Critical factors in assessing exposure to PBDEs via house dust

Assessment of indoor exposure to polybrominated diphenyl ethers (PBDEs) requires a critical examination of methods that may influence exposure estimates and comparisons between studies. We measured PBDEs in residential dust collected from 20 homes in Boston, MA, to examine 5 key questions: 1) Does the choice of dust exposure metric-e.g., concentration (ng/g) or dust loading (ng/m2)-affect analysis and results? 2) To what degree do dust concentrations change over time? 3) Do dust concentrations vary between rooms? 4) Is the home vacuum bag an acceptable surrogate for researcher-collected dust? 5) Are air and dust concentrations correlated for the same room? We used linear mixed-effects models to analyze the data while accounting for within-home and within-room correlations. We found that PBDE dust concentration and surface loading were highly correlated (r=0.86-0.95, p<0.001). Average dust concentrations did not significantly differ over an 8-month period, possibly because home furnishings changed little over this time. We observed significant differences between rooms in the same home: PBDE concentrations in the main living area were 97% higher than the bedroom for decaBDE (p=0.02) and 72% higher for pentaBDE (p=0.05). Home vacuum bag dust concentrations were significantly lower than researcher-collected dust and not strongly correlated. Air (vapor and particulate phase) and dust concentrations were correlated for pentaBDE (p=0.62, p<0.01), but not for decaBDE (p=0.25). In addition, potential markers of BDE 209 debromination (BDE 202 and the BDE197:BDE201 ratio) were also observed in household dust samples. One vacuum bag sample contained the highest concentrations of BDE 209 (527,000 ng/g) and total PBDEs (544,000 ng/g) that have been reported in house dust.     

Bridging Disciplines, Knowledge Systems and Cultures in Pest Management

The success of research in integrated environmental and natural resource management relies on the participation and involvement of different disciplines and stakeholders. This can be difficult to achieve in practice because many initiatives fail to address the underlying social processes required for successful engagement and social learning. We used an action research approach to support a research-based group with a range of disciplinary and stakeholder expertise to critically reflect on their engagement practice and identify lessons around how to collaborate more effectively. This approach is provided here as a guide that can be used to support reflective research practice for engagement in other integration-based initiatives. This paper is set in the context of an integrated wildlife management research case study in New Zealand. We illustrate how multi-, inter- and trans-disciplinary approaches can provide a framework for considering the different conversations that need to occur in an integrated research program. We then outline rubrics that list the criteria required in inter- and trans-disciplinary collaborations, along with examples of effective engagement processes that directly support integration through such efforts. Finally, we discuss the implications of these experiences for other researchers and managers seeking to improve engagement and collaboration in integrated science, management and policy initiatives. Our experiences reaffirm the need for those involved in integrative initiatives to attend to the processes of engagement in both formal and informal settings, to provide opportunities for critical reflective practice, and to look for measures of success that acknowledge the importance of effective social process.     

An overview of the gulf coast aerosol research and characterization study: the Houston fine particulate matter supersite

The Gulf Coast Aerosol Research and Characterization Study ([GC-ARCH], also known as the Houston Fine Particulate Matter [PM] Supersite) examined the spatial and temporal variability in fine PM source contributions and composition and the physical and chemical processes that govern PM formation and transformation in southeastern Texas. This was accomplished through the analysis of data collected in a 16-month field sampling program (August 2000 through November 2001). Three core sites and approximately 15 peripheral sites, jointly operated by the study team and the Texas Commission on Environmental Quality (TCEQ), were used. Key scientific findings related to spatial and temporal variability in fine PM concentrations, sizes and composition of the fine PM, the strength of primary emission sources and causes of secondary fine PM formation are reported.     

An inexpensive dual-chamber particle monitor: laboratory characterization

In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 microm) and fine (mass median diameter, 0.27-0.42 microm) size distributions (average r2 = 0.997 +/- 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries.     

老化测试——为什么您更加需要它

塑料部件的老化测试逐渐成为防止潜在的产品失效的决定性步骤.随着越来越多的原始设备制造商开始向加工商征求设计及材料选择方案,使用过程中的老化失效责任也渐渐地进入了供应链.在汽车用塑料行业中,这种现象尤其明显.原始设备制造商、加工商、合成材料制造商及添加剂供应商对于产品的最终使用环境的交流通常不够充分,而对于如何使用产品及产品使用地点的误解是造成产品失效的原因之一.     

Infiltration of PCE in a system containing spatial wettability variations

A two-dimensional infiltration experiment was conducted to investigate and quantify the effect of spatial wettability variations on DNAPL migration and entrapment in saturated sands. Experimental observations of tetrachloroethylene (PCE) infiltration showed that organic-wet sand lenses acted as very effective capillary barriers, retaining PCE and inhibiting its downward migration. A multiphase numerical simulator was used to model this sand box experiment. The simulator incorporates wettability-modified van Genuchten and Brooks-Corey capillary pressure/saturation relationships as well as Burdine and Mualem relative permeability relationships. PCE mass distributions, estimated by image analysis of digital photographs taken during the infiltration event, were compared to simulation results. Although both relative permeability models were qualitatively able to predict the PCE retention in the organic-wet layers, simulations with the Mualem model failed to capture the observed rate of PCE migration. A traditional multiphase simulator, incorporating water-wet capillary retention relations, failed to predict both PCE pathways and retention behavior. This study illustrates the potential influence of subsurface wettability variations on DNAPL migration and entrapment and supports the use of modified capillary relations in conjunction with the Burdine model in multiphase flow simulators.     

贵阳市臭氧浓度变化及与气象因子的关联性

运用2013—2016年贵阳市环境空气自动监测站臭氧(O_3)的监测数据以及气象观测资料,分析该地区近地面O_3浓度的时空变化特征及与气象因子的关联性。结果表明,近年来贵阳市近地面O_3小时浓度均值有逐年升高趋势,增速为1. 1～5. 0μg/(m~3·a)。O_3浓度昼间变化呈明显单峰形分布,08:00左右出现最低值,15:00—16:00达到最大峰值,浓度高值主要分布在12:00—18:00。日照时数每增加1 h,则近地面O_3日最大8 h平均浓度增加8μg/m~3左右,日照时数大于8 h,则近地面O_3日最大8 h平均浓度超过100μg/m~3; O_3小时浓度与温度呈正相关(r=0. 724,α=0. 01),与相对湿度呈负相关(r=-0. 531,α=0. 01)。当日照时数大于8 h、温度超过25℃、相对湿度小于60%时,贵阳市近地面O_3容易出现高浓度值。     

Remediation of chloroform in fine-textured soil using zero-valent iron

Chloroform, a probable human carcinogen, is mainly produced anthropogenically for industrial use and may be released to the environment from a large number of sources related to its manufacture and use, including pulp and paper mills, hazardous waste sites, and sanitary landfills. Remediation of chloroform through conventional technologies has been met with limited success due to the conditions required and the formation of hazardous substances such as dichloromethane. The objective of this study was to investigate chloroform reduction in multicontaminated fine-textured soil using zero-valent iron (Fe⁰) in anaerobic microcosms. Four amended matrices were tested: simple matrix control (glass beads), soil matrix control (glass beads + soil), Fe⁰ in a simple matrix (glass beads + Fe⁰), and Fe⁰ in a soil matrix (soil + Fe⁰). Headspace chloroform and its transformation products dichloromethane, chloromethane, and methane were measured over 230 days and during short intervals in the initial 3 days. Chloroform (~0.3 mM initial mass) persisted in both control microcosms but was completely transformed in microcosms containing soil + Fe⁰ by 12 h and glass beads + Fe⁰ by 48 h. Reductive dechlorination of chloroform occurred with simultaneous production of dichloromethane (~0.11 to 0.14 mM mass) and chloromethane (~0.02 to 0.13 mM mass). Little methane (~0.07 to 0.26 μM mass) production as an end product of chloroform reduction was observed in microcosms amended with Fe⁰. Produced dichloromethane and chloroform almost disappeared by 230 days. The results showed a complete chloroform transformation pathway that has good potential for the remediation of chlorinated compounds in fine-textured soil. The role of soil clay minerals in redox reactions can be further investigated to improve the reductive dechlorination of chlorinated compounds in contaminated environments.     

The virtue of compassion in compassionate conservation

The role of ethics is becoming an increasingly important feature of biodiversity conservation dialogue and practice. Compassionate conservationists argue for a prohibition of, or at least a strong presumption against, the adoption of conservation policies that intentionally harm animals. They assert that to be compassionate is to care about animals and that it is antithetical to caring for animals to intentionally harm them. Compassionate conservationists thus criticize many existing conservation practices and policies. Two things together challenge the philosophical foundation of compassionate conservation. First, compassionate conservationists ground their theory in virtue ethics, yet virtue ethics permits exceptions to moral rules, so there cannot be an in-principle prohibition on adopting intentional harm-inducing policies and practices. But not all compassionate conservationists advocate for a prohibition on intentionally harming animals, only a strong presumption against it. This leads to the second point: compassion can motivate a person to adopt a harm-inducing conservation policy or practice when doing so is the best available option in a situation in which animals will be harmed no matter what policy or practice is adopted. Combining these insights with the empirical observation that conservationists regularly find themselves in tragic situations, we arrive at the conclusion that conservationists may regularly advocate for harm-inducing policies and practices from a position of compassion. Article Impact Statement: Compassionate conservationists should accept that the virtuously compassionate person may adopt harm-causing conservation policies.