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511.
地下水“三氮”污染来源及其识别方法研究进展 总被引:5,自引:2,他引:3
地下水"三氮"污染来源的识别研究对污染控制与修复有重要的意义.在阐述地下水"三氮"污染来源(大气氮沉降、土壤天然有机氮矿化、地表径流氮输入、人类活动氮排放等)及其在我国的分布特征的基础上,总结了国际上常用的"三氮"污染来源识别方法,包括水化学方法、统计学相关方法、区域氮平衡法、稳定同位素示踪法及一些新型示踪方法.指出由于"三氮"污染来源的多样性及污染形成机制的复杂性,单一识别方法在应用中均有较明显的局限性,目前主流识别手段为稳定同位素示踪法与多种识别方法相综合.进一步提出要加强新型示踪方法的开拓、定量识别方法的优化,污染源识别与迁移转化机制、地下水补排条件、地下水-地表水转化关系等研究相结合为未来发展的主要趋势. 相似文献
512.
为研究岩溶区农业活动为主导的地下河流域硝酸盐污染来源,于2017年5~10月每24 d左右对重庆青木关流域6个采样点进行监测,利用~(15)N和~(18)O同位素技术对示踪硝酸盐来源进行解译,应用IsoSource模型计算出不同端元硝酸盐的贡献率.结果表明:(1)青木关农业区地下河系统存在较大的硝酸盐污染风险,大部分采样点出现不同程度NO_3~--N浓度超标现象.(2)空间上,青木关地下河中NO_3~--N浓度整体呈现由上游向下游升高的趋势.时间上,上游鱼塘和岩口落水洞以及下游姜家泉样点NO_3~--N浓度在5~6月因受农业施肥的影响,均呈上升趋势,6~9月受降水影响而出现不同程度升高或降低,9月之后随着农业活动减少而逐渐降低;中游土壤点NO_3~--N浓度保持较高值;中下游大鹿池NO_3~--N浓度较低且变幅不大.(3)通过硝酸盐~(15)N和~(18)O同位素分析,表明上游鱼塘和岩口落水洞的硝酸盐源于土壤有机氮、动物粪便及污废水混合;中游土壤点硝酸盐源于土壤有机氮、降水和肥料中NH_4~+;中下游大鹿池中硝酸盐来源于动物粪便及污废水、土壤有机氮、降水和肥料中NH_4~+的混合作用.地下河出口处姜家泉硝酸盐污染严重,其源于土壤有机氮、降水和肥料中NH_4~+、动物粪便及污废水、大气沉降的综合作用.(4)基于IsoSource模型对地下河出口处硝酸盐来源进行定量分析,发现动物粪便及污废水贡献率占46.4%,土壤有机氮占32.6%,降水与肥料中NH_4~+占18.6%,大气沉降仅占2.4%. 相似文献
513.
为研究南京北郊不同季节PM_(2.5)中碳质组分的主要来源,分别在2014年1月1—23日和2014年7月3—22日进行PM_(2.5)样品采集,并分析其中有机碳(OC)、元素碳(EC)浓度及总碳同位素组成.结果表明,冬季PM_(2.5)浓度高于夏季,平均值为(146.69±64.67)μg·m-3,OC、EC浓度较高,分别为(14.77±5.58)μg·m-3与(9.01±4.74)μg·m-3;而夏季PM_(2.5)浓度为(57.69±23.80)μg·m-3,OC、EC浓度分别为(5.94±2.20)μg·m-3和(2.78±1.25)μg·m-3.二次有机碳(SOC)占OC比重较小,冬、夏两季分别为36.99%与27.37%,这与采样点紧邻公路主干道使颗粒物未得到充分的二次反应有关.南京北郊冬季δ13C平均值为-25.38‰±0.36‰,夏季为-26.50‰±0.58‰,通过与潜在污染源的δ13C值对比,推断出采样期间冬季主要的潜在碳质污染源为煤炭燃烧及机动车尾气,夏季主要的潜在碳质污染源为生物质燃烧及汽车尾气. 相似文献
514.
利用同位素示踪法对红球菌BAP-1跨膜运输14C-荧蒽的过程进行了研究.结果表明在有ATP抑制剂NaN3的存在下,红球菌BAP-1细胞膜内所结合的14C-荧蒽含量几乎无变化.结合对微生物体内包涵体的观察,说明当有ATP抑制剂存在的情况下,荧蒽无法通过细胞膜进入到微生物的体内.这表明若是荧蒽无法通过跨膜运输进入到红球菌细胞内,就不能得到有效的生物降解.在不同的底物浓度条件下,微生物对14C-荧蒽的跨膜运输过程是主动运输过程;在一定底物浓度条件下,菌体膜结合污染物的量会在一定的条件下达到饱和.结合米氏方程分析了红球菌BAP-1对14C-荧蒽的跨膜运输动力学过程,结果表明底物14C-荧蒽与微生物之间一直保持较高的亲和力,较高的亲和体系有助于跨膜运输过程的顺利进行. 相似文献
515.
Jovandićević B Antić MP Solević TM Vrvić MM Kronimus A Schwarzbauer J 《Environmental science and pollution research international》2005,12(4):205-212
Background, Aims and Scope In oil spill investigations, one of the most important steps is a proper choice of approaches that imply an investigation
of samples taken from different sedimentary environments, samples of oil contaminants taken in different periods of time and
samples taken at different distances from the oil spill. In all these cases, conclusion on the influence of the environment,
microorganisms or migration on the oil contaminants' composition can be drawn from the comparison of chemical compositions
of the investigated contaminants. However, in case of water contaminants, it is very important to define which part of organic
matter has been analyzed. Namely, previous investigations showed that there were some differences in chemical composition
of the same oil contaminant depending on the intensity of its contact with ground water. The aim of this work is to define
more precisely the interactions between oil contaminant and water, i.e. the influence of the intensity of interaction between
the oil contaminant and water on its chemical composition. The study was based on a comparison of four fractionated extracts
of an oil pollutant, after they had been analyzed in details.
Methods Oil polluted surface water (wastewater canal, Pančevo, Serbia) was investigated. The study was based on a comparison of four
extracts of an oil contaminant: extract 1 (decanted part), and extracts 2, 3 and 4 (extracted by shaking for 1 minute, 5 minutes
and 24 hours, respectively). The fractionated extracts were saponified with a solution of KOH in methanol, and neutralized
with 10% hydrochloric acid. The products were dissolved in a mixture of dichloromethane and hexane, and individually fractionated
by column chromatography on alumina and silica gel (saturated hydrocarbon, aromatic, alcohol and fatty acid fractions). n-Alkanes
and isoprenoid aliphatic alkanes, polycyclic alkanes of sterane and triterpane types, alcohols and fatty acids were analyzed
using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). δ13CPDB values of individual n-alkanes in
the aliphatic fractions were determined using gas chromatography-isotope ratio monitoring-mass spectrometry (GC-irmMS).
Results and discussion. Extracts 1 and 2 are characterized by uniform distribution of n-alkanes, whereas extract 3 is characterized
by an even-numbered members dominating the odd-ones, and extract 4 showed a bimodal distribution. Extract 1 is characterized
by the least negative δ13CPDB values of C19-C26 n-alkanes. Sterane and triterpane analysis confirmed that all extracts originated
from the same oil contaminant. n-Fatty acids, C19-C24, in all extracts are very low, being somewhat higher in extract 4. Even-numbered
n-alcohols, C12–C16, were identified in the highest concentration in extract 3. It was assumed that algae were responsible
for the composition of extract 3. Furthermore, a possible reason for higher concentrations of C19–C26 n-alkanes and C19–C24
fatty acids in extract 4 is the formation of inclusion compounds with colloidal micelles formed between the oil contaminant's
NSO-compounds and water.
Conclusion It was undoubtedly confirmed that there were specific differences in the compositions of the different extracts depending
on the intensity of the interaction between the oil contaminant and the surface water.
Recommendation and Outlook. When comparing the composition of oil contaminants from different water samples (regardless of
the ultimate investigation goal) it is necessary to compare the extracts isolated under the same conditions, in other words,
extracts that were in the same or very similar interaction with water. 相似文献
516.
517.
作者采集了西南极南设得兰群岛纳尔逊岛冰盖的冰雪样,并测得其δD和δO~(18)值分别为-67.8~-75.0‰和-8.72~-8.93‰,进而拟合出δD和δ~(18)O关系大致为δD=8δ~(18)O-1.5。本文从“大陆效应”、“温度效应”、“纬度效应”及降雪过程的同位素动力分馏等方面对所获资料作了讨论。 相似文献
518.
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