淹水条件下外源含硫有机物对稻田土壤铜形态转化的影响

含硫有机化合物是水稻典型根系分泌物之一,土壤重金属具有优先与含硫有机官能团结合的趋势,研究含硫有机化合物对重金属铜的形态转化及生物有效性的影响可深入了解土壤铜的生物地球化学循环过程。通过室内淹水模拟实验,研究两种典型含硫有机化合物(半胱氨酸和甲硫氨酸)对铜形态转化的影响及其作用机制,以不添加任何含硫有机物的土壤作为对照,设置半胱氨酸(50、100 mg?kg~(-1))、甲硫氨酸(50、100 mg?kg~(-1))4个处理,保持5 cm左右的淹水层28 d,分别在淹水7、14、21、28d采集土壤样品,分析土壤理化性质及土壤中铜的化学形态。结果表明:随着淹水时间的延长,土壤pH先降低后升高,但含硫有机物的施加对pH影响不显著。淹水21 d后,施加含硫有机物提高了土壤CaCl_2提取态铜含量,而降低DTPA提取态铜含量,然而,淹水28 d后,DTPA提取态铜含量升高。同步辐射X射线近边吸收谱学(XANES)表明,淹水21d后,土壤铜的主要化学形态由缬氨酸铜、针铁矿铜及硫化亚铜组成,半胱氨酸和甲硫氨酸处理组中土壤缬氨酸铜类化合物占比分别增大15.9%和8.5%,与此同时针铁矿结合态铜占比分别降低19.3%和11.4%,且铜主要与缬氨酸的-NH_2结合。     

蚯蚓在植物修复铜、镉污染土壤中的作用

以红壤和高砂土为供试土壤,分别加入3个浓度的重金属铜离子Cu2 (100,200,400 mg kg-1)或镉离子Cd2 (5,10,20 mg kg-1),每钵接种6条蚯蚓(Pheretimasp.),种植黑麦草(Lolium multiflorum),以不加蚯蚓为对照(CK),研究蚯蚓活动对Cu、Cd污染土壤中黑麦草生长及铜、镉生物有效性的影响.结果表明,添加蚯蚓显著提高了Cu2 、Cd2 污染的高砂土中黑麦草地上部分的生物量,增幅为33%~96%;仅增加了Cu2 污染浓度低于200 mg kg-1的红壤中黑麦草地上部分的生物量;添加蚯蚓显著增加了两种土壤中速效N的含量,促进了黑麦草地上部分对N的吸收,对速效P、K的含量以及黑麦草中P、K含量无显著影响;添加蚯蚓显著提高了红壤中铜(Cu)、镉(Cd)DTPA提取态的含量,对高砂土中DTPA提取态Cu、Cd的含量无显著影响;增加了高砂土中和添加Cu污染浓度低于200 mg kg-1的红壤中黑麦草地上部分吸收Cu的总量,而对黑麦草吸收Cd的量无显著影响.加入蚯蚓可以不同程度地改善植物修复技术应用中受制的两个主要因素.表4参30     

土壤中不同老化时间的DDT对小麦根系的生物有效性

研究了水、正己烷、正己烷/丙酮ASE对土壤中不同老化时间的DDT的逐级提取量的差别及其与小麦根吸收的关系。结果表明,有机氯的水提量随老化时间增加而下降,正己烷提取量随老化时间增加而下降,正己烷/丙酮提取量随老化时间增加而上升。植物根吸收随老化时间增加而下降。根吸收与水提量没有确定关系,与正己烷提取量具正相关关系,与正己烷/丙酮提取量有负相关关系。正己烷提取量可被作为土壤有机氯DDT的有效态部分。     

不同施肥处理对水稻根表铁和砷形态的影响

采用XAFS研究盆栽试验砷污染土壤中添加不同肥料后,苗期水稻根表铁膜和砷的矿物学特征.Fe的K边EXAFS谱表明,铁膜主要由2-line水铁矿组成,还有少部分针铁矿和赤铁矿等晶体矿;As的EXAFS谱显示,除了KNO3和K2SO4处理外,其余处理的铁膜中砷以三价砷为主.KNO3处理显著减少了水稻根表铁膜的形成,而且抑制了水稻对砷的吸收.不同的肥料可以影响铁膜中砷的存在形态.     

蚯蚓对土壤中铜、镉形态及高丹草生物有效性的影响

以高沙土和黄泥土为供试土壤,采用塑料盆分装土样,分别加入3个浓度的Cu2 (100、200、300mg kg-1)或Cd2 (5、10、15mg kg-1)模拟土壤污染,待这些污染土壤平衡培养2mo后,设置接种蚯蚓(Pheretima guillemi Michaels-en)处理与不接种蚯蚓处理,并种植高丹草(Sorghum×Sudan,Sorghum bicolor×S.sudanense);采用Tessler连续提取法测定重金属各结合形态,研究蚯蚓活动对土壤中Cu、Cd的主要形态及高丹草有效性的影响,以揭示蚯蚓对铜、镉污染土壤的修复作用.结果表明,蚯蚓活动显著提高了高沙土中碳酸盐结合态铜(Carb-Cu)和铁锰氧化物结合态铜(OxMn-Cu)的含量;显著提高了Cd处理为10、15mg kg-1的高沙土中离子交换态镉(Exch-Cd)和碳酸盐结合态镉(Carb-Cd)的含量,显著提高了黄泥土离子交换态铜(Exch-Cu)和有机结合态铜(WBO-Cu)的含量;通过测定各处理高丹草Cu、Cd含量发现,接种蚯蚓后,高沙土各Cu处理的高丹草的Cu含量显著增加,高沙土5、10mg kg-1Cd处理的高丹草的Cd含量以及黄泥土各Cd处理的高丹草的Cd含量均显著增加.图3表3参32     

广西典型高砷背景地区石漠化土壤中砷形态及相关因子研究

广西的喀斯特地貌分布广泛,部分石漠化地区的土壤砷污染问题比较突出。为深入了解广西重金属高背景地区石漠化土壤中砷的变化特征及其影响因素,采集广西环江县地质背景相似的不同石漠化程度(无石漠化、轻度石漠化、中度石漠化、重度石漠化)的表层土样,分析土壤样品中砷含量及形态,并采用多元线性回归模型分析石漠化土壤中砷形态的主要影响因子。结果表明,随着石漠化程度的加剧,表层土壤中砷含量呈现出逐渐增加的趋势,但是在重度石漠化土壤中砷含量有所下降。石漠化土壤样品中砷含量较高的区域分布在轻度和中度石漠化的中坡和下坡。石漠化土壤中砷形态主要以残渣态为主,其次是可氧化态和可还原态,最低的是水溶态;砷的水溶态、可氧化态、可还原态在土壤中的含量随着石漠化程度的加剧呈现出逐渐减少的趋势。多元回归分析表明阳离子交换量是影响水溶态砷和可氧化态砷的主要因子,p H值是影响弱酸提取态砷和可还原态砷的主要因子,呈极显著正相关(P0.01),总砷含量与残渣态砷呈显著正相关(P0.05)。     

土壤-苦丁茶树系统中Cu的分布及迁移富集规律

采用火焰原子吸收光谱（FAAS）技术,测定出苦丁茶冬青（Ilex kudingcha C．J．Tseng）的根、茎、叶及其栖息土壤中Cu的含量,并对土壤．苦丁茶树系统中Cu的分布特征进行了研究,以探讨苦丁茶树对Cu的富集规律。结果表明：栖息土壤中Cu的含量不同时,苦丁茶树巾Cu的含量表现出吸收根〉嫩叶〉茎〉主根;茶树对Cu的吸收存在饱和特性,表现为随土壤Cu含量升高,茶树对Cu的富集系数和传输效率降低,使得根际土壤中Cu含量高于非根际土壤。同时对土壤剖面不同深度Cu含量研究表明：苦丁茶栖息土壤中Cu含量呈现出随土层深度增加而增加的垂直分布趋势。本研究旨在认清Cu迁移到苦丁茶树的内在规律,以利于进一步研究其迁移的调控,使苦丁茶产品中元素处在安全有效的利用范围内。     

山东省主要果园土壤中Cu、Zn的形态、含量及分布

对我国山东省主要果园土壤中的Cu、Zn元素的形态、含量及分布进行了研究。结果表明 :果园土壤中Cu、Zn元素的全量高于一般粮田土壤。在不同土壤类型中 ,形态分布各具特点 ,Cu元素在棕壤和褐土中的形态分布趋势一致 ,为矿物态 >有机态 >沉淀态 >交换态 ,在潮土和砂姜黑土中一致 ,为矿物态 >沉淀态 >有机态 >交换态 ;而Zn元素在这 4种土壤中的分布趋势相同 ,均为矿物态 >沉淀态 >有机态 >交换态。土壤中交换态的Cu、Zn含量随土壤pH值的增大而减小。Cu、Zn某些形态的含量与土壤中全量间有一定的相关性 ,其中沉淀态Cu与总Cu的关系较为紧密 ,2者呈极显著相关 ;矿物态Zn与总Zn也呈极显著相关。     

耕地土壤铜、镉、锌形态及生物有效性研究

土壤重金属总量常被用来评估土壤质量安全,但是大量事实说明单纯用土壤重金属总量并不能完全说明土壤重金属的生物有效性及其环境风险。相对于国内外常用的Tessier的五态方法,欧共体标准物质局提出的三步提取法(BCR法),中国地质调查局地质连续提取法的七态标准少见报道。本研究选取河南平原耕地样品,采用中国地质调查局地质连续提取法(DD2005-03)进行耕地中重金属元素(Cu、Cd、Zn)的形态分布,结果表明:Cu、Zn主要以残渣态存在,其残渣态分别占全量的55.80%和67.35%。Cd以离子交换态为主,占全量的27.30%。Cu、Cd、Zn各态含量占全量比例的顺序是,Cu:残渣态弱有机结合交换态铁锰氧化态碳酸盐结合态强有机结合态水溶态离子交换态。Cd:离子交换态弱有机结合交换态强有机结合态残渣态碳酸盐结合态铁锰氧化态水溶态。Zn:残渣态铁锰氧化态弱有机盐结合态离子交换态强有机结合态碳酸盐态水溶态。从生物可利用性系数k来看,Cd主要以活动性较大的状态存在,很容易被作物吸收。     

2种茶树对铜胁迫的响应及其组织铜化学形态变化的比较研究

为了分析不同茶树对Cu胁迫的生理响应及其组织中不同化学形态Cu的累积特性,本研究采用水培法,探讨铁观音、肉桂2种茶树在不同浓度Cu胁迫下,茶树根系活力、叶绿素含量、茶树组织Cu含量及不同化学形态Cu含量的变化,以期为重金属对茶树毒害机理和茶树对重金属的自我防御研究提供理论依据。结果表明,随着Cu胁迫浓度的增加,茶树根系活力及叶片叶绿素含量呈现下降趋势,而与对照相比,铁观音下降的幅度远高于肉桂。不同茶树品种在相同浓度Cu胁迫下,其根、茎、叶组织的Cu含量差异不显著,而不同组织中则表现为根叶茎。不同化学形态Cu含量分析结果表明,随着Cu胁迫浓度的升高,2种茶树根部可交换态Cu、碳酸盐结合态Cu、有机结合态Cu含量百分比呈现下降趋势,而铁锰氧化态Cu和残留态Cu呈现上升趋势;茎部可交换态Cu、有机结合态Cu含量百分比呈现下降趋势,碳酸盐结合态Cu、铁锰氧化态Cu和残留态Cu呈现上升趋势;叶部可交换态Cu、碳酸盐结合态Cu、有机结合态Cu含量、铁锰氧化态Cu含量的百分比均呈现上升趋势,而残留态Cu呈现下降趋势。进一步分析发现,Cu胁迫下,铁观音茶树根、叶部主要以采取提高有机结合态Cu的形式来降低Cu离子毒害,而肉桂则以提高铁锰氧化态Cu形式降低Cu离子毒害,叶部则以提高铁锰氧化态Cu和残留态Cu的形式降低Cu离子毒害。可见,不同的茶树在Cu胁迫下所表现解毒模式存在着一定的差异。     

Sequential extraction of copper from soils and relationships with copper in maize

We studied copper uptake by maize grown on soils that have been contaminated with CuSO₄. In soil the total copper level ranged from 24 to 135 mg kg^–1. The copper distribution in soil fractions was assessed by sequential extraction, showing that anthropogenic copper is mainly concentrated in oxides fractions. The copper concentration of maize at the maturity stage reached values from 36.3 to 65.9 mg kg^–1 compared to copper levels usually found in non-contaminated crops (5–30 mg kg^–1). Here we demonstrate that copper can be accumulated by maize and that copper concentration in maize can be predicted by equations including copper concentration of soil fractions.     

Large-scale green synthesis of Cu nanoparticles

This article reports a novel, eco-friendly herbal method to synthesize Cu nanoparticles in large scales. Cu nanoparticles are an alternative to Ag and Au nanoparticles and have potential applications in many industrial areas. Many synthetic routes have been documented for the preparation of copper nanoparticles, but very few routes are eco-friendly and large-scale. We report here the preparation of Cu nanoparticles from aqueous CuSO₄ using non-toxic and inexpensive materials like curd, milk, and herbal extracts such as tamarind and lemon juice as capping agents. X-ray diffraction and transmission electron microscopy show that produced particles are nanocrystalline copper 20–50 nm in size with a face-centered cubic structure. Fourier-transformed infrared spectroscopy evidences the role of organic acids in the capping process. The novelty of this work is the synthesis of Cu nanoparticles from CuSO₄ without electricity and using non-toxic, cheap capping agents.     

Modelling the concentrations of dissolved contaminants (Cd,Cu, Ni,Pb, Zn) in floodplain soils

Central European floodplain soils are often contaminated with potentially toxic metals. The prediction of their aqueous concentrations is a prerequisite for an assessment of environmental concerns. We tested the aqueous concentrations of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) derived from multi-surface adsorption modelling (on hydrous iron, aluminum and manganese oxides, clay and soil organic matter) against those analyzed in situ in the soil solution of four horizons of floodplain soils at the Elbe River, Germany. The input data for the reactive metals were derived from a seven-step sequential extraction scheme or from extraction with 0.43 M nitric acid (HNO₃) and evaluated in four modelling scenarios. In all scenarios, measured and modelled concentrations were positively related, except partially for Pb. Close reproduction of the measured data was obtained using measured data of accompanying cations and anions together with amounts of reactive metals from both the sequential extraction or from 0.43 M HNO₃ extraction, except for Cu, which was often strongly overestimated, and partially Cd. We recommend extraction with 0.43 M HNO₃ to quantify reactive metals in soil because the modelling results were metal-specific with better or equal results using the single extractant, the application of which is also less laborious. Approximations of ion concentrations and water contents yielded similar results. Modelled solid-phase speciation of metals varied with pH and differed from that from sequential extraction. Multi-surface modelling may be an effective tool to predict both aqueous concentrations and solid-phase speciation of metals in soil.     

Copper recovery from waste printed circuit boards concentrated metal scraps by electrolysis

Copper recovery is the core of waste printed circuit boards (WPCBs) treatment. In this study, we proposed a feasible and efficient way to recover copper from WPCBs concentrated metal scraps by direct electrolysis and factors that affect copper recovery rate and purity, mainly CuSO₄·5H₂O concentration, NaCl concentration, H₂SO₄ concentration and current density, were discussed in detail. The results indicated that copper recovery rate increased first with the increase of CuSO₄·5H₂O, NaCl, H₂SO₄ and current density and then decreased with further increasing these conditions. NaCl, H₂SO₄ and current density also showed a similar impact on copper purity, which also increased first and then decreased. Copper purity increased with the increase of CuSO₄·5H₂O. When the concentration of CuSO₄·5H₂O, NaCl and H₂SO₄ was respectively 90, 40 and 118 g/L and current density was 80 mA/cm², copper recovery rate and purity was up to 97.32% and 99.86%, respectively. Thus, electrolysis proposes a feasible and prospective approach for waste printed circuit boards recycle, even for e-waste, though more researches are needed for industrial application.

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Imprinted polymer particles for preconcentration of copper from water and biological samples

Imprinted polymer particles have been developed as a novel adsorbent for the adsorption of copper from aqueous solution. This method has received much attention in various fields because of their high selectivity for template molecules. In this work, separation of copper from water and biological samples by batch solid phase extraction based on molecular imprinting technique is presented. Copper-imprinted polymer was prepared by free radical solution polymerization in a glass tube containing CuSO₄, morin, 4-vinylpyridine as a functional monomer, ethyleneglycoldimethacrylate as a cross-linking monomer, 2,2′- azobisisobutyronitrile as an initiator. The polymer block obtained was ground and sieved, and the Cu-morin complex was removed from polymer particles. The synthesized polymer particles both prior to and after leaching have been characterized by IR and X-ray diffraction studies. The effect of different parameters, such as pH, adsorption and desorption time, type and least amount of the eluent for elution of the complex from polymer were evaluated. The limit of detection of the proposed method was 0.12 μg L⁻¹. The method was applied to the recovery and determination of copper in water and biological real samples.     

Copper sulphate use in South African traditional medicine

Copper (Cu) is an essential element to humans; however, exposure to elevated concentrations through occupational hazard and/or environmental means may be detrimental. This paper provides results of a cross-sectional study aimed to determine the prevalence of copper sulphate (CuSO₄) use in South African traditional medicine by traditional health practitioners (THPs) and details the use thereof. A total of 201 THPs were enrolled from two main municipal areas of KwaZulu-Natal (South Africa). Information on demographic characteristics of THPs, reasons for using or not using CuSO₄ as well as administration methods and age groups of recipients were collected. Of the 201 THPs interviewed, 145 (72 %) use CuSO₄ for healing purposes. The use of CuSO₄ was strongly associated with gender (p = 0.009) where the proportion of CuSO₄ users was higher for female than male THPs. CuSO₄ was reportedly administered to individuals of all ages, including infants and children. The main routes of administration were enema (n = 110; 76 %), oral (n = 40; 28 %) and use in bath (n = 40; 28 %). The reasons cited for use are diverse and included skin rashes (n = 43; 30 %), aches, pains and swelling (n = 38; 28 %) as well as sexually transmitted diseases (n = 28; 19 %). This study identified a high prevalence of THPs using CuSO₄ for healing purposes. These findings support the need to regulate South African traditional medicine to safeguard the user.     

A comparative study of three different methods for the sequential extraction of heavy metals in soil

Three different methods for the sequential extraction of heavy metals from soil (viz those of Tessier et al. (A. Tessier, P.G. Campbell and N. Bisson (1979). Anal. Chem., 51, 844.), Sposito et al. (G. Sposito, L.J. Lund and A.C. Chang (1989). Soil. Sci. Soc. Am. J., 46, 260.) and Mann and Ritchie (S.S. Mann and G.S.P. Ritchie (1993). Aust. J. Soil Res., 31, 255.)) were examined in terms of the distribution of Cu, Zn and Pb in the soil phases and the bioavailability of these elements in soil. To this end, several samples of soils polluted with metals from a copper mine were fractionated by using the three studied methods and analyzed by atomic absorption spectrometry. The results revealed differences in extraction efficiency among the methods due to the extractant used, or its concentration, and to the soil/solution ratio. The three methods were found to provide accurate heavy metal background contents. However, the method of Tessier et al. is to be preferred for quantifying increased levels of heavy metals on account of its high extraction power.     

Voltammetric analysis of metallothioneins and copper (II) in fish for water biomonitoring studies

An major research area in environmental chemistry is the development of methods for the analysis of biomarkers. Metallothioneins are used as biomarkers in studies of heavy metals exposure in water, because metallothioneins are synthesized and accumulated when organisms are exposed to toxic concentrations of pollutants. In this work, simple and sensitive voltammetric methods were developed for metallothionein and copper (II) determinations in fish liver Lepomis gibbosus. Both analytical methodologies were optimized and applied to samples extracted from individuals previously submitted to sub-lethal toxicological trials with copper sulphate (CuSO₄) and cadmium chloride (CdCl₂). The obtained results showed that both methods are very precise, sensitive, and involve simple sample preparation processes. Moreover, metallothioneins showed better correlation with the toxic exposure than Cu²⁺. To the best of our knowledge, this is the first time that hepatic metallothioneins and Cu²⁺ contents are voltammetrically determined in order to be compared in their function as heavy metal biological indicators.     

Acute toxicity of copper oxide nanoparticles to Daphnia magna under different test conditions

The acute toxicity of monodispersed 6 nm and <100 nm poly-dispersed copper oxide nanoparticles toward Daphnia magna was assessed using 48 h immobilization tests. CuSO₄ was used as a reference. Four different exposure conditions were tested, to study whether the toxicity of the nanoparticle suspensions changed in a way similar to what is known for dissolved Cu: first in ISO standard test conditions (pH 7.8), second with slight acidity (pH 6.5), third in the presence of citric acid, and fourth in the presence of humic acid. For all four exposure conditions, the toxicity of Cu employed in the three forms followed the same sequence, i.e., CuSO₄ > monodispersed 6 nm CuO ? poly-dispersed CuO. The toxicity of all Cu forms decreased from pH 6.5, ? pH 7.8, > pH 7.8 + citric acid, to ? pH 7.8 + humic acid. This pattern is in agreement with concentrations of Cu²⁺ calculated using the equilibrium model MINTEQ. These findings show that the acute toxicity of copper oxide nanoparticles is governed by test water composition and the chemical species Cu²⁺.     

Determination of types of interactions exhibited by binary mixtures of heavy metals tested against the hermit crab,Clibanarius africanus

Single and joint action toxicity of heavy metal compounds (ZnCO₃, CuSO₄ and CdSO₄) were carried out against the hermit crab, Clibanarius africanus in laboratory bioassays. On the basis of 96?h LC₅₀ values, CuSO₄ (96?h LC₅₀?=?0.03?mM) was found to be the most toxic followed by CdSO₄ and ZnCO₃ (96?h LC₅₀?=?0.24?mM) in decreasing order of toxicity. The evaluation of the metal compounds in mixtures of ZnCO₃–CuSO₄, ZnCO₃–CdSO₄ and CdSO₄–CuSO₄ in pre-defined molar ratios revealed that interactions between Zn–Cu and Zn–Cd test mixtures were in conformity with the models of antagonism (reduction in toxicity of constituent metals). The synergistic ratios (S.R.s) and relationship between observed/predicted 96?h LC₅₀ values (relative toxic unit, RTU) were consistently below 1, indicating antagonistic interactions. Analysis using isobolograms also indicated the interactions between the mixture components to be antagonistic. However, with regards to CdSO₄–CuSO₄ test mixtures, the interactions between these metals were mainly in conformity with the model of synergism. The S.R. and RTU values were largely above 1, indicating synergistic interactions. The importance of the joint action evaluations for the management and protection of aquatic ecosystems, particularly in the setting up of water quality criteria was discussed.