Recent progress in detection of mercury using surface enhanced Raman spectroscopy — A review

Concerns over exposure to mercury have motivated the exploration of cost-effective, rapid, and reliable method for monitoring Hg^2 + in the environment. Recently, surface-enhanced Raman scattering (SERS) has become a promising alternative method for Hg^2 + analysis. SERS is a spectroscopic technique which combines modern laser spectroscopy with the optical properties of nano-sized noble metal structures, resulting in substantially increased Raman signals. When Hg^2 + is in a close contact with metallic nanostructures, the SERS effect provides unique structural information together with ultrasensitive detection limits. This review introduces the principles and contemporary approaches of SERS-based Hg^2 + detection. In addition, the perspective and challenges are briefly discussed.     

Applications of magnetic nanoparticles in surface-enhanced Raman scattering (SERS) detection of environmental pollutants

Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment. Efficient and reliable detection technologies, which focus on the appearance of emerging environmental and trace pollutants, are urgently needed. Surface-enhanced Raman scattering(SERS) has become an attractive analytical tool for sensing trace targets in environmental field because of its inherent molecular fingerprint specificity and high sensitivity. In this review, we focused on the recent developments in the integration of magnetic nanoparticles(MNPs) with SERS for facilitating sensitive detection of environmental pollutants. An overview and classification of different types of MNPs for SERS detection were initially provided, enabling us to categorize the huge amount of literature that was available in the interdisciplinary research field of MNPs based SERS technology. Then, the basic working principles and applications of MNPs in SERS detection were presented. Subsequently, the detection technologies integrating MNPs with SERS that eventually were used for the detection of various environmental pollutions were reviewed. Finally, the advantages of MNP-basedSERS detection technology for environmental pollutants were concluded, and the current challenges and future outlook of this technology in practical applications were highlighted. The application of the MNPsbasedSERS techniques for environmental analysis will be significantly advanced with the great progresses of the nanotechnologies, optics, and materials.     

Au nanoring arrays as surface enhanced Raman spectroscopy substrate for chemical component study of individual atmospheric aerosol particle

Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy (SERS) substrates to test the individual atmospheric aerosols particle. Compared to other methods used for testing atmospheric aerosols particles, the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte. The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings. The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate, which can improve the accuracy for detecting atmospheric aerosol particles. Combined with Raman mapping, the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually. The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition, mixing state, and other related physicochemical properties.     

基于表面增强拉曼光谱技术的饮用水中痕量恩诺沙星和环丙沙星快速检测

近年来,抗生素的滥用引发抗生素抗性基因在环境中的传播和扩散,对生态系统与人类健康构成潜在威胁,特别是饮用水中抗生素污染事件的相关报道引发社会极大关注.因此,如何实现应急公共卫生事件中的痕量抗生素快检成为研究热点.基于表面增强拉曼光谱（SERS）技术,并结合磁性固相萃取（MSPE）样品前处理方法,构建了饮用水水样中ng ·L^-1水平喹诺酮类抗生素的快速检测方法.借助于磁性氧化石墨烯复合纳米材料（Fe₃ O₄@SiO₂-GO）的高吸附容量所提供的高富集能力,成功实现了饮用水中1.0 ng ·L^-1恩诺沙星（ENR）和5.0 ng ·L^-1环丙沙星（CIP）的加标检出,回收率在77.5%~91.5%之间,满足当前饮用水水质检测的要求.对于有机基质复杂的湖水等环境水样,萃取材料的选择性尚有待于进一步提升.     

A novel colorimetric method for field arsenic speciation analysis

Accurate on-site determination of arsenic (As) concentration as well as its speciation presents a great environmental challenge especially to developing countries. To meet the need of routine field monitoring, we developed a rapid colorimetric method with a wide dynamic detection range and high precision. The novel application of KMnO₄ and CH₄N₂S as effective As(Ⅲ) oxidant and As(V) reductant, respectively, in the formation of molybdenum blue complexes enabled the differentiation of As(Ⅲ) and As(V). The detection limit of the method was 8 μg/L with a linear range (R² = 0.998) of four orders of magnitude in total As concentrations. The As speciation in groundwater samples determined with the colorimetric method in the field were consistent with the results using the high performance liquid chromatography atomic fluorescence spectrometry, as evidenced by a linear correlation in paired analysis with a slope of 0.9990-0.9997 (p < 0.0001, n = 28). The recovery of 96%-116% for total As, 85%-122% for As(Ⅲ), and 88%-127% for As(V) were achieved for groundwater samples with a total As concentration range 100-800 μg/L. The colorimetric result showed that 3.61 g/L As(Ⅲ) existed as the only As species in a real industrial wastewater, which was in good agreement with the HPLC-AFS result of 3.56 g/L As(Ⅲ). No interference with the color development was observed in the presence of sulfate, phosphate, silicate, humic acid, and heavy metals from complex water matrix. This accurate, sensitive, and easy-to-use method is especially suitable for field As determination.     

The dynamic changes of arsenic biotransformation and bioaccumulation in muscle of freshwater food fish crucian carp during chronic dietborne exposure

Dietary uptake is the major way that inorganic arsenic (iAs) enters into benthic fish; however, the metabolic process of dietborne iAs in fish muscle following chronic exposure remains unclear. This was a 40-day study on chronic dietborne iAs [arsenite (AsIII) and arsenate (AsV)] exposure in the benthic freshwater food fish, the crucian carp (Carassius auratus), which determined the temporal profiles of iAs metabolism and toxicokinetics during exposure. We found that an adaptive response occurred in the fish body after iAs dietary exposure, which was associated with decreased As accumulation and increased As transformation into a non-toxic As form (arsenobetaine). The bioavailability of dietary AsIII was lower than that of AsV, probably because AsIII has a lower ability to pass through fish tissues. Dietary AsV exhibited a high potential for transformation into AsIII species, which then accumulated in fish muscle. The largely produced AsIII considered more toxic at the earlier stage of AsV exposure should attract sufficient attention to human exposure assessment. Therefore, the pristine As species and exposure duration had significant effects on As bioaccumulation and biotransformation in fish. The behavior determined for dietborne arsenic in food fish is crucial for not only arsenic ecotoxicology but also food safety.     

Arsenic speciation in fish from Greek coastal areas

Arsenic speciation analysis was conducted on fish samples(sardine and anchovy) collected from six areas along the Greek coastline, i.e. Artemisium Straits, Thermaikos Gulf, Amvrakikos Gulf,Strymonian Gulf, Thracian Sea, and Elefsina Gulf. Total arsenic levels ranging from 11.8 to62.6 mg As/kg dry weight were determined. Arsenobetaine, a non-toxic form of arsenic, was found to be the main arsenic species, present at 8.6 to 58.8 mg As/kg dry weight, accounting for67–95% of the total arsenic. Also detected in all fish samples was dimethylarsinic acid, although at considerably lower concentrations, ranging from 0.072–0.956 mg As/kg dry weight.Monomethylarsonic acid was detected at low levels in all anchovy samples, and only in sardines from one area. Finally, inorganic arsenic in the form of arsenate was detected only in fish at one area, indicating the possible effect of an environmental parameter on its presence at detectable amounts. Statistical analysis revealed the environmental variables, such as salinity,total organic carbon and nitrogen, ammonium, phosphate, total phosphorus, dissolved oxygen and pressure index, are potentially correlated to As species concentrations. Furthermore, based on factor analysis, the biological parameters, such as fish weight, lipids, protein and ash content,that are correlated to As species concentrations of fish were also identified. The interrelationship of arsenobetaine and dimethylarsinic acid concentrations within each fish species was evaluated.     

Arsenic methylation by an arsenite S-adenosylmethionine methyltransferase from Spirulina platensis

Arsenic-contaminated water is a serious hazard for human health. Plankton plays a critical role in the fate and toxicity of arsenic in water by accumulation and biotransformation.Spirulina platensis(S. platensis), a typical plankton, is often used as a supplement or feed for pharmacy and aquiculture, and may introduce arsenic into the food chain, resulting in a risk to human health. However, there are few studies about how S. platensis biotransforms arsenic. In this study, we investigated arsenic biotransformation by S. platensis. When exposed to arsenite(As(Ⅲ)), S. platensis accumulated arsenic up to 4.1 mg/kg dry weight.After exposure to As(Ⅲ), arsenate(As(Ⅴ)) was the predominant species making up 64% to86% of the total arsenic. Monomethylarsenate(MMA(Ⅴ)) and dimethylarsenate(DMA(Ⅴ))were also detected. An arsenite S-adenosylmethionine methyltransferase from S. platensis(Sp Ars M) was identified and characterized. Sp Ars M showed low identity with other reported Ars M enzymes. The Escherichia coli AW3110 bearing Spars M gene resulted in As(Ⅲ) methylation and conferring resistance to As(Ⅲ). The in vitro assay showed that Sp Ars M exhibited As(Ⅲ) methylation activity. DMA(Ⅴ) and a small amount of MMA(Ⅴ) were detected in the reaction system within 0.5 hr. A truncated Sp Ars M derivative lacking the last 34 residues still had the ability to methylate As(Ⅲ). The three single mutants of Sp Ars M(C59S, C186 S, and C238S) abolished the capability of As(Ⅲ) methylation, suggesting the three cysteine residues are involved in catalysis. We propose that Sp Ars M is responsible for As methylation and detoxification of As(Ⅲ) and may contribute to As biogeochemistry.     

去除水体中砷的研究进展与展望

近年来,水体砷污染已成为一个全球性的环境问题,采取有效方法去除水体中的砷已受广泛关注。文章总结了水中砷主要去除方法:沉淀法、吸附法、生物法和膜分离法的原理、特点和应用现状,分析表明,沉淀法和吸附法已广泛应用于含砷水体的处理,其中开发高效的氧化剂和混凝剂是沉淀法的主要研究方向,寻求新型实用的吸附剂是吸附法的研究热点;生物法除砷是近年来的研究热点,加快微生物除砷的理论和应用研究是该方法的主要研究方向;膜分离法适用于对水质要求很高以及小规模的饮用水处理,研究较好的预氧化处理方法是该工艺的重点。将多种方法联合使用以达到最佳除砷效果,是目前水体除砷的发展趋势。     

Uptake and transformation of arsenic during the reproductive life stage of Agaricus bisporus and Agaricus campestris

Fruiting bodies from the Agaricus genus have been found to contain non-toxic arsenobetaine (AB) as a major compound. It is unknown whether AB is formed during the vegetative or reproductive life stages of the fungus, or by the surrounding microbial community, but AB''s structural similarity to glycine betaine has led to the hypothesis that AB may be adventitiously accumulated as an osmolyte. To investigate the potential formation of AB during the reproductive life stage of Agaricus species, growth substrate and fungi were collected during the commercial growth of Agaricus bisporus and analyzed for arsenic speciation using HPLC-ICP-MS. AB was found to be the major arsenic compound in the fungus at the earliest growth stage of fruiting (the primordium). The growth substrate mainly contained arsenate (As(V)). The distribution of arsenic in an A. bisporus primordium grown on As(V) treated substrate, and in a mature Agaricus campestris fruiting body collected from arsenic contaminated mine tailings, was mapped using two dimensional XAS imaging. The primordium and stalk of the mature fruiting body were both found to be growing around pockets of substrate material containing higher As concentrations, and AB was found exclusively in the fungal tissues. In the mature A. campestris the highest proportion of AB was found in the cap, supporting the AB as an osmolyte hypothesis. The results have allowed us to pinpoint the fungus life stage at which AB formation takes place, namely reproduction, which provides a direction for further research.     

砷的发生、形态、污染源及地球化学循环

文章首先总结了砷在地表水、地下水、土壤、沉积物、岩石、大气中的含量和分布;归纳了砷的地球化学循环过程;分析了砷在水和土壤/沉积物固相中的形态;并重点阐述了砷在土壤和沉积物中的迁移转化机理。砷通常与Fe、Al、Mn的氧化物和氢氧化物、粘土矿物、硫化物、磷酸盐和碳酸盐矿物结合,砷的生物可用性和迁移性与其在土壤和沉积物中的形态有密切关系。文章最后定量阐述了砷的污染源,包括金属开采与冶炼,化学燃料的燃烧和含砷化学品使用。     

天然类固醇雌激素源解析、环境行为及其污染控制

天然类固醇雌激素是一种在生物体内具有极强雌激素效应的内分泌干扰物,其在环境中的广泛存在严重影响野生动物尤其是鱼类的正常生长和发育,对环境生态系统所产生的破坏也日趋严重,然而其危害依然没有引起足够的重视。文章研究在阐述天然类固醇雌激素基本理化性质和环境存在形态的基础上,解析其在人类和畜禽的环境来源,分析其在地表水和地下水的污染状况以及环境迁移和生物积累等环境行为,并综合探讨了现今较为常见的如活性污泥法、光降解法以及微滤、纳滤和反渗透等与天然类固醇雌激素相关的污染控制技术,以期为天然类固醇雌激素的毒理性质、污染现状及相关控制方法的深入研究提供支撑。在此基础上,提出深入天然类固醇雌激素微量检测技术研究、加强国家行政管理层面上的污染控制等已十分急迫。     

Review on heterogeneous oxidation and adsorption for arsenic removal from drinking water

The long term exposure of arsenic via drinking water has resulted in wide occurrence of arsenisim globally, and the oxidation of the non-ionic arsenite (As(III)) to negatively-charged arsenate (As(V)) is of crucial importance for the promising removal of arsenic. The chemical oxidants of ozone, chlorine, chlorine dioxide, and potassium permanganate may achieve this goal; however, their application in developing countries is sometimes restricted by the complicate operation and high cost. This review paper focuses on the heterogeneous oxidation of As(III) by solid oxidants such as manganese oxide, and the adsorption of As(V) accordingly. Manganese oxide may be prepared by both chemical and biological methods to achieve good oxidation performance towards As(III). Additionally, manganese oxide may be combined with other metal oxides, e.g., iron oxide, to improve the adsorption capability towards As(V). Furthermore, manganese oxide may be coated onto porous materials of metal organic frameworks to develop novel adsorbents for arsenic removal. To achieve the application in engineering works, the adsorbents granulation may be achieved by drying and calcination, agglomeration, and the active components may also be in situ coated onto the porous materials to maintain the oxidation and adsorption activities as much as possible. The novel adsorbents with heterogeneous oxidation and adsorption capability may be carefully designed for the removal of arsenic in household purifiers, community-level decentralized small systems, and the large-scale drinking water treatment plants (DWTPs). This review provides insight into the fundamental studies on novel adsorbents, the development of innovative technologies, and the demonstration engineering works involved in the heterogeneous oxidation and adsorption, and may be practically valuable for the arsenic pollution control globally.     

环境水体中无机砷现场分析方法研究进展

砷是一种环境中普遍存在的类金属元素,并与人类健康息息相关.砷被列为一类致癌物,地下水中砷导致的慢性中毒是全球性健康问题.环境水体中砷的形态多样和毒性不尽相同,且在采样和运输过程中易于转化,而使实验室分析结果出现误差.因此开发砷的现场分析方法和获得准确的数据是研究砷的形态转化和生物吸收过程和准确判断其毒性的基础.在过去的几十年中,砷的实验室内分析方法迅速发展并逐渐成熟,但砷的现场分析仍然存在着巨大的困难和挑战.总结归纳了近10年来（2011~2022年）环境水体中砷分析方法相关的综述,讨论了砷的比色法、发光法和电化学法等现场分析方法的研究进展,并展望未来环境水体中砷现场分析方法的发展方向,为新方法的建立与应用提供参考.     

Geochemical migration of arsenic and its environmental effect

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Attenuation of arsenic in a karst subterranean stream and correlation with geochemical factors: A case study at Lihu, South China

Arsenic （As） pollutants generated by human activities in karst areas flow into subterranean streams and contaminate groundwater easily because of the unique hydrogeological characteristics of karst areas. To elucidate the reaction mechanisms of arsenic in karst subterranean streams, physical-chemical analysis was conducted by an inductively coupled plasma mass spectrometer and an X-ray fluorescence spectrometer. The results show that inorganic species account for most of the total arsenic, whereas organic arsenic is not detected or occurs in infinitesimal amounts. As（III） accounts for 51.0% ± 9.9% of the total inorganic arsenic. Arsenic attenuation occurs and the attenuation rates of total As, As（III） and As（V） in the Lihu subterranean stream are 51%, 36% and 59%, respectively. To fully explain the main geochemical factors influencing arsenic attenuation, SPSS 13.0 and CANOCO 4.5 bundled with CanoDraw for Windows were used for simple statistical analysis and redundancy analysis （RDA）. Eight main factors, i.e., sediment iron （SFe）, sediment aluminum （SAI）, sediment calcium （SCa）, sediment organic matter （SOM）, sediment manganese （SMn）, water calcium （WCa^2＋）, water magnesium （WMg^2＋）, and water bicarbonate ion （WILCOX） were extracted from thirteen indicators. Their impacts on arsenic content rank as： SFe〉SCa〉WCa^2＋〉SAl〉wHCO3^-〉SMn〉SOM〉WMg^2＋. Of these factors, SFe, SAl, SCa, SOM, SMn, WMg^2＋ and WCa＆2＋ promote arsenic attenuation, whereas WHCO3^- inhibits it. Further investigation revealed that the redox potential （Eh） and pH are adverse to arsenic removal. The dramatic distinction between karst and non-karst terrain is that calcium and bicarbonate are the primary factors influencing arsenic migration in karst areas due to the high calcium concentration and alkalinity of karst water.     

Construction of WCB-11: A novel phiYFP arsenic-resistant whole-cell biosensor

The prediction and assessment of environmental pollution by arsenic are important preconditions of advocating environmental protection and human health risk assessment.A yellow fluorescent protein-based whole-cell biosensor for the detection of arsenite and arsenate was constructed and tested.An arsenic-resistant promoter and the regulatory gene arsR were obtained by PCR from the genome of Escherichia coli DH5α,and phiYFP was introduced into E.coli DH5α as a reporter gene to construct an arsenic-resistant whole-cell biosensor(WCB-11) in which phiYFP was expressed well for the first time.Experimental results demonstrated that the biosensor has a good response to arsenic and the expression of phiYFP.When strain WCB-11 was exposed to As 3+ and As 5+,the expression of yellow fluorescence was time-dependent and dose-dependent.This engineered construct is expected to become established as an inexpensive and convenient method for the detection of arsenic in the field.     

有机污染物多环芳烃检测方法及进展

就近年来有机污染物多环芳烃检测方法及进展作一综述,方法包括高效液相色谱法、气相色谱一质谱联用法、毛细管电泳分析法、荧光法、免疫检测法以及表面增强拉曼散色光谱检测法,为在环境监测、食品检测等方面的应用提供了依据。     

Removal of arsenate with hydrous ferric oxide coprecipitation：Effect of humic acid

Insights from the adverse effect of humic acid(HA) on arsenate removal with hydrous ferric oxide(HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering(SERS), extended X-ray absorption fine structure(EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared(ATR-FTIR) measurement, and charge distribution multisite complexation(CDMUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26–3.31 ?. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms innersphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well.     

氢化物发生-原子荧光光谱法测定水中的砷、硒、汞

自然水体中蕴涵着很多元素,尤其是自来水中的有些痕量元素对人体健康是必不可少的。自来水中的砷、硒、汞含量极低,火焰原子荧光和石墨炉原子荧光的检测能力无法满足测定的要求,运用氢化物发生-原子荧光光谱法对自来水中的砷、硒、汞三种元素进行分析测定,可以提高水中砷、硒、汞检出限,是测量痕量元素的有效方法。