Spectral and photodegradation properties of dissolved organic matter in brines

doi:10.13745/j.esf.sf.2021.1.56

Abstract

Abstract: Dissolved organic matter (DOM) in brines has adverse effects on solar pond performance and evaporite product quality, such as slowing down evaporation rate, reducing evaporation level, and causing pungent smell and heavy coloration in evaporate products. Therefore, characterization of DOM in brines in terms of utilization values is essential to guide DOM removal and new technologies development for better mineral extraction. Here, DOM from salt lake (SLDOM) and oilfield (OFDOM) were size-fractionated into high (MW>1 kDa) and low (MW≤1 kDa) molecular weight fractions and analyzed through dissolved organic carbon (DOC) analysis, absorption spectroscopy, fluorescence parallel factor (PARAFAC) analysis to determine their spectral and photodegradation properties. DOC analysis and fluorescence indexes indicated that SLDOM and OFSDOM had comparable organic carbon contents and BIX (biological index), and they both had higher FIX (fermentation index) than DOM from natural water. Compared to OFDOM, SLDOM had higher HIX and HMW DOM. SUVA₂₅₄ and carbohydrates measurements revealed that aromatic compounds and carbohydrates were mainly in the HMW fraction regardless of sample types. Fluorescence spectra showed that SLDOM mainly consisted of humic-substance, while OFDOM mainly protein-like substances. As for MW fractionation, for SLDDOM, fulvic acids were mainly in HMW DOM while humic acids in LMW DOM; for OFDOM, aromatic amino acids were abundant in HMW DOM. Photodegradation experiment indicated that DOC content in SLDOM and OFDOM decreased by 29.32% and 15.11%, respectively, with increasing light radiation. Further analysis showed that decreasing carbohydrate content and preferential degradation of LMW DOM occurred for both sample types. Moreover, during light irradiation, aromatic content increased and humification status remained stable in SLDOM, whereas in OFDOM aromatics decreased and humification increased. PARAFAC analysis showed that fluorescence intensities of PARAFAC components were enhanced for SLDOM, but reduced for OFDOM.

Key words: dissolved organic matter, salt lake brine, oilfield produced brine, spectral, photodegradation

CLC Number:

YANG Keli, DONG Yaping, LI Wu, PENG Jiaoyu, LIU Haining. Spectral and photodegradation properties of dissolved organic matter in brines[J]. Earth Science Frontiers, 2021, 28(6): 187-195.

References

[1] ZHENG M.Resources and eco-environmental protection of salt lakes in China[J]. Environmental Earth Sciences, 2010, 64(6): 1537-1546.
[2] 宋茜茜. 卤水中有机物检测方法的建立[D]. 北京: 中国科学院大学, 2012.
[3] SHALEV N, LAZAR B, KÖBBERICH M, et al. The chemical evolution of brine and Mg-K-salts along the course of extreme evaporation of seawater: an experimental study[J]. Geochimica et Cosmochimica Acta, 2018, 241(15): 164-179.
[4] 赵秀萍. 卤水中有机物对硫酸钡等产品质量的影响探讨[J]. 无机盐工业, 2008, 40(11): 34-36.
[5] 赵秀萍. 运城盐湖高镁卤水中有机物的膜过滤应用研究[J]. 盐业与化工, 2010, 39(2): 30-33.
[6] WU J, ZHANG H, YAO Q S, et al.Toward understanding the role of individual fluorescent components in DOM-metal binding[J]. Journal of Hazardous Materials, 2012, 215: 294-301.
[7] WANG X, GOUAL L, COLBERG P J. Characterization and treatment of dissolved organic matter from oilfield produced waters[J]. Journal of Hazardous Materials, 2012, 217/218: 164-170.
[8] XU H, ZOU L, GUAN D, et al.Molecular weight-dependent spectral and metal binding properties of sediment dissolved organic matter from different origins[J]. Science of the Total Environment, 2019, 665: 828-835.
[9] 李新宁, 宋茜茜, 李武, 等. 固相萃取-气相色谱/质谱结合保留指数检测卤水中有机物[J]. 分析科学学报, 2011, 27(6): 705-709.
[10] 黄孟丽, 杨克利, 张耀玲, 等. 察尔汗盐湖钾肥生产流程中有机物的组成分析[J]. 盐湖研究, 2015, 23(3): 14-22.
[11] 郑喜玉, 张明刚, 李秉孝, 等. 中国盐湖志[M]. 北京: 科学出版社, 2002: 31-35.
[12] 张彭熹, 张保珍, 唐源, 等. 中国湖泊自然资源及其开发利用[M]. 北京: 科学出版社, 1999: 78-90.
[13] 王永昌. 中国镁工业的未来: 察尔汗盐湖[J]. 科技与企业, 2016(1): 111-112, 114.
[14] 冀康平, 李华. 锂的开发利用[M]. 西宁: 青海人民出版社, 2004: 77-78.
[15] 尹衍升, 师瑞霞, 李嘉, 等. 察尔汗盐湖镁资源的开发及展望[J]. 材料导报, 2002, 10: 6-8.
[16] 宋彭生, 李武, 孙柏, 等. 盐湖资源开发利用进展[J]. 无机化学学报, 2011, 27(5): 801-815.
[17] 邓洪林, 于旭东, 杨建彬, 等. 川东天然卤水资源开发及综合利用工艺研究方向及重点[J]. 中国井矿盐, 2002, 43(2): 14-17.
[18] XU H, GUO L.Molecular size-dependent abundance and composition of dissolved organic matter in river, lake and sea waters[J]. Water Research, 2017, 117: 115-126.
[19] MINOR E C, STEINBRING C J, LONGNECKER K, et al.Characterization of dissolved organic matter in Lake Superior and its watershed using ultrahigh resolution mass spectrometry[J]. Organic Geochemistry, 2012, 43: 1-11.
[20] YANG K, ZHANG Y, DONG Y, et al.Comparative study of solid-phase extraction of dissolved organic matter from oilfield-produced brine by different sorbents[J]. Environmental Engineering Science, 2017, 34(9): 675-686.
[21] YIN Y, SHEN M, TAN Z, et al.Particle coating-dependent interaction of molecular weight fractionated natural organic matter: impacts on the aggregation of silver nanoparticles[J]. Environmental Science & Technology, 2015, 49(11): 6581-6588.
[22] CAWLEY K M, MURRAY A E, DORAN P T, et al.Characterization of dissolved organic material in the interstitial brine of Lake Vida, Antarctica[J]. Geochimica et Cosmochimica Acta, 2016, 183(15): 63-78.
[23] MCKNIGHT D M, BOYER E W, WESTERHOFF P K, et al.Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity[J]. Limnology and Oceanography, 2001, 46(1): 38-48.
[24] YANG L, CHENG Q, ZHUANG W E, et al.Seasonal changes in the chemical composition and reactivity of dissolved organic matter at the land-ocean interface of a subtropical river[J]. Environmental Science and Pollution Research International, 2019, 26(24): 24595-24608.