桂林典型岩溶区和非岩溶区土壤剖面钙镁形态迁移对比

文章以桂林典型岩溶区和非岩溶区土壤剖面为研究对象,采用改进的Tessier元素形态连续提取法,测定岩溶区和非岩溶区土壤钙（Ca）和镁（Mg）元素离子交换态（包括水溶态）、碳酸盐结合态、腐殖酸结合态、铁锰氧化物结合态、强有机质结合态（包括部分硫化物）和残渣态等形态,探讨岩溶区和非岩溶区土壤Ca、Mg形态在土壤剖面中的迁移变化特征。结果表明:（1）岩溶区石灰土剖面中,随剖面深度加深,pH值增大,而土壤有机质、全氮（N）、全磷（P）含量减少,Ca元素主要以交换态存在且在各土壤剖面中含量相近,Mg元素主要是以残渣态赋存在土壤剖面中,随着土壤剖面深度腐殖酸结合态百分比减少,存在累积现象;（2）在非岩溶地区酸性土壤中,土壤总钙较低。在土壤剖面0~60 cm以强有机结合态为主,深层剖面（大于60 cm）以残渣态为主;Mg元素有效态含量较低,非岩溶区土壤Mg元素以腐殖酸结合态和残渣态为主,与岩溶区土壤类似,非岩溶区Mg元素在土壤中也存在一定累积。      

农用地土壤中汞元素形态特征浅析

以第四纪沉积物厚覆盖区农用地表层土壤汞元素为研究对象,分析了汞的水溶态、离子交换态、碳酸盐态、铁锰氧化态、腐殖酸态、强有机结合态、残渣态等7种形态存在特征,研究表明残渣态的含量比例与全量呈正相关关系,其他6种类型形态含量比例则与全量呈负相关关系,农用地土壤中汞的增量主要为残渣态的汞.     

再生铅工业园周边土壤重金属分布特征及来源解析

通过对安徽再生铅工业园周边0～20 cm深度的表层土壤及0～300 cm深度的剖面土壤中重金属含量、分布特征、赋存形态的研究及来源解析,发现土壤中Cd、Hg、As、Pb、Cr、Cu、Ni及Zn含量平均值分别为300.4 ng/g、39.45 ng/g、12.22 mg/kg、42.5 mg/kg、75.4 mg/kg、28.5 mg/kg、33.5 mg/kg、74.1 mg/kg,富集元素主要有Cd、Pb及Hg,其中土壤Cd、Pb富集明显受工业活动影响,Hg富集与工业活动无关。土壤Cd明显富集面积为21 km~2,影响深度为65 cm。土壤Pb明显富集面积为12 km~2,影响深度为20 cm。土壤Hg普遍为中度富集,富集深度为0～65 cm。土壤中Cd以碳酸盐结合态为主,其次为铁锰氧化物结合态,Pb以残渣态、铁锰氧化物结合态为主。Cd的碳酸盐结合态和铁锰氧化物结合态、Pb的残渣态和铁锰氧化物结合态均与其全量呈显著正相关。研究区土壤环境质量较好,仅有9.5%样点Cd含量与5.4%样点Pb含量超过了《GB 15618—2018土壤环境质量农用地土壤污染风险管控标准(试行)》规定的污染风险筛选值。     

广州市黄埔港区土壤中汞的形态分析及分布特征

采用化学浸提技术对广州市黄埔港区土壤中的汞进行形态分析,通过实验确定了可交换态汞(包括水溶性汞)、盐酸溶汞、元素汞、腐殖酸结合态汞、有机质结合态汞、硫化汞、残渣态汞的浸提条件,探讨了各种形态汞在表层及总量在垂直方向上的分布特征。分析结果表明,广州市黄埔港区土壤中汞以比较稳定的形态存在,活动态约占6%。总汞含量随深度增加而降低,总汞在垂直方向中的含量差异在一定程度上反映出汞受人为污染的影响情况。     

茶园土壤不同形态镍的含量及其影响因素

通过自然茶园土壤采样和室内实验分析,探讨浙江、江苏和安徽13个茶园土壤镍的污染状况、形态分布规律以及不同形态镍的含量与土壤镍总量和土壤理化性质的关系。结果表明：部分茶园土壤受到不同程度的镍污染;茶园土壤镍的形态分布有一定差异,按镍的含量多少排序,一般为残渣态＞交换态＞铁锰氧化物结合态＞有机结合态＞碳酸盐结合态;除了交换态以外的所有其他形态的镍含量均随土壤镍含量的增加而显著增加;碳酸盐结合态、铁锰氧化物结合态和残渣态镍含量随土壤pH的升高呈显著增加趋势,而交换态镍则呈减少趋势,但不显著;随土壤有机质含量的增加,铁锰氧化物结合态镍显著减少,而其他形态增加或减少的趋势均不显著;碳酸盐结合态、有机结合态和残渣态的镍含量均随阳离子交换量的增加显著增加;随粘粒含量的增加所有形态中的镍呈增加趋势,但除了残渣态外增加趋势均不显著。     

富硒土壤镉的赋存状态

采用7步提取法对某地富硒土壤样品进行镉的形态分析,发现镉质量分数较高,镉平均为0.374 mg/kg,最高为0.943 mg/kg。各形态含量差异较大,基本是残渣态离子交换态铁锰氧化物结合态腐殖酸结合态强有机结合态碳酸盐态水溶态,在7种形态中以残渣态、离子交换态、铁锰氧化物结合态3种形态占主导。     

北京城区土壤中Hg、Pb、Cd、Cu及Zn化学形态及环境效应

为弄清北京城区土壤中Hg、Pb、Cd、Cu及Zn五种重金属元素的化学形态分布特征,系统采集了126件城区表层土壤样品,采用连续提取法对重金属元素各化学形态含量进行了测定。结果表明:土壤中土壤中Hg、Pb、Cd、Cu、Zn含量差异显著。Hg元素以残渣态和强有机结合态为主,Cd元素离子交换态、碳酸盐结合态、残渣态、铁锰氧化物结合态含量较高,Pb、Cu、Zn元素以残渣态、铁锰氧化物结合态为主。Hg元素的有效态含量最低(不足1%),现情况下不会对环境造成污染;Cd元素的有效态含量最高(40%),生物有效性和潜在生态危害性较大,运用植物修复技术对其治理为经济有效的方法;Pb、Cu、Zn有效态含量较低(约10%),生物有效性和潜在生态危害性均有限。各元素形态与全量之间相关程度虽有差别,但基本呈正相关关系。     

苏州河沉积物中Zn、Cu 、Hg的形态分布研究及沉积特点初探

本文以上海市苏州河沉积物为研究对象,采用Tessier形态分析法研究了沉积物中重金属元素Zn、Cu和Hg的含量变化与形态分布,初步探讨了沉积特点,对苏州河底泥的进一步治理提供了参考.结果表明,样品中Zn 、Cu、 Hg的含量匀接近或高于生物有影响水平;Zn 、Cu分别主要存在于有机态和Fe-Mn氧化物态中,可交换含量较少;Zn 、Cu、 Hg含量随沉积物浓度的变化为:沉积物表层重金属含量较低并略有起伏,中部较高,底层较低.     

巢湖沉积物镉等重金属地球化学分布、赋存特征及危害性研究

对巢湖表层沉积物中8种重金属元素的分布特征和生态风险进行了研究和评价。结果表明：沉积物中Hg、Cd含量总体高于背景值,其中西部沉积物中重金属含量明显高于中东部湖区,并表现出多元素复合污染特征;Hakanson潜在生态危害指数表明巢湖沉积物重金属生态危害变化于轻微-强危害程度,以西北部湖区最为严重,Hg和Cd是主要影响因子,其它元素生态危害性较小;沉积物中As、cd、Hg、Pb元素主要以残渣态（非有效态）形式存在,但沉积物中腐殖酸态的As和Hg、铁锰氧化态的Pb、离子态的Cd占总量比例较高,其中又以Cd易利用态比例最高,生物有效性最强,具有较高的生态危害风险。     

北京市街道灰尘中重金属元素赋存状态及环境效应

采用Tessier的五步提取法,对北京北西—南东剖面所采集的街道灰尘样品粒度≤100μm组分中As、Cd、Cr、Hg、Pb和Zn等6元素的5个形态(可交换态、碳酸盐结合态、铁锰氧化物结合态、有机物结合态、残渣态)的分布特征研究发现,在可交换态和碳酸盐结合态中Cd的含量比都为最高,Pb、Hg、Zn和As在有机物结合态中含量比相近,铁锰氧化物结合态中Pb所占比例最高,而As和Cr主要存在于残渣态中。6种街道灰尘污染元素的相对活动性和潜在生物利用度顺序为:Cd>Zn>Pb>Cr>Hg>As。     

南海湖沉积物重金属形态分布及其对水质影响的研究

通过对包头市南海湖沉积物中Cu、Pb、Zn、Cd的形态、AVS和SEM、上覆水、上覆过滤水及沉积物间隙水重金属的系统分析，结合南海湖为黄河新成牛轭湖的特点，与黄河进行了对比，研究了重金属在固、液两相间的迁移转化规律，结果表明南海湖与黄河沉积物中重金属的残渣态非常接近，反映了沉积的同源性，Pb和Cd次生相则明显在南海湖发生富集，上覆水中重金属81.0%以上均结合在悬浮物上，南海湖水质长期Cu超标的现象是由沉积物的释放造成的，研究证明间隙水为重金属向上覆水迁移起到桥梁通道作用；有机络合物的络合作用超过AVS的沉淀作用，是导致Cu向水相扩散迁移的主导因子。     

Distribution of AVS-SEM, transformation mechanism and risk assessment of heavy metals in the Nanhai Lake in China

Distribution of AVS (acid volatile sulfide)-SEM (simultaneously extracted metals), transformation mechanism and risk assessment of heavy metals in the Nanhai Lake in Baotou City were discussed in this work. The results showed that the content of heavy metals in sediments increased due to the water pumped from the Yellow River, domestic sewage, municipal runoff and yacht waste release. Increasing water depth, domestic sewage influx and hydrophyte booming made the AVS level higher in downstream than upstream. The vertical distribution of AVS is characterized as multiple-peak in the sediment cores from the studied lake. Comparatively, the control abilities of the carbonate and sulfate to the heavy metals were five orders of magnitude lower than the sulfide phase. Therefore, AVS was the key factor controlling the precipitation of heavy metals in the Nanhai Lake. The ratio of SEM/AVS in the sediments, the acute sediment quality criteria and the chronic sediment quality criteria indicated that no acute toxicity for benthic organisms can be expected, and the AVS plays an important role in controlling the bioavailability and toxicity of heavy metals in the Nanhai Lake.     

Mercury speciation and distribution in Aha Reservoir which was contaminated by coal mining activities in Guiyang, Guizhou, China

Two sampling campaigns were carried out in March and August 2005 representing dry and wet seasons, respectively, to investigate the distribution patterns of Hg species in the water column and sediment profiles at two sampling stations in Aha Reservoir located in Guiyang, Southwestern China. Aha Reservoir has been contaminated by Hg due to small scale coal mining activities. Mercury concentrations in both water and sediment were elevated. A clearly seasonal variation of dissolved Hg (DHg), particulate Hg (PHg) and total Hg (THg) concentrations in the water column was observed. The concentrations of these Hg species in the wet season were significantly higher than in the dry season. Runoff input and diffusion of Hg from sediments could be the reasons for elevated concentrations of these Hg species in the wet season. The contaminated sediment is acting as a secondary contamination source for both inorganic Hg (IHg) and methylmercury (MeHg) to the overlying water. The cycling of Mn in the sediment governs the diffusion process of IHg to the water column. In the dry season (winter and spring), Mn occurs as MnO₂ because the uppermost part of sediment is in an oxic condition and Hg ions are absorbed by MnO₂. In the wet season (summer and fall), the uppermost part of the sediment profile is in a reduced condition because of stratification of the water column and MnO₂ is reduced to Mn²⁺, which results in transformation of Hg²⁺ into porewater as Mn²⁺ became soluble. This causes a higher diffusive flux of IHg from sediment to overlying water in the wet season. Both sampling stations showed a consistent trend that THg concentrations decreased in the uppermost part of sediment cores. This demonstrated that the measures taken to reduce ADM contamination to Aha Reservoir also reduced Hg input to the reservoir. Methyl Hg diffusive fluxes from sediment to overlying water were higher in the wet season than the dry season demonstrating that high temperatures favor Hg methylation processes in sediment.     

Interactions between dissolved organic carbon and mercury species in surface waters of the Florida Everglades

An ultrafiltration procedure has been developed to study the interaction between organic C and Hg species in natural waters, and a pilot study was conducted in the surface waters of the Florida Everglades. Compared to total Hg, CH₃Hg shows different distribution patterns in the suspended particulate, colloidal, and truly dissolved phases. Colloidal forms (0.22 μm, 3 kDa) contain the majority of the total dissolved Hg, while the amount found in the truly dissolved fraction (<3 kDa) is small (about 10%). However, CH₃Hg, which shows strong binding capability with low molecular-weight dissolved organic C, is present almost entirely in the lower molecular-weight fraction of the colloids and in the truly dissolved fraction. Quantitative CH₃Hg data correlate well with those for dissolved organic C, an indication that the organic matter present in the system plays an important role in the fate and transport of organomercury. Distribution coefficients between water and the different-sized fractions of the dissolved organic C were determined for both total Hg and CH₃Hg. Results for total Hg were in general agreement with other reports resulting from studies of molecular size distributions of total Hg in freshwater systems. This is, to the best of our knowledge, the first report of such distribution profiles for CH₃Hg between different-sized fractions of dissolved organic C in natural waters.     

The distribution of total mercury and methyl mercury in a shallow hypereutrophic lake (Lake Taihu) in two seasons

To understand the geochemical cycle of Hg in hypereutrophic freshwater lake, two sampling campaigns were conducted in Lake Taihu in China during May and September of 2009. The concentrations of unfiltered total Hg (unfTHg) were in the range of 6.8–83 ng L⁻¹ (28 ± 18 ng L⁻¹) in the lake water and total Hg in the sediment was 12–470 ng g⁻¹, both of which are higher than in other background lakes. The concentration of unfTHg in ∼11% of the lake water samples exceeded the second class of the Chinese environmental standards for surface water of 50 ng L⁻¹ (GB 3838-2002), indicating that a high ecological risk is posed by the Hg in Lake Taihu. However, the concentrations of unfiltered total MeHg (unfMeHg) were relatively low in the lake water (0.14 ± 0.05 ng L⁻¹, excluding two samples with 0.81 and 1.0 ng L⁻¹). Lake sediment MeHg varied from 0.2–0.96 ng g⁻¹, with generally low ratios of MeHg/THg of <1%. The low concentrations of TMeHg in the lake water may have resulted from a strong uptake by the high primary productivity and the demethylation of MeHg in oxic conditions. In addition, contrary to the results of previous research conducted in deep-water lakes and reservoirs, the low concentrations of MeHg and low ratio of MeHg/THg in the lake sediment indicates that the net methylation of Hg was not accelerated by the elevated organic matter load created by the eutrophication of Lake Taihu. The results also showed that sediments were a source of THg and MeHg in the water. Higher diffusion fluxes of THg and MeHg may be partly responsible for the higher concentrations of THg in the lake water in May, 2009.     

Trace metal deposition and mobility in the sediments of two lakes near Sudbury,Ontario

The accumulation and mobility of Fe, Mn, Al, Cu, Ni and Pb in the sediments of two lakes (Clearwater, pH 4.5; and McFarlane, pH 7.5) near Sudbury, Ontario have been investigated. The Al, Cu and Ni concentrations are expectedly relatively high in the overlying waters of Clearwater Lake and much lower for Al and Cu in McFarlane Lake. The low trace metal concentrations found in the anoxic porewaters of Clearwater Lake could be explained by a sharp increase in porewater pH concomitant with SO₄² reduction and H₂S production within the first 1–2 cm of the sediments, which has conceivably led to the precipitation of mineral phases such as AL(OH)₃, NiS, and CuS. In both lakes, Fe concentrations in anoxic porewaters appear to be controlled by FeS and/or FeCO₃ formation. Solubility calculations also indicate MnCO₃ precipitation in McFarlane Lake. In Clearwater Lake, however, both porewater and total Mn were relatively low, a possible result of the continuous loss of Mn(II) through the acidic interface. It is suggested that upwardly decreasing total Mn profiles resulting from the removal of Mn from the top sediment layers under acidic conditions may constitute a reliable symptom of recent lake acidification.The downward diffusion of AI, Cu and Ni from the overlying water to the sediments has been estimated from their concentration gradients at the interface and compared to their total accumulation rates in the sediments. In both lakes the diffusion of Al is negligible compared to its accumulation rate. However, diffusion accounts for 24–52% of the accumulation of Cu in the sediments of Clearwater Lake, but appears negligible in McFarlane Lake. The downward diffusive flux of Ni is important and may explain 76–161% of the estimated Ni accumulation rate in Clearwater Lake, and 59% in McFarlane Lake. The porewater Cu and Ni profiles suggest that the subsurface sedimentary trace metal peaks observed in Clearwater Lake (as in other acid lakes) may not be caused by sediment leaching or by a recent reduction in sedimentation but may have a diagenetic origin instead. Diffusion to the sediments thus appears to be an important and previously overlooked trace metal deposition mechanism, particularly in acid lakes.     

The Influence of Element Diffusion at the Sediment—Water Interface on the Basic Chemical Composition of Overlying Water Mass in Lake Lugu,China

Little work has been done on the influence of seiments on the basic chemical composition of overlying water mass.This paper deals with the vertical profile of the basic constituents such as Ca^ ,K^ ,Na^ ,and HCO3^-,as well as of pH in the overlying water mass and sediment porewater of Lake Lugu-a semi-closed,deep lake in Yunnan Province.The reand sediment porewater of Lake Lugu- a semi-closed,deep lake in Yunnan Province.The results revealed that those basic constituents may diffuse and transport from bottom sediments to overlying water mass through porewater.In the paper are also quantitatively evaluated the diffusive fluxes and the extent of their influence on overlying water mass,indicating that the lake sediment-water interface diffusion plays an important role in controlling the basic chemical composition of water in the whole lake.     

Geochemistry and speciation of metals in sediments of the Maharlu Saline Lake,Shiraz, SW Iran

In this study, the total concentration and speciation of trace elements (As, Cr, Cu, Cd, Pb, Zn, and Ni), in sediments of the Maharlu saline Lake, SW Iran are investigated. Comparison with sediment quality guidelines, calculation of the enrichment factors, and trace metal profiles in the Khoshk River inflow point indicate that Maharlu Lake is in the threat of contamination, especially with respect to Ni and Cd. Sequential extraction analysis reveals that elemental speciation in this lake is strongly affected by oxidizing condition of the lake water. The studied elements (except Cr) are mainly associated with oxide phases, as a result of prevailing oxidizing conditions of the lake and also probably due to the source of elements. The ratio of metals in mobile fractions to sum of fractions in lake sediments is very low. However, metal ratios (except for Cr) in mobile fractions are much higher in surface sediments, indicating the impact of anthropogenic loading of trace metals in the recent years.     

太湖月亮湾湖泛发生过程模拟及水土物化性质的响应

太湖湖泛具有在非确定区域非特定时间突发的特性,在野外很难进行及时有效的跟踪.利用Y-型沉积物再悬浮发生模拟装置,进行了风浪作用下太湖月亮湾藻源性湖泛发生过程的室内模拟,研究了湖泛发生过程中上覆水体及沉积物基本指标的变化特征.结果表明:湖泛发生过程中,上覆水体经历了显著的好氧-缺氧-厌氧阶段,溶解氧(DO)水平从起始阶段...     

A statistical approach for determining the environment impact of surface sediments from the Dongting Lake area,central China

The Dongting Lake, the second biggest freshwater lake in China, consists of three wetlands of national importance, namely the East Dongting Lake, the South Dongting Lake, and the West Dongting Lake. Surface sedi-ments were sampled from 57 locations across the lake. Nutrient concentrations [total organic carbon (TOC), total N (TN) and total P (TP)] and 16 element concentrations (Al, As, B, Ca, Cd, Cr, Cu, K, Fe, Hg, Mn, Ni, Pb, Si, Ti and Zn) in the sediments were measured to investigate the impact of industrialization along the lake's coastline and sev-eral tributaries on the profiles of nutrients and heavy metals in the lake's surface sediments. R-mode cluster analysis (CA) was used to integrate geochemical data. The result showed that euthophication of the Dongting Lake resulted mainly from TN and TOC. The main polluting trace metals are Hg, As, Cd, Zn, Pb and Mn, which are largely ad-sorbed on clay minerals or Fe/Mn oxides, or deposited as carbonates. Principal component analysis (PCA) revealed the source of micropollutants. The worst affected district by heavy metals is the East Dongting Lake, the pollution sources may originate mainly from the Xiangjiang drainage area. The results demonstrated that multivariate methods are the potentially great tools for the interpretation of the environmental data on lake sediments.