Multiple sources of predictive uncertainty in modeled estimates of net ecosystem CO2 exchange

Net ecosystem CO₂ exchange (NEE) is typically measured directly by eddy covariance towers or is estimated by ecosystem process models, yet comparisons between the data obtained by these two methods can show poor correspondence. There are three potential explanations for this discrepancy. First, estimates of NEE as measured by the eddy-covariance technique are laden with uncertainty and can potentially provide a poor baseline for models to be tested against. Second, there could be fundamental problems in model structure that prevent an accurate simulation of NEE. Third, ecosystem process models are dependent on ecophysiological parameter sets derived from field measurements in which a single parameter for a given species can vary considerably. The latter problem suggests that with such broad variation among multiple inputs, any ecosystem modeling scheme must account for the possibility that many combinations of apparently feasible parameter values might not allow the model to emulate the observed NEE dynamics of a terrestrial ecosystem, as well as the possibility that there may be many parameter sets within a particular model structure that can successfully reproduce the observed data. We examined the extent to which these three issues influence estimates of NEE in a widely used ecosystem process model, Biome-BGC, by adapting the generalized likelihood uncertainty estimation (GLUE) methodology. This procedure involved 400,000 model runs, each with randomly generated parameter values from a uniform distribution based on published parameter ranges, resulting in estimates of NEE that were compared to daily NEE data from young and mature Ponderosa pine stands at Metolius, Oregon. Of the 400,000 simulations run with different parameter sets for each age class (800,000 total), over 99% of the simulations underestimated the magnitude of net ecosystem CO₂ exchange, with only 4.07% and 0.045% of all simulations providing satisfactory simulations of the field data for the young and mature stands, even when uncertainties in eddy-covariance measurements are accounted for. Results indicate fundamental shortcomings in the ability of this model to produce realistic carbon flux data over the course of forest development, and we suspect that much of the mismatch derives from an inability to realistically model ecosystem respiration. However, difficulties in estimating historic climate data are also a cause for model-data mismatch, particularly in a highly ecotonal region such as central Oregon. This latter difficulty may be less prevalent in other ecosystems, but it nonetheless highlights a challenge in trying to develop a dynamic representation of the terrestrial biosphere.     

Correlation analysis between sulphate content and leaching of sulphates in recycled aggregates from construction and demolition wastes

In some recycled aggregates applications, such as component of new concrete or roads, the total content of soluble sulphates should be measured and controlled. Restrictions are usually motivated by the resistance or stability of the new structure, and in most cases, structural concerns can be remedied by the use of techniques such as sulphur-resistant cements. However, environmental risk assessment from recycling and reuse construction products is often forgotten. The purpose of this study is to analyse the content of soluble sulphate on eleven recycled aggregates and six samples prepared in laboratory by the addition of different gypsum percentages. As points of reference, two natural aggregates were tested. An analysis of the content of the leachable amount of heavy metals regulated by European regulation was included. As a result, the correlation between solubility and leachability data allow suggest a limiting gypsum amount of 4.4% on recycled aggregates. This limit satisfies EU Landfill Directive criteria, which is currently used as reference by public Spanish Government for recycled aggregates in construction works.     

儿童肺功能的多因子及交互影响分析

在儿童肺功能横断面数据基础上,运用多元线性回归,研究了影响儿童肺功能的多因子及其交互效应.结果表明,儿童肺功能指标主要受儿童基本体质情况、呼吸系统疾病和家庭室内暴露因子以及这些因子的交互影响.儿童肺功能与空气颗粒物(PM10-2.5和TSP)的负相关比较显著,未发现与SO₂和NO_x有显著相关性.作者还对空气颗粒物与年均取暖期燃煤取暖、母乳喂养、呼吸系统疾病等因子的交互效应进行了研究,发现细颗粒物对儿童肺功能的影响更为不利.     

Conservation resource allocation,small population resiliency,and the fallacy of conservation triage

Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.     

Status and prospects of environmental protection in Hong Kong

Summary Environmental protection in Hong Kong traditionally has been neglected by the government and private sector, with citizens showing little interest. The overwhelming pre-occupation with economic growth and a plethora of pressing social needs are often cited as the main excuses for past apathy. Since the late 1970s, the government has taken positive steps to establish administrative structures and statutes to arrest environmental decline. Legislative processes, however, have often been delayed and the effectiveness of the laws trimmed by the strong industrial lobby. The erratic developments in the 1980s nevertheless allowed the enactment of four dedicated environmental laws and a complement of ancillary control measures. The current status of the environment in the fields of water, waste, air and noise has been assessed to highlight the pertinent maladies and shortcomings. The 1989 White Paper provided a clear package of official policies and programmes to correct past ills in a ten-year comprehensive plan. The ameliorative measures, both present and projected, are evaluated for their effectiveness and prospects. Some issues that deserve more attention and improvements are suggested.     

空气污染对儿童及其父母呼吸系统健康的影响

 根据空气污染数据对广州、武汉、兰州、重庆4城市8个点位进行了空气污染的聚类分析,并按空气污染程度进行了排序.在此基础上,分析了空气污染程度与儿童及其父母呼吸系统健康的关系.发现儿童11种患病率随空气污染程度加重而呈上升趋势.污染最重组的患病率是污染较轻组的1.71(3.95倍.污染最重组的比数比(即OR值)是污染较轻组的3.313(6.942倍.空气污染对儿童父母的呼吸系统患病率也有轻度至中度的影响.     

Selenium Distribution in Topsoils and Plants of a Semi-arid Mediterranean Environment

Selenium was determined from 25 topsoils and 25 plants in the semi-arid Central Spain where large extents of soils are developed on evaporitic materials. Some species of vegetation associated with them are of the genera Astragalus, Salsola, Mercurialis, Phlomis, Thymus and Atriplex. Total selenium in soils was determined and its bioavailability assessed by chemical sequential fractionation. Se content in soils was adequate (in the range 0.17–0.39 mg kg⁻¹) or large (in the range 0.50–4.38 mg kg⁻¹) and appeared in highly and/or potentially available forms. Several plant species showed high Se levels (in the range 5–14.3 mg kg⁻¹), which can be a potential risk of toxicity to animals. Data obtained from the study area can be used as a guide to the range of values in soils and plants of the European Mediterranean area that are relatively unpolluted from industrial sources, allowing comparison with more polluted areas.     

Combustion sources of particles. 1. Health relevance and source signatures

Combustion processes result in generation of a large number of particle and gaseous products that create health and environmental risks. Of particular importance are the very small particles that are emitted in large quantities from all the combustion sources, and that have been shown to be potentially more significant in terms of their impact on health than larger particles. To control and mitigate the particles with a view of health and environmental risk reduction, a good understanding is necessary of the relative and absolute contribution from the emission sources to the airborne concentrations. This understanding could only be achieved by developing source signature libraries through direct emission measurements from the sources on one hand, and by measuring particle concentrations in the air, and apportioning them to the specific local and distant sources using the signatures, on the other hand. This paper is a review of particle characteristics that are used as source signatures as well as their general advantages and limitations. The second part of the paper reviews source signatures of the most common combustion pollution sources.     

Biomarker approach to evaluating the impact of scientific stations on the Antarctic environment using Trematomus bernacchii as a bioindicator organism

A biomonitoring study was performed to evaluate the human impact on two small coves adjacent to the Italian Scientific Station at Terra Nova Bay in November 1995. The study used the fish species Trematomus bernacchii as a bioindicator organism for a biomarker analysis based on porphyrin levels, and BPMO (Benzo(a)pyrene MonoOxygenase) and EROD (Ethoxyresorufin-O-deethylase) activities. Porphyrin levels and EROD and BPMO activities were found to be generally low. In contrast to previous years, no statistically significant difference was found between the potentially contaminated cove and the control cove after the Italian expedition had been active nearby for a period of one month. This indicates a marked decrease in certain types of contaminants such as organochlorines and trace metals, mainly due to improvements in waste disposal.     

Control of ozone precursors in a complex industrial terrain by using multiscale-nested air quality models with fine spatial resolution (1 km2)

The location of the northeastern Iberian Peninsula (NEIP) in the northwestern Mediterranean basin, the presence of the Pyrenees mountain range (with altitudes > 3000 m), and the influence of the Mediterranean Sea and the large valley canalization of Ebro river induce an extremely complicated structure for the dispersion of photochemical pollutants. Air pollution studies in very complex terrains such as the NEIP require high-resolution modeling for resolving the very complex dynamics of flows. To deal with the influence of larger-scale transport, however, high-resolution models have to be nested in larger models to generate appropriate initial and boundary conditions for the finer resolution domains. This article shows the results obtained through the utilization of the MM5-EMICAT2000-CMAQ multiscale-nested air quality model relating the sensitivity regimes for ozone (O3)-nitrogen oxides (NOx)-volatile organic compounds (VOCs) in an area of high geographical complexity, like the industrial area of Tarragona, located in the NEIP. The model was applied with fine temporal (one-hour) and spatial resolution (cells of 24 km, 2 km, and 1 km) to represent the chemistry and transport of tropospheric O3 and other photochemical species with respect to different hypothetical scenarios of emission controls and to quantify the influence of different emission sources in the area. Results indicate that O3 chemistry in the industrial domain of Tarragona is strongly sensitive to VOCs; the higher percentages of reduction for ground-level O3 are achieved when reducing by 25% the emissions of industrial VOCs. On the contrary, reductions in the industrial emissions of NOx contribute to a strong increase in hourly peak levels of O3. At the same time, the contribution of on-road traffic and biogenic emissions to ground-level O3 concentrations in the area is negligible with respect to the pervasive weight of industrial sources. This analysis provides an assessment of the effectiveness of different policies for the control of emission of precursors by comparing the modeled results for different scenarios.