极端梯度提升与随机森林融合的天然气露点预测方法

目的 解决目前水露点数据多为人工采用测量仪器测得,时效性低且成本高昂的问题。方法 建立一种基于极端梯度提升(XGBoost)和随机森林(RF)的天然气水露点预测方法。采用XGBoost方法对所有监测工艺参数进行分析,筛选出主要影响水露点的关键工艺特征参数,以排除无关特征参数对预测的干扰。建立RF预测模型,输入关键特征集参数,实现对水露点的实时预测。以重庆气矿某脱水监测系统监测数据与生产数据为例,对所提预测方法进行对比分析验证。结果 相较于XGBoost、SVM等预测方法,RF模型具有最佳的预测性能,且经过XGBoost特征选择后,RF预测结果的MAE值降低了0.016 9 ℃,RMSE值降低了0.014 6 ℃。结论 基于极端梯度提升与随机森林融合的水露点预测方法具有更优的预测精度与鲁棒性,对指导脱水现场生产具有积极作用。     

Molecularly imprinted polymer for analysis of trace atrazine herbicide in water

A molecularly imprinted polymer (MIP) for atrazine was synthesized by non-covalent method. The binding capacity of MIP was 1.00 mg g^{? 1} polymer. The selectivity and recovery were investigated with various pesticides which are mostly, found in the environment, for both similar and different chemical structure of atrazine. The competitive recognition between atrazine and structurally similar compounds was evaluated and it was found that the system provided highest recovery and selectivity for atrazine while low recovery and selectivity were obtained for the other compounds. The highest recovery was obtained from MIP compared with non-imprinted polymer (NIP), a commercial C₁₈ and a granular activated carbon (GAC) sorbent. The method provided high recoveries ranged from 94 to 99% at two spiked levels with relative standard deviations less than 2%. The lower detection limit of the method was 80 ng L^{? 1}. This method was successfully applied for analysis of environmental water samples.     

垃圾焚烧飞灰处理处置研究进展

针对作为危险废物的垃圾焚烧飞灰,介绍了近年来国内外对其进行处理处置的研究情况.飞灰的固化/稳定化处理主要从水泥(沥青)固化、熔融固化及化学药剂固化几方面进行论述,飞灰中重金属的提取主要从酸碱浸提、生物浸提、螯合剂浸提及电渗析法提取几方面进行论述.     

气相色谱-质谱法分析污水中溶解态有机物

采用0.45μm玻璃纤维滤膜将污水分离为悬浮态和溶解态有机物质,以二氯甲烷为萃取剂,采用液液萃取-气质联用法对污水中溶解态有机物进行测定,同时还对萃取条件(萃取次数,萃取时间,无机盐加入量)进行优化.结果表明:萃取回收率最高的是每个pH范围各萃取2次、静置5 min,氯化钠加入15g.该方法分析时间短,准确度好(样品平均加标回收率为91.1％ ～ 103％),精密度高(相对标准偏差小于5％),易于操作.     

大气气溶胶中元素种态研究

应用化学逐级提取流程对国际原子能机构（简称IAEA）气溶胶、室内和室外气溶胶、煤飞灰中元素的组成和种态进行了分析，应用仪器中子活化法测定了各种态中元素的含量，计算出元素在各种态中的分配比例。按照气溶胶中元素不同种态的环境和生物活性以及主要来源来分类，评述了元素在环境和生态系统中的吸收和转化能力，并对气溶胶中元素对环境的影响作出了初步的探讨。实验数据表明，气溶胶中的不同元素在各种态中的分布是有差异的。地壳来源元素中，Sc,Al,Fe和Ti主要分布在不溶物态中，稀土元素主要分布在氧化物态和不溶物态；不溶物态沉降到地表后不易进行迁移和转化，对环境的影响较小；氧化物态性质比较活泼，可以在大气中发生化学反应。Mn在气溶胶中主要分布在水可溶态和氧化物态，环境可交换性要比Al,Fe,Ti等大得多。人为来源元素的环境可交换态的比例都比较高，这说明它们通过干、湿清除过程沉降到地表后，水可溶态可以直接进入水循环；碳酸盐、氧化物和有机物态可以在适当的条件下与环境中的其他物质发生化学反应，生成易溶于水的化合物进入生态环境中，对环境影响较大。     

芳香酸稀溶液的络合萃取研究

络合萃取法分离极性有机物稀溶液具有高效性和高选择性。本文利用三辛胺或磷酸三丁酯为络合剂，四氯化碳、三氯甲烷、正辛醇或煤油为稀释剂，实验测定了苯甲酸、邻硝基苯甲酸稀溶液的萃取相平衡分配系数，讨论了影响因素。     

微波萃取技术在分析土壤中有机污染物的应用

介绍了微波萃取技术及其使用的试剂、设备和条件，对微波萃取在分析土壤中有机污染物的应用予以综述，阐述了微波萃取技术是分析土壤中有机污染物的好方法。     

Speciation and transport of arsenic in an acid sulfate soil-dominated catchment, eastern Australia

Factors controlling the transport of geogenically-derived arsenic from a coastal acid sulfate soil into downstream sediments are identified in this study with both solid-phase associations and aqueous speciation clearly critical to the mobility and toxicity of arsenic. The data from both sequential extractions and X-ray adsorption spectroscopy indicate that arsenic in the unoxidised Holocene acid sulfate soils is essentially non-labile in the absence of prolonged oxidation, existing primarily as arsenopyrite or as an arsenopyrite-like species, likely arsenian pyrite. Anthropogenically-accelerated pedogenic processes, which have oxidised this material over time, have greatly enhanced the potential bioavailability of arsenic, with solid-phase arsenic almost solely present as As(V) associated with secondary Fe(III) minerals present. Analyses of downstream sediments reveal that a portion of the arsenic is retained as a mixed As(III)/As(V) solid-phase, though not at levels considered to be environmentally deleterious. Determination of arsenic speciation in pore waters using high performance liquid chromatography/Inductively Coupled Plasma-Mass Spectrometry shows a dominance of As(III) in upstream pore waters whilst an unidentified As species reaches comparative levels within the downstream, estuarine locations. Pore water As(V) was detected at trace concentrations only. The results demonstrate the importance of landscape processes to arsenic transport and availability within acid sulfate soil environments.     

超声波提取-恒波长同步荧光法测定淡水藻中叶绿素a的含量

针对绿藻,采用超声波提取,以荧光激发-发射波长差216nm,建立了同步荧光法测定绿藻叶绿素a含量的新方法,其线性范围为0.02～1.25 mg/L,检出限为1.6ug/L,加标回收率在97.0%～104%之间。与分光光度法测定叶绿素a的对比试验结果表明,两者无显著性差异,但该方法具有快速、灵敏,其他常见色素不干扰测定的优点,能够满足供水中绿藻叶绿素a含量快速检测的需要。     

ASE—GPC—GC—MS快速分析土壤中的PAHs

建立了土壤中多环芳烃的气相色谱—质谱联用的快速检测方法。样品经过加速溶剂萃取、凝胶色谱净化、GC—MS分离测定,优化了加速溶剂萃取和凝胶色谱净化的条件。结果表明,多环芳烃的平均回收率为82.1%~106.4%,相对标准偏差为1.2%~4.8%。方法具有灵敏度高、准确度好、快速、消耗溶剂少的优点,适用于土壤等固体样品中多环芳烃的分离、净化和分析。