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排序方式: 共有1077条查询结果,搜索用时 140 毫秒
1.
Dong Cao Ziyu Rao Fanglan Geng Hongyun Niu Yali Shi Yaqi Cai Yuehui Kang 《环境科学学报(英文版)》2020,32(11):67-74
Molecular level characterization of dissolved organic sulfur (DOS) by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS) is necessary for further understanding of the role of DOS in the environment. Here, ESI spray solvent, a key parameter for ion production during ESI process, was investigated for its effect on the molecular characterization of DOS by ESI-FTICR MS. 100% MeOH as spray solvent was found for the first time to remarkably enhance the ionization efficiency of the majority of CHOS-molecules in NOM, which facilitated a total of 1473 CHOS-molecular formulas with one sulfur atom to be detected. The number of CHOS-molecular formulas obtained using 100%MeOH as spray solvent increased notably over 740 in comparison with those using 50% MeOH aqueous solution (731) or 50% ACN aqueous solution (653). Moreover, due to the enhancement of ionization efficiency of DOS during ESI processes, the tandem mass spectra of the NOM CHOS-molecules could be easily obtained using 100% MeOH as spray solvent, which were hardly obtained using 50% MeOH aqueous solution as spray solvent. The results of the tandem mass spectra suggested the first discovery of organosulfates or sulfonic acids in Suwannee River NOM sample. A simple method based on 100% MeOH as ESI spray solvent for advanced molecular characterization of DOS by ESI-FTICR MS was proposed and applied, and the results revealed more molecular information of DOS in sea DOM samples. 相似文献
2.
选取我国华中丘陵区的湖南省长沙县一个典型水稻种植区,对2015与2016年2年雨水样中的SO42-S和大气SO2的沉降量进行监测,分析雨水中SO42-、NO3-的关系,解析大气硫沉降的主要来源.结果表明,研究区大气中SO2-S和雨水中SO42--S的年均浓度分别为8.5 μg/m3和1.1mg/L,大气硫沉降年均总量为26.8kgS/(hm2·a),其中年均降雨混合沉降量18.2kgS/(hm2·a),年均干沉降量为8.6kgS/(hm2·a).研究区域硫素干、混合沉降量存在明显的季节差异,硫素混合沉降春季高于夏、秋、冬季,而硫素干沉降冬季高于春、夏、秋季.雨水中NO3-/SO42-的质量比大多小于1,表明研究区大气硫素主要来自固定污染源(燃煤).华中丘陵区稻田具有较高的硫沉降,但硫沉降量已较21世纪初出现了较大幅度下降,农业生产中需要根据农田硫素收支状况酌情补充硫肥来保证作物高产稳产. 相似文献
3.
Gałuszka A 《Environmental monitoring and assessment》2005,110(1-3):55-70
In June of 2000, biogeochemical study was carried out in three ecosystems of the Holy Cross Mountains (south-central Poland).
This paper presents element concentrations and stable sulfur (and in one site lead) isotope ratios in rocks, detailed soil
profiles, and plant bioindicators including epiphytic lichen Hypogymnia physodes (L.) Nyl., mosses (Pleurozium schreberi (Brid.) Mitt., Hypnum cupressiforme Hedw. S. Str., Hylocomium splendens (Hedw.) B.S.G.), Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth.), aspen (Populus tremula L.) and English oak (Quercus robur L.). Chemical analyses were performed with ICP-AES and AAS methods in the accredited laboratory (Central Chemical Laboratory
of the Polish Geological Institute in Warsaw). The principal objective of this study was to compare the chemical composition
of rocks, soils and selected plant bioindicators between investigation sites using the same methods of sample collection,
preparation and analyses. The results of this study have shown that there is a high variability in concentrations of elements
in plant bioindicators from the same sites that can not be explained only by soil properties or anthropogenic influence. This
conclusion indicates that for biomonitoring purposes (especially with vascular plants) we cannot neglect individual features
of the species examined. 相似文献
4.
Ports can generate large quantity of pollutants in the atmosphere due to various activities like loading and unloading,transportation, and construction operations. Determination of the character and quantity of emissions from individual sources is an essential step in any project to control and minimize the emissions.In this study a detailed emission inventory of total suspendedparticulate matter (TSP), particulate matter less than 10 m(PM10), sulfur dioxide (SO2) and nitrogen oxides (NOx) for a port and harbour project near Mumbai is compiled. Results show that the total annual average contributions of TSP and PM10 from all the port activitieswere 872 and 221 t yr-1, respectively. Annual average emissions of gaseous pollutants SO2 and NOxwere 56 and 397 t yr-1, respectively, calculatedby using emission factors for different port activities. The maximum TSP emission (419 t yr -1) was from paved roads, while the least (0.4 t yr-1) was from bulk handling activity. The maximum PM10 emission (123 t yr-1) was from unpaved roads and minimum (0.2 t yr-1) from bulk handling operations. Similarly the ratio of TSP and PM10 emission was highest (5.18) from paved roads and least (2.17) from bulk handling operations. Regression relation was derivedfrom existing emission data of TSP and PM10 from variousport activities. Good correlation was observed between TSP andPM10 having regression coefficient >0.8. 相似文献
5.
6.
干旱与半干旱地区土地生产潜力的测定──以新疆阜康县为例 总被引:1,自引:0,他引:1
本文探讨了一个通过土壤有效水分含量来确定土地等级和土地生产力的方法。这个方法采用倍增参量形式来确定土壤有效水分。其变量包括潜水位、土层厚度、土壤质地、坡度和盐分。此项研究证明用这种方法获得的土地初级生产力与实测值比较一致。因此,我们可以在类似环境下用这种方法估测土地生产潜力。 相似文献
7.
8.
湿式脱硫除尘技术在开发应用中的几点看法 总被引:1,自引:0,他引:1
当前,随着经济的快速发展,全国燃煤量不断增加,二氧化硫、烟尘超标排放已导致严重的环境污染问题.二氧化硫、烟尘排放量的控制,可采用选用清洁煤,改变燃烧技术及末尾脱硫除尘技术.比较而言,烟气除尘脱硫技术是一种技术成熟较为经济的应用技术.其中湿式脱硫除尘技术已得到广泛推广与应用,但该技术中仍存在不能消除黑烟、二氧化硫脱除不稳定因素多、设备腐蚀问题.本文通过对实际测试结果分析及脱硫效率影响因素的分析,提出了相应的看法与建议. 相似文献
9.
张志杰 《辽宁城乡环境科技》2006,26(1):29-30,33
目前测定空气中SO2主要采用甲醛吸收-副玫瑰苯胺分光光度法。该法操作比较严格,测试结果的准确度受诸多因素的影响。因此文中对这些影响因素进行了探讨,主要为试剂质量、显色温度和显色时间、溶液加入顺序、比色皿、空气采样器流量、采样温度、导气管的吸附等因素对测定结果的影响进行了探讨。 相似文献
10.
建立土壤硫释放过程的人工神经网络模型 总被引:2,自引:0,他引:2
以温度、土壤含水率、胱氨酸添加量和土壤pH值作为土壤释放挥发性含硫化合物的主要影响因素,采用正交实验方法分析这些因素与土壤硫释速率的关系,利用BP神经网络算法对实验结果建模,并用模型对不同影响因素下的土壤硫释放情况进行预测。结果表明,网络模型对学习过的样本有较高预测精度,预测结果相对误差在2%以下,对未学生过的样本,误差为10%左右,表明人工神经网络方法建立的模型适用于土壤硫释放预测。 相似文献