Research Progress on Influencing Factors and Mechanisms of Chromium Valence State Transformation in Soil
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摘要:
土壤中铬(Cr)污染是全球性环境问题，六价铬Cr(Ⅵ)因其高毒性及致癌性而成为关注焦点。土壤中的Cr主要以Cr(Ⅲ)和Cr(Ⅵ) )的形式存在，两者之间的转化受到诸如土壤pH值、氧化还原电位(Eh)、天然氧化还原剂、有机质和微生物的影响。随着工农业活动的增多，土壤中的Cr浓度不断增加，并通过植物吸收进入食物链等多种途径，对生态系统和人体健康构成威胁。本文对Cr在全球范围内的污染现状及来源、土壤中Cr的不同价态及其毒性特征进行了评述，并分析了pH、Eh对土壤中Cr的具体存在形态与价态的影响，及天然氧化还原剂、有机质等因素利用自身化学性质充当电子供体或受体的角色对土壤中Cr价态进行转化的氧化还原机理，以及不同影响因素之间的相互作用关系，从而可以全面理解土壤中Cr价态转化的行为机制。此外，在对Cr价态影响因素深入了解的基础上，总结了以生物炭和纳米材料为代表的先进修复技术方法，这些材料和方法由于能够将Cr(Ⅵ) 有效地还原为毒性较小的Cr(Ⅲ)，从而降低生态环境风险，因而是一类具有巨大潜在应用价值的修复材料和修复方法，但大规模应用的可行性及其修复效果仍需要进一步验证。
要点(1) 土壤中的Cr(Ⅵ)主要以铬酸盐(CrO4 2−)、氢铬酸盐(HCrO4 − )和重铬酸盐(Cr2O7 2−)等氧化离子的形式存在，是土壤中毒性最大的Cr价态。
(2) 土壤中Cr价态受Eh、有机质等多种因素影响，这些因素可以促进或抑制Cr(Ⅵ)的还原。
(3) 生物炭和纳米材料等新型修复技术能够将Cr(Ⅵ)有效地还原为低毒性的Cr(Ⅲ)，是治理Cr(Ⅵ)污染的一种可行技术方案。
HIGHLIGHTS(1) Cr(Ⅵ) in soil mainly exists in the form of oxidized ions such as chromate (CrO4 2− ), hydrogen chromate (HCrO4 − ), and dichromate (Cr2O7 2− ), and is the most toxic Cr valence state in soil.
(2) The valence state of Cr in soil is affected by Eh, organic matter and other factors, which can promote or inhibit the reduction of Cr(Ⅵ).
(3) New remediation technologies such as biochar and nanomaterials can effectively reduce Cr(Ⅵ) to low toxicity Cr(Ⅲ), which is a feasible technical solution for treating Cr(Ⅵ) pollution.
Abstract:Chromium (Cr) pollution in soil is a global environmental problem, and hexavalent chromium [Cr(Ⅵ)] has become a focus of attention due to its high toxicity and carcinogenicity. Cr in soil mainly exists in the form of Cr(Ⅲ) and Cr(Ⅵ), and the transformation between the two is influenced by factors such as soil pH, redox potential (Eh), natural redox agents, organic matter, and microorganisms. This article provides an overview of the global pollution status and sources of Cr in soil, as well as the different valence states and toxicity characteristics of Cr in soil. It also analyzes the redox mechanisms of chromium valence state transformation in soil affected by different factors, as well as the interactions between different factors. In addition, through a deep understanding of the factors affecting the valence state of Cr, advanced remediation techniques represented by biochar and nanomaterials have emerged. These methods can effectively reduce Cr(Ⅵ) to less toxic Cr(Ⅲ), thereby reducing ecological and environmental risks. Therefore, they are a potentially valuable remediation material and technique. However, the feasibility and effectiveness of large-scale applications still need further verification. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202401180007.
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Keywords:
- chromium pollution /
- chromium valence state /
- natural redox agent /
- organic matter; remediation technology
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铊属于稀散元素，常分散赋存于岩石中；在地球化学上既有亲石性，又有亲硫性。亲石性表现为以类质同象的形式与钾、钠等元素在云母和钾长石等富钾矿物共生；而在低温高硫环境中，则表现为亲硫性，以类质同象的形式进入各种铅锌铜铁等硫化物矿物中。20世纪70年代，为了寻找放射性同位素205Pb曾经存在的证据和探究核素合成的机理，科研人员开始了对铊同位素的研究［1］。在早期的研究中，由于测试用的热电离质谱仪(TIMS)的质量分馏不稳定，且难以激发高电离能的元素，导致铊同位素分析结果的精密度较差，不能满足大部分研究的需要。近些年，随着具备高电离能力的多接收器电感耦合等离子体质谱仪(MC-ICP-MS)的出现，同时得益于铅对分析过程中铊同位素分馏的校正，使分析结果的精密度有了大幅提高(优于0.05‰)［2-5］。
由于铊兼有亲石和亲硫性，其同位素组成对吸附、共沉淀、氧化还原等过程较为敏感，因此可以被应用于天体演化［6］、古环境变化［7］、矿床成因［8］及污染物迁移［9-11］等过程的示踪。但因为自然界样品中铊的含量低(地壳中铊的平均含量仅为0.75mg/kg)，且同位素组成的变化范围和自然分馏效应很小［12］，导致很难获得高精度和高准确度的铊同位素数据。因此，除高精度的仪器测量外，样品的消解、分离和纯化等化学前处理流程对铊同位素分析结果的准确与否也至关重要。对于铊含量的分析，分解试样时如果不知道矿石中铊的赋存状态，一般选用含有氢氟酸的混合酸或强碱性熔剂分解［13-16］。而对于富含有机质的样品，由于亚铊的氧化物、氯化物等具有挥发性，应避免使用直接灼烧法除去有机质，而是采用湿法氧化分解［14，16］。目前国内外地质样品中铊同位素测定的消解方法主要为电热板加热法。这种方法便于在洁净的化学实验室完成，但清洗容器和样品消解过程的用时较长，耗时往往超过一周［4］。根据地质样品岩性的不同，消解所用的混合酸体系也不相同，尚无统一的标准。铊的分离和纯化一般利用Tl+和Tl3+在盐酸介质中与Cl−络合能力的不同。需要注意的是，在纯化后的铊馏分中应尽可能减小铅量，否则由于残留的铅同位素组成是未知的(校正时添加标液的铅同位素是已知的)，会影响铊的同位素分馏校正；此外，天然样品204Pb的自然丰度虽然仅有铅总量的1.4%，但204Pb1H多原子离子干扰对于铊同位素的高精度测量仍不可忽视。目前，使用阴离子交换树脂(如AG1-X8或AG-MP-1M树脂)二次过柱是普遍采用的铊提纯方法。该方法由Rehkämper等［2］首次提出，后经Nielsen等［3］、Baker等［6］、Owens等［17］研究团队发展和完善。该方法两次过柱均采用同一种阴离子交换树脂，第一次分离时采用装有1.5mL树脂的石英柱，依次用硝酸-氢溴酸-饱和溴水淋洗液洗脱基体元素、盐酸-饱和溴水淋洗液洗脱干扰元素铅，最后用盐酸-二氧化硫淋洗液收集铊。收集到的铊馏分经硝酸蒸干后，加入氢溴酸-饱和溴水提取液进行二次过柱，以保证完全消除干扰组分的影响。第二次过柱时，除所用体积与第一次不同之外，淋洗液的类型和浓度均与第一次相同。此外，Wang等［5］开发了磷酸三丁酯(TBP)树脂和AG50W-X12阳离子交换树脂的两级串联分离纯化方案，以NIST 997为参考物质测定BHVO-2、BCR-2、AGV-2、GSP-2、COQ-1、NOD-P-1、NOD-A-1、GBW07406、SCO-1共9种地质标准样品的同位素组成，获得了理想的结果。
微波消解是一种利用微波的穿透性和激活反应能力加热密闭容器内的试剂和样品的技术，具有省时、省酸、安全、空白值低、易实现自动监控、污染小以及损失少等优点，已广泛应用于食物［18-19］、环境［20］、生物［21］、植物［22］以及矿物［23-26］等样品中重金属元素的分析。本文为提高铊同位素分析中化学前处理流程的效率，研究了利用微波消解技术分解地质样品进行铊同位素分析的可行性，比较了硝酸-氢氟酸-盐酸-过氧化氢和硝酸-氢氟酸-高氯酸混合酸体系对样品的消解情况。消解后的样品经AG1-X8阴离子交换树脂分离纯化后，采用MC-ICP-MS结合铅标准溶液(NIST SRM981)质量分馏校正法进行同位素分析。使用优化后的实验方案分析了4个地质标准物质的铊同位素组成，获得较为满意的结果。
1. 实验部分
1.1 仪器和主要装置
铊同位素组成的测试运用Neptune plus多接收器电感耦合等离子体质谱仪(MC-ICP-MS，美国ThermoFisher公司)完成，进样系统包括双路气旋式雾化室、Jet样品锥和X截取锥，检测器包括9个法拉第杯和1个离子计数器。
淋洗曲线标定及回收率测试应用7500cx电感耦合等离子体质谱仪(ICP-MS，美国Agilent公司)完成，内标溶液为10ng/mL铑(2%硝酸介质)。MC-ICP-MS和ICP-MS质谱仪的主要工作参数见表1。
表 1 MC-ICP-MS和ICP-MS仪器主要工作参数Table 1. Main operation conditions of MC-ICP-MS and ICP-MS instruments工作参数 设定值 MC-ICP-MS ICP-MS 冷却气(Ar)流速(L/min) 16.00 14.95 辅助气(Ar)流速(L/min) 0.86 0.28 雾化气(Ar)流速(L/min) 0.05 0.92 射频功率(W) 1152 1470 积分时间(s) 4.194 / 每组测量次数 30 / 测量组数 1 / 实验用水由超纯水系统(美国Millipore公司)制备，电阻率18.2MΩ·cm。
高纯酸由NJ-SCH-I酸纯化器(南京滨正红仪器有限公司)纯化。
样品消解由Ethos1微波消解仪(意大利Milestone公司)完成。
PFA微型离子交换柱：北京博明远科技有限公司，下部为0.65cm(内径)×10.0cm(高)，上部为1.5cm(内径)×5cm(高)，总容量约15mL，底部为孔径20μm的亲水性筛板。
1.2 标准物质和主要试剂
铅同位素标准溶液NIST SRM981、铊标准溶液GSB 04-1758-2004和地质标准物质(NOD-P-1、NOD-A-1、GBW07406、GSP-2)详细信息见表2。
表 2 地质标准物质和同位素标准溶液的详细信息Table 2. Details of geological reference materials and isotope reference solutions标准物质编号 样品类型 研制单位 推荐值 铊 铅 NIST SRM 981 铅同位素标准溶液 美国标准与技术研究院(NIST) / 10μg/mL GSB 04-1758-2004 铊标准溶液 中国有色金属及电子材料分析测试中心 1000μg/mL / NOD-P-1 铁锰结核 美国地质调查局(USGS) 210±2μg/g 560±6μg/g NOD-A-1 铁锰结核 美国地质调查局(USGS) 120±1.0μg/g 846±8.2μg/g GBW07406 土壤 中国地质科学院地球物理地球化学勘查研究所 2.2±0.6μg/g 314±25μg/g GSP-2 花岗岩 美国地质调查局(USGS) 1.1±0.1μg/g 43±3μg/g 阴离子交换树脂(AG1-X8，100～200目)：购自美国Bio-Rad公司。
优级纯的盐酸、硝酸和氢氟酸(上海国药集团化学试剂有限公司)：经二次亚沸蒸馏纯化后使用；高氯酸(优级纯，上海国药集团化学试剂有限公司)；过氧化氢、饱和溴水(分析纯，广州西陇化工股份有限公司)；二氧化硫标准气体(99.9%，广东英德市西洲气体有限公司)。
0.1mol/L盐酸-6%二氧化硫溶液的配制：将二氧化硫标准气体通入0.1mol/L盐酸中，使其质量增加6%，现用现配。
1.3 样品消解
根据铊在样品中的含量，称取50～300mg粉末状样品(200目，105℃烘干2h)于干净的PFA(可溶性聚四氟乙烯)消解罐中，用少量水润湿，加入2mL氢氟酸、2mL硝酸和0.5mL高氯酸；充分混匀，放置反应1h后，加盖拧紧；按表3的升温程序进行微波消解。冷却后，缓慢泄压放气，打开消解罐，将样品转移至15mL 聚四氟乙烯杯中180℃加热至白烟冒尽，加入2mL 6mol/L盐酸溶解，120℃蒸干，重复一次(除尽氢氟酸、硝酸和高氯酸)。最后加入2mL 2mol/L硝酸-1%饱和溴水，加盖密闭后80℃加热12h，待溶液冷却，离心后进行色谱分离。
表 3 样品处理微波消解程序Table 3. Microwave digestion procedure for sample pretreatment步骤 消解温度
(℃)消解功率
(W)加热时间
(min)保持时间
(min)1 120 400 5 5 2 150 800 5 5 3 190 1200 5 20 需要特别注意的是：①所有的敞口操作必须在超净工作台进行，以防外部环境中铅及其他元素的污染；②为避免酸的损失和安全伤害，消解罐必须完全冷却后才能泄压开盖［22］。
1.4 铊的纯化
铊的纯化流程在Nielsen等［3，27］的研究基础上作了部分优化，优化内容主要包括：①将双柱淋洗修改为单柱淋洗；②控制淋洗液的总体积在28mL。详细步骤如下(流程见表4)：采用湿法填充树脂柱，将约2mL AG1-X8树脂置于微型离子交换柱中，依次用1mL 0.1mol/L盐酸-6%二氧化硫和1mL超纯水清洗两遍，再用2mL 2mol/L硝酸-1%溴水平衡树脂2次；然后将离心后的样品溶液加载于树脂柱上，用2mL 2mol/L硝酸-1%溴水淋洗6次和2mL超纯水淋洗1次，以除去基体元素；随后用2mL 0.1mol/L盐酸-6%二氧化硫淋洗5次，收集铊。最后将收集到的0.1mol/L盐酸-6%二氧化硫溶液置于电热板120℃蒸干，然后用0.5mL 0.1%硫酸-2%硝酸溶解，准备进行质谱测试。
表 4 铊同位素的离子交换流程(2mL AG1-X8树脂，100～200目)Table 4. Chemical purification procedure for Tl isotopes (2mL AG1-X8 resin, 100-200 mesh)步骤 淋洗液 淋洗液体积
(mL)淋洗
次数实验目的 1 0.1mol/L盐酸-6%二氧化硫 1 2 清洗树脂 2 超纯水 1 2 清洗树脂 3 2mol/L硝酸-1%溴水 2 2 清洗/平衡树脂 4 2mol/L硝酸-1%溴水 2 / 装载样品 5 2mol/L硝酸-1%溴水 2 6 洗脱基质 6 超纯水 2 1 洗脱NO3−和BrO− 7 0.1mol/L盐酸-6%二氧化硫 2 5 收集铊 1.5 铊同位素分析
铊同位素的分析测定在桂林理工大学广西隐伏金属矿产勘查重点实验室进行。由于自然界样品的铊同位素组成的变化范围很小，用传统的千分偏差“δ”往往不能有效地反映其同位素组成的差异，所以国际上铊同位素测试结果普遍以万分偏差“ε”来表示［1］。另外，由于未购买到国际上普遍认可的铊同位素标准物质NIST 997，本文选择以中国有色金属及电子材料分析测试中心研制的铊同位素物质GSB 04-1758-2004为参照，即用ε205TlGSB Tl表示：
$$ \varepsilon^{205}\mathrm{T}\mathrm{l}_{\mathrm{G}\mathrm{S}\mathrm{B}\ \mathrm{T}\mathrm{l}}=\left[\frac{(^{205}\mathrm{T}\mathrm{l}/^{203}\mathrm{T}\mathrm{l})_{\mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}}}{(^{205}\mathrm{T}\mathrm{l}/^{203}\mathrm{T}\mathrm{l})_{\mathrm{G}\mathrm{S}\mathrm{B}\mathrm{ }\ \mathrm{T}\mathrm{l}}}-1\right]\times10000 $$ 测试时MC-ICP-MS仪器的法拉第杯结构为：L3(202Hg)、L2(203Tl)、L1(204Pb)、C(205Tl)、H1(206Pb)、H2(207Pb)、H3(208Pb)，其他主要工作参数见表1。样品引入时的介质均采用2%的硝酸，2ng/mL GSB 04-1758-2004标准溶液对应205Tl电压信号约为1.2V。测试过程产生的质量歧视通过加入已知铅同位素组成的溶液(NIST SRM981)进行校正，计算方法参考文献[5]。在这项研究中，铅标准溶液的质量按照mPb/mTl=10/1加入。在每次测量开始之前，都需要仔细调整仪器参数，以确保铊和铅的信号强度最大化；同时，进行重复的质量扫描，以检查法拉第杯位置是否合适并监测峰形，确保同位素比值测量的仪器条件。此外，为了校正样品的铊同位素组成，在每次分析前后均测量一次标准物质GSB 04-1758-2004。
2. 结果与讨论
2.1 消解条件的优化
2.1.1 无机酸组成及用量的影响
针对土壤和沉积物样品中的金属总量分析，中国环境保护标准《土壤和沉积物 金属元素总量的消解-微波消解法》(HJ 832—2017)推荐使用11mL硝酸-氢氟酸-盐酸的混合酸组合对样品进行消解。然而，若地质样品中的有机质或难溶矿物含量较高时，样品难以被完全分解，需使用硝酸-氢氟酸-高氯酸进行二次消解［28］。高氯酸和过氧化氢可以提高消解体系的分解能力，因此，本文试验了硝酸-氢氟酸-盐酸-过氧化氢和硝酸-氢氟酸-高氯酸两种混合酸体系对样品的消解情况。此外，为了控制干扰元素(特别是铅)的引入，实验中对酸的用量也进行了优化。
选择土壤标样GBW07406，称样量0.2g，加入不同的混合酸组合，按表3中程序进行微波消解，测定结果见表5。在硝酸-氢氟酸-盐酸-过氧化氢混合酸体系中，当用酸量总体积为4mL(组号1-1)时，消解液中有少量不溶的白色沉淀，此时铊回收率仅有84.7%，说明酸用量太少，不足以将0.2g样品消解完全。将酸用量进一步提升(组号1-2和1-3)，所得消解液为清亮透彻的黄色溶液，铊回收率均接近100%，说明硝酸-氢氟酸-盐酸-过氧化氢体系中，7mL酸用量(组号1-2)就可以将0.2g样品消解完全。在硝酸-氢氟酸-高氯酸混合酸体系中，消解样品所用的酸量要少，仅4.5mL(组号2-2)就可将0.2g样品消解完全，此时得到的消解液为清澈透亮的黄色溶液，铊回收率为98.2%。鉴于同位素分析中尽可能低本底的需求，本实验选择2mL硝酸-2mL氢氟酸-0.5mL高氯酸(组号2-2)的混合酸体系对样品进行消解。
表 5 不同无机酸种类及用量的消解效果对比(n=3)Table 5. Comparison of digestion effects of different types and volumes of inorganic acids (n=3)混合酸体系 实验组号 混合酸体系各酸用量
(mL)样品消解效果观察 铊回收率
(%)硝酸-氢氟酸-
盐酸-过氧化氢1-1 1+1+1+1 有少量不溶白色沉淀 84.7 1-2 2+2+2+1 黄色消解液清澈透亮 98.4 1-3 5+3+3+1 黄色消解液清澈透亮 98.6 硝酸-氢氟酸-
高氯酸2-1 1+1+0.5 有少量不溶白色沉淀 81.9 2-2 2+2+0.5 黄色消解液清澈透亮 98.2 2-3 5+3+0.5 黄色消解液清澈透亮 99.0 需要特别指出的是，高氯酸与有机质在密闭系统中反应剧烈，易发生爆炸，使用时不仅要严格控制其用量，还要在微波消解之前放置反应一段时间(本文建议时长为1h)。
2.1.2 微波消解程序的选择
为了考察微波消解程序中的最高温度和保持时间对消解效果影响，本文选择土壤标样GBW07406为试验样品，保持其他条件不变；以表3中步骤3的消解温度和保持时间为因素，进行正交试验，分析结果如表6所示。结果表明，当消解温度设定在190℃，保持时间为20min时，铊的回收率大于98%。继续升高消解温度和增加保持时间并不能使铊的回收率显著提高，且高温高压易造成微波消解内管变形，影响其密闭性。因此，190℃保持20min为本文推荐使用的微波消解条件，此时总的微波消解时间为45min。
表 6 消解温度和保持时间的正交试验结果(n=3)Table 6. Orthogonal test results of digestion temperature and holding time (n=3)编号 因素水平 铊回收率
(%)消解温度(℃) 时间(min) 1 180 15 86.6 2 180 20 93.1 3 190 15 94.0 4 190 20 98.2 5 200 15 97.8 6 200 20 99.1 2.2 铊在阴离子交换树脂上的淋洗曲线
203Tl和205Tl的干扰主要来自163Dy40Ar、165Ho40Ar、187Re16O、189Os16O、202Hg1H、204Hg1H和204Pb1H等多原子离子团，因此在进行铊的纯化时需特别关注共存元素镝、钬、铼、锇、汞和铅的分离情况。
选择0.2g消解后的标准物质GBW07406为试验样品，按表4中铊同位素的离子交换流程，以1mL为单位接取馏分；利用ICP-MS测定各馏分中相应元素的含量并绘制淋洗曲线，结果如图1所示。从淋洗曲线中可以看出，绝大多数基质元素及干扰元素(包括镝、钬、铼、锇、汞和铅)被最开始的6mL 2mol/L硝酸-1%溴水洗脱。为了尽可能地减少铅的残留，本课题组继续使用了6mL 2mol/L硝酸-1%溴水淋洗；接下来，用2mL超纯水将树脂中的氧化性离子(NO3−和BrO−)洗脱。随后以10mL 0.1mol/L盐酸-6%二氧化硫淋洗并收集馏分中的铊。通过对该馏分的组分分析发现，铊的回收率约为98.5%，镝、钬、铼、锇和汞几乎无残留，铅的残留量不足铊量的1/10，钡有一定的残留，约为总钡量的4%。其中，接取液中钡和极少量铅的残留对铊的同位素测试没有影响，当地质样品中的铅/铊比值大于1000时，铅的残留可能会导致铊同位素组成测定结果偏高［5］，此时建议进行二次过柱。
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图 1 铊的淋洗曲线(AG1-X8树脂，100～200目)，其中2mol/L硝酸-1%溴水洗脱基体元素，超纯水洗脱残留NO3−和BrO−，0.1mol/L盐酸-6%二氧化硫收集铊Figure 1. Elution curves of Tl (AG1-X8 resin, 100-200 mesh), 2mol/L HNO3-1% Br2 for eluting matrix elments, ultrapure water for eluting NO3− and BrO−, 0.1mol/L HCl-6% SO2 for collecting Tl.2.3 基质中铁钙铝对铊测量的影响
铊在地质样品中的含量通常低于0.1μg/g，往往需要加大称样量来提高测试精度。大多数样品以硅质或碳质为主，经消解后，硅和碳都挥发除去，所留下的盐分很少，而富含赤铁矿(铁高)、灰岩(钙高)和高岭土(铝高)等类型的地质样品，消解后的溶液中金属离子的浓度很高，而树脂的总离子交换容量一般在3～6mmol/g(干基)或1～2mmol/g(湿基)。因此，为考察这三种阳离子对淋洗流程的干扰，本文采用标准加入法考察了三氧化二铁、氧化钙和三氧化二铝对上述淋洗曲线中铊回收率的影响。操作步骤为：取三组1mL 1μg/mL铊标准溶液(GSB 04-1758-2004)，分别加入0.1～0.5g的Fe2O3、CaO和Al2O3，按第1.3、1.4、1.5节进行前处理和样品测试。三种元素的加入量与铊回收率之间的关系如图2所示。
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图 2 三氧化二铁、氧化钙和三氧化二铝对铊回收率的影响(n=3)Figure 2. Influences of the load of Fe2O3, CaO and Al2O3 on the recovery of Tl (n=3)从图2可以看出，CaO的加入对铊回收率的影响很小，可以忽略。Fe2O3的影响最大，当其加入量为0.4g(约2.56mmol)时，铊的回收率开始下降，约为90%；当加入量为0.5g时，铊的回收率下降到只有75%左右。这可能是因为随着样品中Fe3+的增多，用盐酸淋洗时容易形成络合物FeCl4−，占据离子交换反应位点，使树脂的交换容量达到饱和，从而降低了铊的回收率。而对于Al2O3，当其加入量为0.5g(约4.90mmol)时，铊的回收率略有下降，约为93%，从观察到的实验现象判断，原因应是Al2O3有部分结晶，夹杂着少量铊进入固相析出而导致的。因此，对于基质中含铁、铝矿物较高的样品应控制其称样量，以防树脂的交换容量饱和而导致铊回收率偏低。
2.4 流程空白
通过三份空白试验使用第1.3、1.4、1.5节步骤中的流程进行铊同位素分析，最终确定整个实验流程中铊的空白值低于10pg，远低于普通地质样品中铊含量的1‰，对测试结果的影响可以忽略［23］。
2.5 地质标准物质中铊同位素组成的测定结果
为了确保MC-ICP-MS测定铊同位素的长期可重复性，对铊标准溶液GSB 04-1758-2004进行40次测量，结果如图3所示。图中的205Tl/203Tl值是以铅标准溶液NIST SRM981为外标校正后的结果(相对于208Pb/206Pb=2.1076)。本实验室的测量结果为205Tl/203Tl=2.38775，标准偏差(2σ)为0.00011，说明仪器的稳定性较好。
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图 3 铊标准溶液GSB 04-1758-2004测量结果的稳定性(n=40)Figure 3. The reproducibility of analytical results for Tl standard solution GSB 04-1758-2004 (n=40)按照优化后的化学流程，处理4个地质标准物质，并进行铊同位素组成的测定。从表7中的测定结果可以发现，4个标准物质的2SD均优于0.3(n=6)，说明本方法具有较高的精密度。由于与文献选用的同位素标准物质不同，方法的准确度可以用两者间差值变化情况来考察。通过与文献的结果对比发现，标准物质NOD-P-1、GBW07406和GSP-2的ε205Tl差值(ε205TlNIST 997−ε205TlGSB Tl)均为0.8，NOD-A-1的ε205Tl差值为0.7，说明方法具有较好的准确性；此外，可以估算标准物质GSB 04-1758-2004相对于NIST 997的ε205Tl值应约等于0.8。
表 7 地质标准物质中铊同位素组成的测定结果及文献对比Table 7. Comparison of analytical results of Tl isotope composition in geological reference materials determined by this method and those in the literatures3. 结论
通过对铊同位素分析中的消解方法、淋洗曲线和流程空白的分析讨论可知，采用微波消解法，在2mL硝酸-2mL氢氟酸-0.5mL高氯酸的混合酸体系中选用适当的消解程序，可以将0.2g土壤标准物质GBW07406彻底消解；利用AG1-X8阴离子交换树脂，依次以2mL 2mol/L硝酸-1%饱和溴水淋洗6次、2mL超纯水淋洗1次和2mL 0.1mol/L盐酸-6%二氧化硫淋洗5次，并收集0.1mol/L盐酸-6%二氧化硫的馏分，可有效地纯化地质样品中的铊。该淋洗流程所允许上样溶液中含有三价铁和三价铝离子的量分别不应超过2.56mmol和4.90mmol，否则引起树脂的离子交换容量饱和而导致铊回收率降低。与前人相比，该流程缩短了消解时间，采用AG1-X8树脂单柱法进行铊同位素的纯化，将淋洗液的总体积优化至24mL。本工作提高了铊同位素分析中化学前处理流程的效率，将此方法应用于4个不同地质标准物质的铊同位素比值的测定，结果证明具有较好的精密度和准确性。
需要指出的是，由于外界因素的制约，国际上普遍认可的NIST 997标准物质在中国已很难购买，影响了国内铊同位素地球化学研究工作的开展，所以中国亟需研制出国际上认可的铊同位素标准物质。
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图 1 土壤中的有机质对Cr的“吸附—还原—络合”机理
Figure 1. The mechanism of “adsorption—reduction—complexation” of Cr by organic matter in soil
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图 2 酚羟基对Cr(Ⅵ)的还原作用
Figure 2. The reduction effect of phenolic hydroxyl groups on Cr(Ⅵ)
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图 3 Fe(Ⅲ)/Fe(Ⅱ)通过Fe3S4改性的生物炭完成对Cr(Ⅵ)的还原
Figure 3. The reduction of Cr(Ⅵ) by Fe(Ⅲ)/Fe(Ⅱ) modified biochar with Fe3S4
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图 4 有机质(OM)中的持久性自由基在光照条件下对Cr(Ⅵ)的还原作用
Figure 4. The reduction effect of persistent free radicals in organic matter (OM) on Cr(Ⅵ) under light conditions
表 1 不同国家土壤Cr污染现状
Table 1 Current situation of Cr pollution in different countries
研究场地 Cr(Ⅲ)含量
(mg/kg)Cr(Ⅵ)含量
(mg/kg)总Cr含量
(mg/kg)对照标准 是否污染
地下水埃塞俄比亚某制革厂周边
污染区域土壤［19］791.5～1811.4 0.621～0.973 792.47～1812.21 制革厂90公里外某处未受污染土壤样品：Cr(Ⅲ)浓度0.18mg/kg，
Cr(Ⅵ)未检出，总Cr浓度0.18mg/kg是 意大利南部一处往年被长期非法掩埋皮革工业废物的农田［20］ — 0.15～11.18 48～6831 意大利议会制定的关于土壤中Cr(Ⅵ)筛选值2mg/kg，
总Cr筛选值150mg/kg未评估 中国重庆某铬盐生产场地
遗留旧址［21］— 168.8～203.4 — 《土壤环境质量标准》
(GB 36600—2018)限值5.7mg/kg未评估 中国天津原同生化工厂残渣垃圾堆放场地及周边表层土壤［22］ — — 8571.4～10711.4 《土壤环境质量标准》
(GB 15618—2018) 限值250mg/kg是 中国宁夏回族自治区某煤化
化工厂周边土壤［23］— 6.480～11.750 73.800～107.080［24］ 中国土壤Cr(Ⅵ)背景值6.100mg/kg；宁夏土壤Cr(Ⅵ)背景值6.000mg/kg 未评估 注：“—”表示数据缺失。 
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[1] Sharma A, Kapoor D, Wang J, et al. Chromium bioaccumulation and its impacts on plants: An overview[J]. Plants-Basel, 2020, 9(1): 100. doi: 10.3390/plants9010100
[2] Pourret O, Hursthouse A. It’s time to replace the term “Heavy Metals”with “Potentially Toxic Elements” when reporting environmental research[J]. International Journal of Environmental Research and Public Health, 2019, 16(22): 4446. doi: 10.3390/ijerph16224446
[3] Rashid A, Schutte B J, Ulery A, et al. Heavy metal contamination in agricultural soil: Environmental pollutants affecting crop health[J]. Agronomy-Basel, 2023, 13(6): 1521. doi: 10.3390/agronomy13061521
[4] Rinklebe J, Antoniadis V, Shaheen S M, et al. Health risk assessment of potentially toxic elements in soils along the Central Elbe River, Germany[J]. Environment International, 2019, 126: 76−88. doi: 10.1016/j.envint.2019.02.011
[5] 林晓梅, 曹玉莹, 赵上勇, 等. 激光诱导击穿光谱技术对土壤中重金属元素Cr的定量分析[J]. 光谱学与光谱分析, 2021, 41(3): 875−879 doi: 10.3964/j.issn.1000-0593(2021)-0875-05 Lin X M, Cao Y Y, Zhao S Y, et al. Quantitative analysis of Cr in soil by laser-induced breakdown spectroscopy[J]. Spectroscopy and Spectral Analysis, 2021, 41(3): 875−879. doi: 10.3964/j.issn.1000-0593(2021)-0875-05
[6] Mortada W I, El-Naggar A, Mosa A, et al. Biogeochemical behaviour and toxicology of chromium in the soil-water-human nexus: A review[J]. Chemosphere, 2023, 331: 138804. doi: 10.1016/j.chemosphere.2023.138804
[7] Prado C, Ponce S C, Pagano E, et al. Differential physiological responses of two Salvinia species to hexavalent chromium at a glance[J]. Aquatic Toxicology, 2016, 175: 213−221. doi: 10.1016/j.aquatox.2016.03.027
[8] Wei Y, Usman M, Farooq M, et al. Removing hexavalent chromium by nano zero-valent iron loaded on attapulgite[J]. Water Air and Soil Pollution, 2022, 233(2): 48. doi: 10.1007/s11270-022-05513-z
[9] Mongaa A, Fulkea A B, Dasguptab D. Recent developments in essentiality of trivalent chromium and toxicity of hexavalent chromium: Implications on human health and remediation strategies[J]. Journal of Hazardous Materials Advances, 2022, 7: 100113. doi: 10.1016/j.hazadv.2022.100113
[10] den Braver-Sewradj S P, van Benthem J, Staal Y C M, et al. Occupational exposure to hexavalent chromium. Part Ⅱ. Hazard assessment of carcinogenic effects[J]. Regulatory Toxicology and Pharmacology, 2021, 126: 105045. doi: 10.1016/j.yrtph.2021.105045
[11] Yan X, Yan Z H, Zhu X Z, et al. Comparing different strategies for Cr(Ⅵ) bioremediation: Bioaugmentation, biostimulation, and bioenhancement[J]. Sustainability, 2023, 15(16): 12522. doi: 10.3390/su151612522
[12] Sayed D, Alturki A A, Farag H, et al. A novel rotating fixed bed batch reactor for hexavalent chromium reduction[J]. Journal of Ecological Engineering, 2022, 23(11): 273−280. doi: 10.12911/22998993/154061
[13] Kang Z, Gao H, Ma X, et al. Fe-Ni/MWCNTs nano-composites for hexavalent chromium reduction in aqueous environment[J]. Molecules, 2023, 28(11): 4412. doi: 10.3390/molecules28114412
[14] Guo H, Chen Y, Hu H, et al. High hexavalent chromium concentration in groundwater from a deep aquifer in the Baiyangdian Basin of the North China Plain[J]. Environmental Science & Technology, 2020, 54(16): 10068−10077. doi: 10.1021/acs.est.0c02357
[15] Deng L Y, Liu F, Ding Z C, et al. Effect of natural organic matter on Cr(Ⅵ) reduction by reduced nontronite[J]. Chemical Geology, 2023, 615: 121198. doi: 10.1016/j.chemgeo.2022.121198
[16] Enbaia S, Eswayah A, Hondow N, et al. Detoxification, active uptake, and intracellular accumulation of chromium species by a methane-oxidizing bacterium[J]. Applied and Environmental Microbiology, 2021, 87(2): e00947−e00920. doi: 10.1128/AEM.00947-20
[17] Pei Y, Yang Y, Chen L, et al. Remediation of chromium-contaminated soil in semi-arid areas by combined chemical reduction and stabilization[J]. Environmental Pollutants and Bioavailability, 2023, 35(1): 2157332. doi: 10.1080/26395940.2022.2157332
[18] Li S, Xie Y, Jiang S, et al. Biochar decreases Cr toxicity and accumulation in sunflower grown in Cr(Ⅵ)-polluted soil[J]. Toxics, 2023, 11(9): 787. doi: 10.3390/toxics11090787
[19] Gezahegn A M, Feyessa F F, Tekeste E A, et al. Chromium laden soil, water, and vegetables nearby tanning industries: Speciation and spatial distribution[J]. Journal of Chemistry, 2021, 2021: 5531349. doi: 10.1155/2021/5531349
[20] Caporale A G, Agrelli D, Rodríguez-González P, et al. Hexavalent chromium quantification by isotope dilution mass spectrometry in potentially contaminated soils from South Italy[J]. Chemosphere, 2019, 233: 92−100. doi: 10.1016/j.chemosphere.2019.05.212
[21] Zhong W, Bai W, Li G. Reduction of hexavalent chromium from soil of the relocated factory area with rice straw hydrothermal carbon modified by nano zero-valent iron (nZVI)[J]. International Journal of Environmental Research and Public Health, 2023, 20(4): 3089. doi: 10.3390/ijerph20043089
[22] Liu Y, Li Y, Hu Y C, et al. Adsorption characteristics and transport behavior of Cr(Ⅵ) in shallow aquifers surrounding a chromium ore processing residue (copr) dumpsite[J]. Journal of Chemistry, 2019, 2019: 4932837. doi: 10.1155/2019/4932837
[23] Zhang K, Yang J, Wang Y, et al. All-region human health risk assessment of Cr(Ⅵ) in a coal chemical plant based on Kriging[J]. Polish Journal of Environmental Studies, 2020, 29(1): 429−439. doi: 10.15244/pjoes/99226
[24] Zhang K, Qiang C D, Liu J. Spatial distribution characteristics of heavy metals in the soil of coal chemical industrial areas[J]. Journal of Soils and Sediments, 2018, 18(5): 2044−2052. doi: 10.1007/s11368-018-1972-9
[25] Li Y, Pan S, Wang L, et al. Soil chromium accumulation in industrial regions across China: Pollution and health risk assessment, spatial pattern, and temporal trend (2002—2021)[J]. Toxics, 2023, 11(4): 363. doi: 10.3390/toxics11040363
[26] Xiang J, Xu P, Chen W, et al. Pollution characteristics and health risk assessment of heavy metals in agricultural soils over the past five years in Zhejiang, Southeast China[J]. International Journal of Environmental Research and Public Health, 2022, 19(22): 14642. doi: 10.3390/ijerph192214642
[27] Wu D, Liu H, Wu J, et al. Bi-directional pollution characteristics and ecological health risk assessment of heavy metals in soil and crops in Wanjiang Economic Zone, Anhui Province, China[J]. International Journal of Environmental Research and Public Health, 2022, 19(15): 9669. doi: 10.3390/ijerph19159669
[28] Wu Z, Zhang D, Xia T, et al. Characteristics, sources and risk assessments of heavy metal pollution in soils of typical chlor-alkali residue storage sites in Northeastern China[J]. PLOS One, 2022, 17(9): e0273434. doi: 10.1371/journal.pone.0273434
[29] Li X, Zhang J, Ma J, et al. Status of chromium accumulation in agricultural soils across China (1989—2016)[J]. Chemosphere, 2020, 256: 127036. doi: 10.1016/j.chemosphere.2020.127036
[30] Kanagaraj G, Elango L. Chromium and fluoride contamination in groundwater around leather tanning industries in Southern India: Implications from stable isotopic ratio δ53Cr/δ52Cr, geochemical and geostatistical modelling[J]. Chemosphere, 2019, 220: 943−953. doi: 10.1016/j.chemosphere.2018.12.105
[31] Chrysochoou M, Theologou E, Bompoti N, et al. Occurrence, origin and transformation processes of geogenic chromium in soils and sediments[J]. Current Pollution Reports, 2016, 2(4): 224−235. doi: 10.1007/s40726-016-0044-2
[32] Kierczak J, Pietranik A, Pedziwiatr A. Ultramafic geoecosystems as a natural source of Ni, Cr, and Co to the environment: A review[J]. Science of the Total Environment, 2021, 755: 142620. doi: 10.1016/j.scitotenv.2020.142620
[33] Briffa J, Sinagra E, Blundell R. Heavy metal pollution in the environment and their toxicological effects on humans[J]. Heliyon, 2020, 6(9): e04691. doi: 10.1016/j.heliyon.2020.e04691
[34] Coetzee J J, Bansal N, Chirwa E M N. Chromium in environment, its toxic effect from chromite-mining and ferrochrome industries, and its possible bioremediation[J]. Exposure and Health, 2020, 12(1): 51−62. doi: 10.1007/s12403-018-0284-z
[35] Pushkar B, Sevak P, Parab S, et al. Chromium pollution and its bioremediation mechanisms in bacteria: A review[J]. Journal of Environmental Management, 2021, 287: 112279. doi: 10.1016/j.jenvman.2021.112279
[36] 贾琼琳, 韩俊艳, 何丹. 土壤中重金属铬污染及其治理方法的研究进展[C]//中国环境科学学会2021年科学技术年会——环境工程技术创新与应用分会场. 北京: 中国环境科学学会, 2021: 354−357, 380. Jia Q L, Han J Y, He D. Research progress of heavy metal chromium pollution in soil and its control methods[C]//China Environmental Science Society 2021 Science and Technology Annual Conference—Environmental Engineering Technology Innovation and Application Sub-forum. Beijing: Chinese Society for Environmental Sciences, 2021: 354−357, 380.
[37] Gupta D K, Chatterjee S, Datta S, et al. Role of phosphate fertilizers in heavy metal uptake and detoxification of toxic metals[J]. Chemosphere, 2014, 108: 134−144. doi: 10.1016/j.chemosphere.2014.01.030
[38] 耿源濛, 张传兵, 张勇, 等. 我国城市污泥中重金属的赋存形态与生态风险评价[J]. 环境科学, 2021, 42(10): 4834−4843. doi: 10.13227/j.hjkx.202101145 Geng Y M, Zhang C B, Zhang Y, et al. Speciation and ecological risk assessment of heavy metal(loid)s in the municipal sewage sludge of China[J]. Environmental Science, 2021, 42(10): 4834−4843. doi: 10.13227/j.hjkx.202101145
[39] 白宇明, 李永利, 周文辉, 等. 典型工业城市土壤重金属元素形态特征及生态风险评估[J]. 岩矿测试, 2022, 41(4): 632−641. doi: 10.15898/j.cnki.11-2131/td.202109030113 Bai Y M, Li Y L, Zhou W H, et al. Speciation characteristics and ecological risk assessment of heavy metal elements in soils of typical industrial city[J]. Rock and Mineral Analysis, 2022, 41(4): 632−641. doi: 10.15898/j.cnki.11-2131/td.202109030113
[40] Ali W, Mao K, Zhang H, et al. Comprehensive review of the basic chemical behaviours, sources, processes, and endpoints of trace element contamination in paddy soil-rice systems in rice-growing countries[J]. Journal of Hazardous Materials, 2020, 397: 122720. doi: 10.1016/j.jhazmat.2020.122720
[41] Bai J, Xun P, Morris S, et al. Chromium exposure and incidence of metabolic syndrome among American young adults over a 23-year follow-up: The CARDIA trace element study[J]. Scientific Reports, 2015, 5: 15606. doi: 10.1038/srep15606
[42] Sharma P, Singh S P, Parakh S K, et al. Health hazards of hexavalent chromium (Cr(Ⅵ)) and its microbial reduction[J]. Bioengineered, 2022, 13(3): 4923−4938. doi: 10.1080/21655979.2022.2037273
[43] Ulhassan Z, Gill R A, Huang H, et al. Selenium mitigates the chromium toxicityin Brassicca napus L. by ameliorating nutrients uptake, amino acids metabolism and antioxidant defense system[J]. Plant Physiology and Biochemistry, 2019, 145: 142−152. doi: 10.1016/j.plaphy.2019.10.035
[44] Kundu D, Dey S, Raychaudhuri S S. Chromium(Ⅵ) induced stress response in the plant Plantago ovata Forsk in vitro[J]. Genes and Environment, 2018, 40: 21. doi: 10.1186/s41021-018-0109-0
[45] Aziz S, Altaf J, Khalil A, et al. Human cancer risk due to chromium and its bioaccumulation in physids in Central Punjab, Pakistan[J]. Environmental Science and Pollution Research, 2023, 30(29): 74223−74235. doi: 10.1007/s11356-023-27664-0
[46] Banu S K, Stanley J A, Taylor R J, et al. Sexually dimorphic impact of chromium accumulation on human placental oxidative stress and apoptosis[J]. Toxicological Sciences, 2018, 161(2): 375−387. doi: 10.1093/toxsci/kfx224
[47] Guo S, Xiao C, Zhou N, et al. Speciation, toxicity, microbial remediation and phytoremediation of soil chromium contamination[J]. Environmental Chemistry Letters, 2020, 19(2): 1413−1431. doi: 10.1007/s10311-020-01114-6
[48] Ertani A, Mietto A, Borin M, et al. Chromium in agricultural soils and crops: A review[J]. Water Air and Soil Pollution, 2017, 228(5): 190. doi: 10.1007/s11270-017-3356-y
[49] Wani K I, Naeem M, Aftab T. Chromium in plant-soil nexus: Speciation, uptake, transport and sustainable remediation techniques[J]. Environmental Pollution, 2022, 315: 120350. doi: 10.1016/j.envpol.2022.120350
[50] Xiao L, Guan D, Chen Y, et al. Distribution and availability of heavy metals in soils near electroplating factories[J]. Environmental Science and Pollution Research, 2019, 26(22): 22596−22610. doi: 10.1007/s11356-019-04706-0
[51] Xiao W, Ye X, Yang X, et al. Effects of alternating wetting and drying versus continuous flooding on chromium fate in paddy soils[J]. Ecotoxicology and Environmental Safety, 2015, 113: 439−445. doi: 10.1016/j.ecoenv.2014.12.030
[52] Shahid M, Shamshad S, Rafiq M, et al. Chromium speciation, bioavailability, uptake, toxicity and detoxification in soil-plant system: A review[J]. Chemosphere, 2017, 178: 513−533. doi: 10.1016/j.chemosphere.2017.03.074
[53] Liang J, Huang X, Yan J, et al. A review of the formation of Cr(Ⅵ) via Cr(Ⅲ) oxidation in soils and groundwater[J]. Science of the Total Environment, 2021, 774: 145762. doi: 10.1016/j.scitotenv.2021.145762
[54] Li B, Yang J X, Sun W T, et al. Carbonization of plant residues decreased their capability of reducing hexavalent chromium in soils[J]. Water Air and Soil Pollution, 2019, 230(12): 300. doi: 10.1007/s11270-019-4353-0
[55] Zhang Z, Ren J, Liang J, et al. New insight into the natural detoxification of Cr(Ⅵ) in Fe-rich surface soil: Crucial role of photogenerated silicate-bound Fe(Ⅱ)[J]. Environmental Science & Technology, 2023, 57(50): 21370−21381. doi: 10.1021/acs.est.3c05767
[56] Hao Y, Ma H, Wang Q, et al. Complexation behaviour and removal of organic-Cr(Ⅲ) complexes from the environment: A review[J]. Ecotoxicology and Environmental Safety, 2022, 240: 113676. doi: 10.1016/j.ecoenv.2022.113676
[57] Bokare A D, Choi W. Advanced oxidation process based on the Cr(Ⅲ)/Cr(Ⅵ) redox cycle[J]. Environmental Science & Technology, 2011, 45(21): 9332−9338. doi: 10.1021/es2021704
[58] Jiang B, Gong Y, Gao J, et al. The reduction of Cr(Ⅵ) to Cr(Ⅲ) mediated by environmentally relevant carboxylic acids: State-of-the-art and perspectives[J]. Journal of Hazardous Materials, 2019, 365: 205−226. doi: 10.1016/j.jhazmat.2018.10.070
[59] Zheng C, Yang Z, Si M, et al. Application of biochars in the remediation of chromium contamination: Fabrication, mechanisms, and interfering species[J]. Journal of Hazardous Materials, 2021, 407: 124376. doi: 10.1016/j.jhazmat.2020.124376
[60] Shi Y, Shan R, Lu L, et al. High-efficiency removal of Cr(Ⅵ) by modified biochar derived from glue residue[J]. Journal of Cleaner Production, 2020, 254: 119935. doi: 10.1016/j.jclepro.2019.119935
[61] Li H, Wang J, Zhao B, et al. The role of major functional groups: Multi-evidence from the binding experiments of heavy metals on natural fulvic acids extracted from lake sediments[J]. Ecotoxicology and Environmental Safety, 2018, 162: 514−520. doi: 10.1016/j.ecoenv.2018.07.038
[62] Xu J, Dai Y, Shi Y, et al. Mechanism of Cr(Ⅵ) reduction by humin: Role of environmentally persistent free radicals and reactive oxygen species[J]. Science of the Total Environment, 2020, 725: 138413. doi: 10.1016/j.scitotenv.2020.138413
[63] Zhang J, Yin H, Wang H, et al. Reduction mechanism of hexavalent chromium by functional groups of undissolved humic acid and humin fractions of typical black soil from Northeast China[J]. Environmental Science and Pollution Research, 2018, 25(17): 16913−16921. doi: 10.1007/s11356-018-1878-5
[64] Xu Z, Xu X, Zhang Y, et al. Pyrolysis-temperature depended electron donating and mediating mechanisms of biochar for Cr(Ⅵ) reduction[J]. Journal of Hazardous Materials, 2020, 388: 121794. doi: 10.1016/j.jhazmat.2019.121794
[65] Wang X, Xu J, Liu J, et al. Mechanism of Cr(Ⅵ) removal by magnetic greigite/biochar composites[J]. Science of the Total Environment, 2020, 700: 134414. doi: 10.1016/j.scitotenv.2019.134414
[66] Odinga E S, Waigi M G, Gudda F O, et al. Occurrence, formation, environmental fate and risks of environmentally persistent free radicals in biochars[J]. Environment International, 2020, 134: 105172. doi: 10.1016/j.envint.2019.105172
[67] Fan Z, Zhang Q, Gao B, et al. Removal of hexavalent chromium by biochar supported nZVI composite: Batch and fixed-bed column evaluations, mechanisms, and secondary contamination prevention[J]. Chemosphere, 2019, 217: 85−94. doi: 10.1016/j.chemosphere.2018.11.009
[68] 陈壮, 梁媛, 赵奔, 等. 改性生物炭对Cr(Ⅵ)的吸附特性研究[J]. 复旦学报(自然科学版), 2021, 60(6): 779−788. doi: 10.15943/j.cnki.fdxb-jns.2021.06.007 Chen Z, Liang Y, Zhao B, et al. Adsorption characteristics and mechanism of modified biochar to Cr(Ⅵ)[J]. Journal of Fudan University (Natural Science), 2021, 60(6): 779−788. doi: 10.15943/j.cnki.fdxb-jns.2021.06.007
[69] Li K, Huang Z, Zhu S, et al. Removal of Cr(Ⅵ) from water by a biochar-coupled g-C3N4 nanosheets composite and performance of a recycled photocatalyst in single and combined pollution systems[J]. Applied Catalysis B-Environmental, 2019, 243: 386−396. doi: 10.1016/j.apcatb.2018.10.052
[70] Peng X X, Gai S, Cheng K, et al. Roles of humic substances redox activity on environmental remediation[J]. Journal of Hazardous Materials, 2022, 435: 129070. doi: 10.1016/j.jhazmat.2022.129070
[71] Zhu S, Huang X, Yang X, et al. Enhanced transformation of Cr(Ⅵ) by heterocyclic-N within nitrogen-doped biochar: Impact of surface modulatory persistent free radicals (PFRs)[J]. Environmental Science & Technology, 2020, 54(13): 8123−8132. doi: 10.1021/acs.est.0c02713
[72] Fang G, Liu C, Wang Y, et al. Photogeneration of reactive oxygen species from biochar suspension for diethyl phthalate degradation[J]. Applied Catalysis B-Environmental, 2017, 214: 34−45. doi: 10.1016/j.apcatb.2017.05.036
[73] Yu Y, An Q, Jin L, et al. Unraveling sorption of Cr(Ⅵ) from aqueous solution by FeCl3 and ZnCl2-modified corn stalks biochar: Implicit mechanism and application[J]. Bioresource Technology, 2020, 297: 122466. doi: 10.1016/j.biortech.2019.122466
[74] Geng A, Xu L, Gan L, et al. Using wood flour waste to produce biochar as the support to enhance the visible-light photocatalytic performance of BiOBr for organic and inorganic contaminants removal[J]. Chemosphere, 2020, 250: 126291. doi: 10.1016/j.chemosphere.2020.126291
[75] Wang T, Liu S, Mao W, et al. Novel Bi2WO6 loaded N-biochar composites with enhanced photocatalytic degradation of rhodamine B and Cr(Ⅵ)[J]. Journal of Hazardous Materials, 2020, 389: 121827. doi: 10.1016/j.jhazmat.2019.121827
[76] Alsaiari M. Biomass-derived active carbon (AC) modified TiO2 photocatalyst for efficient photocatalytic reduction of chromium(Ⅵ) under visible light[J]. Arabian Journal of Chemistry, 2021, 14(8): 103258. doi: 10.1016/j.arabjc.2021.103258
[77] Jalili B, Sadegh-Zadeh F, Jabari-Giashi M, et al. Lead bioimmobilization in contaminated mine soil by Aspergillus niger SANRU[J]. Journal of Hazardous Materials, 2020, 393: 122375. doi: 10.1016/j.jhazmat.2020.122375
[78] Hussain S, Maqbool Z, Shahid M, et al. Simultaneous removal of reactive dyes and hexavalent chromium by a metal tolerant pseudomonas sp. Ws-d/183 harboring plant growth promoting traits[J]. International Journal of Agriculture and Biology, 2020, 23(2): 241−252. doi: 10.17957/IJAB/15.1282
[79] Tariq M, Waseem M, Rasool M H, et al. Isolation and molecular characterization of the indigenous Staphylococcus aureus strain K1 with the ability to reduce hexavalent chromium for its application in bioremediation of metal-contaminated sites[J]. Peerj, 2019, 7: e7726. doi: 10.7717/peerj.7726
[80] Pattnaik S, Dash D, Mohapatra S, et al. Improvement of rice plant productivity by native Cr(VI) reducing and plant growth promoting soil bacteria Enterobacter cloacae[J]. Chemosphere, 2020, 240: 124895. doi: 10.1016/j.chemosphere.2019.124895
[81] Sha C Y, Wu J, Wu J Q, et al. Effects of different fertilizers on soil microbial diversity during long-term fertilization of a corn field in Shanghai, China[J]. Diversity-Basel, 2023, 15(1): 78. doi: 10.3390/d15010078
[82] Jin Q, Zhang Y, Wang Q, et al. Effects of potassium fulvic acid and potassium humate on microbial biodiversity in bulk soil and rhizosphere soil of Panax ginseng[J]. Microbiological Research, 2022, 254: 126914. doi: 10.1016/j.micres.2021.126914
[83] Tang X, Huang Y, Li Y, et al. Study on detoxification and removal mechanisms of hexavalent chromium by microorganisms[J]. Ecotoxicology and Environmental Safety, 2021, 208: 111699. doi: 10.1016/j.ecoenv.2020.111699
[84] Gu B H, Chen J. Enhanced microbial reduction of Cr(Ⅵ) and U(Ⅵ) by different natural organic matter fractions[J]. Geochimica et Cosmochimica Acta, 2003, 67(19): 3575−3582. doi: 10.1016/S0016-7037(3)00162-5
[85] Chen Y, Wu H, Sun P, et al. Remediation of chromium-contaminated soil based on bacillus cereus WHX-1 immobilized on biochar: Cr(Ⅵ) transformation and functional microbial enrichment[J]. Frontiers in Microbiology, 2021, 12: 641913. doi: 10.3389/fmicb.2021.641913
[86] Huang X N, Min D, Liu D F, et al. Formation mechanism of organo-chromium(Ⅲ) complexes from bioreduction of chromium(Ⅵ) by Aeromonas hydrophila[J]. Environment International, 2019, 129: 86−94. doi: 10.1016/j.envint.2019.05.016
[87] Tan H, Wang C, Zeng G, et al. Bioreduction and biosorption of Cr(Ⅵ) by a novel Bacillus sp. CRB-B1 strain[J]. Journal of Hazardous Materials, 2020, 386: 121628. doi: 10.1016/j.jhazmat.2019.121628
[88] Zhuang L, Li Q, Chen J, et al. Carbothermal preparation of porous carbon-encapsulated iron composite for the removal of trace hexavalent chromium[J]. Chemical Engineering Journal, 2014, 253: 24−33. doi: 10.1016/j.cej.2014.05.038
[89] Shaheen S M, Niazi N K, Hassan N E E, et al. Wood-based biochar for the removal of potentially toxic elements in water and wastewater: A critical review[J]. International Materials Reviews, 2019, 64(4): 216−247. doi: 10.1080/09506608.2018.1473096
[90] Liu W, Jin L, Xu J, et al. Insight into pH dependent Cr(Ⅵ) removal with magnetic Fe3S4[J]. Chemical Engineering Journal, 2019, 359: 564−571. doi: 10.1016/j.cej.2018.11.192
[91] Lee S, Roh Y, Koh D C. Oxidation and reduction of redox-sensitive elements in the presence of humic substances in subsurface environments: A review[J]. Chemosphere, 2019, 220: 86−97. doi: 10.1016/j.chemosphere.2018.11.143
[92] Zhu S, Huang X, Wang D, et al. Enhanced hexavalent chromium removal performance and stabilization by magnetic iron nanoparticles assisted biochar in aqueous solution: Mechanisms and application potential[J]. Chemosphere, 2018, 207: 50−59. doi: 10.1016/j.chemosphere.2018.05.046
[93] Gustafsson J P, Persson I, Oromieh A G, et al. Chromium(Ⅲ) complexation to natural organic matter: Mechanisms and modeling[J]. Environmental Science & Technology, 2014, 48(3): 1753−1761. doi: 10.1021/es404557e
[94] 刘爱科, 顾梦琪, 魏书斋, 等. 蒽醌-2,6-二磺酸(AQDS)强化厌氧降解直接蓝15[J]. 净水技术, 2019, 38(2): 63−68. doi: 10.15890/j.cnki.jsjs.2019.02.011 Liu A K, Gu M Q, Wei S Z, et al. Enhanced anaerobic degradation of direct blue 15 by anthraquinone-2,6-disulfonate (AQDS)[J]. Water Purification Technology, 2019, 38(2): 63−68. doi: 10.15890/j.cnki.jsjs.2019.02.011
[95] Tomaszewski E J, Ginder-Vogel M. Decreased electron transfer between Cr(Ⅵ) and AH2DS in the presence of goethite[J]. Journal of Environmental Quality, 2018, 47(1): 139−146. doi: 10.2134/jeq2017.08.0316
[96] Langer M, Jamal M U, Conklin A, et al. Chromium removal in the presence of NOM during Fe(Ⅱ) reductive precipitation for drinking water treatment[J]. Water, 2022, 14(18): 2903. doi: 10.3390/w14182903
[97] Wittbrodt P R, Palmer C D. Effect of temperature, ionic strength, background electrolytes, and Fe(Ⅲ) on the reduction of hexavalent chromium by soil humic substances[J]. Environmental Science & Technology, 1996, 30(8): 2470−2477. doi: 10.1021/es950731c
[98] Song C X, Sun S Q, Wang J T, et al. Applying fulvic acid for sediment metals remediation: Mechanism, factors, and prospect[J]. Frontiers in Microbiology, 2023, 13: 1084097. doi: 10.3389/fmicb.2022.1084097
[99] Bao Z J, Feng H Y, Tu W Y, et al. Method and mechanism of chromium removal from soil: A systematic review[J]. Environmental Science and Pollution Research, 2022, 29(24): 35501−35517. doi: 10.1007/s11356-022-19452-z
[100] Zulfiqar U, Haider F U, Ahmad M, et al. Chromium toxicity, speciation, and remediation strategies in soil-plant interface: A critical review[J]. Frontiers in Plant Science, 2023, 13: 1081624. doi: 10.3389/fpls.2022.1081624
[101] 张兆鑫, 曹宁宁, 李林记, 等. 原位吸附技术修复六价铬污染土壤[J]. 岩矿测试, 2024, 43(2): 302−314. doi: 10.15898/j.ykcs.202307090090 Zhang Z X, Cao N N, Li L J, et al. In situ adsorption technology for remediation of Cr(Ⅵ) contaminated soil[J]. Rock and Mineral Analysis, 2024, 43(2): 302−314. doi: 10.15898/j.ykcs.202307090090
[102] 杨梦楠, 孙晗, 曹海龙, 等. 生物炭-壳聚糖磁性复合吸附剂的制备及去除地下水中铅和铜[J]. 岩矿测试, 2023, 42(3): 563−575. doi: 10.15898/j.ykcs.202208230155 Yang M N, Sun H, Cao H L, et al. Preparation and application of biochar-chitosan magnetic composite adsorbent for removal of lead and copper from groundwater[J]. Rock and Mineral Analysis, 2023, 42(3): 563−575. doi: 10.15898/j.ykcs.202208230155
[103] Peng H, Gao P, Chu G, et al. Enhanced adsorption of Cu(Ⅱ) and Cd(Ⅱ) by phosphoric acid-modified biochars[J]. Environmental Pollution, 2017, 229: 846−853. doi: 10.1016/j.envpol.2017.07.004
[104] Mandal S, Sarkar B, Bolan N, et al. Enhancement of chromate reduction in soils by surface modified biochar[J]. Journal of Environmental Management, 2017, 186: 277−284. doi: 10.1016/j.jenvman.2016.05.034
[105] Murad H A, Ahmad M, Bundschuh J, et al. A remediation approach to chromium-contaminated water and soil using engineered biochar derived from peanut shell[J]. Environmental Research, 2022, 204: 112125. doi: 10.1016/j.envres.2021.112125
[106] Aparicio J D, Lacalle R G, Artetxe U, et al. Successful remediation of soils with mixed contamination of chromium and lindane: Integration of biological and physico-chemical strategies[J]. Environmental Research, 2021, 194: 110666. doi: 10.1016/j.envres.2020.110666
[107] Su H, Fang Z, Tsang P E, et al. Remediation of hexavalent chromium contaminated soil by biochar-supported zero-valent iron nanoparticles[J]. Journal of Hazardous Materials, 2016, 318: 533−540. doi: 10.1016/j.jhazmat.2016.07.039
[108] Ahmed T, Noman M, Ijaz M, et al. Current trends and future prospective in nanoremediation of heavy metals contaminated soils: A way forward towards sustainable agriculture[J]. Ecotoxicology and Environmental Safety, 2021, 227: 112888. doi: 10.1016/j.ecoenv.2021.112888
[109] Mondal P, Anweshan A, Purkait M K. Green synthesis and environmental application of iron-based nanomaterials and nanocomposite: A review[J]. Chemosphere, 2020, 259: 127509. doi: 10.1016/j.chemosphere.2020.127509
[110] Wei Y Z, Chu R, Zhang Q H, et al. Nano zero-valent iron loaded corn-straw biochar for efficient removal of hexavalent chromium: Remediation performance and interfacial chemical behaviour[J]. RSC Advances, 2022, 12(41): 26953−26965. doi: 10.1039/d2ra04650d
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