Kinetic studies of O3 reactions with 3-bromopropene and 3-iodopropene in the temperature range 288–328 K

The kinetics of the reactions of O₃ with 3-bromopropene and 3-iodopropene has been studied over the temperature range of 288–328 K at atmospheric pressure. The results obtained for the room temperature rate constants are (1.88 ± 0.22) × 10^?18 and (3.52 ± 0.43) × 10^?18 cm³ molecule^?1 s^?1, and the proposed Arrhenius expressions are k = (3.47 ± 1.28) × 10^?15 exp[(?2233 ± 110)/T] and k = (8.17 ± 2.12) × 10^?14 exp[(?2991 ± 80)/T] cm³ molecule^?1 s^?1 for 3-bromopropene and 3-iodopropene, respectively. The atmospheric chemical lifetimes of these two compounds with O₃ were also estimated from these values.     

声场中PM2.5颗粒碰撞运动模型

建立了声场中PM2.5颗粒碰撞运动模型。模拟结果表明,颗粒碰撞前速度与水平面的夹角θ是影响颗粒运动轨迹的一个重要因素,它的改变将决定颗粒在声场中是否碰撞、碰撞的位置以及碰撞后颗粒如何运动;颗粒碰撞前的速度大小将决定颗粒碰撞后是沿声波方向运动还是逆声波方向运动或是停留在原地振动;声场频率的不同改变了颗粒在发生碰撞时的运动趋势及颗粒的在碰撞时的运动趋势,同时,声场频率的改变将影响碰撞后颗粒的振幅;声场声强的改变不但影响了颗粒运动的振幅,而且影响了颗粒碰撞后运动趋势。     

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.     

Impact of long-range transport and under-cloud scavenging on precipitation chemistry in East China

Introduction  

Two hundred twenty-five precipitation samples were collected at high- (summit, 1,534 m ASL) and low-elevation (base, 218 m ASL) sites between 2005 and 2008 in eastern China. The present work focused on the roles of long-range transport and under-cloud/boundary layer scavenging on chemical composition of precipitation collected at the two sites.     

Influences of influent carbon source on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge

It is necessary to understand the bioflocculation, settling and dewatering characteristics in the activated sludge process in order to establish more efficient operational strategies. The influences of carbon source on the extracellular polymeric substances (EPS) and flocculation, settling and dewatering properties of the activated sludge were investigated. Laboratory-scale completely mixed activated sludge processes were used to grow the activated sludge with different carbon sources of starch, glucose and sodium acetate. The sludge fed with acetate had highest loosely bound EPS (LB-EPS) and that fed with starch lowest. The amount of tightly bound EPS (TB-EPS), protein content in LB-EPS, polysaccharide content and protein contents in TB-EPS, were independent of the influent carbon source. The polysaccharide content in LB-EPS of the activated sludge fed with sodium acetate was lower slightly than those of starch and glucose. The sludge also had a nearly consistent flocs size and the sludge volume index (SVI) value. ESS content of the sludge fed with sodium acetate was higher initially, although it was similar to those fed with glucose and starch finally. However, the specific resistance to filtration and normalized capillary suction time fluctuated first, but finally were stable at around 5.0 × 10⁸ m kg⁻¹ and 3.5 s L g⁻¹ SS, respectively. Only the protein content in LB-EPS weakly correlated with the flocs size and SVI of the activated sludge. But there was no correlation between any other EPS contents or components and the physicochemical properties of the activated sludge.     

The Forest‐Streamflow Relationship in China: A 40‐Year Retrospect1

Abstract: The relationship between forests and streamflows has long been an important research interest in China. The purpose of this paper is to summarize progress and lessons learned from the forest‐streamflow studies over the past four decades in China. To better measure the research gaps between China and other parts of the world, a brief global review on the findings from paired watershed studies over the past 100 years was also provided. In China, forest management shifted in the later 1990s from timber harvesting to forest restoration. Forest‐streamflow research was accordingly changed from assessing harvesting impacts to evaluating both harvesting and forestation effects. Over the past four decades, Chinese forest hydrology research has grown substantially. Significant progress has been made on measuring individual processes, but little solid, long‐term data were available to assess the relationship between forest changes and streamflows because of an absence of standard paired watersheds. In addition, misuse of statistical analyses was often found in the literature. A unique opportunity exists in China to study the forestation effects on streamflow as several large‐scale forestation programs are being implemented. Such an opportunity should include a robust paired watershed design under an integrated watershed ecosystem framework to avoid repeating the lessons already learned. Recommendations on future forest‐streamflow research directions in China are provided.     

生物质炭对土霉素胁迫下小白菜种子萌发的影响

采用土培模拟污染实验,将甘蔗渣炭、菠萝渣炭和木薯渣炭分别以0%、0.1%、0.5%和1.0%的炭土比添加到砖红壤中,研究土霉素胁迫下小白菜种子萌发效应。结果表明:(1)生物质炭促进种子萌发;土霉素在0~300 mg·kg~(-1)胁迫下种子发芽率未受明显影响,300~500 mg·kg~(-1)时受轻微抑制。(2)土霉素为0~100 mg·kg~(-1)时对种子根及芽伸长呈促进作用,促进率最高达33.05%。100~500 mg·kg~(-1)呈抑制效应,最大抑制率63.98%;种子对土霉素的敏感顺序依次为:根伸长>芽伸长>发芽率。(3)在土霉素胁迫下炭土比与种子根伸长呈显著正相关。3种生物质炭对小白菜种子根及芽伸长的促进效果呈:木薯渣炭>菠萝渣炭>甘蔗渣炭。(4)生物质炭和低浓度土霉素共同促进小白菜萌发,对高浓度土霉素毒性有缓解作用。     

洚解菌Pigmentiphagasp．strainD-2对啶虫脒污染土壤的生物修复作用

啶虫脒属于一种新型的氯化烟碱类杀虫剂,被认为是替代有机磷农药的重要品种之一,在世界范围内已经得到了广泛的应用,其在环境中的残留备受关注,利用微生物修复异源污染物是一种有效的措施。在实验室条件下,研究了高效降解菌D-2（噬染料菌属,Pigmentiphagasp．）对被啶虫脒污染土壤的修复作用及其影响因素。结果表明,降解菌株在未灭菌土壤中的降解效果要略好于灭菌土壤,在土壤外源添加降解菌2×10^8cfu／g,温度20～40℃,弱碱性（pH7．5）的条件下,该菌株能有效降解土壤中1～200mg／kg的啶虫脒。啶虫脒施用对土壤种群结构有一定的影响,可以刺激细菌和真菌的生长,从而使土壤微生物群落结构发生改变,而降解菌的施用可缓解啶虫脒对土壤微生物的影响,修复受污染土壤。因此,人工接种降解菌D-2可提高土壤中啶虫脒的降解率,有效降低其在土壤中的残留。     

好氧反硝化苯酚降解菌的分离鉴定及动力学

从驯化菌群中分离筛选出一株好氧反硝化苯酚降解细菌,经生理生化反应及16S rDNA测序,鉴定为Diaphorobacter属细菌。在好氧条件下,该菌株以苯酚为唯一碳源和能源,利用NO-3-N作为反硝化电子受体,其生长与反硝化特性研究表明:在接种量5%(体积分数),30℃,180 r/min振荡培养条件下,菌株降酚能力可达1 400 mg/L,同时,能有效去除初始浓度为165 mg/L的硝酸盐氮,60 h其去除率为91.5%,高含量苯酚对菌体生长有一定的抑制作用。应用Haldane方程对其生长过程进行动力学模拟,拟合曲线与实验测定值相关性良好,各参数分别为μmax(最大比增长率)0.324 h-1,Ks(半饱和常数)9.36 mg/L,Ki(抑制常数)146.72 mg/L,通过理论分析及实验验证得,该菌株苯酚降解动力学与其生长动力学表现出相似的趋势。