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81.
稻田CO2通量对光强和温度变化的响应特征 总被引:8,自引:1,他引:7
采用涡度相关法对我国亚热带稻田生态系统CO2通量进行了连续监测,并对CO2通量随光强和温度变化的响应特征进行了分析.结果表明,白天稻田生态系统CO2通量对光强的响应过程可以用直角双曲线方程进行描述.随光强的增加,CO2通量(绝对值)呈增加趋势,当光强大于1 000μmol/(m2·s)时,CO2通量变化比较稳定.早、晚稻间以及不同生育期水稻的光量子利用效率和最大光合速率存在一定的差异.晚稻的光量子利用效率(0.046 5~0.099 9 μmol/μmol)高于早稻(0.0176~0.0541μmol/μmol),并以水稻生长旺盛期的光量子利用效率和最大光合速率最高.夜间稻田生态系统呼吸速率随土壤温度的升高呈指数增加,5 cm土层温度可以作为反映稻田呼吸速率变化的温度指标.早稻生长季生态系统呼吸对温度的变化明显较晚稻生长季更为敏感. 相似文献
82.
交联壳聚糖-CdS颗粒可见光催化脱色甲基橙研究 总被引:1,自引:0,他引:1
利用壳聚糖对金属离子的配位络合作用和吸附性能,模拟生物矿化仿生制备交联壳聚糖/CdS复合粒子。以甲基橙为处理对象,氙灯模拟可见光,研究了该复合材料对甲基橙的降解脱色性能。用Langmuir-Hinshelwood方程从动力学的角度,考察了不同催化剂浓度、甲基橙的初始浓度、反应体系的pH值、外加无机阴离子等对甲基橙降解脱色的影响。结果表明,该复合材料的吸附性能和光催化活性产生的协同作用能较有效促进甲基橙染料的脱色,在低质量浓度条件下可见光催化过程为假一级反应。光催化剂的最佳用量为1.5g/L,甲基橙降解的最佳pH为4.0。Cl-和Br-均对MO的光催化脱色起抑制作用,而NO3-的添加明显促进MO的光催化速率。 相似文献
83.
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 Unfortunately, many hazardous substances do not have OELs or the OEL could be outdated.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
84.
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
85.
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
86.
87.
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
88.
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
89.
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
90.
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