Physical,chemical and biological behaviour of fumigants on cottonseed

Fumigation is required to protect cottonseed in storage and pre-shipment from insect pests and/or microorganisms. Fumigation of cottonseed with carbon disulphide (CS₂), carbonyl sulphide (COS), ethanedinitrile (C₂N₂), ethyl formate (EF), methyl bromide (MB) and phosphine (PH₃) showed that >85% of the fumigants disappeared within 5?h of exposure. COS maintained >20?mg L^–1 for 24?h. After 1?day of aeration, 75%–85% of the absorbed COS and MB and 20%–40% of the absorbed CS₂, EF and PH₃ were released from treated cottonseed. The fumigant residues were reduced by 80% for COS, 50% for EF or MB and 25% for CS₂ after 1?day of aeration. After 13?days of aeration, fumigant residues were reduced by 95% for MB, 65% for EF, 55% for CS₂ and to natural levels in the COS residue. Carbon disulphide, COS, PH₃, EF and C₂N₂ had no effect on the germination of cottonseed, but germination was reduced to 50% by MB. COS has potential as a fumigant for control of insect pests in cottonseed because it dissipates quickly and does not negatively impact germination. On the other hand, MB appears to strongly absorb and requires an extended period for residues to dissipate, and it negatively impacts germination.     

Clay mineral adsorbents for heavy metal removal from wastewater: a review

Environmental Chemistry Letters - Heavy metal pollution such as water contamination by Pb, Hg, Cu, Cd and Cr ions is induced by rapid urbanization and industrialization and is a major threat to...     

天津市气溶胶折射指数及消光特征

根据2005年5月17～23日Grimm气溶胶粒谱分析仪观测结果,考察天津市气溶胶消光特征.利用天津市2000年非采暖季PM10源解析的结果,初步得出天津市气溶胶的折射指数为1.585-0.118i.通过Mie理论计算得出天津市气溶胶散射消光占到总消光的60 0A以上;气溶胶消光主要集中于粒径小于1.00 μm的颗粒物,消光贡献率为80%以上.其中粒径为O.30～0.35 μm的颗粒物的消光贡献率最大,达20.7%.     

地表水中隐孢子虫和贾第鞭毛虫微球的混凝去除

以向地表水中投加的隐孢子虫微球和贾第鞭毛虫微球为对象,研究通过对给水混凝工艺对其的去除效果进行比较,着重考察了不同混凝剂种类、投加量及水样pH值对去除效果的影响.结果表明,混凝工艺可较为有效地去除地表水中的两虫微球,去除率最高可达4 lg.相比常规的金属盐类混凝剂,高分子的PAC、PAFC混凝剂对两虫微球的混凝去除率更...     

Quantification of net carbon flux from plastic greenhouse vegetable cultivation: a full carbon cycle analysis

Plastic greenhouse vegetable cultivation (PGVC) has played a vital role in increasing incomes of farmers and expanded dramatically in last several decades. However, carbon budget after conversion from conventional vegetable cultivation (CVC) to PGVC has been poorly quantified. A full carbon cycle analysis was used to estimate the net carbon flux from PGVC systems based on the combination of data from both field observations and literatures. Carbon fixation was evaluated at two pre-selected locations in China. Results suggest that: (1) the carbon sink of PGVC is 1.21 and 1.23 Mg C ha⁻¹ yr⁻¹ for temperate and subtropical area, respectively; (2) the conversion from CVC to PGVC could substantially enhance carbon sink potential by 8.6 times in the temperate area and by 1.3 times in the subtropical area; (3) the expansion of PGVC usage could enhance the potential carbon sink of arable land in China overall.     

Effect of topography on nitrous oxide emissions from winter wheat fields in Central France

We assessed nitrous oxide (N₂O) emissions at shoulder and foot-slope positions along three sloping sites (1.6–2.1%) to identify the factors controlling the spatial variations in emissions. The three sites received same amounts of total nitrogen (N) input at 170 kg N ha⁻¹. Results showed that landscape positions had a significant, but not consistent effect on N₂O fluxes with larger emission in the foot-slope at only one of the three sites. The effect of soil inorganic N (NH₄⁺ + NO₃⁻) contents on N₂O fluxes (r² = 0.55, p < 0.001) was influenced by water-filled pore space (WFPS). Soil N₂O fluxes were related to inorganic N at WFPS > 60% (r² = 0.81, p < 0.001), and NH₄⁺ contents at WFPS < 60% (r² = 0.40, p < 0.01), respectively. Differences in WFPS between shoulder and foot-slope correlated linearly with differences in N₂O fluxes (r² = 0.45, p < 0.001). We conclude that spatial variations in N₂O emission were regulated by the influence of hydrological processes on soil aeration intensity.     

不同温度条件水解酸化-好氧工艺处理高矿化度采油废水

采用不同温度组合的水解酸化-好氧工艺对胜利油田某联合处理站经过"隔油-混凝-过滤"处理的高矿化度采油废水进行处理.结果表明:水解酸化反应器内的微生物能够适应高温(55℃)的环境,而好氧反应器中微生物的活性会受到高温较大的抑制;"高温水解酸化-中温好氧工艺"和"中温水解酸化-中温好氧工艺"可以使出水COD达到低于80 mg/L的外排要求,停留时间分别为15 h和7.5 h.采用水解酸化-好氧工艺处理高矿化度油田采油废水足可行的.     

Cu(Ⅱ)-AgNbO3紫外光催化亚甲基蓝脱色性能研究

采用浸渍法制备了Ca(Ⅱ)-AgNbO3光催化剂,并运用XRD、FT-IR、DRS、XPS和SEM对催化剂进行表征和分析.实验以亚甲基蓝为模拟污染物,在紫外光下考察Cu(Ⅱ)掺杂对AgNbO3光催化效果的影响.分析显示,掺杂Cu(Ⅱ)后AgNbO3晶型及表面形貌没有发生变化,但在可见光区的吸光度得到有效提高.光催化脱色结果表明,当Cu(Ⅱ)的掺杂量为2%(质量比),热处理温度为300℃,催化剂用量为1 g/L,亚甲基蓝初始浓度为10 mg/L,溶液pH值为7.15时,Cu(Ⅱ)-AgNbO3紫外光催化亚甲基蓝脱色的效果最好,3 h后,亚甲基蓝脱色率可达97.1%.     

地震作用下客运专线黄土路基变形分析

以郑(州)-西(安)高速铁路为例,选择潼关路段为研究区,建立了高速铁路黄土路基动力学数值模型.研究了50年10%和2%的超越概率水平的地震作用下黄土路基的永久变形,以及地基处理后黄土地基的永久变形.结果显示,沉降主要发生在Q3,黄土中,强夯可以有效的减少地基黄土的沉降变形,但是当处理深度不够时.在强地震作用下仍然可以产生较大沉降.研究成果为地基抗震处理提供了依据.