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1.
研究了污泥与煤按不同质量比例混烧后,底灰中的重金属形态分布与浸出毒性.结果表明:30:70的泥煤比使底灰中重金属硫化物及有机态和残渣态所占比例最大,即生物无效部分比例最大;在浸出毒性实验中,30:70的泥煤比使底灰重金属浸出量最小.由此推出,对环境毒害程度最小的泥煤质量比为30:70,即该实验条件下最优泥煤质量比为30:70.  相似文献   

2.
大气沉积颗粒中铅的赋存状态研究   总被引：1，自引：0，他引：1  
从大气沉积颗粒中的重金属铅污染入手，采用连续化学浸提萃取的方法，对西安大气沉积颗粒中的微量金属元素铅的赋存状态进行了分析研究，发现铅元素主要以残渣态和铁-锰结合态存在。水溶态、交换态和有机质结合态存在的量虽然很少，但都以矿物质形式存在，这说明金属离子比较稳定，不易迁移和转化，对周围环境和人体的危害比较持久。  相似文献   

3.
连霍高速郑商段路旁土壤重金属积累初探   总被引：2，自引：1，他引：1  
以连霍高速郑州-商丘段路旁土壤为研究对象,在野外调查采样和实验室分析的基础上,探讨了公路交通对周围土壤中Ni、Pb、Cr、Cu、Zn和Cd 6种重金属含量与分布的影响,计算了表层土壤的重金属元素积累速率与积累通量.结果表明:Cu、Pb和Cd是典型的交通源重金属,其含量在公路两侧随着距离的增加,呈先增加后减少的趋势,含量峰值出现在离路基25-50 m之间.公路运营时间越长,交通源重金属含量就越高.两断面绝大部分样点Pb、Cu和Cd的积累速率和通量均为正值,且Cu＞Pb＞Cd,小王庄断面大于湾刘断面,Cu和Pb的通量远远超过国际上正常土壤标准.  相似文献   

4.
为了解太子河本溪城区段河流水体中重金属分布特性及形态特征,对城区段河流干支流中的重金属Zn,Pb,Cd,Cu,M n,Cr,Se的含量和分布状况进行了分析,并使用PHREEQC软件对重金属存在形态进行了模拟计算。结果表明:采样区河段7种重金属中污染较重的为Mn和Cr,平均值均超过国家地表水环境质量Ⅳ类标准(GB 3838-2002)。多元统计分析表明,7种重金属可以归为两个主成分,其中第一主成分PC-I(Mn,Cd,Se)主要受人为污染因素的影响;第二主成分PC-Ⅱ(Zn)主要受自然地质背景影响。重金属污染指数范围在28. 49—473. 76之间,表明采样区段部分水体的重金属污染程度已超过可接受水平。形态分析表明,在水体中7种重金属大多以胶体(Cu(OH)_2)或沉淀(ZnCO_3、PbCO_3、MnCO_3等)的形态存在,溶解态含量较低。本研究结果可为太子河本溪城区段水污染防治与河流水体修复提供参考。  相似文献   

5.
沈大高速公路两侧土壤重金属污染分布特征研究   总被引：8，自引：0，他引：8       下载免费PDF全文
对沈大高速公路沈阳、辽阳、鞍山、营口和大连段两侧土壤中铅、镉、锌、铬、镍和铜的含量进行测定。结果表明:在距路肩250 m范围内,各段土壤中铅、镉均有不同程度的累积,锌、铬、镍、铜污染不显著。土壤中铅、镉最大污染指数为3.34和2.42,污染较高值出现在距路肩50 m内,尤以20—40 m为高,除铅外其余重金属含量在距路肩150 m以外趋于背景值,但土壤中铅污染为250 m以外。  相似文献   

6.
在河南省某高校校区内的规模绿地上采集21个土壤样品,在郊区农田采集2个对照样品。按照国家标准方法,测定了土壤Cu、Zn、Ni、Pb和Cr的含量。结果发现:校园土壤中Ni、Zn和Cr发生了不同程度的富积;土壤重金属含量空间变异明显;校园土壤普遍发生了Zn污染,平均污染分指数达2.48,中度和重度污染样点占总样点的57.14%;绝大部分样点的综合污染指数均大于1,其中轻度污染样点13个,中度污染样点5个,重度污染样点2个。根据校园土壤的实际,应从严格控制污染物排放、翻土和客土改良、增施有机肥料、植物修复等方面防治校园土壤重金属污染。  相似文献   

7.
在南京市浦口和大厂的五大主要功能区（工业区、交通干线、居民区、蔬菜生产基地和风景区）分别布置采样点,共采集了75个菜地耕层土壤样品,以Cd、Cu、Pb和Zn等典型污染重金属元素的全量数据为基础,运用经典统计分析、综合污染指数和地统计分析相结合的方法对土壤重金属污染进行评价。结果表明,Cd、Cu和Zn分别超出其南京地区土壤背景值的5．42、1．84和1．14倍,Pb未超出。不同功能区菜地土壤的重金属全量水平存在明显差异,其中工业区菜地土壤的重金属污染较为严重。对于Cd和Cu,单因子污染指数大于1的样点数达100％,Zn为52％,Pb为2．67％。研究区内菜地土壤重金属的综合污染指数为4．12,属于中度污染。Cu的空间相关性很弱,Cd、Pb和Zn具有中等的空间结构性;四种重金属的空间相关尺度较为接近。Cd、Cu和Zn的单因子污染指数具有相似的空间分布,总体呈现出南高北低的带状递减趋势,且高峰值具有空间分布的趋同性,而Pb的单因子污染指数分布呈现西北和东南两端高,中间较低的趋势。综合污染指数的空间分布显示,研究区大部分菜地土壤处于中度重金属污染水平,钢铁生产厂周边的斑块状区域重金属污染更加严重。  相似文献   

8.
陇海铁路圃田段路旁土壤重金属潜在生态风险评价   总被引：2，自引：0，他引：2  
以陇海铁路圃田段为例,采用Hakanson指数法,对铁路旁土壤重金属(Cd、Pb、Cu、Zn、Cr和Ni)的潜在生态风险进行了评价.结果表明,铁路旁土壤中重金属元素出现不同程度富集,以Zn和Pb的积累最为明显,最大含量都分布在距路基30 m范围内.Cd的潜在生态风险最大,在距路基100 m范围内,单项风险系数均在80以上,呈重度风险,最大风险值出现在路基处,高达138,之后逐渐降低;其余重金属呈低风险状态.距路基20 m范围内,潜在生态风险指数均在150以上,达到中等生态风险程度,之后逐渐降低.镉(Cd)的潜在风险占总风险的68.20%～73.37%,其他重金属的贡献很小.  相似文献   

9.
陇海铁路圃田段路旁土壤重金属潜在生态风险评价   总被引：1，自引：0，他引：1  
以陇海铁路圃田段为例,采用Hakanson指数法,对铁路旁土壤重金属（Cd、Pb、Cu、Zn、Cr和N i）的潜在生态风险进行了评价。结果表明,铁路旁土壤中重金属元素出现不同程度富集,以Zn和Pb的积累最为明显,最大含量都分布在距路基30 m范围内。Cd的潜在生态风险最大,在距路基100 m范围内,单项风险系数均在80以上,呈重度风险,最大风险值出现在路基处,高达138,之后逐渐降低;其余重金属呈低风险状态。距路基20 m范围内,潜在生态风险指数均在150以上,达到中等生态风险程度,之后逐渐降低。镉（Cd）的潜在风险占总风险的68.20%-73.37%,其他重金属的贡献很小。  相似文献   

10.
反硝化过程是维系闭合氮循环所必需的氮素形态转化环节。土壤反硝化过程速率及产物比的直接测定是研究氮循环过程机理的基础,但却是一个难题。为解决此难题,德国卡尔斯鲁厄技术研究所与中国科学院大气物理研究所最近合作新建了一套通过氦环境培养-气体同步直接测定土壤反硝化气体--氮气（N2）、氧化亚氮（N2O）、一氧化氮（NO）和二氧化碳（CO2）排放的系统和与之配套的三阶段培养方法。为检验该新建系统和配套方法测定土壤反硝化过程的准确性和可靠性,以华北地区广泛分布的盐碱地农田土壤（采自山西运城）为研究对象开展实验室培养试验,在初始可溶性有机碳（DOC）供应比较充足约300 mgC kg–1干土（d.s.）的条件下,测试了不同初始土壤硝态氮含量水平（10、100 mgN kg–1d.s.左右,分别表示为10N和100N）的反硝化气体和CO2排放过程。结果显示：100N的反硝化速率（定义为N2、N2O 和NO 排放速率之和）显著高于10N 处理（统计检验显著水平p＜0.01）;两个处理的反硝化产物均以N2为主（质量比分别占77%和75%）,产物的NO/N2O摩尔比分别为1.2和1.5,N2O/N2摩尔比均为0.19;土壤反硝化气体动态排放速率及相关指标的测定结果表明,培养土壤中消失的硝态氮被回收81%～87%,培养前后的氮平衡率达92%～95%。因此,该新建方法测定土壤反硝化速率和产物比的结果具有很好的可靠性,为定量研究土壤反硝化过程提供了有效的直接测定手段。研究中检测到的土壤反硝化产物NO/N2O摩尔比大于1,不同于以往用液体培养基纯培养反硝化细菌得出的NO/N2O摩尔比远小于1的结论。这意味着,不能用NO/N2O摩尔比小于1与否来推断土壤排放的N2O和NO是主要来源于反硝化作用还是硝化作用。  相似文献   

11.
An established three stage sequential leach scheme was applied to a series of selected high volume aerosol samples (n = 35) collected from the Turkish Eastern Mediterranean coastline (Erdemli). Samples were selected according to their air mass back trajectory history to reflect the contrasting mixtures of aerosol material present in the Eastern Mediterranean marine aerosol. Two populations were adopted, those samples which were classed as “anthropogenic” and those which were “Saharan” dominated aerosol populations. Applying the three stage leach it was possible to define the proportion for each of the considered metals (Al, Fe, Cu, Pb, Cd, Zn and Mn) present in the (a) “exchangeable” (b) “carbonate / oxide” and (c) “refractory” phases, representing novel solid state aerosol speciation data for this marine system. Clear trends were established, conforming with data from previous studies with mainly crustal derived metals (Al and Fe) being present in the refractory phases (Al > 88%; Fe > 84%) and those influenced by anthropogenic sources being dominating in the exchangeable phase, although for these metals the variability was comparatively high (12–64%; 19–85%; 40–100% for Zn, Pb and Cd, respectively). For the majority, greater exchangeable fractions were present the lower the crustal source contribution to the aerosol population, whereas the “refractory” fraction exhibited contrasting behaviour. This was illustrated by the novel application of the mixing diagram, presenting each of the three speciation stages against the corresponding percent anthropogenic contribution to each collected sample. Zn, Pb and Cd all illustrated progressive decrease in the percent exchangeable with increasing crustal contribution to the aerosol population. The percent exchangeable was discussed in terms of its use to represent the upper limit of the bioavailable fraction of metal associated with the aerosol, post deposition. The mixing diagram approach enabled the prediction of the residual fractions for Cd, Pb and Zn (41 ± 4%; 62 ± 4% and 82 ± 5%, respectively,) in Saharan end-member material.  相似文献   

12.
In addition to increasing plant C inputs, strategies for enhancing soil C sequestration include reducing C turnover and increasing its residence time in soils. Two major mechanisms, (bio)chemical alteration and physicochemical protection, stabilize soil organic C (SOC) and thereby control its turnover. With (bio)chemical alteration, SOC is transformed by biotic and abiotic processes to chemical forms that are more resistant to decomposition and, in some cases, more easily retained by sorption to soil solids. With physicochemical protection, biochemical attack of SOC is inhibited by organomineral interactions at molecular to millimeter scales. Stabilization of otherwise decomposable SOC can occur via sorption to mineral and organic soil surfaces, occlusion within aggregates, and deposition in pores or other locations inaccessible to decomposers and extracellular enzymes. Soil structure is a master integrating variable that both controls and indicates the SOC stabilization status of a soil. One potential option for reducing SOC turnover and enhancing sequestration, is to modify the soil physicochemical environment to favor the activities of fungi. Specific practices that could accomplish this include manipulating the quality of plant C inputs, planting perennial species, minimizing tillage and other disturbances, maintaining a near-neutral soil pH and adequate amounts of exchangeable base cations (particularly calcium), ensuring adequate drainage, and minimizing erosion. In some soils, amendment with micro- and mesoporous sorbents that have a high specific surface – such as fly ash or charcoal – can be beneficial. All authors contributed equally to this article.  相似文献   

13.
基于通用陆面模式（Common Land Model, CoLM）,首次评估了两套最新的全球土壤数据集GSDE（Global Soil Dataset for Earth System Model）和SG（SoilGrids）对全球陆面过程模拟的影响。比较分析了两套数据中砂粒、粘粒、砾石、有机碳的含量和容重这五个土壤属性在全球分布上的差异以及这种差异造成的对模式估计的土壤特性参数、水力热力变量的影响。结果表明,土壤特性参数在全球的空间分布主要受土壤粒径分布（砂粒、粉粒和粘粒）影响,同时也受砾石、有机碳和容重的影响。土壤资料对全球模拟结果影响主要体现在区域差异,对水文学变量的影响（Re最大达到±100%）大于对土壤热力学变量的影响（Re<±10%）,对地表辐射变量的影响较小（Re<±5%）。其中,土壤体积含水量在加拿大中部及西北部、俄罗斯东南部及中西部和澳大利亚中部地区模拟结果相差较大,总径流在低纬地区模拟结果出现较大的差异,热力学变量在非洲北部、加拿大西北部以及俄罗斯中北部的差异稍大。将模拟的土壤体积含水量与站点观测相比,两套数据的表现接近,与站点观测相比都存在一定的偏差,但SG更接近观测,其中在Molly Caren站点（39°57′N,83°27′W）上SG相比GSDE整体提高约0.01～0.02。本研究表明,模式模拟结果受不同土壤数据集的影响显著,可优先考虑诸如SG较准确的土壤数据。土壤属性对陆面模拟的影响需进一步研究。  相似文献   

14.
Mercury speciation was determined in rainwater from 76 storms in southeastern North Carolina between September 1, 2003 and September 30, 2005. Volume-weighted average concentrations of total Hg (THg), total dissolved Hg (TDHg), particulate Hg (Hgpart) and dissolved monomethyl Hg (MMHg) were 45.5 pM, 34.8 pM, 12.0 pM and 1.1 pM respectively. TDHg accounted for 77% of THg in precipitation which is similar to Cu but significantly higher than Cr or Fe. Concentrations of the various Hg species were very similar during summer and winter indicating that there was not a dominant seasonal influence on Hg speciation in rainwater at this location. THg, TDHg, and MMHg concentrations were also not significantly impacted by storm origin suggesting that they are relatively well mixed regionally and that air mass back trajectory is not the dominant factor controlling their concentration at this location. Concentrations of TDHg and Hgpart were inversely correlated in rainwater samples subjected to irradiation with simulated sunlight, suggesting the distribution between dissolved and particulate Hg may be controlled by photochemical transformations. Unlike TDHg and Hgpart, no significant changes in MMHg were observed upon photolysis of rainwater indicating that its distribution is not significantly driven by sunlight-mediated reactions, in contrast to what has been observed in surface waters. Results presented in this study indicate that the speciation of Hg in rainwater is dynamic and is driven by a complex combination of natural and anthropogenic processes as well as interactions with sunlight.  相似文献   

15.
有机碳氮是影响陆地生态系统的重要因子,保持并提高土壤碳氮储量,是稳定生态系统生产力的关键.以南京紫金山土壤为研究对象,依照海拔高度进行采样,对比分析了土壤有机碳氮的变化规律.研究结果表明:紫金山土壤有机碳氮受地表植被的影响比较大,混交林>林地>草地,土壤有机碳氮总量随海拔的升高呈现上升趋势,土壤碳氮比高达34~45,且随海拔升高呈下降趋势.相关分析表明,紫金山土壤有机碳与全氮质量分数呈显著正相关关系,由此说明氮素主要以有机氮的形式存在于有机质中.  相似文献   

16.
Summary Minimum tillage, no-tillage and mulching have been broadly used in modern Chinese agricultural production in the past 20 years. The application area has reached 12.34 million hectares, and a corn, soybean, rape, wheat, peanut and rice have been involved in these tillage systems. These techniques have provided obvious benefits of soil and water conservation on sloping farm-land in the hill regions; obtained remarkable effects of storing water and reducing drought in the dryland farming regions; and resulted in some success in the reclamation of saline soil. The common characteristics in different regions are building a good agri-ecological environment, improving soil physical properties, enhancing the capacity of storing water, regulating the activity of soil micro-organisms, improving the accumulation of soil organic matter and nutrients, fertilizing the land and increasing crop production. In comparison with the traditional tillage systems, crop production increased 10–20% and the benefit of soil and water conservation was 40–90%.With 2 Figures  相似文献   

17.
Forests play an important role in sequestrating carbon from the atmosphere. Since the 1980s, reforestation activities have been implemented in the area surrounding the Qianyanzhou Forest Experimental Station in Jiangxi Province, China. Farmland and heavily eroded waste land were replanted with fruit, orchards and forest plantations. The area surrounding the Qianyanzhou Forest Experimental Station was selected as research site to analyze the potential of reforestation in carbon sequestration. This study evaluates the variation of soil organic carbon storage under the different land use types. Soil organic carbon storage varied greatly with land use types. From 1984 to 2002, soil organic carbon storage increased 2.45 × 106 kg across eight land use types. This study demonstrates the potential for carbon sequestration in soils from reforestation. However, a complete understanding of soil carbon fluxes at the landscape scale will depend on the potential and retention period of soil organic carbon.  相似文献   

18.
Incorporating organic soil into a global climate model   总被引：3，自引：1，他引：2  
Organic matter significantly alters a soil’s thermal and hydraulic properties but is not typically included in land-surface schemes used in global climate models. This omission has consequences for ground thermal and moisture regimes, particularly in the high-latitudes where soil carbon content is generally high. Global soil carbon data is used to build a geographically distributed, profiled soil carbon density dataset for the Community Land Model (CLM). CLM parameterizations for soil thermal and hydraulic properties are modified to accommodate both mineral and organic soil matter. Offline simulations including organic soil are characterized by cooler annual mean soil temperatures (up to ∼2.5°C cooler for regions of high soil carbon content). Cooling is strong in summer due to modulation of early and mid-summer soil heat flux. Winter temperatures are slightly warmer as organic soils do not cool as efficiently during fall and winter. High porosity and hydraulic conductivity of organic soil leads to a wetter soil column but with comparatively low surface layer saturation levels and correspondingly low soil evaporation. When CLM is coupled to the Community Atmosphere Model, the reduced latent heat flux drives deeper boundary layers, associated reductions in low cloud fraction, and warmer summer air temperatures in the Arctic. Lastly, the insulative properties of organic soil reduce interannual soil temperature variability, but only marginally. This result suggests that, although the mean soil temperature cooling will delay the simulated date at which frozen soil begins to thaw, organic matter may provide only limited insulation from surface warming.  相似文献   

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