六道沟小流域地形序列土壤碳剖面分布特征及影响因素

为了更好地理解黄土高原植被恢复与生态重建过程对土壤碳循环过程的影响,研究选取位于黄土高原六道沟小流域的典型土壤地形序列(东北坡NE序列,西坡W序列),分析了不同坡向间及同一坡向内随植被类型变化土壤有机碳和无机碳的剖面分布特征及其影响因素。结果表明:六道沟小流域地形序列土壤有机碳含量在0—50cm土层内随土层深度增加而显著降低,50cm土层以下基本趋于稳定,且剖面上层(0—50cm)有机碳含量显著高于剖面下层(50—200cm,p0.05),但在同一深度土层(0—50,50—200,0—200cm)不同坡向林地和草地土壤有机碳平均含量均没有显著差异(p0.05)。与有机碳相比,无机碳含量相对较高并且主要在剖面下部(50cm以下)不同深度土层富集。NE序列林地和草地剖面无机碳平均含量接近(p0.05),而W序列林地剖面无机碳平均含量显著高于草地(p0.05);不同坡向草地剖面无机碳平均含量无显著差异(p0.05),但不同坡向林地剖面无机碳平均含量表现为W序列显著高于NE序列(p0.05)。0—50cm土层有机碳含量与pH、容重和土壤含水量均呈极显著负相关关系,而与土壤总孔隙度呈极显著正相关关系;50—150cm土层无机碳含量与pH和土壤总孔隙度均呈极显著负相关关系,而与容重、黏粒含量和土壤含水量均呈极显著正相关关系。NE序列和W序列2 m土体总碳密度相当,分别为15.2~47.4kg/m~2和18.3~51.3kg/m~2,其中无机碳密度占78%~94%,1—2m土层总碳密度占2m土体总碳密度的35%~74%。若只考虑土壤有机碳库或只考虑浅层1m土壤碳库,六道沟小流域2m土体总碳储量平均将被低估88%和51%。     

Biomonitoring of Trace Elements in Air and Soil Compartments Along the Major Motorway in France

The impact on the environment of Cd, Pb and Zn emissions from the A1 motorway, one of the busiest in France, was based on a simultaneous analysis of lichens, fungi and soil.The study was conducted in 12 rest areas located along a 55 kmstretch of the motorway. Cd, Pb and Zn concentrations in the top soil horizon (0–10 cm) largely exceeded their concentrations at the control site.The Cd-, Pb- and Zn levels in fruiting bodies of fungi Armillaria mellea, Coprinus comatus, Marasmius oreades and Paxillus involutus were highly variable between sites. The contamination degree of transplanted thalliof Parmelia caperata was well correlated to the cumulated traffic on the western side. On the eastern side, heavy metals originated from the traffic but also from neighbouring sources (urbanization and agricultural practices). Although lead levels are decreasing, leaded petrol is still on offer and lead remains an indicator of vehicle pollution.     

恩施典型富硒区土壤硒与其他元素组合特征及来源分析

硒是重要的人体和动物必需微量元素之一,在功能农业发展中起着重要的作用。为了研究高硒土壤中硒与其他元素组合特征及来源,从而支撑富硒资源的安全有效利用,本研究在恩施市沙地乡系统采集并分析了200个表层土壤样和2组土壤垂向剖面样品,运用统计学工具进行了聚类分析和因子分析。结果表明:研究区表层土壤硒含量平均值为1.88 mg/kg±2.51 mg/kg,明显高于全国表层土壤硒含量平均值。研究区土壤元素组合特征可分为三类,第一类中硒与钼、钒、铬、镉和镍等元素具有较强的伴生关系,与黑色岩系分布密切相关;第二类为三氧化二铝、铅和砷等元素/氧化物,与土壤中黏土矿物有关;第三类为钙和锶等元素,表明该同族元素的地球化学性质具有相似性。因子分析结果进一步证实了土壤硒和镉伴生主要发生在黑色岩系,不同成土母质硒等元素差异较大。     

Building upon the Conceptual Model for Soil Mercury Flux: Evidence of a Link Between Moisture Evaporation and Hg Evasion

Parameters known to influence mercury (Hg) release from soils include substrate and air Hg concentration, light, atmospheric oxidants, temperature, and soil moisture. However, for low Hg-containing soils, the influence of these parameters has been shown to vary across space and time. Here, we expand upon previous work by investigating whether soil–water evaporative loss, which integrates the influence of multiple parameters, could be applied for predicting Hg flux from soil with low Hg concentrations when bare and planted. To investigate our hypothesis, Hg flux was measured from three soil types (<100 ng Hg g^?1). When these soils were saturated, flux was suppressed. Soil moisture evaporative stage was used to partition the parameters most important for controlling Hg flux as the soils dried. Classification and regression tree (CART) analyses showed that soil moisture was the most important parameter predicting Hg flux. Results also showed an important predictor for Hg flux was whether actual evaporation (E _a) was equal to potential evaporation (E _p) or E _a < E _p. Depending on evaporative stage, the parameters with the next highest correlation to Hg flux were light, temperature, and soil moisture evaporation rate. The presence of vegetation also influenced flux with lower Hg flux when the plants were transpiring. Results indicate for those developing models that estimate Hg flux from low Hg-containing soils, soil moisture and evaporative stage are useful tools for predicting flux.

     

Soil and Foliar Mercury Emission as a Function of Soil Concentration

The goal of this study was to investigate net mercury flux associated with seedlings of two species (Populus tremuloides and Pinus ponderosa) grown in three soil exposure concentrations (0.010 ± 0.001, 6.15 ± 0.86, and 25.56 ± 2.10 µg Hg g^-1) and to determine if mercury flux from vegetation was directly correlated with mercury concentration in the soil. Net mercury flux was measured using a gas exchange system. Mercury emission from foliage was not influenced by mercury concentration in the soil. Experiments were also done to assess the significance of mercury emission from vegetation relative to that occurring from associated soils. Mean soil mercury emissions were 1 to 3 orders of magnitude higher than that from plants grown in similar soil mercury concentrations. Light and the addition of water were found to significantly increase mercury emission from soils, and the magnitude of the flux response to watering was correlated with soil mercury concentration.     

Robot系统测定旱地N2排放的方法优化及其与其他方法的对比研究

反硝化是生态系统氮循环的最后一环同时也是活性氮转化为惰性氮（N2）的最主要过程。由于空气中背景N2浓度高达78%,在如此高的背景浓度N2环境中直接和准确测定反硝化过程产生的微量N2,一直是个巨大的挑战。Robot系统（Robotized incubation and analyzing system）是基于无N2背景（氦环境）的用以研究纯菌或土壤体系N2排放速率的方法,该系统平台搭建简单且测定效率高,目前应用比较广泛。但该系统在运行过程中需要频繁利用微量注射器进行取样和测定,极易造成外界N2的渗漏。为解决这一问题,本文通过使用预先置于氦（He）环境的橡胶隔垫、采用充He后的蒸馏水配制溶液及实施破坏性取样的处理,对Robot系统测定旱地N2排放速率的方法进行了优化,同时与乙炔抑制法和RoFlow系统（Robotized continuous flow incubation system）的测定结果进行了对比。研究结果表明,通过方法优化,可以大幅降低Robot系统的N2渗漏率,未优化前系统的渗漏率为5.15 μL·L-1·h-1,方法优化后系统的渗漏率在0～0.8 μL·L-1·h-1之间。优化后的Robot系统对碳源和氮源添加后N2排放速率差异的响应较好,并且对旱地土壤背景N2排放速率的测定误差最小（0.003～0.045 mg·kg-1·d-1）,显著优于乙炔抑制法（0.34～3.29 mg·kg-1·d-1）和RoFlow系统（0.41～1.02 mg·kg-1·d-1）。综上,优化后的Robot系统在测定旱地N2排放速率时具有N2渗漏率低,对外源底物添加响应好及测定结果精确度高的特点,未来在研究旱地土壤背景N2排放及相关机理方面有较好的应用前景。     

红壤中腐殖酸对外源稀土形态的影响

本实验研究了腐殖酸 (HumicAcid ,又名胡敏酸 )对外源稀土元素在土壤中形态分布的影响和各形态的有效性。结果发现 ,加入腐殖酸后 ,土壤中稀土的交换态和碳酸盐结合态含量降低 ,有机结合态含量上升 ,而且腐殖酸浓度与稀土有机结合态含量有良好的相关性 ,说明腐殖酸能够提高稀土元素在土壤中的固定性 ,减少有效态稀土含量     

Assessing the Influence of Different Atmospheric and Soil Mercury Concentrations on Foliar Mercury Concentrations in a Controlled Environment

This study vividly presents results from a seasonal particulate matter measurement campaign conducted at world’s largest ship-breaking yard i.e., Alang-Sosiya (Gujarat, India) at six locations and a reference station at Gopnath which is 30 km south of this ship-breaking yard. The collected suspended particulate matter (SPM) 24-h samples were critically analyzed for heavy metals (Pb, Cd, Co, Ni, Cr, Mn, Fe, Cu, Zn). The average concentration of SPM within the ship-breaking yard during the investigation was 287.5 ± 20.4 μg m^?3 and at reference station it was 111.13 ± 5.81 μg m^?3. These values are found to be in excess of the permitted national standards. The levels of heavy metals at Alang-Sosiya are very high as compared to US EPA and WHO guidelines. The mean concentrations of all metals are in the order: Fe >>Zn >Cu > Mn > Cd >Pb > Co >Ni >Cr. The results on enrichment factors (EF) suggest that most of the metals in the ship-breaking yard exhibit EF values of near or above 100 which must have been comprehensively affected by ship-breaking activities. Metal data was used to evaluate the role of spatial factors on their distribution characteristics. Thereafter, factor analysis was carried out to identify the main components liable for the variance of the data set.     

土壤中汞的存在形态及过量汞对生物的不良影响

随着汞在工业、农业、医药等方面的广泛应用,由汞及其化合物所造成的环境污染问题日益严重,汞对环境和人类带来的危害愈来愈引起普遍的关注。本文着重介绍汞在自然环境和土壤中的各种存在形态,阐述不同形态汞对植物进而对人类健康的危害,以及汞不同形态情况下人体的中毒症状和中毒机理,并对减少汞污染的治理提出一定的建议。     

Soil and Sediment Geochemistry of the Iron Quadrangle, Brazil

Soils and sediments around gold ore deposit and mining sites in the Iron Quadrangle present positive As anomalies (median concentrations > 100 mg kg^-1) and wide ranges (< 20 to > 2000 mg kg^-1) even in densely populated areas. These anomalies can be related to geological structures, to hydrothermal ore deposits and to their continuous exploitation over the past three centuries. The paper presents new data on both As geochemistry and soil and sediment geochemistry in general, and discusses consequences of the encountered anomalies, their reasons and potential effects and how they compare with current screening and threshold values. While surface soil As-val-ues are reproducible at a given site, sediment anomalies show a strong seasonal variation that can be explained by tropical hydrologicai variances. Suggestions are presented on how to minimize the As-load in densely populated areas that might otherwise pose a potential health risk.     

Controlling Acid Drainage in a Pyritic Mine Waste Rock. Part II: Geochemistry of Drainage

Mine waste rock can produce acid rock drainage (ARD) when constituent sulphide minerals (for example, pyrite) oxidize upon exposure to the atmosphere. Outdoor experiments were performed to test techniques for preventing and controlling ARD in a pyritic mine waste rock. The experiments involved lysimeter (plastic drum) experiments in which the crushed (25–50 mm particle sizes), amended and unamended waste rock was exposed to natural weather conditions (rain, drying, freezing and thawing) for 125 weeks. The amendments consisted of separately covering the waste rock with compacted soil, wood bark and water and mixing with limestone and phosphate rock at 1 and 3%. Waters draining the various rocks were collected and analyzed for acidity, pH, sulphate and metals. In general, concentrations of SO₄ ^2-, Fe, As, Cu, Al and Mg in the drainage from the control rock increased gradually in the first year, peaked in the second year and increased further in the third year, reflecting increasing acid generation with time. SO₄ ^2- displayed strong positive correlation (0.91 to 0.98) with Al, As, Cu, Fe and Mg.Concentrations of Zn, Mn and Cd reached their maximumin the second year. Geochemical analysis of thecomplete water quality data using the equilibriumspeciation model WATEQ4F suggested waste rockoxidation was most likely controlled by Fe³⁺. Al, SO₄ ^2- and Fe concentrations in thecontrol rock appeared to be controlled by alunite(KAl₃(SO₄)₂(OH)₆), jarosite(KFe₃(SO₄)₂(OH)₆) and amorphousferric hydroxide [(am)Fe(OH)₃] during the firstyear. Ion activity product data (log IAP) forFe³⁺ and OH^- generally ranged between –37and –34 in the first two years but decreased to –39and –40 in the third year, suggesting that amorphousferric hydroxides were beginning to crystallize intomore stable forms such as ferrihydrite (Fe[OH]₃)and goethite (FeOOH) in the third year. The addedlimestone lost its effectiveness after a while,probably because of precipitation of secondaryminerals on the limestone particles. The phosphaterock could not sustain the drainage pH above 6 andlost its effectiveness before the limestone did. Underthe conditions of the experiments, the soil cover didnot work as expected, probably because of sidewallpassage of oxygen and water. The water cover was themost effective control method, reducing the acidproduction rate data from 41 to only 0.08 mgCaCO₃ week^-1 kg^-1 waste rock. The wood bark was theworst performer and accelerated acid production by 170%.     

人与自然和谐相处的水土保持理念探讨

人与自然不和谐相处就会加剧环境恶化、危及国家生态安全、制约经济社会可持续发展 ,因此要转变观念 ,调整思路 ,突出水土资源的高效利用、有效保护和优化配置 ,分类指导、整体推进 ,高度重视生态自我修复 ,应用社会化机制 ,加快新技术的研究和推广 ,促进人与自然和谐相处。     

Soil Covers for Controlling Acid Generation in Mine Tailings: a Laboratory Evaluation of the Physics and Geochemistry

To evaluate the effectiveness of soil covers, column experiments were conducted on tailings protected by a three-layer soil cover and tailings directly exposed in the open laboratory for a period of 760 days. Periodic rain application was performed to simulate field conditions, and at four times during the experiments the pore water was completely flushed out of each column for analysis. Profiles of oxygen, temperature, and volumetric water content were measured throughout the experiment, and the post-testing pore water quality was also characterized. A one-dimensional semi-analytic diffusion model was used to simulate oxygen profiles in the uncovered tailings. Modelling performed using the geochemical code MINTEQ showed that in the laboratory, aluminium concentrations in the tailings pore water were controlled by Al(OH)SO₄, sulphate by gypsum and Al(OH)SO₄and iron by lepidocrocite in the upper half and by ferrihydrite in the lower half. In the field, however, the iron oxyhydroxide minerals formed in the oxidized zone appear to be dissolving. It was found that the cover was effective in preventing significant desaturation of the clay, even over a 150-day drying period. The covered tailings did not oxidize much during the experiments. In the uncovered tailings, oxygen modelling and examination of the geochemistry show that the rate of gross oxidation and the advancement of the oxidation front decreases with time. However, pore water quality is controlled by geochemical processes other than oxidation, as reported in the field.     

Extractability and Bioavailability of Mercury from a Mercury Sulfide Contaminated Soil in Oak Ridge, Tennessee, USA

Historically as part of its national security mission, the U.S. Department of Energy’s Y-12 National Security Facility in Oak Ridge, TN acquired a significant fraction of the world’s supply of elemental mercury. During the 1950s and 1960s, a large amount of elemental mercury escaped confinement and is still present in the watershed surrounding the Y-12 facility. A series of remediation efforts have been deployed in the watersheds around the Oak Ridge site. However, most recently, concentration of total mercury in fish and water of the lower East Fork Poplar Creek (EFPC) of Oak Ridge has increased although majority of the mercury contamination in the local soils is present in the form of mercury sulfide. We have studied the extractability, solubility, and bioavailability of mercury sulfide in Oak Ridge soils. Dynamics of the dissolution of mercury sulfide by various extractants, including acids and a chelating agent, have been investigated. After three seasons of planting, soil mercury sulfide is more easily dissolved by both 4 M and 12 M nitric acid than is pure mercury sulfide reagent as indicated by their dissolution kinetics. Mercury release by EDTA from HgS-contaminated soil increased with time of reaction and soil mercury level. This chelating chemical increases the solubility of mercury in HgS-contaminated Oak Ridge soil. The results also show that mercury sulfide in contaminated Oak Ridge soils was still to some extent bioavailable to plants. The increase of bioavailability of soil mercury sulfide after three seasons of planting may contribute to the recent increase of mercury levels in water of the Lower East Fork Popular Creek (LEFPC) of Oak Ridge.     

Behavior of Mercury in Soil Profiles: Impact of Increased Precipitation, Acidity, and Fertilization on Mercury Methylation

The behaviour of Hg in mineral pine forest (Pinussylvestris soil profiles (0–16 cm) was studied usinga lysimeter experimental design combined with thelabeling technique with ²⁰³HgCl₂. Thelabeled surface soils were exposed to four differenttreatments: (i) normal precipitation (600 mma^-1), (ii) four-fold precipitation, (iii) soilP-K fertilizing with normal precipitation, and (iv) the increased acidity in the rainwater with normalamount of precipitation. After the treatment period of97 days the ²⁰³Hg and methyl ²⁰³Hg weremeasured. The distribution of Hg in different soilmatrices was determined by extracting the soil withdistilled water, 1 M NH₄-acetate, 1 M HCl, and 0.1 M NaOH.The results showed that the organic surface layer,especially the living moss (Pleuroziumschreberi), was the dominant scavenger of the added²⁰³Hg. Methyl ²⁰³Hg formation was mostintensive in this layer, too. Increased precipitationmobilized a part of the ²⁰³Hg from the moss layerto the deeper layers and leachate water. In thefertilized soil with increased pH, the accumulation ofboth total ²⁰³Hg and methyl ²⁰³Hg wasrecorded in the organic surface soil. A small increasein rainwater acidity had no clear effect on thebehavior of ²⁰³Hg in soil. ²⁰³Hg was mainlyassociated in the organic fraction (NaOH-extractable)whether in the living moss or humus layer. Thefertilized soil yielded the highest concentration ofwater extractable ²⁰³Hg. In view of the climatechange with increasing precipitation, the use offertilizers, in the watersheds should be minimal andwell-controlled. This is, because soil fertilizingseems to increase the availability of Hg formethylation, and because the mobilization of bothtotal Hg and methyl Hg from watershed soils to lakes,and probably to ground water, increases whenprecipitation increases.     

石漠化山区露石岩面流对岩-土界面土壤氮磷淋溶与输入作用的研究

基岩出露的石漠化区露石岩面在承接降水（含穿透雨）后易形成岩面流，并携带岩面有机或无机物质输送至岩周土壤中，对岩-土界面土壤养分变化具有重要影响。为探明岩面流对岩-土界面土壤氮磷的淋溶与输入影响，选取基岩明显出露的休耕地（1年岩面流作用）、退耕灌草地（5年岩面流作用）和坡耕地（无/少岩面流作用）3种样地，并分别选择外凸、平直和内凹3种特殊的岩面形状，研究了距岩面不同水平距离及土层的岩-土界面及非岩-土界面土壤的全氮和全磷变化特征。结果表明：岩面流对0～10 cm表层岩-土界面土壤氮磷产生输入或淋溶作用，对10～20 cm层岩-土界面土壤氮磷作用不明显。不同岩面形状形成的岩面流对岩-土界面土壤氮磷的淋溶与输入作用强度依次为：内凹型>平直型>外凸型。其中，在1年岩面流作用的休耕地中，内凹型岩面形成的岩面流对岩-土界面土壤氮素的影响主要表现为淋溶，而平直型和外凸型岩面表现为输入作用；不同形状岩面流对岩-土界面土壤磷素的影响均表现为淋溶。然而，在植被生长较好的退耕灌草地中，5年岩面流作用下不同形状岩面流对岩-土界面土壤氮磷的影响主要表现为输入。研究结果可为深入认识出露岩石对喀斯特生态系统土壤特性的影响提供科学依据。     

草甸沼泽土壤硝化-反硝化作用和有机碳矿化对氮输入的响应

通过室内培养实验.研究了草甸沼泽土壤N2O排放和反硝化损失对氮输入的响应特征,结果表明,在培养期(23 d)内N2O平均排放速率为0.32(NO).0.87(N1).17.69(N2),28.07(N3)μgN2O-N/(kg±·h),反硝化平均损失速率为0.25(NO),0.81(NI),22.29(N2),30.28(N3)μgN2O--N/(kg±·h).两者都随氮输入量增高而升高.其中,N3处理N2O平均排放速率和反硝化平均损失速率与对照差异显著(p<0.05),N1和N2与对照差异不显著.N2O排放总量占氮输入的比例为0.03%(N1),1.04%(N2).1.76%(N3),反硝化损失总量占氮输入的比例为0.04%(N1),1.29%(N2),1.93%(N3).均表现为随氮输入量的增大而增高.N1处理下有机碳矿化速率低于对照,而N2和N3有机碳矿化速率高于对照,说明低氮输入对有机碳矿化有一定抑制作用,.高氮输入促进有机碳矿化.     

土体构型对土壤水氮储运的影响研究进展

土体构型是土壤剖面中不同质地层次的排列、组合状况,其对土壤水分、溶质运移过程和作物生长等均具有显著影响,具有重要的农学和环境意义。本文对该领域的研究动态和最新进展作了综述,重点探讨了土体构型对土壤水分和氮素储存、运动过程的影响机理及其农学效应,并对今后有关土体构型的研究和改良技术的发展趋势进行了展望。     

Distribution of Mercury and Other Heavy Metals in Core Sediments of the Northern Adriatic Sea

Seven sediment cores were collected along a transect about20 km off from the mouth of the Po River, in the northernAdriatic Sea (Italy). Cores were characterised by differentdepositional sequences associated with late Pleistocene-Holocene lowstand (LST), transgressive (TST) and highstand (HST) system tracts. Sediment samples were analysed for mercury, copper, nickel, chromium, manganese and iron, aswell as for total organic matter. Metal distributiongenerally showed vertical and spatial variability ascribed tograin size effects with no significant anthropogenicperturbation. Conversely, mercury showed vertical profilescharacterised by surface enrichment, with concentrations inthe upper layer (50–230 ng g^-1) exceeding 3–11 times the background value of 20 ng g^-1 determined in bottomcores. Surface maxima were attributed to anthropogenic mercurydelivered mainly by the Po River.