Personal monitoring of exposure to particulate matter with a high temporal resolution

Background

Continuous monitoring of air quality is implemented by government institutions at fixed ambient sites. However, the correlation between fixed site measurements and exposure of individual persons to air contaminants is likely to be weak.

Materials and methods

We measured particulate matter both outdoors and indoors by following the spatial movement of individuals. Sixteen test persons took part and carried a measurement backpack for a 24-h period. The backpack was comprised of a Grimm Aerosol Spectrometer model 1.109, a GPS device, and a video camera for tracking of human behavior. The spectrometer provided information about particle numbers and mass in 32-size classes with a high temporal resolution of 6 s.

Results

The personal exposure of individuals during 24 h could significantly exceed the outdoor particulate matter (PM)₁₀ concentrations measured at the fixed sites. The average 24-h exposure of all test persons for PM₁₀ varied from 27 to 322 ??g m^?3. Environmental tobacco smoke and cooking emissions were among the main indoor sources for PM. The amount of particulate matter a test person was exposed to was highly dependent on the spatial behavior and the surrounding microenvironment conditions.

Discussion

Large-scale experiments including personal measurements might help to improve modeling approaches to approximate the actual exposure on a statistically sound basis.     

Estimation of emission fluxes from a horizontal flux budget method, exemplified with determination of pesticide volatilization

The paper describes an experimental set-up designed to measure the volatilization of different pesticides after application under full-scale field conditions. The pesticides were sprayed around the circumference of a circle and measurements of meteorology and air concentrations of pesticides were taken in the centre of the circle. The paper describes how the dimensions like the radius of the circle and height of the mast in the experimental set-up are found from theoretical considerations. A method to increase the confidence of the flux calculations is described. It utilizes that several substances were applied simultaneously and that a certain parameter in the fitted concentration profiles depends on turbulence only and thus have the same value for all substances. The design was used during two campaigns, conducted on the same location, one during fall on bare soil and one in spring on a barley crop.     

Analysis of accumulation, extractability, and metabolization of five different phenylarsenic compounds in plants by ion chromatography with mass spectrometric detection and by atomic emission spectroscopy

Phenylated arsenic compounds occur as highly toxic contaminants in former military areas where they were formed as degradation products of chemical warfare agents. Some phenylarsenic compounds such as roxarsone and aminophenylarsonic acids were applied as food additive and veterinary drugs in stock-breeding and therefore pose an environmental risk in agricultural used sites. Very few data exist in the literature concerning uptake and effects of phenylarsenic compounds in plants growing on contaminated soils. In this study, the accumulation, extractability, and metabolization of five different phenylarsenic compounds, phenylarsonic acid, p- and o-aminophenylarsonic acid, phenylarsine oxide, and 3-nitro-4-hydroxyphenylarsonic acid called roxarsone, by the terrestrial plant Tropaeolum majus were investigated. Ion chromatography coupled to inductively coupled plasma mass spectrometry was used to differentiate these arsenic compounds, and inductively coupled plasma atomic emission spectroscopy was used for total arsenic quantification. All compounds considered were taken up by the roots and transferred to stalks, leaves, and flowers. The strongest accumulation was observed for unsubstituted phenylarsonic acid followed by its trivalent analogue phenylarsine oxide that was mostly oxidized in soil whereas the amino- or nitro- and hydroxy-substituted phenylarsonic acids were accumulated to a smaller degree.The highest extraction yield of 90% for ground leaf material was achieved by 0.1 M phosphate buffer, pH 7.7, in a two-step extraction with a total extraction time of 24 h. The extraction of higher amounts of arsenic (50–70% of total arsenic present in leaves depending on arsenic species application) from non-ground intact leaves with deionized water in comparison with the buffer (20–40% of total arsenic) is ascribed to osmotic effects. The arsenic species analysis revealed a cleavage of the amino groups from the phenyl ring for plants treated with aminophenylarsonic acids. A further important metabolic effect consisted in the production of inorganic arsenate and arsenite from the phenylated arsonic acid groups.     

联合基于野外的代谢组学和化学分析手段筛选优先关注新兴污染物：在五大湖流域的案例研究

由于毒性评估项目很难与日渐增长的需要测试的污染物保持同步,所以较难将关注点集中在影响水生生态系统的最为生物相关的污染物上。由于评估潜在毒性污染物所造成的生物影响已被证明是有效的,内生性代谢物的研究（代谢组学）对于剔除那些较低可能造成生物影响的污染物或许有一定帮助,从而找出生物重要性最高的污染物。本研究在北美五大湖流域的18个地点针对置于笼中的黑头软口鲦（Pimephales promelas）进行实验。我们测定了水体温度和水样中的污染物浓度（目标污染物132种,检出86种）,并使用1H-NMR谱测量了肝极性提取物中的内生性代谢物。利用偏最小二乘法回归来比对内生性代谢物的相对丰度与污染物浓度和环境温度。结果表明内生性极性代谢物的指标与最多49种污染物存在共同变化。因此我们认为至多52%的检出污染物与内生性代谢物变化的共同变化不显著,表明这些污染物很可能不会在这些地点造成可以检测到的影响。这是通过缩短对于实验地点有着潜在影响的污染物列表从而扫描出检出污染物生物相关性的第一步。类似的信息有助于风险评估者区分不同污染物的重要性并将重点毒性测试放在最为生物相关的污染物上。
精选自Nicol Janecko, Lucie Pokludova, Jana Blahova, Zdenka Svobodova, Ivan Literak. Linking field-based metabolomics and chemical analyses to prioritize contaminants of emerging concern in the Great Lakes basin. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2493–2502, October 2016. DOI: 10.1002/etc.3409
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3409/full
     

Impact of Arenicola marina (Polychaeta) on the microbial assemblages and meiobenthos in a marine intertidal flat

The benthic microbial food web can be responsible for a large proportion of benthic carbon cycling yet there are few data on the trophic interactions between this food web and macrobenthos. A large-scale field experiment was conducted to investigate effects of eliminating the polychaete Arenicola marina on benthic microbes (prokaryotes, heterotrophic and autotrophic protists) and metazoan meiofauna in a marine intertidal flat of the North Sea, Germany. Over a period of 2 years, quantity and composition of micro- and meiobenthos from unmanipulated sites were compared to those from sites deplete of lugworms. These grazer treatments were cross-classified with different sediment characteristics (low- and mid-intertidal areas). Lugworm removal resulted in an initial increase in abundance of prokaryotes and nanoflagellates, which became less pronounced in the second year. Ciliates were not affected quantitatively, but in the absence of lugworms, diversity and the proportion of carnivorous forms increased. Meiobenthos (nematodes, ostracods and copepods) were affected only moderately. The observed changes are probably due to a combination of release from grazing/predation pressure, changes in the species composition of higher trophic levels (namely large polychaetes) and altered environmental conditions (such as depth of the oxygenated layer and sediment grain size). Spatial differences between sites of different tidal exposure/grain size appeared to be as large as temporal differences during the 2 years following the manipulation of the system. We conclude that in intertidal sediments, indirect effects due to habitat transformation are as important as direct biological interactions (grazing pressure and competition) for the dynamics of the benthic microbial food web.     

Modelling of spatio-temporal population dynamics of earthworms under wetland conditions—An integrated approach

Both the effects of earthworms on soils and the effects of soil conditions on earthworms have been studied with the help of experiments and modelling. This paper provides a model architecture allowing coupling both effects to a dynamic interaction in changing environmental conditions. We chose for a spatio-temporally explicit model and focussed on wetland conditions. Soil temperature and humidity have been modelled by means of finite volumes and were used to determine the spatial habitat suitability. The life cycles of earthworms have been modelled by Leslie matrices where soil humidity, soil temperature and population densities have been used to parametrize survival and transition probabilities. Earthworm dispersion has been described by a cellular automaton of the domain providing spatial population densities for both the life cycle submodel and the soil conditions submodel.     

Environmental regulation of exploration and mining operations in Asian countries

This paper offers a new perspective on the environmental laws in Asian nations affecting the exploration, mining, and reclamation activities of the mineral resource industry: the perspective of the senior government officials in those countries, whose job is to enforce these new environmental laws. The article presents the results of a 1998 survey of national environmental officials in Asia conducted by the Colorado School of Mines and the Metal Mining Agency of Japan. Officials in 10 diverse countries—Cambodia, China, Indonesia, Lao PDR, Malaysia, Myanmar, Mongolia, Philippines, Thailand and Vietnam—responded to a detailed questionnaire covering applicable laws, agencies, protected areas, covered mineral activities, financial assurance, environmental impact assessment, public involvement, environmental standards, permit and reclamation requirements.
The survey confirms that Asian nations are part of the global trend towards national government regulatory structures that balance mineral development objectives with environmental considerations. The survey also shows developing regulatory systems (some embryonic, some more mature) utilizing a combination of mining and environmental acts, and often an 'insider' perspective of the national officials administering the laws. While that perspective is not without its biases (not least the rigor of enforcement), it may nevertheless be of use in company planning. The emerging regulatory picture contradicts the conventional notion that it is the 'lower' level of regulation in Asia that is attracting foreign direct investment in mining.     

PEAKING STORAGE TANKS FOR WATER SUPPLY SYSTEMS1

ABSTRACT: Construction of a “peaking storage tank” may reduce the operational cost of municipal water in the availability of a time-of-use energy rate. A peaking storage tank is used for storing water that is pumped from wells or other sources of supply during off-peak periods when energy costs are less for use during periods of on-peak water demand. The optimal size of a peaking storage tank is that which results in the minimum total cost, which includes both the storage construction cost and the cost of operation of the pumps. The operational cost for a given time-of-use rate is determined by help of a pipe network simulation model solved by the Newton-Raphson technique and a dynamic programming optimization model. A more simplified method is also introduced. Analyses show that low off-peak energy costs make the construction of peaking storage tanks economically attractive and reduce on-peak energy use, which results in electrical load leveling.     

Microbial metabolism of chlorobiphenyls

Photochemical reactions induced by sunlight contribute to the overall chemistry of natural water systems in many ways. The degradation of pollutants, dissolution of iron and manganese sediments, cycling of trace metal nutrients, and reactions of aquatic nitrogen and oxygen species are some of the many processes having solar photolysis pathways. This paper reviews recent research concerned with photo‐decomposition of pollutants, photolysis of nitrite and nitrate, photosensitization by humic materials and the generation of reactive intermediates. In addition, background material is presented concerning the basic principles of photochemistry and the limited wavelength range of effective solar radiation.     

Characterization of 14C-naphthol uptake in excised root segments of clover (Trifolium pratense L.) and fescue (Festuca arundinaceae Screb.)

An isolated root uptake test (IRUT) was used to characterize the bioaccumulation of ¹⁴C-naphthol in excised root segments obtained from 6-month-old hydroponically grown plants: two varieties of fescue (Festuca arundinaceae Schreb.) and one variety of clover (Trifolium pratense L.). Naphthol uptake rates were directly related to naphthol concentration in the range 0.01 to 0.2 uM. The incubation time required for equilibrium to be reached between naphthol in root tissue and in solution was between 9 and 12 h. Tests using metabolic inhibitors, KCN, NaN₃, and DNP, indicated that naphthol uptake may be the result of both passive and active mechanisms. Q₁₀ values for naphthol uptake ranged from 1.05 to 1.16.