离心法应用于高浊度地表水中氨氮测定预处理过程中的方法

比较多种预处理方法去除浊度对地表水氨氮测定的影响,结果表明在测定高浊度地表水氨氮的过程中,采用离心法可较好地去除悬浮物对水样测定的干扰。较清水样用比色前离心方法,对于较浑浊的水样用絮凝沉淀结合比色前离心方法,可明显去除浊度的干扰,得到稳定的氨氮数值。2种方法的准确度和精密度均满足质控要求。     

絮凝沉淀法测定地表水中氨氮的方法改进

本文通过比较监测黑臭河流氨氮时人员比对的结果,对絮凝沉淀预处理过程的关键因素进行了改进。结果表明,直接在离心管中絮凝沉淀、离心、取样分析,精密度和准确度更好,而且方便快捷,值得推广。     

Dissolved organic matter in pore water of freshwater sediments: effects of separation procedure on quantity, quality and functionality

Pore water was separated either with or without water extraction prior to centrifugation (7600 or 20 000 × g) in order to investigate the effects of separation procedure on the amount and properties of dissolved organic matter (DOM i.e. the material passing through a 0.45-μm filter) in three freshwater sediments. On the basis of solubility in alkaline, organic matter was concluded to compose of humic substances in two (S1 and S3) and of humin (S2) in one of the sediments. DOM in the samples was quantified by total organic carbon measurement. Specific UV-absorption (SUVA) and high performance size exclusion chromatography (HPSEC) analyses were used to characterize DOM. Sorption of pyrene was used as a measure for functionality of DOM. Both water extraction and centrifugation speed were shown to affect the properties of DOM; however, the effects were sediment dependent. Water extraction increased the amount of DOM separated from the two sediments that had humic character (S1 and S3). In most cases water extraction increased SUVA and shifted the molecular size distribution of DOM towards larger sizes. The separation procedure had also an effect on the functionality of DOM. In water extracted samples of S2 and S3 the sorption of pyrene was higher than in the corresponding samples separated without water extraction, whereas in S1 similar effect was not found. Generally, centrifugation speed had smaller effects on the properties of DOM than water extraction. The fact that the effects of separation procedure on DOM depend on the sediment characteristics complicates the comparison between samples and evaluation of functionality in field conditions.     

荧光分光光度法测定海洋生物体中石油烃前处理方法优化

海洋生物体中的石油烃质量分数是海洋环境监测评价体系的重要指标,现行分析方法标准为《海洋监测规范第6部分:生物体分析》(GB 17378.6—2007)荧光分光光度法,该标准方法中前处理操作较为复杂,实际样品分析中存在样品平行性差、加标回收率范围宽等问题。由于样品均匀性、皂化进程、萃取分离操作手法等因素均会影响样品测定结果的平行性和精密度水平。因此,对比了不同制备方式的样品(干样和匀浆样),通过过滤或离心的方式去除了皂化液中的非石油烃大分子干扰;并对比了不同皂化温度和时间,获得了最优的前处理方法,提升了方法的准确度和精密度。对实际海洋生物体样品的分析表明,优化后的方法检出限为0.9 mg/kg,变异系数为7.02%~14.4%,加标回收率为67.4%~138%,精密度和准确度良好,基本满足海洋生物体中石油烃测定的要求。     

离心法在土壤颗粒分级技术中的应用

用离心法进行土壤颗粒分级,优化了离心时间和转速,并对河北保定,浙江嘉兴,磐安、永康和温州五地典型土壤样品进行了土壤颗粒粒径分布的初步研究,探讨了土壤颗粒直径和土壤有机质.土壤pH值之间的相关关系.结果显示:离心法土壤分级技术的回收率为96.73%～99.74%,实验按照粒径尺寸将土壤样品分成四级,分别是砂粒(>20 μm),粗粉砂(5～20μm),细粉砂(2～5μm)和粘粒(<2 μm).保定土壤的砂粒含量最高,达92.68%,磐安土样的粗粉砂含量最高,达4.12%,各样品细粉砂颗粒含量相当,均值为1.73%,粘粒含量很少,均值为0.44%.土壤有机质含量以磐安土壤最高,达9.15%,而土壤pH值则是保定土壤最高,为8.14.     

制浆,黑液碱回收试验研究

本文对造纸工业制浆黑液中的碱回收问题进行了探讨,在实验的基础上,提出了一种切实可行而且比传统的燃烧法投资更省的碱回收工艺,即将多效蒸发后的浓缩黑液经等离子处理后得到的黑粉,稀释后用离心过滤脱水的办法再进行碱回收。     

Priority and emerging pollutants in sewage sludge and fate during sludge treatment

This paper aims at characterizing the quality of different treated sludges from Paris conurbation in terms of micropollutants and assessing their fate during different sludge treatment processes (STP). To achieve this, a large panel of priority and emerging pollutants (n = 117) have been monitored in different STPs from Parisian wastewater treatment plants including anaerobic digestion, thermal drying, centrifugation and a sludge cake production unit. Considering the quality of treated sludges, comparable micropollutant patterns are found for the different sludges investigated (in mg/kg DM – dry matter). 35 compounds were detected in treated sludges. Some compounds (metals, organotins, alkylphenols, DEHP) are found in every kinds of sludge while pesticides or VOCs are never detected. Sludge cake is the most contaminated sludge, resulting from concentration phenomenon during different treatments. As regards treatments, both centrifugation and thermal drying have broadly no important impact on sludge contamination for metals and organic compounds, even if a slight removal seems to be possible with thermal drying for several compounds by abiotic transfers. Three different behaviors can be highlighted in anaerobic digestion: (i) no removal (metals), (ii) removal following dry matter (DM) elimination (organotins and NP) and iii) removal higher than DM (alkylphenols – except NP – BDE 209 and DEHP). Thus, this process allows a clear removal of biodegradable micropollutants which could be potentially significantly improved by increasing DM removal through operational parameters modifications (retention time, temperature, pre-treatment, etc.).     

分光光度法测定土壤阳离子交换量的方法优化

为了提高土壤阳离子交换量测定的准确度,针对《土壤阳离子交换量的测定三氯化六氨合钴浸提-分光光度法》(HJ 889—2017)标准的不足,对有机质、pH值、浸提时间、离心时间、浸提液过滤等条件进行优化。结果表明,酸性土壤在测试前调节pH值为6.0~8.0,振荡1 h,离心10 min,能够很好地解决测试结果偏低的问题。当有机质质量分数较高,且在380 nm处吸光度很高时,才需要在475 nm处进行吸光度校正。当实际样品基质复杂时,可采用针头过滤的方法,使得测试结果更准确。优化后的方法适用于各种类型土壤的大批量测定。