Contaminants in the coastal karst aquifer system along the Caribbean coast of the Yucatan Peninsula, Mexico

Intensive land development as a result of the rapidly growing tourism industry in the “Riviera Maya” region of the Yucatan Peninsula, Mexico may result in contamination of groundwater resources that eventually discharge into Caribbean coastal ecosystems. We deployed two types of passive sampling devices into groundwater flowing through cave systems below two communities to evaluate concentrations of contaminants and to indicate the possible sources. Pharmaceuticals and personal care products accumulated in the samplers could only have originated from domestic sewage. PAHs indicated contamination by runoff from highways and other impermeable surfaces and chlorophenoxy herbicides accumulated in samplers deployed near a golf course indicated that pesticide applications to turf are a source of contamination. Prevention and mitigation measures are needed to ensure that expanding development does not impact the marine environment and human health, thus damaging the tourism-based economy of the region.     

Particle size distribution of airborne Aspergillus fumigatus spores emitted from compost using membrane filtration

Information on the particle size distribution of bioaerosols emitted from open air composting operations is valuable in evaluating potential health impacts and is a requirement for improved dispersion simulation modelling. The membrane filter method was used to study the particle size distribution of Aspergillus fumigatus spores in air 50 m downwind of a green waste compost screening operation at a commercial facility. The highest concentrations (approximately 8 × 10⁴ CFU m⁻³) of culturable spores were found on filters with pore diameters in the range 1–2 μm which suggests that the majority of spores are emitted as single cells. The findings were compared to published data collected using an Andersen sampler. Results were significantly correlated (p < 0.01) indicating that the two methods are directly comparable across all particles sizes for Aspergillus spores.     

Choice of parameters for passive shielding of power-frequency magnetic fields

Epidemiological studies suggesting the possibility of harmful effects on human (specifically children’s leukaemia) due to long-term exposure to magnetic fields of extremely low frequency (e.g. 50/60 Hz) and relatively low values (i.e. over the microtesla range) have stirred high activity in the topic of magnetic field mitigation. To reduce these fields, it is common to use passive metal screens (e.g. plates made of aluminium or steel). To design them, effective and fast numerical computations are highly desirable. In this article, a method is presented, which computes various parameters of screens in a given shielding problem and yields magnetic field distribution and shielding factors. The method takes into consideration the 3D field distribution and is able to solve systems with large aspect ratios (thin thickness in comparison with its other dimensions); this is a common problem where other methods such as finite elements often experience difficulties. The presented method computes separately the field inside and outside the screens. Afterwards, the solutions are “stitched” together along the border of the subregions. Two practical examples are given of the developed numerical method.     

Which compounds contribute most to elevated airborne exposure and corresponding health risks in the Western Balkans?

A majority of ongoing monitoring of persistent organic pollutants (POPs) is currently focused on chemicals emphasized in the Stockholm Convention. Quantitative detection of other substances (especially those with numerous anthropogenic sources such as polyaromatic hydrocarbons (PAHs)) is, however, also needed since their concentrations are usually several orders of magnitude higher. A goal of this study was to determine how various groups of compounds contribute to total human health risks at the variety of sampling sites in the region of Western Balkan. Distribution of the risks between the gas and particulate phases was also addressed. Results showed that inhalation exposure to organochlorine pesticides (OCPs) does not represent a significant risk to humans, while polychlorinated biphenyls (PCBs) re-volatilized to the atmosphere from contaminated soils and buildings can pose a problem. PCB evaporation from primary sources (currently used PCB-filled transformers or non-adequate storage facilities) generally resulted in much higher atmospheric concentrations than evaporation from the secondary sources (soils at the sites of war destructions). A majority of the human health risks at the urban sites were associated with PAHs. Between 83 and 94% of the cumulative risk at such sites was assigned to chemicals sorbed to particles, and out of it, PAHs were responsible for 99%.     

Mapping of tritium emissions using absorption vapour samplers

Püspökszilágy Radioactive Waste Treatment and Disposal Facility (RWTDF) is a typical near-surface engineered repository designated to store low- and intermediate-level wastes from various institutes, research facilities and hospitals in Hungary. Two automatic combined ¹⁴C–tritium sampling units installed at the facility sample the air 2 m above surface. The one installed near the vaults detects tritium (T) activities two orders of magnitude higher than the far reference sampling unit. To localize the T emissions, 19 small absorption vapour samplers filled with silica gel were settled onto the ground surface. After the saturation of the silica gel, the water was recovered and its T concentration was measured with a low-background liquid scintillation counter. The absorption vapour samplers are cheap, simple and easy-to-use. We present the samplers and the T distribution map constructed from the data, which helps to localize the T emission.     

Temporal and spatial patterns of micropollutants in urban receiving waters

Based on a monitoring program over the course of a year, we characterize the temporal and spatial distribution of selected micropollutants in an urban watershed within the city of Leipzig, Germany. Micropollutants revealed a ubiquitous presence in untreated and treated wastewater, surface water and groundwater. The loads of 4-nonylphenol in the effluents of the municipal wastewater treatment plant followed a seasonal trend, whereas the loads of all other micropollutants were highly variable and not correlated to seasons. In the surface water, load seasonality of caffeine, galaxolide and tonalide resulted from a rapid removal with increased water temperature. The loads of 4-nonylphenol and of caffeine in the colder months increased when rainfall occurred. In the groundwater, complex spatial and temporal patterns were apparent and were related to varying input, retardation and removal processes. As a consequence, an assessment of micropollutants in urban waters should consider different micropollutants' temporal and spatial variability.     

我国煤矿劳动防护用品使用现状调查分析及对策研究

劳动防护用品是保障从业人员安全与健康的最后一道防线.本文在对全国部分重点产煤省份煤矿劳动防护用品现场调研的基础上,分析了不同类型煤矿劳动防护用品的现状及存在的问题,提出了进一步做好煤矿劳动防护用品管理工作的对策.     

Fenton 法降解抗生素磺胺间甲氧嘧啶钠

应用Fenton高级氧化技术降解水溶液中抗生素磺胺间甲氧嘧啶钠(SMMS),系统探讨了起始pH、CSMMS、CFe2+、CH2O2和温度等因素对SMMS降解效果的影响。结果表明:CSMMS=4.53 mg/L,pH=4.0,CH2O2=0.49 mmol/L,CFe2+=19.51μmol/L,T=25℃为最佳反应条件。在最佳条件下,87.4%的SMMS可以在120 min内降解。反应动力学研究表明Fenton氧化降解SMMS分为两个阶段,快速反应阶段和慢速反应阶段,并建立了两阶段动力学模型,模型拟合结果较好。研究结果为含有SMMS的污废水处理提供了基础数据和科学参考。     

高性能纤维在个体防护装备上的应用现状及前景分析

高性能纤维是从化学纤维演化而来,是指耐高温、耐气候、耐化学腐蚀、质量轻、强度高、模量高的特种纤维材料。本文结合几种典型的高性能纤维的具体性能,对高性能纤维在个体防护装备上的应用现状及前景作了分析,旨在进一步推动高性能纤维在个体防护装备上的应用,从而在不同的使用情况下增强个体防护装备对人体的保护功能。     

Identification of Odor Causing Compounds in a Commercial Dairy Farm

The odorous air emissions from confined animal feeding operations (CAFOs), such as swine, poultry and dairy farms, are increasingly raising community complaints. Odorous emissions can result in health damages, psychological discomforts and adverse aesthetic effects in the community. However, these emissions are not well characterized up to now due to the lack of legislation, the limitations in sampling and instrumentation techniques, and the complexity of the emissions themselves. This study is aimed at the development of a high volume sampler and sorbent assembly to identify the odor causing compounds from a diary CAFO. The sorbent was custom designed to target the potential compounds that may exist in a dairy farm and was validated in laboratory with a synthetic odor from the swine manure. The actual samples at the diary farm were collected in spring and summer of 2005. The sorbents were solvent extracted and individual odor compounds were identified using GC–MS (gas chromatography–mass spectroscopy). The data obtained indicated that high volume sampling can shorten the sampling time from days to within 4 h. Both volatile organic compounds (VOCs) and volatile fatty acids (VFAs) have been identified from the dairy farm, such as phenol, methylphenol, 4-ethyl phenol, indole, methyl indole, benzyl alcohol, hexanoic acid, valeric acid and iso-valeric acid, together with some nitrogen containing compounds that have not been reported before.