低压天然气回收再利用与节能环保

凝析油气藏在开采后期,由于地层压力自然递减加快,开采难度加大,而后期的工业及民用天然气需求量不断增加,导致凝析气藏产气量逐年缩减与天然用量逐步增多的矛盾日益明显。为缓解这一矛盾,考虑将不能输送的放空低压气进行技术增压,达到输送压力后,进入输送管道,从而增加天然气输送量,减少天然气放空对环境的污染。     

甘蔗蔗糖磷酸合成酶SPSⅡ cDNA片段克隆与表达分析

蔗糖磷酸合成酶(Sucrose phosphate synthase,SPS)是蔗糖合成途径的关键限速酶,在蔗糖积累和碳分配中具有重要作用.在茎组织中SPSⅡ表达量占SPS转录总量的40%,表明SPSⅡ cDNA的克隆与表达对蔗茎中蔗糖的积累有着重要的影响.通过RT-PCR技术克隆分离SPSⅡ基因cDNA片段.序列分析表明该cDNA片段包含1个3 183 bp的开放读码框,可编码1 060个氨基酸.GenBank登录号为EU269038.通过实时荧光定量PCR检测SPSⅡ基因在甘蔗糖分积累的不同时期、不同组织部位的相对表达量.结果表明,在糖分积累初期蔗茎中的SPSⅡ相对表达量最大,在糖分积累中期蔗叶中的SPSⅡ相对表达量达到最高峰;同组织部位中,糖分积累初期SPSⅡ相对表达量高于糖分积累中期、后期.图6参11     

The function of constructed wetland in reducing the risk of heavy metals on human health

Irrigation with polluted water from the upper Yellow River (YR) channel of Northwest China has resulted in agricultural soil being contaminated by heavy metals (HMs). This causes major concerns due to the potential health risk to the residents in this area. The present study aims to assess the efficiency of constructed wetland (CW) in reducing the heavy metal contamination in irrigation water and food crops, thus in reduction of potential health risk to the residents. The associated risk was assessed using hazard quotient (HQ) and hazard index (HI). The results showed a potential health risk to inhabitants via consumption of wheat grain irrigated with untreated water from YR. However CW could greatly reduce the human health risk of HMs contamination to local residents through significantly decreasing the concentrations of HMs in wheat grain. In theory, the reduction rate of this risk reached 35.19% for different exposure populations. Therefore, CW can be used as a system to pre-treat irrigation water and protect the residents from the potential HMs toxicity.     

NO2对二甲苯光氧化生成SOA及其吸光度影响

NO₂是大气中常见污染气体,影响大气二次有机气溶胶（Secondary organic aerosol,SOA）的形成.运用实验室烟雾箱模拟二甲苯大气光氧化反应过程,研究NO₂对二甲苯SOA生成量、光学特性和化学组成的影响.结果显示,NO₂促进二甲苯SOA的形成,NO₂浓度从0增长到900×10^-9,二甲苯SOA的质量浓度增长2倍左右,并且邻二甲苯SOA质量浓度大于对二甲苯SOA.这是因为邻位取代基相比于对位取代基更倾向于形成醛,有利于聚合反应形成低聚物,促进SOA形成.此外,NO₂浓度增加显著提高所生成SOA的单位质量吸光度（Mass absorption coefficients,MAC）,这是由于前体物邻二甲苯和对二甲苯化学结构不同,邻二甲苯所生成的含氮有机物具有更强吸光性,从而导致邻二甲苯SOA的MAC_{λ=365 nm}大于对二甲苯SOA的MAC_{λ=365 nm}.在线气溶胶质谱仪分析结果进一步显示：二者光化...     

Activation of cadmium under simulated solar illumination and its impact on the mobility of Cd in flooded soils

In waterlogged paddy soils, cadmium (Cd) can be precipitated as cadmium sulfide (CdS) under reductive environment, thereby limiting the absorption of Cd by plants. Multiple environmental factors (such as water, pH, and Eh) played a role in the control of Cd mobility and bioavailability. In this study, we investigated the influence of the solar irradiation on the photodissolution of synthetic CdS-montmorillonite composites (CdS-M) in solution and the stability of Cd in natural soil. The release kinetic of Cd²⁺ showed that after the irradiation of simulated sunlight, CdS-M composites became less stable compared to the dark control. The solar irradiation seemed to enhance the release of Cd²⁺ from CdS significantly and continuously. Electron paramagnetic resonance (EPR) and quenching experiments confirmed that the photogenerated holes, ?O₂^? and ?OH, were possibly involved in the photo-induced release of Cd²⁺, while the holes was primarily responsible for the reaction. Irradiation under alkaline solution or the presence of DOM, PO₄^3?, CO₃^2?, and urea markedly inhibited the photodissolution process of CdS. The photo-mediated activation of Cd was further confirmed in paddy soil under natural sunlight, with a nearly threefold increase in concentration of extractable Cd during the 15 days of irradiation. This study highlights the importance of photochemical transformation of Cd in the environmental water and soil.