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The identities and concentrations of low-molecular-weight organic acids (LMWOAs) were determined by ion chromatography throughout a 20-m water column in Hongfeng Lake, China. The spatiotemporal variations of LMWOAs and their contributions to dissolved organic matter (DOM) in a research period of 24 hr were also investigated. The results demonstrated that five LMWOAs (lactic, acetic, pyruvic, sorbic, oxalic acid) were detected, and their total concentration and proportion in DOC were 6.55 μmol/L and 7.47%. Their average levels were 2.50, 0.65, 2.35, 0.96 and 0.09 μmol/L, respectively. LMWOAs were higher during daytime (10:00-18:00 on Jun 13, 2008) than nighttime (21:00-6:00 the next morning), in particular 4.99 μmol/L high in the epilimnion ( 1 m water depth), reflecting the fact that direct import from terrigenous sources and photochemical production from humic materials were dominant during LMWOAs’ origin and accumulation. The same factors caused LMWOAs to be 0.63 μmol/L in the epilimnion higher than in the hypolimnion. The rapid decrease of total organic acid (TOA) up until 18:00 mainly resulted from bio-uptake and mineralization in the hypolimnion (>1 m water depth). Pyruvic acid increased with time in the epilimnion and decreased in the hypolimnion, largely related to the two contrary processes of continuous degradation and synthesis of macromolecular organic matter during life materials’ cycle mediated by organisms. Simultaneously, plankton behavior and thermal stratification played a pivotal role in LMWOAs’ behavior in the water column, causing decreasing and increasing profiles. The distribution of LMWOAs represents an interesting resource for biogeochemical research of DOM in aquatic ecosystems. 相似文献
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微电解-催化氧化法处理高浓度甲醇废水 总被引:6,自引:2,他引:4
采用微电解一催化氧化法处理某化工厂的高浓度甲醇生产废水。实验结果表明:在进水pH为2.0、铁炭质量比为2、微电解时间为14h、空气流量为500mL/min的条件下,废水经微电解处理后,出水COD由原来的约7000mg/L降至约1000mg/L,COD去除率达85%以上;在过滤后微电解出水COD约为950mg/L、微电解出水pH为6.5、空气流量为300mL/min、催化氧化时间为3h时的条件下,经催化氧化处理后,出水COD降至100mg/L以下,出水水质达到GB8978--1996《污水综合排放标准》的二级标准。 相似文献
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为提高稻秆的降解率及其厌氧发酵甲烷产量,采用高氨氮畜禽废水作为氮源以驯化稻田土壤微生物,优化其降解稻秆的初始pH值,并评估水解产物液体发酵产甲烷性能.结果表明,混合组驯化的微生物产纤维素酶活性及对稻秆木质素的降解率高于其它组及先前文献报道,分别达到4.01 IU和51.96%,且后期水解液中总有机碳(Total organic carbon, TOC)及还原糖含量最高.随着初始pH值的提高,稻秆中纤维素、半纤维素和木质素的降解率显著增加,稻秆水解液中的挥发性脂肪酸(Volatile fatty acids, VFAs)和TOC含量均显著增加,并在第7 d达到最高值.将水解稻秆7 d的水解液进行厌氧发酵显示,在初始pH=9.0条件下累积甲烷产量达到最大,为37.60 mL·mL-1水解液.本实验结果表明, 驯化的稻田土微生物在碱性条件下可以更有效地降解稻秆,提高水解液中TOC及VFAs含量,从而提高厌氧发酵的甲烷产量. 相似文献
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有机氯农药六六六污染土壤的植物修复研究 总被引:5,自引:0,他引:5
我国20世纪六七十年代大量施用的有机氯农药,由于其性质极其稳定,在土壤至今仍有残留。植物修复有机农药污染土壤并不多见,但具有广阔的应用前景。此项研究对提高土壤环境质量、保证农产品的安全、实现农业可持续发展等有着重要的理论和现实意义。文章以多花黑麦草(Lolium multiforum Lan.)、紫花苜蓿(Medicago sativa L.)和籽粒苋(Amaranthus hypochondriacus L.)作为供试植物,在有机氯农药六六六(HCH)质量分数为1.09 mg.kg-1的污染土壤中种植3个月,研究了种植不同植物条件下土壤中HCH的消解情况。研究结果表明,与对照相比,种植植物大大提高了土壤中微生物数量和酶的活性,并且微生物的数量和酶的活性与土壤中HCH的消解密切相关。试验结束后,不同处理中HCH及其4种异构体的总含量降低幅度为43.87%~65.79%,其中种植紫花苜蓿和多花黑麦草的处理中HCH消解较快,对HCH污染土壤修复的效果较好。可见,植物修复技术是一种可行的环境友好的修复六六六污染土壤的技术。 相似文献
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Kaihui Zhao Huihong Luo Zibing Yuan Danni Xu Yi Du Shu Zhang Yuqi Hao Yonghua Wu Jianping Huang Ying Wang Rongsheng Jiang 《环境科学学报(英文版)》2021,33(4):373-383
Understanding ozone (O3) formation regime is a prerequisite in formulating an effective O3 pollution control strategy. Photochemical indicator is a simple and direct method in identifying O3 formation regimes. Most used indicators are derived from observations, whereas the role of atmospheric oxidation is not in consideration, which is the core driver of O3 formation. Thus, it may impact accuracy in signaling O3 formation regimes. In this study, an advanced three-dimensional numerical modeling system was used to investigate the relationship between atmospheric oxidation and O3 formation regimes during a long-lasting O3 exceedance event in September 2017 over the Pearl River Delta (PRD) of China. We discovered a clear relationship between atmospheric oxidative capacity and O3 formation regime. Over eastern PRD, O3 formation was mainly in a NOx-limited regime when HO2/OH ratio was higher than 11, while in a VOC-limited regime when the ratio was lower than 9.5. Over central and western PRD, an HO2/OH ratio higher than 5 and lower than 2 was indicative of NOx-limited and VOC-limited regime, respectively. Physical contribution, including horizontal transport and vertical transport, may pose uncertainties on the indication of O3 formation regime by HO2/OH ratio. In comparison with other commonly used photochemical indicators, HO2/OH ratio had the best performance in differentiating O3 formation regimes. This study highlighted the necessities in using an atmospheric oxidative capacity-based indicator to infer O3 formation regime, and underscored the importance of characterizing behaviors of radicals to gain insight in atmospheric processes leading to O3 pollution over a photochemically active region. 相似文献
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Ding Zhikun Liu Rongsheng Yuan Hongping 《Environmental science and pollution research international》2021,28(24):30499-30527
Environmental Science and Pollution Research - Over the years, numerous studies have been conducted to investigate construction and demolition waste (CDW) management problems. However, the massive... 相似文献
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柠檬酸废渣石膏主要由二水石膏组成,化学成分与天然石膏相近,只要工艺合理,就可以实现柠檬酸废渣石膏的资源化利用。综述了柠檬酸废渣石膏生产石膏粉、石膏砌块和石膏板材,用于硫铝酸盐水泥生产,用作水泥缓凝剂、制备晶须等方面的研究进展;提出了柠檬酸废渣石膏在生产粉笔、用于水泥矿化剂和与石英尾砂等工业废渣联合使用等方面的应用前景。 相似文献
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