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91.
Jean-Franois Cabaraux Franois-Xavier Philippe Martine Laitat Bernard Canart Marc Vandenheede Baudouin Nicks 《Agriculture, ecosystems & environment》2009,130(3-4):86-92
Gaseous emissions from agriculture contribute to a number of environmental effects. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are greenhouse gases taking part to the global problem of climate change. Ammonia (NH3) emissions are responsible of soil acidification and eutrophication and contribute also to indirect emissions of N2O. This work evaluated the influence of the type of floor on the emissions of these gases in the raising of weaned pigs. Two trials were carried out. In the first trial, the animals were kept either on fully slatted floor or on straw-based deep litter and, in the second one, either on fully slatted floor or on sawdust-based deep litter. For each trial and on each type of floor, 2 successive batches of weaned pigs were raised without changing the litter or emptying the slurry pit between the 2 batches. The rooms were automatically ventilated to maintain a constant ambient temperature.The performance of the animals was not significantly different according to the floor type. In trial 1, the nitrogen contents of the straw deep litter (including the substrate) and slurry were respectively 276 and 389 g pig−1. In trial 2, the sawdust deep litter and slurry nitrogen contents were respectively 122 and 318 g pig−1.Raising pigs on straw deep litter produced proportionately around 100% more NH3 than raising pigs on slatted floor (0.61 g NH3-N d−1 pig−1 vs. 0.31 g NH3-N d−1 pig−1; P < 0.05). Differences in CO2, H2O and CH4 emissions were not significant between systems. Raising pigs on sawdust deep litter produced also proportionately more NH3 (+52%; 0.55 g NH3-N d−1 pig−1 vs. 0.36 g NH3-N d−1 pig−1; P < 0.01) but also more CO2 (+25%; 427 g d−1 pig−1 vs. 341 g d−1 pig−1; P < 0.001) and H2O (+65%; 981 g d−1 pig−1 vs. 593 g d−1 pig−1; P < 0.001) and less CH4 (−40%; 0.52 g d−1 pig−1 vs. 0.86 g d−1 pig−1; P < 0.001) than raising pigs on slatted floor. Practically no N2O emission was observed from rooms with slatted floor while the N2O emissions were 0.03 and 0.32 g N2O-N d−1 pig−1 for the straw and sawdust deep litter respectively. The warming potential of the greenhouse gases (N2O + CH4), were about 22, 34 and 168 g CO2 equivalents per day and per pig on fully slatted floor, straw or sawdust deep litter respectively.In conclusion, pollutant gas emissions from rearing of weaned pig seem lower with fully slatted plastic floor system than with deep litter systems. 相似文献
92.
Occupational exposure limits (OELs) developed by authorities play a key role in the implementation of programs to protect workers against hazardous chemicals. Unfortunately, many hazardous substances do not have OELs or the OEL could be outdated. To assure the health of the workers, it is therefore useful for companies to develop corporate OELs. An inhouse strategy will be presented hereafter. Expertise in toxicology, industrial hygiene, and occupational health should be available within the company and clear selection criteria for substances are needed. A corporate OEL is only developed for hazardous substances (e.g., carcinogenic or reprotoxic) with a high potential for worker exposure when an appropriate national OEL or threshold limit value is not available. The methodology to calculate corporate OELs is based on the existing methods for national or community OELs and also on the guidance from the European Union's (EU) regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). For carcinogenic substances with a nonthreshold mode of action, there is always a residual chance that a cancer develops even when the exposure of workers is low. To establish an OEL for these substances, the “German traffic light model” is recommended. It is pragmatic, defines an unacceptable, tolerable, and acceptable risk level when workers are exposed to these substances, and determines risk management for exposure reduction. Overall, the professional practice to develop OELs is a good example of corporate leadership to proactively protect the health of workers. 相似文献
93.
Grzegorz Owczarek Grzegorz Gralewicz Natalia Skuza Piotr Jurowski 《International journal of occupational safety and ergonomics》2016,22(1):66-70
In this research the factors used to evaluate the light transmission through two types of acrylic hydrophobic intraocular lenses, one that contained yellow chromophore that blocks blue light transmission and the other which did not contain that filter, were defined according to various light condition, e.g., daylight and at night. The potential influence of light transmission trough intraocular lenses with or without yellow chromophore on functional vision in everyday environmental conditions was analysed. 相似文献
94.
以移动烟团积分模式为基础,采用数学模型分析法,从理论上导出了小风和静风状态下的TSP大气扩散模式。该模式描述了重力沉降和地面不完全反射对颗粒物大气扩散过程的影响;与现有的大气扩散模式体系完全相容,可以方便地应用于小风和静风状态下TSP地面浓度的预测计算 相似文献
95.
96.
芳纶1414是重要的高性能芳香族聚酰胺纤维且在个体防护领域应用非常广泛,但在光老化作用下力学性能下降非常明显,从而影响其使用寿命。本文从耐光性研究、耐光性能评价方法、耐光防护三个方面综述了芳纶1414在光辐射下的稳定性和安全化研究进展。耐光性研究方面,国内外对于芳纶1414在光辐射下的损伤机理的解释,尚难达成一致;耐光性能评价方法方面,现有的评价方法不能直观地反映出光老化作用对织物实际性能的影响情况,从防弹性能的保留率角度对其耐光性能进行评价是未来研究的方向;耐光防护方面,溶胶-凝胶法是目前应用最为广泛的织物抗光老化整理方法,但该法也仅限于对芳纶织物表面处理,对里层纤维的紫外防护有限,如何提高芳纶织物整体抗紫外性能需进一步深入研究。 相似文献
97.
Visible light is a major fraction of the solar spectrum; however, information on visible light radiation of macrophyte detritus is lacking. In this study, we conducted a microcosm experiment to assess the effects of visible light radiation on degradation of two litter species: Potamogeton malaianus (P. malaianus) and Phragmites australis (Ph. australis). This research represents an investigation of mass loss, microbial activity and nutrients released over a period of 168 days. Overall, we found that visible light radiation had significant effects on litter decomposition, but it did not affect the microbial activities which degrade cellulose and lignin. The decomposition rate order of the three components in P. malaianus and Ph. australis in treatments was: cellulose?>?hemicellulose?>?lignin. The visible light radiation mainly affected the degradation of lignin, which is the primary compound in litter susceptible to photodegradation. The exposure to visible light radiation up to 17.6?Wm?2 stimulated the dissolved organic carbon release and reduced the molecular weight to less reactive. Meanwhile, no obvious difference in nutrient contents (TP, TN, NO3–N, NO2–N, and NH3–N) was observed among different visible light intensities. The results of this study contribute to better understanding of the photochemical behaviour of macrophyte litter in shallow lakes. 相似文献
98.
于2013年冬季在天津大气边界层观测站利用Andersen撞击式采样器采集了26 d的颗粒物样品,并进行化学组分分析,同步观测颗粒物吸收系数、数浓度、能见度及其他气象要素. 对比分析了污染日和清洁日颗粒物质量浓度及其化学组成的粒径分布特征,在此基础上,利用Mie模型计算外混、内混、“核-壳” 3种混合态假设下颗粒物的消光系数、散射系数和吸收系数. 与实测吸收系数的比较可知,颗粒物的混合态可能更加接近“核-壳”态. “核-壳”态假设下颗粒物平均消光系数模拟值为(517.44±308.42)Mm-1,其中污染日平均值为(668.39±307.30)Mm-1,清洁日为(275.91±37.90)Mm-1,相对湿度对颗粒物的消光系数有显著影响. 污染日颗粒物中OM(有机质)、(NH4)2SO4、NH4NO3、EC和其他物质对消光系数的贡献率分别为30.4%、25.5%、17.7%、8.1%和18.3%,清洁日分别为49.8%、11.0%、7.2%、10.6%和21.4%. PM0.4~1.1、PM>1.1~2.1、PM>2.1~10的消光系数贡献率分别为69.6%±6.7%、13.9%±3.3%和16.5%±6.4%. 污染日高浓度的细粒子是导致能见度下降的主要原因,其中亚微米颗粒物对消光占据主导地位,(NH4)2SO4、NH4NO3、OM是主要的消光化学组分. 相似文献
99.
Wendong WANG Qinghai FAN Zixia QIAO Qin YANG Yabo WANG Xiaochang WANG 《Frontiers of Environmental Science & Engineering》2015,9(1):147
The presence of humic acid in drinking water treatment has received significant attention in recent years because of its adverse effects on the removal of many pollutants in coagulation. In this paper, the effects of water quality including pH, turbidity, alkalinity, and hardness on the removal of humic acid were investigated in a UV light hybridized coagulation process. Our results suggested that UV light radiation could effectively improve the removal rate of humic acid in coagulation under both neutral and basic conditions, and the variations of the selected water quality parameters had little adverse effect on the function of UV light. After UV light radiation, the removal rate of the nitro-humic acid (NHA) increased from 20% to 60% in coagulation, and increased further to 75% and 85% for the raw waters with 10.0 NTU kaolin and 100 mg·L-1 hardness, respectively. In addition to NHA, the removal rates of the humic acid extracted from peat coal (PHA) and the humic acid provided by Japan metals and chemicals company (JHA) in coagulation were also improved, both in the range of 80%–90% after undergoing UV light radiation. By changing the radiation location from prior to coagulation to the flocculation process, similar experimental results were obtained. The formation of positive charged sites after UV light radiation was considered to be the primary factor that led to an enhanced removal of the humic acid in coagulation. 相似文献
100.
快速城市化时期中国城市建成区植被状况的时空分异特征 总被引:1,自引:0,他引:1
基于植被变化视角,以中国656 个建制城市的建成区为研究对象,选择1992、2000 和2010 年DMSP/OLS 夜间灯光数据和植被数据,选用城市建成区内归一化植被指数(Normalized Difference Vegetation Index,NDVI)的均值反映建成区植被的状况;用建成区内NDVI均值和背景区内NDVI均值的比值(NDVI比值)衡量人为因素对城市建成区植被的影响情况。结果表明:①同一年份,城市规模越大,建成区植被越差;近20 a 来,除小城市植被变差外,其他等级城市植被总体在变好。②同一年份,规模小的城市人为因素产生的不利影响相对较小。近20 a 来,人为因素对特大城市和大城市植被产生的不利影响在减小,而中等城市基本不变,小城市则变大。③同一年份,从湿润半湿润森林带、半干旱草原带到干旱荒漠带的城市建成区内的植被逐渐变差;近20 a 来,干旱荒漠带的建成区植被状况略微变差,其余植被带内建成区植被变好。④同一年份,从湿润半湿润森林带、半干旱草原带到干旱荒漠带人为因素对建成区植被的不利影响逐渐减小;近20 a 来,湿润半湿润森林带内人为因素对建成区植被的不利影响在减小,而其他植被带内,人为因素的不利影响在增加。 相似文献