepresentation of scientific consensus. We first develop reliable, valid, and more nuanced measures of often-conflated types of uncertainty and opinion divergence frames. Then we analyse the co-occurrence combinations of those distinct types of opinions, sources, and topics in mainstream climate change news stories between 2005 and 2015. Results indicate that while uncertainty and opinion divergence frames are indeed frequent, once clearly distinguished, they in general accurately reference non-scientist sources (e.g. government officials) and topics that do not have a scientific consensus (e.g. the severity of climate change effects).     

Metal exposures in an inner-city neonatal population

ObjectivesWe measured concentrations of lead (Pb), manganese (Mn), chromium (Cr), and copper (Cu) in umbilical cord whole blood and examined sources of environmental Pb exposures in a predominantly African-American population.MethodsBetween April and July 2006, we collected reproductive histories, questionnaires, and blood samples from 102 women, aged 16–45 years, who delivered at a Memphis, TN hospital.ResultsThe prevalence of preeclampsia and low birth weight infancy in the study population was 11% and 10%, respectively. Twenty-eight percent of mothers reported living near a potential Pb-contaminated area, while 43% lived in a residence built before 1978. Geometric mean (GM) concentrations for umbilical cord blood in the study population were 1.3, 3.5, 9.0, and 52.0 µg/dL for Pb, Mn, Cr, and Cu, respectively. Six neonates had cord blood Pb (CBL) concentrations above 10 µg/dL, while 20 had CBL concentrations ≥ 2 µg/dL. GM umbilical CBL levels were higher in neonates born to women living near a potential Pb-contaminated area (2.2 vs. 1.1 µg/dL) and those with friends, family or household members exposed to lead products (1.6 vs. 1.1 μg/dL). Some evidence of an exposure–response relationship was also detected between all four metal concentrations and an increasing number of maternal lead exposures. After adjustment for confounding, proximity to a Pb-contaminated area was the strongest environmental determinant of CBL levels among neonates with CBL concentrations of ≥ 2 µg/dL (odds ratio = 5.1; 95% CI = 1.6, 16.7).ConclusionsMetal concentrations were elevated in this population, and CBL levels were associated with proximity to Pb-contaminated areas.     

Science and Decision Making: Water Management and Tree‐Ring Data in the Western United States1

Abstract: Growing populations, limited resources, and sustained drought are placing increased pressure on already over‐allocated water supplies in the western United States, prompting some water managers to seek out and utilize new forms of climate data in their planning efforts. One source of information that is now being considered by water resource management is extended hydrologic records from tree‐ring data. Scientists with the Western Water Assessment (WWA) have been providing reconstructions of streamflow (i.e., paleoclimate data) to water managers in Colorado and other western states (Arizona, New Mexico, and Wyoming), and presenting technical workshops explaining the applications of tree‐ring data for water management for the past eight years. Little is known, however, about what has resulted from these engagements between scientists and water managers. Using in‐depth interviews and a survey questionnaire, we attempt to address this lack of information by examining the outcomes of the interactions between WWA scientists and western water managers to better understand how paleoclimate data has been translated to water resource management. This assessment includes an analysis of what prompts water managers to seek out tree‐ring data, how paleoclimate data are utilized by water managers in both quantitative and qualitative ways, and how tree‐ring data are interpreted in the context of organization mandates and histories. We situate this study within a framework that examines the coproduction of science and policy, where scientists and resource managers collectively define and examine research and planning needs, the activities of which are embedded within wider social and political contexts. These findings have broader applications for understanding science‐policy interactions related to climate and climate change in resource management, and point to the potential benefits of reflexive interactions of scientists and decision makers.     

What Is the Potential Measurement Error in Occupational Exposure Studies?

ABSTRACT

This paper demonstrates statistical methods that estimate measurement error from available industrial hygiene data. Errors in measuring a continuous exposure variable may arise when all individuals in a work area are assigned the same exposure. An example is when the mean of exposure measurements obtained on a sample of individuals is assigned to all workers with similar jobs. This may lead to inaccurate point and interval estimates in exposure-response modeling. A method of simulating the distribution of true (i.e., unobserved) individual exposures is described in order to estimate the mean and variance of measurement error. The minimum variance unbiased estimator approximates the mean of lognormally distributed exposure measurements. The distribution of true individual exposures is approximated by the distribution of simulated estimates of mean exposure. The methodology is illustrated by exposure data from work areas manufacturing refractory ceramic fiber (RCF) and RCF products. Results show that exposure is slightly underestimated in work areas with between 25 and 113 exposure measurements; measurement error variance averages about 1.3% of the total variance.     

Enforcement Authority and Vegetation Change at Kumbhalgarh Wildlife Sanctuary,Rajasthan, India

Land cover change in protected areas is often associated with human use, especially illicit extraction, but the direction and spatial distribution of such effects and their drivers are poorly understood. We analyze and explain the spatial distribution of vegetation change at the Kumbhalgarh Wildlife Sanctuary in the Aravalli range of Rajasthan, India using remotely sensed data and observation of conservation institutions. Two satellite images are examined in time series over the 13 years following the founding of the sanctuary through a cross-tabulation technique of dominant classes of vegetation density. The resulting change trajectories are compared for their relative distance to high-traffic forest entrance points for local users. The results show 28% of the study area undergoing change, though in multiple trajectories, with both increasing and decreasing density of vegetation in discrete patches. Areas of change are shown to be closer to entrance points than areas experiencing no change. The patchiness of change results from complex issues in local enforcement authority for middle and lower-level officials in Forest Department bureaucracy, leading to further questions about the efficacy and impact of use restrictions in Protected Areas.