A biomonitoring plan for assessing potential radionuclide exposure using Amchitka Island in the Aleutian chain of Alaska as a case study

With the ending of the Cold War, the US and other nations were faced with a legacy of nuclear wastes. For some sites where hazardous nuclear wastes will remain in place, methods must be developed to protect human health and the environment. Biomonitoring is one method of assessing the status and trends of potential radionuclide exposure from nuclear waste sites, and of providing the public with early warning of any potential harmful exposure. Amchitka Island (51 degrees N lat, 179 degrees E long) was the site of three underground nuclear tests from 1965 to 1971. Following a substantive study of radionuclide levels in biota from the marine environment around Amchitka and a reference site, we developed a suite of bioindicators (with suggested isotopes) that can serve as a model for other sites contaminated with radionuclides. Although the species selection was site-specific, the methods can provide a framework for other sites. We selected bioindicators using five criteria: (1) occurrence at all three test shots (and reference site), (2) receptor groups (subsistence foods, commercial species, and food chain nodes), (3) species groups (plants, invertebrates, fish, and birds), (4) trophic levels, and (5) an accumulator of one or several radionuclides. Our major objective was to identify bioindicators that could serve for both human health and the ecosystem, and were abundant enough to collect adjacent to the three test sites and at the reference site. Site-specific information on both biota availability and isotope levels was essential in the final selection of bioindicators. Actinides bioaccumulated in algae and invertebrates, while radiocesium accumulated in higher trophic level birds and fish. Thus, unlike biomonitoring schemes developed for heavy metals or other contaminants, top-level predators are not sufficient to evaluate potential radionuclide exposure at Amchitka. The process described in this paper resulted in the selection of Fucus, Alaria fistulosa, blue mussel (Mytilus trossulus), dolly varden (Salvelinus malma), black rockfish (Sebastes melanops), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and glaucous-winged gull (Larus glaucescens) as bioindicators. This combination of species included mainly subsistence foods, commercial fish, and nodes on different food chains.     

On “China-measures related to the exportation of various raw materials” case in terms of DSB’s interpretations

The Appellate Body report in January 2012 had supported the decision of Panel in the “China-measures related to the exportation of various raw materials” case (WT/DS394,395,398) and affirmed that China’s restrictions (such as tariffs and quota measures) on the exportation of raw materials violated rules put forth by the WTO, which were required to be modified. In this case China’s right to invoke Article 20 of GATT1994 (“general exception”) to justify its exemption from the guidelines in Article 11.3 of the WTO Accession Protocol was denied by the Panel and the Appellate Body. This was due to the fact that the phrasing in Article 11.3 of Protocol failed to mention “GATT.” This was the consequence of the two interpretation approaches the Dispute Settlement Body (DSB) adopted – a narrow textual interpretation and a subjective presumption of “legislative silence.” The inappropriate use of the two methods of interpretation lead to an imbalance between the right and obligation of China under the additional obligations that were imposed upon China by the WTO, which create a negative impact on China’s rare earth case and the protection of domestic natural resources.     

Applying phytochemical analysis in the pre-selection process of plant-based substrates for biomethanation: the case of avocado oil processing byproducts

Journal of Material Cycles and Waste Management - Phytochemicals in avocado oil processing byproducts were evaluated in this study. This information was used to make inferences use of these...     

Featured Collection Introduction: Connectivity of Streams and Wetlands to Downstream Waters

Connectivity is a fundamental but highly dynamic property of watersheds. Variability in the types and degrees of aquatic ecosystem connectivity presents challenges for researchers and managers seeking to accurately quantify its effects on critical hydrologic, biogeochemical, and biological processes. However, protecting natural gradients of connectivity is key to protecting the range of ecosystem services that aquatic ecosystems provide. In this featured collection, we review the available evidence on connections and functions by which streams and wetlands affect the integrity of downstream waters such as large rivers, lakes, reservoirs, and estuaries. The reviews in this collection focus on the types of waters whose protections under the U.S. Clean Water Act have been called into question by U.S. Supreme Court cases. We synthesize 40+ years of research on longitudinal, lateral, and vertical fluxes of energy, material, and biota between aquatic ecosystems included within the Act's frame of reference. Many questions about the roles of streams and wetlands in sustaining downstream water integrity can be answered from currently available literature, and emerging research is rapidly closing data gaps with exciting new insights into aquatic connectivity and function at local, watershed, and regional scales. Synthesis of foundational and emerging research is needed to support science‐based efforts to provide safe, reliable sources of fresh water for present and future generations.     

Modeling the effects of concentration history on the slow desorption of trichloroethene from a soil at 100% relative humidity

To determine the effects of concentration history on slow sorption processes, desorption kinetic profiles for trichloroethene (TCE) were measured for a soil at 100% relative humidity subject to different exposure concentrations and exposure times. Exposure concentrations ranged from 1% to 80% of the saturation vapor pressure (Ps) for TCE, and exposure times (i.e., time allowed for sorption before desorption begins) ranged from 1 to 96 days. A spherical diffusion model based on a gamma distribution of sorption rates and a gamma distribution of desorption rates was developed and applied to the data. At 80% P/Ps, the entire gamma distributions of sorption and desorption rates were available for TCE. In accordance with a micropore filling mechanism, the fraction of these distributions available for TCE sorption decreased with decreasing P/Ps. Experimental results are consistent with a micropore-filling mechanism, where the amount of slow desorbing mass decreased with decreasing exposure time, and the fraction of slow desorbing sites filled decreased with decreasing exposure concentration. Simulation results suggest that diffusion limits the rates that micropores fill, and that rates of sorption and desorption for soil contaminated at smaller values of P/Ps are, on average, less than those at larger values of P/Ps (i.e., slow desorption rates are a function of exposure concentration). Simulation results also suggest that the model adequately describes the effects of exposure concentration and exposure time on the rates of sorption and desorption, but not on the capacity of the slow sites for TCE. This work is important because contaminant concentrations in the subsurface vary in space and time, and the proposed model represents a new and mechanistically based approach to capture the effects of this heterogeneity on slow desorption.     

Limited change in the diversity and structure of subtidal communities over four decades

A unique archive of photographs from 1969 to 1974 permitted a test of the hypothesis that the diversity and composition of contemporary epilithic communities on subtidal rock walls in the San Juan Islands, WA, USA, has changed over 40 years. Notably, the richness and diversity of sessile taxa was significantly higher in 2008–2011. Furthermore, the multivariate community structure of sessile and mobile taxa differed between the historic and modern eras. Historic communities were characterized by a high percent cover of bare rock and non-calcified algal crusts, consistent with the effects of grazing by chitons and urchins. The rate of sessile community turnover, an index less susceptible to spatial sampling artifacts than richness or diversity, was not significantly different between the two eras. Together with the naturally high spatial variability in these epilithic communities, and the limited replication of historic quadrats, we interpret cautiously the data as evidence of limited change despite a clear shift in temperature and predator (fish) guild composition. The lack of substantial change in rock wall communities may be due in part to their vertical topography, which limits physical disturbance and the preemption of space by weedy algae, two processes that are often associated with “phase-shifts” in other marine ecosystems.     

Endosulfan reduces fertilization success and causes abnormal embryo development to zebrafish

Abstract

Reproductive and teratogenic effects of endosulfan were investigated by exposure of mature breeding zebrafish (Danio rerio) to environmentally relevant concentrations of 0.01–1.2?μg L^?1 and monitoring their spawning, fertilization success, and gonad histology. Fertilization success was negatively correlated to duration of exposure at endosulfan concentration of 1.2?μg L^?1. No apparent effect was observed on fish gonads after histological examination. Teratogenic effects were assayed by exposing newly spawned embryos to endosulfan at 1.0–200?μg L^?1 and determining coagulation, tail development, eye formation, and spontaneous movements 24?h after fertilization; pigmentation, heart rate, edema, and mortality after 48?h and hatch time, mortality, and spinal deformations after 144?h. At 50–100?μg L^?1, endosulfan caused impaired tail development and differentiation, and at 10–200?μg L^?1 spinal deformation and increased mortality, depending upon the timing of exposure.     

On equilibrium in resource markets with scale economies and stochastic prices

In this paper, I show the existence and the characteristics of equilibrium in a non-renewable resource market where extraction costs are non-convex and market price is subject to stochastic shocks, an empirically relevant setting. In my model firms may be motivated to hold inventories to facilitate production smoothing, which allows them to continue producing at a smooth pace at any instant when extraction ceases, e.g. when reserves are exhausted. This aspect of the model then supports a competitive equilibrium in the presence of non-convex costs. Casual empirical evidence is provided that supports the central features of my model for a variety of non-renewable resources, lending credence to the explanation for equilibrium I propose.