三峡库区城乡消落带人工植被恢复土壤放线菌多样性特征

为研究人工植被恢复后消落带土壤放线菌群落多样性特征,以三峡库区典型城市消落带重庆江北嘴大剧院消落带和乡村消落带忠县汝溪河流域消落带为研究区域,于2015年6月原位采集0~20 cm、20~40 cm、40~60 cm土壤,利用限制性末端长度多态性(terminal restriction fragment length polymorphism,T-RFLP)方法,对消落带人工恢复植被土壤不同土层的放线菌群落多样性进行研究.结果发现:(1)三峡库区城乡消落带人工植被恢复后的土壤放线菌多样性有差异,表现为城市消落带土壤放线菌多样性高于乡村消落带土壤(P0.05),特别是在表层土壤.(2)在城乡消落带中,林地土壤放线菌多样性高于草地,且在土层之间放线菌多样性无显著性差异.(3)三峡库区城乡消落带人工植被恢复后的土壤放线菌优势种有差异.(4)冗余分析(redundancy analysis,RDA)和蒙特卡罗置换检验(Monte-Carlo permutation test)表明,城市消落带中含水量、速效氮含量显著影响放线菌群落多样性;乡村消落带中土壤含水量、有机质、速效氮和速效钾含量显著影响放线菌群落多样性.结论表明在消落带人工植被修复后,城市消落带土壤放线菌多样性均高于乡村消落带,这有可能是人为干扰和土壤养分增加所致.     

我国注册安全工程师注册现状分析

根据注册安全工程师初始注册申请表以及注册安全工程师注册信息管理数据库、国家安全生产监督管理总局和人事部人事考试中心提供的数据,对目前已注册的17441名注册安全工程师的年龄结构、学历结构、安全生产相关工作年限和受聘单位性质进行了统计分析。结果表明,我国现有注册安全工程师年龄、学历结构合理,但数量上仍不能满足需要。笔者提出应通过制订考试标准等方式加快注册安全工程师专业技术人才队伍建设的建议。     

Acoustic Observations of Bottom Surge From Dredged Material Discharge in the Open Ocean

Bottom surges generated from dredged material discharges in the open ocean have been observed using high frequency acoustic concentration profilers in several field studies during the past five years. the locations, water depths, bottom slopes, oceanographic conditions, and dredged material composition differed from study to study. Observed surges at three dredged material disposal sites may develop more than one surge peak for a single discharge. for water depths of the order of 10 m, surge height of the leading peak was estimated to be about one quarter of the water depth. for water of greater depth, of the order of 100 m, surge height reached 70 m, about 70% of the water depth. Surge height is established instantaneously when dredged material hits the bottom, and remains relatively constant as the surge advances horizontally. Total surge length reached 150 m for water depths of 10 m when measured from the impact point to the leading edge. for water depths of more than 100 m, the surge length reached more than 100 m. Length of the leading surge peak was as large as 45 m at this water depth.

Dimensional analysis was applied to relate the surge height of the leading surge peak to discharge parameters and oceanographic conditions. Results showed that the ratio of surge height to water depth was proportional to 1/10 power of the ratio of discharge volume to the third power of water depth.     

大气污染暴露与育龄妇女月经周期长度的关联

招募343名山西常住的育龄妇女,开展大气污染暴露与育龄妇女月经周期长度的横断面研究.基于妇女月经周期生理特点,设置大气污染暴露的时间窗口期.采集妇女所在城市的空气质量监测点大气SO₂、NO₂、PM_2.5和O₃的日报浓度,分别计算不同暴露时间的大气污染物浓度水平.采用广义线性模型,分析大气污染暴露与育龄妇女月经周期长度的关联效应,阐明大气污染暴露对妇女生育力的潜在健康风险.结果表明,当控制混杂因素后,妇女在SO₂暴露窗第1期(0.053,95%CI:0.022,0.083)、第2期(0.049,95%CI:0.02,0.078)和第3期(0.045;95%CI:0.017、0.073),Q4组SO₂的暴露水平与月经周期总长度呈显著的正相关;而且,SO₂与月经周期总长度的正相关主要表现在卵泡期长度的延长上.在NO₂暴露窗第1期(0.060,95CI:0.035,0.085)、第2期(0.056,95CI:0.030,...     

城市间运输货车行驶工况构建与应用

为研究城市间运输货车行驶工况特性与典型工况构建方法。运用车载数据采集系统采集了在珠三角区域城市间运输的货运车辆行驶车速等瞬态数据。基于13个工况特征参数解析工况特性,运用运动学片段理论将工况速度数据分成284个工况片,基于主成分分析和聚类分析法将工况片分成5类,选出12片代表工况片,按工况片平均速度从小到大的顺序排列,再将工况时长等比例压缩至1 800 s后最终构建出典型行驶工况。构建工况与实测样本的各项特征参数符合度大于80%,结果表明提出的典型工况构建方法可行,构建工况符合城市间货运车辆实际运行特性。构建工况的最大车速为80 km/h,主要分布在60~80 km/h,C-WTVC工况在0~90 km/h较均匀分布,平均车速为41.0 km/h,较构建工况低15.8%。基于构建工况进行重型货车排放性能仿真测算,得出CO_(2e)排放因子为764.81 g/km,较C-WTVC工况测算值低10.97%,表明运行工况不同导致碳排放测算值有较大差异。     

安徽省冬季采暖耗能对全球气候变暖的响应

基于1971—2018年安徽省77个气象站均一化日平均温度资料,采用趋势分析等方法,研究气候变暖对冬季采暖耗能的影响。结果表明：近48年安徽省冬季显著增暖,采暖初日推迟、终日提前,采暖期长度缩短,采暖强度显著下降。冬季温度在1989年发生突变,此后进入升温通道,因而将研究序列划分为基准时段（1971—1989年）和变暖期（1990—2018年）。相比于基准时段,变暖期内采暖期长度呈现空间一致性缩短,变化幅度自东北向西南递减,皖北北部及江淮之间东部缩短程度最大,大别山及皖南山区为全省低值区。全省采暖强度均减少,减少幅度自北向南递减。采暖节能贡献率介于3.6%~8.9%之间,高值区主要位于皖北北部、江淮之间北部和沿江东部,低值区则位于大别山及皖南两大山区。     

土壤湿度和机械长度对棉花秸秆分解率的影响

新疆棉花秸秆产量巨大,但是棉花秸秆的木质素和纤维素含量较高,不易被分解,很难作为饲料利用。本文研究了棉花秸秆在不同条件（土壤水分、棉花机械长度）处理下的分解速率。从土壤水分条件来看,棉花秸秆在50%土壤饱和含水量下的分解最为理想,其分解率在100 d后达到54.08%;从棉花秸秆粉碎程度来看,棉花秸秆粉碎越细越有利于其分解,但是3 cm处理100 d后分解率为54.12%,而1 cm处理100 d后分解率只有47.42%,说明棉花秸秆分解需要一定的孔隙度。另外,棉花秸秆分解之后对土壤肥力也有很大影响。此次试验结果可为推广大田试验提供科学依据。     

Community dynamics of ammonia oxidizing bacteria in a full-scale wastewater treatment system with nitrification stability

To determine whether the functional stability of nitrification was correlated to a stable community structure of ammonia oxidizing bacteria (AOB) in a full-scale wastewater treatment plant, the AOB community dynamics in a wastewater treatment system was monitored over one year. The community dynamics were investigated using specific PCR followed by terminal restriction fragment length polymorphism (T-RFLP) analysis of the amoA gene. The T-RFLP results indicated that during the period of nitrification stability, the AOB community structure in the full-scale wastewater treatment system was relatively stable, and the average change rate every 15 d of the system was 6.6%±5.8%. The phylogenetic analysis of the cloned amoA gene showed clearly that the dominant AOB in the system was Nitrosomonas spp. The results of this study indicated that throughout the study period, the AOB community structure was relatively stable in the full-scale wastewater treatment system with functional stability of nitrification.