Pub Date : 2021-12-24DOI: 10.3389/fenvc.2021.762052
Xian-Yang Shi, Jingchan Zhao, Yongchen Wang, R. Mason
Transformations of mercury (Hg) forms in the aquatic environment is a crucial aspect of Hg fate, transport and the bioaccumulation of methylmercury (CH3Hg; MeHg), which is the form that drives most human health concerns. Transformations between Hg forms on surfaces have been inadequately studied but here we report on the interaction of inorganic Hg (HgII) and MeHg with chalcogenide nanoparticles (NPs); specifically L-cysteine capped CdSe nanocrystals. The study sheds light on the transformation of the Hg species and the interaction mechanisms, by examining the product composition, reaction mass balance and the distribution between the liquid and solid phase. The results showed that the quenching of the photoluminescence (PL) of CdSe NPs was greater for HgII than MeHg, and that HgII caused significant PL quenching even when its concentration was in the nM range. Over 90% of HgII was found associated with the solid phase while most MeHg existed in the liquid phase in the experimental solutions. No dimethylmercury ((CH3)2Hg; DMeHg) was produced from the interaction of MeHg and the NPs, in contrast to findings with microparticles. However, a fast and complete MeHg transformation into HgII occurred when the MeHg + NPs mixture was exposed to light. A scheme for the MeHg degradation was derived and is presented, and it was concluded that the precipitation of HgSe accelerated the MeHg degradation. These results provide insight into the abiotic pathways for MeHg degradation in environmental waters in the presence of NPs.
{"title":"The Transformation of Inorganic and Methylmercury in the Presence of l-Cysteine Capped CdSe Nanoparticles","authors":"Xian-Yang Shi, Jingchan Zhao, Yongchen Wang, R. Mason","doi":"10.3389/fenvc.2021.762052","DOIUrl":"https://doi.org/10.3389/fenvc.2021.762052","url":null,"abstract":"Transformations of mercury (Hg) forms in the aquatic environment is a crucial aspect of Hg fate, transport and the bioaccumulation of methylmercury (CH3Hg; MeHg), which is the form that drives most human health concerns. Transformations between Hg forms on surfaces have been inadequately studied but here we report on the interaction of inorganic Hg (HgII) and MeHg with chalcogenide nanoparticles (NPs); specifically L-cysteine capped CdSe nanocrystals. The study sheds light on the transformation of the Hg species and the interaction mechanisms, by examining the product composition, reaction mass balance and the distribution between the liquid and solid phase. The results showed that the quenching of the photoluminescence (PL) of CdSe NPs was greater for HgII than MeHg, and that HgII caused significant PL quenching even when its concentration was in the nM range. Over 90% of HgII was found associated with the solid phase while most MeHg existed in the liquid phase in the experimental solutions. No dimethylmercury ((CH3)2Hg; DMeHg) was produced from the interaction of MeHg and the NPs, in contrast to findings with microparticles. However, a fast and complete MeHg transformation into HgII occurred when the MeHg + NPs mixture was exposed to light. A scheme for the MeHg degradation was derived and is presented, and it was concluded that the precipitation of HgSe accelerated the MeHg degradation. These results provide insight into the abiotic pathways for MeHg degradation in environmental waters in the presence of NPs.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46679287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-09DOI: 10.3389/fenvc.2021.798785
Z. A. Yacouba, G. Lesage, J. Mendret, F. Zaviska, E. Petit, S. Brosillon
Occurrence of emerging organic micropollutants in water bodies and their effects are a concern related to quality of reused water. Advanced oxidation processes have demonstrated promising results to address this challenge. Nonetheless, these processes may lead to the generation of more toxic oxidation by-products. The aim of this study was to investigate the coupling of ozonation and nanofiltration (NF) applied to carbamazepine (CBZ). It consisted in monitoring the degradation and fate of CBZ and its subsequent by-products, their fate and toxicity. CBZ was completely degraded after 5 min of ozonation and six identified transformation by-products were formed: I (hydroxycarbamazepine), BQM [1-(2-benzaldehyde)-4-hydro-(1H, 3H)-quinazoline-2-one], II (2-(1H)-quinazolinone), BaQM [1-(2-benzoic acid)-4-hydro-(1H, 3H)-quinazoline-2-one], BQD [1-(2-benzaldehyde)-(1H, 3H)-quinazoline-2,4-dione] and BaQD [1-(2-benzoic acid)-(1H, 3H)-quinazoline-2,4-dione]. Mineralization rate of ozonation never exceeded 12% even with high ozone dose. Bioassays with Vibrio fischeri revealed that BQM and BQD are responsible for toxicity. NF is able to remove total organic carbon with removal rate up to 93% at 85% of permeate recovery rate. CBZ and its different ozonation by-products were almost completely retained by NF, except the II, which had an MW slightly lower than the membrane molecular weight cut-off, for which the removal rate was still between 80 and 96% depending on the recovery rate.
{"title":"Fate and Toxicity of Carbamazepine and Its Degradation By-Products During Coupling of Ozonation and Nanofiltration for Urban Wastewater Reuse","authors":"Z. A. Yacouba, G. Lesage, J. Mendret, F. Zaviska, E. Petit, S. Brosillon","doi":"10.3389/fenvc.2021.798785","DOIUrl":"https://doi.org/10.3389/fenvc.2021.798785","url":null,"abstract":"Occurrence of emerging organic micropollutants in water bodies and their effects are a concern related to quality of reused water. Advanced oxidation processes have demonstrated promising results to address this challenge. Nonetheless, these processes may lead to the generation of more toxic oxidation by-products. The aim of this study was to investigate the coupling of ozonation and nanofiltration (NF) applied to carbamazepine (CBZ). It consisted in monitoring the degradation and fate of CBZ and its subsequent by-products, their fate and toxicity. CBZ was completely degraded after 5 min of ozonation and six identified transformation by-products were formed: I (hydroxycarbamazepine), BQM [1-(2-benzaldehyde)-4-hydro-(1H, 3H)-quinazoline-2-one], II (2-(1H)-quinazolinone), BaQM [1-(2-benzoic acid)-4-hydro-(1H, 3H)-quinazoline-2-one], BQD [1-(2-benzaldehyde)-(1H, 3H)-quinazoline-2,4-dione] and BaQD [1-(2-benzoic acid)-(1H, 3H)-quinazoline-2,4-dione]. Mineralization rate of ozonation never exceeded 12% even with high ozone dose. Bioassays with Vibrio fischeri revealed that BQM and BQD are responsible for toxicity. NF is able to remove total organic carbon with removal rate up to 93% at 85% of permeate recovery rate. CBZ and its different ozonation by-products were almost completely retained by NF, except the II, which had an MW slightly lower than the membrane molecular weight cut-off, for which the removal rate was still between 80 and 96% depending on the recovery rate.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42204203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-22DOI: 10.3389/fenvc.2021.792814
V. Srivastava
The tremendous growth in industrialization and urbanization has resulted in generation of large amount of wastewater as well as hazardous waste (Chai et al., 2021; Titchou et al., 2021). Heterogenous solid waste usually ends up in landfills which undergoes various physicochemical change (Xiong et al., 2019; Patel et al., 2021)The nature and composition of hazardous waste varies depending on the source materials. Leachate from landfill sites has the potential to affect the water quality if it further enters into water streams via rainwater/stormwater (Bishop et al., 1986; Gautam et al., 2019). Accumulation of hazardous pollutants result in soil, water and air pollution (Quesada et al., 2019; Alemany et al., 2021; Dionne andWalker, 2021; Nikolaeva et al., 2021; Yadav et al., 2021; Łyszczarz et al., 2021). Heavy metals are widely used in different industries and due to their inefficient removal, they can directly or indirectly gain entry into water bodies. Metals are non-biodegradable and can easily accumulate in the environment (Gholizadeh and Hu, 2021; Xu et al., 2021). Different industries like textile, cosmetics, tannery, food and beverages release toxic bio-recalcitrant hazardous pollutants in the environment (Choina et al., 2013;Muszyński et al., 2019; Quesada et al., 2019; Keskin et al., 2021). The presence of both organic and inorganic pollutants in water bodies can harmfully affect the aquatic environment. Additionally, highly acidic or alkaline wastewater can also pose detrimental effects on aquatic environment. Further, various organic pollutants like pharmaceuticals, EDCs, refractory organic and dyes can generate more toxic species due to degradation or interaction with other available pollutant species (Tijani et al., 2013). Sometimes, degraded byproducts are even more toxic in comparison to their parent compound (Yin et al., 2017). The presence of emerging contaminants (ECs) in the environment is of great concern due to their harmful impacts on one hand and great challenges in existing water treatment technologies in terms of their removal efficiency on the other hand (Ahmed et al., 2021; Zamri et al., 2021). Consumption of polluted water can result in a great threat to living beings hence the wastewater needs to be properly treated before being discharged into the water bodies (Gitis and Hankins, 2018; Hussein and Jasim, 2021). It is noteworthy that due to water scarcity and environmental pollution by emission of pollutants, there is a continual rising global concern regarding the treatment of wastewater in order to make it available for reuse (Hussein and Jasim, 2021; Patel et al., 2021). Due to inefficient traditional treatment technologies, varieties of pollutants reach into the environment which directly and/or indirectly affects flora and fauna. Removal of lower concentrations of pollutants is more challenging and varied concentrations of emerging pollutants can be detected in the municipal sludge and effluents of municipal waste
工业化和城市化的迅猛发展产生了大量的废水和有害废物(Chai et al.， 2021;Titchou et al.， 2021)。非均质固体废物通常最终进入垃圾填埋场，并经历各种物理化学变化(Xiong et al.， 2019;Patel et al.， 2021)危险废物的性质和成分因来源材料而异。垃圾填埋场的渗滤液如果通过雨水/雨水进一步进入水流，可能会影响水质(Bishop et al.， 1986;Gautam等人，2019)。有害污染物的积累导致土壤、水和空气污染(Quesada等人，2019;Alemany等人，2021;迪翁和沃克，2021;Nikolaeva et al.， 2021;Yadav et al.， 2021;Łyszczarz et al.， 2021)。重金属广泛应用于不同行业，由于其去除效率低，可直接或间接进入水体。金属是不可生物降解的，很容易在环境中积累(Gholizadeh和Hu, 2021;Xu等人，2021)。纺织、化妆品、制革、食品和饮料等不同行业在环境中释放有毒的生物顽固性有害污染物(china等，2013;Muszyński等，2019;Quesada等人，2019;Keskin et al.， 2021)。水体中有机和无机污染物的存在都会对水生环境产生有害影响。此外，高酸性或高碱性废水也会对水生环境造成不利影响。此外，各种有机污染物，如药物、EDCs、难降解有机物和染料，由于降解或与其他可用污染物相互作用，会产生更多的有毒物质(Tijani等，2013)。有时，降解的副产物比它们的母体化合物毒性更大(Yin et al.， 2017)。环境中新出现的污染物(ECs)的存在引起了人们的高度关注，一方面是它们的有害影响，另一方面是现有水处理技术在去除效率方面面临的巨大挑战(Ahmed et al.， 2021;Zamri et al.， 2021)。饮用受污染的水会对生物造成巨大威胁，因此废水在排放到水体之前需要进行适当处理(Gitis和Hankins, 2018;Hussein and Jasim, 2021)。值得注意的是，由于水资源短缺和污染物排放造成的环境污染，全球对废水处理的关注不断增加，以使其可重复使用(Hussein和Jasim, 2021;Patel et al.， 2021)。由于传统处理技术效率低下，各种污染物进入环境，直接和/或间接影响动植物。去除较低浓度的污染物更具挑战性，在城市污泥和城市污水处理厂的流出物中可以检测到不同浓度的新污染物。危险废物和废水可以通过物理、化学、热、生物和物理化学方法进行处理。常规技术主要用于废水和危险固体废物的处理，如物理化学和生物处理方法。编审:刘希涛，北京师范大学，北京，中国
{"title":"Grand Challenges in Chemical Treatment of Hazardous Pollutants","authors":"V. Srivastava","doi":"10.3389/fenvc.2021.792814","DOIUrl":"https://doi.org/10.3389/fenvc.2021.792814","url":null,"abstract":"The tremendous growth in industrialization and urbanization has resulted in generation of large amount of wastewater as well as hazardous waste (Chai et al., 2021; Titchou et al., 2021). Heterogenous solid waste usually ends up in landfills which undergoes various physicochemical change (Xiong et al., 2019; Patel et al., 2021)The nature and composition of hazardous waste varies depending on the source materials. Leachate from landfill sites has the potential to affect the water quality if it further enters into water streams via rainwater/stormwater (Bishop et al., 1986; Gautam et al., 2019). Accumulation of hazardous pollutants result in soil, water and air pollution (Quesada et al., 2019; Alemany et al., 2021; Dionne andWalker, 2021; Nikolaeva et al., 2021; Yadav et al., 2021; Łyszczarz et al., 2021). Heavy metals are widely used in different industries and due to their inefficient removal, they can directly or indirectly gain entry into water bodies. Metals are non-biodegradable and can easily accumulate in the environment (Gholizadeh and Hu, 2021; Xu et al., 2021). Different industries like textile, cosmetics, tannery, food and beverages release toxic bio-recalcitrant hazardous pollutants in the environment (Choina et al., 2013;Muszyński et al., 2019; Quesada et al., 2019; Keskin et al., 2021). The presence of both organic and inorganic pollutants in water bodies can harmfully affect the aquatic environment. Additionally, highly acidic or alkaline wastewater can also pose detrimental effects on aquatic environment. Further, various organic pollutants like pharmaceuticals, EDCs, refractory organic and dyes can generate more toxic species due to degradation or interaction with other available pollutant species (Tijani et al., 2013). Sometimes, degraded byproducts are even more toxic in comparison to their parent compound (Yin et al., 2017). The presence of emerging contaminants (ECs) in the environment is of great concern due to their harmful impacts on one hand and great challenges in existing water treatment technologies in terms of their removal efficiency on the other hand (Ahmed et al., 2021; Zamri et al., 2021). Consumption of polluted water can result in a great threat to living beings hence the wastewater needs to be properly treated before being discharged into the water bodies (Gitis and Hankins, 2018; Hussein and Jasim, 2021). It is noteworthy that due to water scarcity and environmental pollution by emission of pollutants, there is a continual rising global concern regarding the treatment of wastewater in order to make it available for reuse (Hussein and Jasim, 2021; Patel et al., 2021). Due to inefficient traditional treatment technologies, varieties of pollutants reach into the environment which directly and/or indirectly affects flora and fauna. Removal of lower concentrations of pollutants is more challenging and varied concentrations of emerging pollutants can be detected in the municipal sludge and effluents of municipal waste","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43363145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-10DOI: 10.3389/fenvc.2021.771759
A. Yamakawa, Kimiyo Nagano, Miyuki Ukachi, K. Onishi, K. Yamashita, T. Shibata, Kazunari Takamiya, T. Kani, S. Bérail, O. Donard, D. Amouroux
An interlaboratory study of the National Institute for Environmental Studies (NIES) certified reference material (CRM) No. 28 Urban Aerosols collected from the filters of a central ventilating system in a building in the Beijing city center from 1996 to 2005 was performed to obtain an information value of the Sr isotopic composition. The Sr isotopic composition was measured using multi-collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) to confirm the CRM’s within- and between-bottle homogeneity, and the results showed a 87Sr/86Sr ratio of 0.710227 ± 0.000019 (2SD, n = 18). The Sr isotopic compositions were intercompared using thermal ionization mass spectrometry (TIMS), which showed good agreement with values obtained at NIES. Subsequently, a consistent 87Sr/86Sr ratio was observed between two dissolution (hotplate vs. high-pressure bomb) and Sr separation (Sr spec resin vs. cation exchange resin) methods. To validate and reproduce the accuracy of our analytical methods, the Sr isotopic compositions of secondary reference materials, JB-1b and JA-2, were also measured. Our results showed that NIES CRM No. 28 is appropriate for the quality control of Sr isotope measurements of particulate matter analyses for environmental and geochemical studies.
{"title":"Sr Isotopic Composition of NIES Certified Reference Material No. 28 Urban Aerosols","authors":"A. Yamakawa, Kimiyo Nagano, Miyuki Ukachi, K. Onishi, K. Yamashita, T. Shibata, Kazunari Takamiya, T. Kani, S. Bérail, O. Donard, D. Amouroux","doi":"10.3389/fenvc.2021.771759","DOIUrl":"https://doi.org/10.3389/fenvc.2021.771759","url":null,"abstract":"An interlaboratory study of the National Institute for Environmental Studies (NIES) certified reference material (CRM) No. 28 Urban Aerosols collected from the filters of a central ventilating system in a building in the Beijing city center from 1996 to 2005 was performed to obtain an information value of the Sr isotopic composition. The Sr isotopic composition was measured using multi-collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) to confirm the CRM’s within- and between-bottle homogeneity, and the results showed a 87Sr/86Sr ratio of 0.710227 ± 0.000019 (2SD, n = 18). The Sr isotopic compositions were intercompared using thermal ionization mass spectrometry (TIMS), which showed good agreement with values obtained at NIES. Subsequently, a consistent 87Sr/86Sr ratio was observed between two dissolution (hotplate vs. high-pressure bomb) and Sr separation (Sr spec resin vs. cation exchange resin) methods. To validate and reproduce the accuracy of our analytical methods, the Sr isotopic compositions of secondary reference materials, JB-1b and JA-2, were also measured. Our results showed that NIES CRM No. 28 is appropriate for the quality control of Sr isotope measurements of particulate matter analyses for environmental and geochemical studies.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45957960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-01DOI: 10.3389/fenvc.2022.1063667
H. Ahkola, J. Juntunen, K. Krogerus, T. Huttula
In this study we measured the total concentration of BTCs using grab water sampling, dissolved concentration with passive samplers, and particle-bound fraction with sedimentation traps in a Finnish inland lake. The sampling was conducted from May to September over two study years. In grab water samples the average concentration of MBT at sampling sites varied between 4.8 and 13 ng L−1, DBT 0.9–2.4 ng L−1, and TBT 0.4–0.8 ng L−1 during the first study year and 0.6–1.1 ng L−1, DBT 0.5–2.2 ng L−1 and TBT < LOD-0.7 ng L−1 during the second year. The average BTC concentrations determined with passive samplers varied between 0.08 and 0.53 ng L−1 for MBT, 0.10–0.14 ng L−1 for DBT and 0.05–0.07 ng L−1 for TBT during the first study year and 0.03–0.05 ng L−1 for MBT, 0.02–0.05 ng L−1 for DBT and TBT 0.007–0.013 ng L−1 during the second year. The average BTC concentrations measured in sedimented particles collected with sedimentation traps were between 1.5 and 9.0 ng L−1 for MBT, 0.61–22 ng L−1 for DBT and 0.05–1.8 ng L−1 for TBT during the first study year and 3.0–12 ng L−1 for MBT, 1.7–9.8 ng L−1 for DBT and TBT 0.4–1.2 ng L−1 during the second year. The differences between sampling techniques and the detected BTCs were obvious, e.g., tributyltin (TBT) was detected only in 4%–24% of the grab samples, 50% of the sedimentation traps, and 93% of passive samplers. The BTC concentrations measured with grab and passive sampling suggested hydrological differences between the study years. This was confirmed with flow velocity measurements. However, the annual difference was not observed in BTC concentrations measured in settled particles which suggest that only the dissolved BTC fraction varied. The extreme value analysis suggested that grab sampling and sedimentation trap sampling results contain more extreme peak values than passive sampling. However, all high concentrations are not automatically extreme values but indicates that BTCs are present in surface water in trace concentrations despite not being detected with all sampling techniques.
在这项研究中，我们测量了芬兰内陆湖中btc的总浓度，用被动采样器测量了溶解浓度，用沉淀池测量了颗粒结合分数。在为期两年的研究中，从5月到9月进行了抽样调查。在研究的第一年，各采样点的MBT平均浓度在4.8 ~ 13 ng L−1之间，DBT为0.9 ~ 2.4 ng L−1,TBT为0.4 ~ 0.8 ng L−1，第二年，DBT为0.6 ~ 1.1 ng L−1,DBT为0.5 ~ 2.2 ng L−1,TBT < lod ~ 0.7 ng L−1。在第一年的研究中，被动采样器测定的BTC平均浓度在MBT的0.08 ~ 0.53 ng L−1之间，DBT的0.10 ~ 0.14 ng L−1之间，TBT的0.05 ~ 0.07 ng L−1之间，第二年MBT的0.03 ~ 0.05 ng L−1之间，DBT的0.02 ~ 0.05 ng L−1之间，TBT的0.007 ~ 0.013 ng L−1之间。在第一年的研究中，沉淀池收集的沉积物颗粒中测量到的BTC平均浓度在MBT的1.5 ~ 9.0 ng L−1之间，DBT的0.61 ~ 22 ng L−1和TBT的0.05 ~ 1.8 ng L−1之间，第二年MBT的3.0 ~ 12 ng L−1,DBT的1.7 ~ 9.8 ng L−1和TBT的0.4 ~ 1.2 ng L−1之间。采样技术和检测到的三丁基锡之间的差异是明显的，例如，三丁基锡(TBT)仅在4%-24%的抓取样品中检测到，50%的沉淀陷阱和93%的被动采样器中检测到。抓取和被动采样测量的BTC浓度显示了研究年份之间的水文差异。流速测量证实了这一点。然而，在沉淀颗粒中测量的BTC浓度没有观察到年差异，这表明只有溶解的BTC部分变化。极值分析表明，抓斗取样和沉淀池取样结果比被动取样包含更多的极值峰值。然而，并非所有高浓度都自动成为极端值，而是表明尽管所有取样技术都未检测到，但btc仍以微量浓度存在于地表水中。
{"title":"Monitoring and modelling of butyltin compounds in Finnish inland lake","authors":"H. Ahkola, J. Juntunen, K. Krogerus, T. Huttula","doi":"10.3389/fenvc.2022.1063667","DOIUrl":"https://doi.org/10.3389/fenvc.2022.1063667","url":null,"abstract":"In this study we measured the total concentration of BTCs using grab water sampling, dissolved concentration with passive samplers, and particle-bound fraction with sedimentation traps in a Finnish inland lake. The sampling was conducted from May to September over two study years. In grab water samples the average concentration of MBT at sampling sites varied between 4.8 and 13 ng L−1, DBT 0.9–2.4 ng L−1, and TBT 0.4–0.8 ng L−1 during the first study year and 0.6–1.1 ng L−1, DBT 0.5–2.2 ng L−1 and TBT < LOD-0.7 ng L−1 during the second year. The average BTC concentrations determined with passive samplers varied between 0.08 and 0.53 ng L−1 for MBT, 0.10–0.14 ng L−1 for DBT and 0.05–0.07 ng L−1 for TBT during the first study year and 0.03–0.05 ng L−1 for MBT, 0.02–0.05 ng L−1 for DBT and TBT 0.007–0.013 ng L−1 during the second year. The average BTC concentrations measured in sedimented particles collected with sedimentation traps were between 1.5 and 9.0 ng L−1 for MBT, 0.61–22 ng L−1 for DBT and 0.05–1.8 ng L−1 for TBT during the first study year and 3.0–12 ng L−1 for MBT, 1.7–9.8 ng L−1 for DBT and TBT 0.4–1.2 ng L−1 during the second year. The differences between sampling techniques and the detected BTCs were obvious, e.g., tributyltin (TBT) was detected only in 4%–24% of the grab samples, 50% of the sedimentation traps, and 93% of passive samplers. The BTC concentrations measured with grab and passive sampling suggested hydrological differences between the study years. This was confirmed with flow velocity measurements. However, the annual difference was not observed in BTC concentrations measured in settled particles which suggest that only the dissolved BTC fraction varied. The extreme value analysis suggested that grab sampling and sedimentation trap sampling results contain more extreme peak values than passive sampling. However, all high concentrations are not automatically extreme values but indicates that BTCs are present in surface water in trace concentrations despite not being detected with all sampling techniques.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43259051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-01DOI: 10.3389/fenvc.2021.706254
Ting Xu, R. Qu, Ying Zhang, Changmei Sun, Ying Wang, Xiangyun Kong, Xue Geng, Chun-nuan Ji
Amino-thiol bifunctional polysilsesquioxane/carbon nanotubes (PSQ/CNTs) magnetic composites were prepared by sol-gel method with two types of functional siloxanes coating on carboxyl CNTs simultaneously. The composites were served as efficient adsorbents for removing Hg(II) in aqueous solution and the adsorption properties were investigated systematically. The optimal pH of bifunctional composites for Hg(II) removal is at pH 4.5. The thermodynamic fitting curves are more consistent with the Langmuir model and the adsorption capacities of the bifunctional composites for Hg(II) varied from 1.63 to 1.94 mmol g−1 at 25°C according to the Langmuir model. The kinetics curves are more fitted to the pseudo-second-order model and the composites could selectively adsorb Hg(II) in a series of binary metal ions solution. The elution regeneration tests showed that the adsorption rate could still reach 78% after repeat cycle three times. It is expected that the bifunctional PSQ/CNTs magnetic composites can be potentially applied to remove low concentration Hg(II) from waste water.
{"title":"Amino-Thiol Bifunctional Polysilsesquioxane/Carbon Nanotubes Magnetic Composites as Adsorbents for Hg(II) Removal","authors":"Ting Xu, R. Qu, Ying Zhang, Changmei Sun, Ying Wang, Xiangyun Kong, Xue Geng, Chun-nuan Ji","doi":"10.3389/fenvc.2021.706254","DOIUrl":"https://doi.org/10.3389/fenvc.2021.706254","url":null,"abstract":"Amino-thiol bifunctional polysilsesquioxane/carbon nanotubes (PSQ/CNTs) magnetic composites were prepared by sol-gel method with two types of functional siloxanes coating on carboxyl CNTs simultaneously. The composites were served as efficient adsorbents for removing Hg(II) in aqueous solution and the adsorption properties were investigated systematically. The optimal pH of bifunctional composites for Hg(II) removal is at pH 4.5. The thermodynamic fitting curves are more consistent with the Langmuir model and the adsorption capacities of the bifunctional composites for Hg(II) varied from 1.63 to 1.94 mmol g−1 at 25°C according to the Langmuir model. The kinetics curves are more fitted to the pseudo-second-order model and the composites could selectively adsorb Hg(II) in a series of binary metal ions solution. The elution regeneration tests showed that the adsorption rate could still reach 78% after repeat cycle three times. It is expected that the bifunctional PSQ/CNTs magnetic composites can be potentially applied to remove low concentration Hg(II) from waste water.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44345065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.3389/fenvc.2021.732219
Runhua Wang, Yajuan Huang, Qian Hu, G. Cao, Rongshu Zhu
Secondary organic aerosols (SOA) play an important role in global climate change and air quality, and SOA tracers can directly characterize the source and reaction mechanism of SOA. However, it is not well known that whether the tracers can be oxidized or how the instability of the tracers in the atmosphere. In this paper, in-situ FTIR was used to analyze the chemical structure changes of erythritol, analogue of 2-methyl erythritol (AME) that is, a tracer of isoprene SOA, and 2, 3-dihydroxy-4-oxopentanoic acid (DHOPA), a tracer of toluene SOA, when exposed to high concentration of ozone for short periods. Under the condition of 20 ppm ozone exposure for 30 min, the change rate of absorption area of AME at 3,480 and 1700 cm−1 was −0.0134 and 0.00117 int.abs/s, respectively, and the change rate of the absorption area of DHOPA at 1,640 and 3340cm−1 was −0.00191 and 0.00218 int.abs/s, respectively. The pseudo-first-order reaction rate constant k app were 1.89 × 10−8 and 2.12 × 10−7 s−1, and the uptake coefficients of ozone on the surface of AME and DHOPA were (1.3 ± 0.8) × 10−8 and (4.5 ± 2.7) × 10−8, respectively. These results showed the oxidation processes of AME and DHOPA were slow in the presence of high concentrations of ozone, which implied that AME and DHOPA could be considered to be stable in the atmospheric environment with ozone as the main oxidant.
{"title":"In-Situ FTIR Study of Heterogeneous Oxidation of SOA Tracers by Ozone","authors":"Runhua Wang, Yajuan Huang, Qian Hu, G. Cao, Rongshu Zhu","doi":"10.3389/fenvc.2021.732219","DOIUrl":"https://doi.org/10.3389/fenvc.2021.732219","url":null,"abstract":"Secondary organic aerosols (SOA) play an important role in global climate change and air quality, and SOA tracers can directly characterize the source and reaction mechanism of SOA. However, it is not well known that whether the tracers can be oxidized or how the instability of the tracers in the atmosphere. In this paper, in-situ FTIR was used to analyze the chemical structure changes of erythritol, analogue of 2-methyl erythritol (AME) that is, a tracer of isoprene SOA, and 2, 3-dihydroxy-4-oxopentanoic acid (DHOPA), a tracer of toluene SOA, when exposed to high concentration of ozone for short periods. Under the condition of 20 ppm ozone exposure for 30 min, the change rate of absorption area of AME at 3,480 and 1700 cm−1 was −0.0134 and 0.00117 int.abs/s, respectively, and the change rate of the absorption area of DHOPA at 1,640 and 3340cm−1 was −0.00191 and 0.00218 int.abs/s, respectively. The pseudo-first-order reaction rate constant k app were 1.89 × 10−8 and 2.12 × 10−7 s−1, and the uptake coefficients of ozone on the surface of AME and DHOPA were (1.3 ± 0.8) × 10−8 and (4.5 ± 2.7) × 10−8, respectively. These results showed the oxidation processes of AME and DHOPA were slow in the presence of high concentrations of ozone, which implied that AME and DHOPA could be considered to be stable in the atmospheric environment with ozone as the main oxidant.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45117369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.3389/fenvc.2021.677813
Rui Hu, A. Ndé-Tchoupé, Viet Cao, W. Gwenzi, C. Noubactep
The suitability of remediation systems using metallic iron (Fe0) has been extensively discussed during the past 3 decades. It has been established that aqueous Fe0 oxidative dissolution is not caused by the presence of any contaminant. Instead, the reductive transformation of contaminants is a consequence of Fe0 oxidation. Yet researchers are still maintaining that electrons from the metal body are involved in the process of contaminant reduction. According to the electron efficiency concept, electrons from Fe0 should be redistributed to: i) contaminants of concern (COCs), ii) natural reducing agents (e.g., H2O, O2), and/or iii) reducible co-contaminants (e.g. NO3-). The electron efficiency is defined as the fraction of electrons from Fe0 oxidation which is utilized for the reductive transformations of COCs. This concept is in frontal contradiction with the view that Fe0 is not directly involved in the process of contaminant reduction. This communication recalls the universality of the concept that reductive processes observed in remediation Fe0/H2O systems are mediated by primary (e.g., FeII, H/H2) and secondary (e.g., Fe3O4, green rusts) products of aqueous iron corrosion. The critical evaluation of the electron efficiency concept suggests that it should be abandoned. Instead, research efforts should be directed towards tackling the real challenges for the design of sustainable Fe0-based water treatment systems based on fundamental mechanisms of iron corrosion.
{"title":"Metallic Iron for Environmental Remediation: The Fallacy of the Electron Efficiency Concept","authors":"Rui Hu, A. Ndé-Tchoupé, Viet Cao, W. Gwenzi, C. Noubactep","doi":"10.3389/fenvc.2021.677813","DOIUrl":"https://doi.org/10.3389/fenvc.2021.677813","url":null,"abstract":"The suitability of remediation systems using metallic iron (Fe0) has been extensively discussed during the past 3 decades. It has been established that aqueous Fe0 oxidative dissolution is not caused by the presence of any contaminant. Instead, the reductive transformation of contaminants is a consequence of Fe0 oxidation. Yet researchers are still maintaining that electrons from the metal body are involved in the process of contaminant reduction. According to the electron efficiency concept, electrons from Fe0 should be redistributed to: i) contaminants of concern (COCs), ii) natural reducing agents (e.g., H2O, O2), and/or iii) reducible co-contaminants (e.g. NO3-). The electron efficiency is defined as the fraction of electrons from Fe0 oxidation which is utilized for the reductive transformations of COCs. This concept is in frontal contradiction with the view that Fe0 is not directly involved in the process of contaminant reduction. This communication recalls the universality of the concept that reductive processes observed in remediation Fe0/H2O systems are mediated by primary (e.g., FeII, H/H2) and secondary (e.g., Fe3O4, green rusts) products of aqueous iron corrosion. The critical evaluation of the electron efficiency concept suggests that it should be abandoned. Instead, research efforts should be directed towards tackling the real challenges for the design of sustainable Fe0-based water treatment systems based on fundamental mechanisms of iron corrosion.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48259803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-21DOI: 10.3389/fenvc.2021.737391
Biwek Gairhe, Wenwen Liu, O. Batuman, P. Dittmar, D. Kadyampakeni, Ramdas G. Kanissery
Chemical weed control using herbicide glyphosate to manage emerged weeds is an important production practice in Florida citrus. Despite the extensive use of glyphosate in citrus orchards, very limited information is available on its environmental fate and behavior in Florida soils that are predominantly sandy in nature. Hence, the study’s objective was to understand the adsorption-desorption, dissipation dynamics, and vertical movement or leaching of glyphosate in sandy soils in citrus orchards. Laboratory, field, and greenhouse experiments were conducted at Southwest Florida Research and Education Center in Immokalee, Florida. The adsorption-desorption behavior of glyphosate in the soils from three major citrus production areas in Florida was studied utilizing a batch equilibrium method. The dissipation of glyphosate was tracked in the field following its application at the rate of 4.20 kg ae ha−1. Soil leaching columns in greenhouse conditions were used to study the vertical movement of glyphosate. The results suggest that glyphosate has a relatively lower range of adsorption or binding (Kads = 14.28–30.88) in the tested soil types. The field dissipation half-life (DT50) of glyphosate from surface soil was found to be ∼26 days. Glyphosate moved vertically or leached into the soil profile, up to 40 cm in the soil column, when analyzed 40 days after herbicide application. The primary degradation product of glyphosate, i.e., aminomethyl phosphonic acid (AMPA), was also detected up to the depth of 30 cm below the soil surface, indicating the presence of microbial metabolism of glyphosate in the soil.
{"title":"Environmental Fate and Behavior of the Herbicide Glyphosate in Sandy Soils of Florida Under Citrus Production","authors":"Biwek Gairhe, Wenwen Liu, O. Batuman, P. Dittmar, D. Kadyampakeni, Ramdas G. Kanissery","doi":"10.3389/fenvc.2021.737391","DOIUrl":"https://doi.org/10.3389/fenvc.2021.737391","url":null,"abstract":"Chemical weed control using herbicide glyphosate to manage emerged weeds is an important production practice in Florida citrus. Despite the extensive use of glyphosate in citrus orchards, very limited information is available on its environmental fate and behavior in Florida soils that are predominantly sandy in nature. Hence, the study’s objective was to understand the adsorption-desorption, dissipation dynamics, and vertical movement or leaching of glyphosate in sandy soils in citrus orchards. Laboratory, field, and greenhouse experiments were conducted at Southwest Florida Research and Education Center in Immokalee, Florida. The adsorption-desorption behavior of glyphosate in the soils from three major citrus production areas in Florida was studied utilizing a batch equilibrium method. The dissipation of glyphosate was tracked in the field following its application at the rate of 4.20 kg ae ha−1. Soil leaching columns in greenhouse conditions were used to study the vertical movement of glyphosate. The results suggest that glyphosate has a relatively lower range of adsorption or binding (Kads = 14.28–30.88) in the tested soil types. The field dissipation half-life (DT50) of glyphosate from surface soil was found to be ∼26 days. Glyphosate moved vertically or leached into the soil profile, up to 40 cm in the soil column, when analyzed 40 days after herbicide application. The primary degradation product of glyphosate, i.e., aminomethyl phosphonic acid (AMPA), was also detected up to the depth of 30 cm below the soil surface, indicating the presence of microbial metabolism of glyphosate in the soil.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46635621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.3389/fenvc.2021.729779
R. McGregor, Leticia Benevenuto
Per-and polyfluoroalkyl substances (PFAS) have been identified as emerging contaminants of concern in the environment in a wide variety of media including groundwater. Typically, PFAS-impacted groundwater is extracted by pump and treat systems and treated using sorptive media such as activated carbon and ion exchange resin. Pump and treat systems are generally considered ineffective for the remediation of dissolved phase contaminants including PFAS but instead are considered applicable for plume containment. An alternative to pump and treat is in-situ treatment. The demonstrated use of in-situ treatment for PFAS-impacted groundwater is limited with only colloidal activated carbon (CAC) being shown to effectively attenuate PFAS over short and moderate time periods. Active research topics for the in-situ treatment of PFAS include the effect of heterogeneity on the distribution of the CAC, the lifespan of the CAC itself, the effect of competitive adsorption/absorption, and the effect of other geochemical conditions on the removal process. This study looked at the effect of heterogeneity on the distribution of CAC and subsequent treatment of PFAS at a site with a multiple aquifer system. The site’s geology varied from a silty sand to sand to fractured bedrock with all three units being impacted by PFAS and benzene (B), toluene (T), ethylbenzene (E), and xylene (X). Parameters evaluated included the distribution of the CAC as well as the subsequent treatment of the PFAS and BTEX. Results of groundwater sampling indicated that the PFAS detected within the groundwater were treated effectively to below their respective reporting limits for the duration of the 1-year test in both the silty sand and sand aquifers. The PFAS in the fractured rock aquifer showed a different treatment profile with longer carbon chained PFAS being attenuated preferentially compared to the shorter carbon chained PFAS. These results suggest that competitive sorptive reactions were occurring on the CAC within the fractured rock. Analysis of the unconsolidated aquifer materials determined that direct push injection of the CAC was effective at delivering the CAC to the target injection zones with post-injection total organic carbon (TOC) concentrations increasing by up to three orders of magnitude compared to pre-injection TOC concentrations. Heterogeneity did have an impact on the CAC distribution with higher hydraulic conductivity zones receiving more CAC mass than lower hydraulic conductivity zones.
{"title":"The Effect of Heterogeneity on the Distribution and Treatment of PFAS in a Complex Geologic Environment","authors":"R. McGregor, Leticia Benevenuto","doi":"10.3389/fenvc.2021.729779","DOIUrl":"https://doi.org/10.3389/fenvc.2021.729779","url":null,"abstract":"Per-and polyfluoroalkyl substances (PFAS) have been identified as emerging contaminants of concern in the environment in a wide variety of media including groundwater. Typically, PFAS-impacted groundwater is extracted by pump and treat systems and treated using sorptive media such as activated carbon and ion exchange resin. Pump and treat systems are generally considered ineffective for the remediation of dissolved phase contaminants including PFAS but instead are considered applicable for plume containment. An alternative to pump and treat is in-situ treatment. The demonstrated use of in-situ treatment for PFAS-impacted groundwater is limited with only colloidal activated carbon (CAC) being shown to effectively attenuate PFAS over short and moderate time periods. Active research topics for the in-situ treatment of PFAS include the effect of heterogeneity on the distribution of the CAC, the lifespan of the CAC itself, the effect of competitive adsorption/absorption, and the effect of other geochemical conditions on the removal process. This study looked at the effect of heterogeneity on the distribution of CAC and subsequent treatment of PFAS at a site with a multiple aquifer system. The site’s geology varied from a silty sand to sand to fractured bedrock with all three units being impacted by PFAS and benzene (B), toluene (T), ethylbenzene (E), and xylene (X). Parameters evaluated included the distribution of the CAC as well as the subsequent treatment of the PFAS and BTEX. Results of groundwater sampling indicated that the PFAS detected within the groundwater were treated effectively to below their respective reporting limits for the duration of the 1-year test in both the silty sand and sand aquifers. The PFAS in the fractured rock aquifer showed a different treatment profile with longer carbon chained PFAS being attenuated preferentially compared to the shorter carbon chained PFAS. These results suggest that competitive sorptive reactions were occurring on the CAC within the fractured rock. Analysis of the unconsolidated aquifer materials determined that direct push injection of the CAC was effective at delivering the CAC to the target injection zones with post-injection total organic carbon (TOC) concentrations increasing by up to three orders of magnitude compared to pre-injection TOC concentrations. Heterogeneity did have an impact on the CAC distribution with higher hydraulic conductivity zones receiving more CAC mass than lower hydraulic conductivity zones.","PeriodicalId":73082,"journal":{"name":"Frontiers in environmental chemistry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48296863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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