Effects of aging and sediment composition on hexachlorobenzene desorption resistance compared to oral bioavailability in rats

Studies were conducted to assess the effects of black carbon, clay type and aging (1-1.5yr) on desorption and bioavailability of hexachlorobenzene (HCB) in spiked artificial sediments. Tenax (a super sorbent)-mediated desorption was used to examine the effects of these parameters on the physicochemical availability of HCB. The Tenax-mediated desorption of HCB from the four aged artificial sediments exhibited biphasic kinetics. The fast desorbing fractions ranged from 64.8% to 22.3%, showing reductions of 4.0-18.9% compared with freshly-spiked sediments. Statistical analysis on the fast desorbing fractions showed that all three treatment effects (i.e., montmorillonite clay, black carbon content, and aging) were significant. Two sediments with higher black carbon content exhibited much greater aging effects (i.e., greater reduction in fast desorbing fraction) than the other two sediments without the addition of black carbon. For both freshly-spiked and aged sediments, the desorption resistant sediment-bound HCB (i.e., slow desorbing fraction) correlated reasonably well to previously reported rat fecal elimination of HCB, which is a measure of the non-bioavailable fraction of sediment-bound HCB. A similar correlation was also observed between fast desorbing fraction and previously reported accumulation of HCB in the rat body (carcass+skin). These observations suggest that physicochemical availability, as defined by the desorption of HCB from sediments, provides a reasonable prediction of the oral bioavailability of sediment-bound HCB to rats. These results showed that montmorillonite clay, black carbon and aging reduced physicochemical availability and ultimately bioavailability of sediment-bound HCB.     

化学品生态毒性测试鱼类模式生物的应用与展望

水生生物毒性测试广泛应用于评估化学品的水生态环境安全,而鱼类生态毒性数据为水生生态风险评估与风险管理提供基础。本文总结了现有的鱼类水生毒性测试标准及常用的物种。阐述了常用水生鱼类模式生物,如斑马鱼Danio rerio、青鳉鱼Oryzias latipes、黑头软口鲦Pimephales promelas等作为模式鱼类的特征及在生态毒性测试中的应用。环保部7号令推荐稀有鮈鲫Gobiocypris rarus作为中国本土生物在水生毒性测试中使用。目前公开发表的利用稀有鮈鲫的水生毒性研究多集中在急性毒性方面,对其他类型的研究如法规毒理相关的长期慢性毒性有待开展。     

Mediating the Science: Symbolic and Structural Influences on Communicating Climate Change Through New Zealand's Television News

Climate change presents scientists, politicians, and media producers with a challenge of articulating to diverse stakeholders both the complexity of issues and the urgency of action. Analyses of how climate change is represented and constructed in broadcast media are useful to capture a reflection of contemporary values. We use an analysis of news frames and production values as well as a limited “circuit of culture” approach to explore climate change communication as both a news product and cultural phenomenon. Our focus is New Zealand, a country which ratified the Kyoto agreement but which is currently noncompliant. Using qualitative framing analysis and in-depth interviews with leading media producers, politicians, and scientists, we examine how climate change is produced, represented, and consumed by New Zealanders via their broadcast media.     

Wind Tunnel Testing of Open Top Field Chambers for Plant Effects Assessment

ABSTRACT

This study reports the first field measurements of airborne exavalent chromium (Cr(vi)) in southwestern Ontario. Hexavalent chromium was identified as an inhalation carcinogen and an air toxic of concern during the 1991-93 Windsor Air Quality Study. The results of that study indicated that approximately 20% of the routinely monitored ambient airborne chromium (Cr) was in the hexavalent form. In addition, the range of carcinogenic health risks attributable to airborne Cr(vi) was determined to be between 1.4 x IO⁶ and 3.0 x 10^-4 for people living in the Windsor area. During the summer of 1993, analyses of concurrent indoor and outdoor 24-hour air quality samples taken at 33 residences in Hamilton resulted in geometric mean Cr(vi) concentrations of 0.20 r|g/m³ and 0.55 r|g/m³, respectively, and little or no relationship between the indoor and outdoor sample sets. During the summer of 1994, an airborne Cr(vi) size-fractionation study was conducted in Hamilton, the results of which suggested that the majority of the Cr(vi) was in the inhalable fraction.     

Continuous Emissions Monitoring Using Spark-Induced Breakdown Spectroscopy

ABSTRACT

A new technology for monitoring airborne heavy metals on aerosols and particulates based on spark-induced breakdown spectroscopy (SIBS) was evaluated at a joint U.S. Environmental Protection Agency (EPA)/U.S. Department of Energy test at the rotary kiln incinerator simulator (RKIS) facility at EPA/Research Triangle Park, NC, in September 1997. The instrument was configured to measure lead and chromium in a simulated combustion flue gas in real time and in situ at target levels of 15 and 75 u, g/dry standard cubic meters. Actual metal concentrations were measured during the tests using EPA Reference Method (RM) 29.

The SIBS technology detected both lead and chromium at the low- and high-level concentrations. Additionally, the hardware performed without failure for more than 100 hr of operation and acquired data for 100% of the RM tests. The chromium data were well correlated with concentration increases resulting from duct operations and pressure fluctuations that are known to entrain dust.     

Sisters in sustainability: municipal partnerships for social,environmental, and economic growth

While debates about sustainable development tend to focus on national- and international-scale problems, sustainability programs and research generally focus on the regional, county, municipal, or even household level. Less research has focused on evaluating the benefits of pairing two cities (i.e., sister city partnerships) with different needs and capabilities to jointly enhance the potential for sustainable practices between the cities. Given shrinking state and federal budgets and the nascent national climate policy, how might US cities use existing resources to achieve greater levels of sustainability? This paper presents a new data-driven mathematical tool—the partnership assessment for intra-regional sustainability—that city planners can use to explore the prospects for improving sustainability practices by leveraging existing resources and establishing synergistic partnerships with neighboring cities. The efficacy of the tool is assessed through the presentation of a Southern California case study and the results of a psychological survey of Southern California residents. Results indicate that cities of different size and scale would benefit from synergistic sustainability programs that pool the resources and needs of both cities. The paper concludes with a discussion of potential societal implications, methodological issues, and barriers to implementation.     

The mudsnail genus Hydrobia s.s. in the northern Atlantic and western Mediterranean: a phylogenetic hypothesis

The mudsnail taxon Hydrobia s.l. plays a major role in numerous ecological and parasitological studies. Yet, its taxonomy is confusing and its biogeography is poorly understood. A principal problem is that taxa of Hydrobia s.l. belong to morphostatic radiations – widely allopatric species radiations with little or no habitat diversification and a low level of anatomical change. So far, three morphostatic radiations can be identified within Hydrobia s.l.: Hydrobia s.s., Peringia, and Ventrosia. These radiations are identical with the putative genera of Hydrobia s.l. The purpose of the paper is to infer phylogenetic relationships within one of these radiations, Hydrobia s.s. in the northern Atlantic and western Mediterranean. A total of 22 populations, including topotypical populations of five commonly used taxa, were studied genetically using partial sequences of the mitochondrial cytochrome c oxidase subunit I gene. Based on molecular data and the species concept we define, the following species and subspecies were identified: Hydrobia acuta acuta (Draparnaud, 1805) [=H. minoricensis (Paladilhe, 1875)], H. acuta neglecta Muus, 1963, and H. glyca (Servain, 1880) (=H. joossei van Aartsen, Menkhorst and Gittenberger, 1984). One population from Djerba, Tunisia (Hydrobia sp. A) and one population from Mallorca, Spain (Hydrobia sp. B) are genetically distinct from all other taxa studied here. Both populations potentially represent new species. Due to the fact that only one population each has been studied, and so the degree of variation within these two taxa cannot be assessed, a final decision regarding their species level cannot yet be made. Received: 6 October 1999 / Accepted: 12 September 2000     

Validation of FLACS against experimental data sets from the model evaluation database for LNG vapor dispersion

The siting of facilities handling liquefied natural gas (LNG), whether for liquefaction, storage or regasification purposes, requires the hazards from potential releases to be evaluated. One of the consequences of an LNG release is the creation of a flammable vapor cloud, that may be pushed beyond the facility boundaries by the wind and thus present a hazard to the public. Therefore, numerical models are required to determine the footprint that may be covered by a flammable vapor cloud as a result of an LNG release. Several new models have been used in recent years for this type of simulations. This prompted the development of the “Model evaluation protocol for LNG vapor dispersion models” (MEP): a procedure aimed at evaluating quantitatively the ability of a model to accurately predict the dispersion of an LNG vapor cloud.This paper summarizes the MEP requirements and presents the results obtained from the application of the MEP to a computational fluid dynamics (CFD) model – FLACS. The entire set of 33 experiments included in the model validation database were simulated using FLACS. The simulation results are reported and compared with the experimental data. A set of statistical performance measures are calculated based on the FLACS simulation results and compared with the acceptability criteria established in the MEP. The results of the evaluation demonstrate that FLACS can be considered a suitable model to accurately simulate the dispersion of vapor from an LNG release.     

Risk of motor vehicle crash for older adults after receiving a traffic charge: A case–crossover study

Objective: After the age of 65, the number of motor vehicle crashes per mile driven increases. Traffic-related charges issued by law enforcement can help identify drivers who are at a higher risk of having a crash. This study examines the relationship between motor vehicle crashes and traffic-related charges among older adult drivers.

Methods: Iowa Department of Transportation crash data from 2011–2012 were linked with Iowa Court Information System data for moving violations that occurred during 2009–2012 for drivers over the age of 50. A time-stratified case–crossover design was used matching on time periods 1 year apart. Case exposure was defined as having a traffic-related charge 30 days before the crash. Control exposure was the same 30-day time period 1 year before the crash for each individual. Conditional logistic regression was used to analyze the self-matched pairs. Additional time periods of 31–60, 61–90, 91–120, 121–150, 151–180, and 181–210 days before the crash were also assessed.

Results: There were 38,171 adults at least 50 years of age with an Iowa driver's license who were involved in a crash in Iowa between 2011 and 2012. In addition, 13,129 adults over the age of 50 received a charge during 2009–2012. Relative to the control time period, experiencing a traffic-related charge in the 30-day time period before the crash increased the risk of a crash by 21% (odds ration [OR] = 1.21, 95% confidence interval [CI], 1.03–1.42) for all drivers included in the study. This crash risk was similar for adults aged 50–64 (OR = 1.20, 95% CI, 1.00–1.45) and adults 65 and older (OR = 1.24, 95% CI, 0.90–1.72). In the 30 days after receiving a traffic-related charge, the risk of a crash was also increased for crashes occurring in adverse weather (OR = 1.79, 95% CI, 1.12–2.84) or during night, dawn, or twilight (OR = 1.89, 95% CI, 1.31–2.72).

Conclusions: A traffic-related charge for an adult over the age of 50 indicates an increased risk of experiencing a crash in the 30 days following the charge. The risk for crashes occurring in adverse conditions or outside of daylight hours was also increased in the 30 days after receiving a traffic-related charge. The risk of experiencing a crash decreases as time passes after receiving a charge. Measures to restrict or increase driving safety during these conditions could help reduce the crash risk for older adults who receive a traffic-related charge.