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191.
Atrazine contamination in agricultural soils from the Yangtze River Delta of China and associated health risks 总被引:1,自引:0,他引:1
J. T. Sun L. L. Pan Yu Zhan Daniel C. W. Tsang L. Z. Zhu X. D. Li 《Environmental geochemistry and health》2017,39(2):369-378
Atrazine is one of the most widely applied and persistent herbicides in the world. In view of limited information on the regional contamination of atrazine in soils in China, this study investigated the spatial distribution and environmental impacts of atrazine in agricultural soils collected from the Yangtze River Delta (YRD) as an illustrative analysis of rapidly developing regions in the country. The results showed that the concentrations of atrazine in the YRD agricultural soils ranged from <1.0 to 113 ng/g dry weight, with a mean of 5.7 ng/g, and a detection rate of 57.7 % in soils. Pesticide factory might be a major source for the elevated levels of atrazine in Zhejiang Province. The contamination of atrazine was closely associated with land use types. The concentrations and detection rates of atrazine were higher in corn fields and mulberry fields than in rice paddy fields. There was no significant difference in compositions of soil microbial phospholipids fatty acids among the areas with different atrazine levels. Positive relationship (R = 0.417, p < 0.05, n = 30) was observed between atrazine and total microbial biomass. However, other factors, such as soil type and land management practice, might have stronger influences on soil microbial communities. Human health risks via exposure to atrazine in soils were estimated according to the methods recommended by the US EPA. Atrazine by itself in all the soil samples imposed very low carcinogenic risks (<10?6) and minimal non-cancer risks (hazard index <1) to adults and children. 相似文献
192.
193.
Mingxuan Mao Li Zhang Qichang Duan O.J.K Oghorada Pan Duan Bei Hu 《International Journal of Green Energy》2017,14(8):694-702
The power-voltage (P-V) characteristic curves of a PV array are nonlinear and have multiple peaks under partially shaded conditions (PSCs). This paper proposes a novel maximum power point tracking (MPPT) method for a PV system with reduced steady-state oscillation based on a two-stage particle swarm optimization (PSO) algorithm. The grouping method of the shuffled frog leaping algorithm (SFLA) is incorporated in the basic PSO algorithm (PSO-SFLA), ensuring fast and accurate searching of the global extremum. An adaptive speed factor is also introduced into the improved PSO to further enhance its convergence speed. Test results show that the proposed method converges in less than half the time taken by the conventional PSO method, and the power is improved by 33% under the worst PSCs, which confirms the superiority of the proposed method over the standard PSO algorithm in terms of tracking speed and steady-state oscillations under different PSCs. 相似文献
194.
2006~2008年,对长江中游的一个浅水湖泊--肖四海进行了水质和水生植被研究,并结合历史资料分析了肖四海1987~2008年不同渔业发展阶段的水环境特征。研究结果表明:1987~2008年期间,该湖营养状况经历了中营养→富营养→中营养→富营养→中营养的变化过程,沉水植被经历了消亡→恢复→旺盛→衰退的演替过程,这种变化主要受不同阶段的渔业方式的影响。草食性鱼类和河蟹的过量放养、化肥的大量使用以及饵料的大量投放等不合理的渔业方式导致了水生植被的消亡和水体的富营养化,而合理的渔业方式不会对水体环境产生消极影响,并据此提出了长江中下游湖泊渔业可持续发展的建议 相似文献
195.
通过静态动力学和热力学吸附实验,研究了温度、共存离子以及溶质的初始浓度对As(V)在金红石TiO2颗粒表面吸附的影响,探讨了As(V)在金红石TiO2颗粒表面吸附特性及机理。结果表明,在As(V)初始浓度为10mg/L,pH为7的条件下,25℃时的吸附量0.41mg/g高于30℃时的吸附量0.31mg/g,As(V)在金红石TiO,上的吸附为放热过程。CaCl2和MgCl2的添加对As(V)在金红石TiO2表面吸附起到明显的促进作用。T=25℃,Ca2+或Mg2+浓度为10mmol/L时,As(V)吸附量分别为0.64和0.56mg/g,Ca2+比Mg2+对As(V)吸附促进作用强。As(V)在金红石TiO2的吸附等温线符合Frendlich方程,Lagergren二级动力学方程能较好地描述As(V)在金红石TiO2颗粒表面吸附的动力学过程。 相似文献
196.
Kuan Lun Pan Sheng Jen Yu Shaw Yi Yan 《Journal of the Air & Waste Management Association (1995)》2014,64(11):1260-1269
Direct decomposition of N2O by perovskite-structure catalysts including La2NiO4, LaSrNiO4, and La0.7Ce0.3SrNiO4 was investigated. The catalysts were prepared by the Pechini method and characterized by x-ray diffraction (XRD), BET, scanning electron microscopy (SEM), and O2-TPD. Experimental results indicate that the properties of La2NiO4 are significantly improved by partially substituting La with Sr and Ce. N2O decomposition efficiencies achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 are 44 and 36%, respectively, at 400ºC. As the temperature was increased to 600ºC, N2O decomposition efficiency achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 reached 100% at an inlet N2O concentration of 1,000 ppm, while the space velocity was fixed at 8,000 hr?1. In addition, effects of various parameters including oxygen, water vapor, and space velocity were also explored. The results indicate that N2O decomposition efficiencies achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 are not significantly affected as space velocity is increased from 8,000 to 20,000 hr?1, while La0.7Ce0.3SrNiO4 shows better tolerance for O2 and H2O(g). On the other hand, N2 yield with LaSrNiO4 as catalyst can be significantly improved by doping Ce. At a gas hour space velocity of 8,000 hr?1, and a temperature of 600ºC, high N2O decomposition efficiency and N2 yield were maintained throughout the durability test of 60 hr, indicating the long-term stability of La0.7Ce0.3SrNiO4 for N2O decomposition.
Implications:Nitrous oxide (N2O) not only has a high global warming potential (GWP100 = 310), but also potentially destroys ozone in the stratosphere. Pervoskite-type catalysts including La2NiO4, LaSrNiO4, and La0.7Ce0.3SrNiO4 are applied for direct N2O decomposition. The results show that N2O decomposition can be enhanced as Sr and Ce are doped into La2NiO4. At 600ºC, N2O decomposition efficiencies achieved with LaSrNiO4 and La0.7Ce0.3SrNiO4 reach 100%, demonstrating high activity and good potential for direct N2O decomposition. Effects of O2 and H2O(g) contents on catalytic activities are also evaluated and discussed. 相似文献
197.
Enhanced rice production but greatly reduced carbon emission following biochar amendment in a metal-polluted rice paddy 总被引:1,自引:0,他引:1
198.
餐厨垃圾中有机物大部分以大分子的形式存在,对其进行热处理,破坏大分子有机物的存在形式,将会影响其干式厌氧发酵的过程。实验对餐厨垃圾进行了热处理(100℃),处理后将其在含固率(TS)20%、接种率25%的条件下进行高温55℃厌氧发酵。实验结果表明,热处理后,餐厨垃圾的理化性质发生显著变化,累计产气量、TS和VS的去除率均增大。当热处理时间为15 min时,餐厨垃圾的SCOD值最高,为59.49 g/L,比未处理时提高了3.3倍。同样该条件下,累计产气量也最高,为2 782.8 m L,与未处理相比累积产气量提高58.30%,第二产气高峰比未处理提前3天。各发酵瓶发酵前后TS、VS去除率的变化趋势与累计产气量的变化基本一致,累计产气量越大,TS、VS的去除率越大。 相似文献
199.
Omar Faruk Mohini Sain Ramin Farnood Yuanfeng Pan Huining Xiao 《Journal of Polymers and the Environment》2014,22(3):279-288
The green rigid polyurethane (PU) foam has been developed with 100 % soy polyol after optimization of formulation ingredients and lignin has been introduced and isocyanate content reduced in the green rigid PU foam. The cellulosic nanofibers have also been successfully incorporated and dispersed in green rigid PU foam to improve the rigidity. The influence of nano cellulose fiber modification (enzymatic treatment, hydrophobic modification with latex) on the foam density, open cell content, foam raise height, water vapor, and mechanical properties of rigid PU foam were studied. The foamed structures were examined using scanning electron microscopy to determine the cell size and shape due to the addition of cellulosic nanofibers. The odor test were performed to evaluate the odor concentration 100 % soyol based PU foam including lignin and nanofiber and compared to 100 % synthetic based polyol PU foam. The experimental results indicated that the compression and impact properties improved due to the modification of nano cellulosic fibers. The odor concentration level of nanofiber reinforced rigid PU foam reduced significantly compared to 100 % PU foam due to the replacing of isocyanate content. It can be said that with an appropriate combination of replacing isocyanate by lignin and addition of nanofiber, rigid PU foam properties could be improved. 相似文献
200.
氨基膦酸树脂是一种常用的广谱性重金属螯合树脂,对水中的Pb(Ⅱ)具有很好的选择性分离去除能力,但吸附Pb(Ⅱ)后的树脂再生较为困难。系统研究了盐酸脱附Pb(Ⅱ)-负载氨基膦酸树脂D860的基本性能,优化了基本脱附参数。实验表明,采用盐酸作为脱附剂具有较为良好的脱附效果,10%吸附量树脂脱附反应平衡较快仅需10 min,脱附本身受Pb(Ⅱ)在盐酸溶液中的溶解度影响显著。脱附流速从1 BV/h升高到5 BV/h,脱附效果受到的影响很小。升高温度可以提高PbCl2溶解度,进而提高脱附效率。固定床脱附采用1.0 mol/L盐酸,在1 BV/h和303 K条件下,仅需7 BV脱附剂即可实现较高的脱附效率。 相似文献