Field intercomparison of throughfall measurements performed within the framework of the Pan European intensive monitoring program of EU/ICP Forest

A 6-month field intercomparison study on throughfall measurements was performed at Speulder forest near the west coast in The Netherlands. Twenty throughfall sampling systems were evaluated on accuracy, sampling strategy and performance under field conditions. Throughfall fluxes of NO3-, K+ and Kjeldahl-N generally could be determined with a larger accuracy than fluxes of SO4(2-), NH4+, Na+, Cl-, Mg2+, Ca2+, and alkalinity. Throughfall fluxes of H+ generally had the lowest accuracy. Only 20% of the sampling systems differed more than 20% from the best estimate, whereas 45% of the systems stayed within a 10% range from the best estimate. The difference from the best estimate was mainly caused by aspects related to sampling strategy, like, for example, collecting area, sampler placement. The inaccuracy induced by the sampling system appeared to be much larger than that resulting from the analysis of the samples by different laboratory as determined by ring-tests. The field intercomparison described in this article gave a good insight in the different aspects contributing to the overall accuracy of the measurements. However, performing a future field intercomparison is recommended for throughfall and stemflow in order to also take in account other aspects that might influence the performance of the different measurement systems (e.g. tree species, climate zone, summer/winter period).     

Relative importance of school bus-related microenvironments to children's pollutant exposure

Real-time concentrations of black carbon, particle-bound polycyclic aromatic hydrocarbons, nitrogen dioxide, and fine particulate counts, as well as integrated and real-time fine particulate matter (PM2.5) mass concentrations were measured inside school buses during long commutes on Los Angeles Unified School District bus routes, at bus stops along the routes, at the bus loading/unloading zone in front of the selected school, and at nearby urban "background" sites. Across all of the pollutants, mean concentrations during bus commutes were higher than in any other microenvironment. Mean exposures (mean concentration times time spent in a particular microenvironment) in bus commutes were between 50 and 200 times greater than those for the loading/unloading microenvironment, and 20-40 times higher than those for the bus stops, depending on the pollutant. Although the analyzed school bus commutes represented only 10% of a child's day, on average they contributed one-third of a child's 24-hr overall black carbon exposure during a school day. For species closely related to vehicle exhaust, the within- cabin exposures were generally dominated by the effect of surrounding traffic when windows were open and by the bus's own exhaust when windows were closed. Low-emitting buses generally exhibited high concentrations only when traveling behind a diesel vehicle, whereas high-emitting buses exhibited high concentrations both when following other diesel vehicles and when idling without another diesel vehicle in front of the bus. To reduce school bus commute exposures, we recommend minimizing commute times, avoiding caravanning with other school buses, using the cleanest buses for the longest bus routes, maintaining conventional diesel buses to eliminate visible emissions, and transitioning to cleaner fuels and advanced particulate control technologies as soon as possible.     

Sources and remediation for mercury contamination in aquatic systems--a literature review

Sources of mercury contamination in aquatic systems were studied in a comprehensive literature review. The results show that the most important anthropogenic sources of mercury pollution in aquatic systems are: (1) atmospheric deposition, (2) erosion, (3) urban discharges, (4) agricultural materials, (5) mining, and (6) combustion and industrial discharges. Capping and dredging are two possible remedial approaches to mercury contamination in aquatic systems, and natural attenuation is a passive decontamination alternative. Capping seems to be an economical and effective remedial approach to mercury-contaminated aquatic systems. Dredging is an expensive remedial approach. However, for heavily polluted systems, dredging may be more effective. Natural attenuation, involving little or no cost, is a possible and very economical choice for less contaminated sites. Proper risk assessment is necessary to evaluate the effectiveness of remedial and passive decontamination methods as well as their potential adverse environmental effects. Modeling tools have a bright future in the remediation and passive decontamination of mercury contamination in aquatic systems. Existing mercury transport and transformation models were reviewed and compared.     

Field performance of woodburning stoves in crested butte,Colorado

The carbon monoxide (CO) and particulate matter (PM) emissions of woodburning stoves have been measured under field conditions. Both conventional airtight stoves and newly installed airtight stoves certified by the U.S. Environmental Protection Agency to be low emitters of PM were monitored. The certified stoves were of two types, catalytic and noncatalytic. Compared to the conventional stoves, PM emission rates (g/hr) were reduced approximately 70% by both types of certified stoves. The CO emission rates were reduced 71% and 53% by catalytic and noncatalytic stoves respectively. These rate reductions occur because the certified stoves burn cleaner (less pollutant formation per kg of wood burned) and the average burn rate of certified stoves in field use is less than the average burn rate of conventional stoves.     

Irrigated Agriculture and Wildlife Conservation: Conflict on a Global Scale

/ The demand for water to support irrigated agriculture has led to the demise of wetlands and their associated wildlife for decades. This thirst for water is so pervasive that many wetlands considered to be hemispheric reserves for waterbirds have been heavily affected; for example, the California and Nevada wetlands in North America, the Macquarie Marshes in Australia, and the Aral Sea in central Asia. These and other major wetlands have lost most of their historic supplies of water and some have also experienced serious impacts from contaminated subsurface irrigation drainage. Now mere shadows of what they once were in terms of biodiversity and wildlife production, many of the so-called "wetlands of international importance" are no longer the key conservation strongholds they were in the past. The conflict between irrigated agriculture and wildlife conservation has reached a critical point on a global scale. Not only has local wildlife suffered, including the extinction of highly insular species, but a ripple effect has impacted migratory birds worldwide. Human societies reliant on wetlands for their livelihoods are also bearing the cost. Ironically, most of the degradation of these key wetlands occurred during a period of time when public environmental awareness and scientific assertion of the need for wildlife conservation was at an all-time high. However, designation of certain wetlands as "reserves for wildlife" by international review boards has not slowed their continued degradation. To reverse this trend, land and water managers and policy makers must assess the true economic costs of wetland loss and, depending on the outcome of the assessment, use the information as a basis for establishing legally enforceable water rights that protect wetlands from agricultural development.     

FACTORS IN THE COMMUNITY PERCEPTION OF WATER RESOURCE PROBLEMS1

ABSTRACT The study explores the perception of community problems, including flooding and pollution, among leaders in four different communities, ranging in size from 10,000 to 20,000. Water-related problems were considered in the context of other community problems which were defined by these leaders. Among these leaders, water-related problems were characterized by low salience and by low consensus. In seeking solutions, these leaders see water problems as being less likely to be solved at the local community level and to necessitate extra-community assistance. They also see water-related problems as requiring a relatively low level of community coordination and as being primarily the responsibility of the public sector. Local governmental leaders were seen as being more important in problem solving in water-related problems than they were in other community problems.     

低碳发展应被视为一种机会

抓住机会德班会议对于各国来说都是一次难得的将问题转化为机遇,将现有体系持续提高形成各种转型解决方案的契机.但同时,各国也面临一个转折点,即中国提出的解决方案将起核心作用.对于中国以及那些最近开始对低碳问题深度关注的其他国家来说,重要的是要了解,目前西方国家政府和组织上正在进行的工作已经变得过时.     

Sexual dimorphism in immune function changes during the annual cycle in house sparrows

Difference between sexes in parasitism is a common phenomenon among birds, which may be related to differences between males and females in their investment into immune functions or as a consequence of differential exposure to parasites. Because life-history strategies change sex specifically during the annual cycle, immunological responses of the host aiming to reduce the impact of parasites may be sexually dimorphic. Despite the great complexity of the immune system, studies on immunoecology generally characterise the immune status through a few variables, often overlooking potentially important seasonal and gender effects. However, because of the differences in physiological and defence mechanisms among different arms of the immune system, we expect divergent responses of immune components to environmental seasonality. In male and female house sparrows (Passer domesticus), we measured the major components of the immune system (innate, acquired, cellular and humoral) during four important life-history stages across the year: (1) mating, (2) breeding, (3) moulting and (4) during the winter capture and also following introduction to captivity in aviary. Different individuals were sampled from the same population during the four life cycle stages. We found that three out of eight immune variables showed a significant life cycle stage × sex interaction. The difference in immune response between the sexes was significant in five immune variables during the mating stage, when females had consistently stronger immune function than males, while variables varied generally non-significantly with sex during the remaining three life cycle stages. Our results show that the immune system is highly variable between life cycle stages and sexes, highlighting the potential fine tuning of the immune system to specific physiological states and environmental conditions.