Preliminary study on heavy metals contamination of soil using solid phase speciation and the influence on groundwater in Bozanta–Baia Mare Area,Romania

Abstract

A preliminary study on soil contamination with heavy metals and As based on solid phase speciation according to the Tessier scheme and the influence on groundwater in an area under anthropogenic influence (Bozanta-Baia Mare, Romania) was conducted. The partitioning of Al, As, Cd, Cu, Fe, Mn, Pb and Zn in five fractions is discussed in relation to soil characteristics, pH, organic matter content, mineralogical composition and distribution of the same elements in airborne particulate matter. The airborne particulate matter contains high quantities of As, Cd, Cu, Pb and Zn as exchangeable fraction. The sequential extraction carried out on soil samples revealed the main role of Fe-Mn oxides surface in the immobilization of metals. Organic matter has a specific role in complexation of Cu, Pb, As and Al, since high contents of these metals were recovered in the oxidizable fraction. Cadmium has a high selectivity for carbonate minerals. The amendment of soil with natural fertilizer increases the exchangeable fraction of metals with the highest toxicity. The available fraction for plants (exchangeable + carbonate-bound species) exceeded the alert values in soil, therefore the continuous monitoring of the area is necessary. The soil is unsuitable for agricultural use due to high contamination on surface with toxic elements resulted from anthropogenic activities. Groundwater is contaminated with very toxic elements (As, Cd and Pb) but also with Cu, Mn and Zn and is unsuitable as supply for drinking water.     

Accumulation of trace elements in agricultural topsoil under different geological background

For establishing rational farming mechanism, it is essential to know the relative contribution of different geological background and anthropogenic activities to trace elements in agricultural soil. In this paper, 282 surface soil samples were collected based on the different geological background. Five harmful trace elements (As, Cd, Cr, Hg and Pb) were analyzed. The results indicated most of trace elements contents were far beyond the threshold of uncultivated soil background, which indicate anthropogenic input strongly influenced on trace elements in agricultural soil. In addition, correlation analysis showed trace element contents exhibited high relationships with soil pH, C/N and physical clay (<0.01 mm) (p?<?0.05). The principal component analysis showed that the first component included Cd, Cr and Hg, while Pb and As formed the second component. Furthermore, in the agricultural topsoil derived from carbonate rock, the high background values of trace elements and alkaline condition made the enrichments of Cd, Cr and Hg were the most significant. In the agricultural topsoil derived from red residua, the Pb and As contents was the highest values among the soil categories, partly because the type of soil had amount of physical clay (<0.01 mm). In the agricultural topsoil derived from shale, the pH or physical clay had significant relationship with Cd, Pb, Hg and As (p?<?0.01). In the agricultural topsoil derived from sand stone, the acid condition and loose texture might account for the lowest values of Cd, Cr, Pb and As content to some extent.     

贵州水银洞金矿紫茎泽兰重金属元素测定与分析

利用原子吸收法对贵州水银洞金矿紫茎泽兰及其基质中Cr、Pb、Zn、Cd、Hg和As含量进行了测定和分析。结果表明,贵州水银洞金矿废水处理区土壤Hg(12.575 mg·kg^-1)和As(501.374 mg·kg^-1)已严重超标,Hg和As的平均含量分别是国家土壤环境质量三级标准(GB15618-1995)的8.383倍和12.534倍,污染极为严重;紫茎泽兰对该矿区不同的重金属富集能力不同,尤其对该矿区Cr有较强的富集作用,具有一定的Cr污染修复潜力。紫茎泽兰对所测定的6种重金属元素的吸收转移能力有较大的差异,整个植株对Pb、Zn 和Cr具有很强的吸收转移能力。其茎、叶对不同的重金属元素的吸收转移能力也呈现出很大的差异,紫茎泽兰茎对Cr、Pb和Cd具有很强的吸收转移能力,而叶对Zn、Pb和Hg具有很强的吸收转移能力。除As外,紫茎泽兰对Cr、Pb、Zn、Cd和Hg都具有不同程度的耐受能力,对该矿区的生态恢复具有重要的作用。     

Concentrations and chemical forms of heavy metals in agricultural soil near the world’s largest and oldest tungsten mine located in China

Abstract

Tungsten (W) mining has taken place in Ganzhou in China for about 100 years. Such long-term W mining may release large amount of metals to soils and waters around these mines. Twenty soil samples were taken from the area around the W mines and 10 soil samples from an area much farther away. These soil samples were analysed for physicochemical properties, heavy metal content and their chemical forms. Results show that long-term W mining significantly increased both total and labile contents of Cd, Cu, Pb and Zn, but did not, or only slightly, increased the total content of Co, Cr and Ni in the soil near the mine. Average enrichment factor (EF) in the agricultural soils was 4.0, 2.4, 2.2, and 2.0 for Cd, Cu, Pb and Zn, respectively. The labile fraction was dominated by the carbonate-bound fraction for Cd (54.5%) and organic matter-bound fraction for Cu (37.9%), while the major labile fractions for Pb and Zn were associated with carbonates (30.2% and 6.4%), oxides (17.9% and 10.6%) and organic matter (9.2% and 18.8%). Consequently, there is a need to be cautious about Cd in the soils contaminated by W mining.     

Controlling Factors and Pollution Assessment of Potentially Toxic Elements in Topsoils of the Issyk-Kul Lake Region,Central Asia

The Issyk-Kul Lake region is well known for its magnificent scenery and unique scientific significance. With multivariable statistical methods, the contents of several geochemical elements (Fe, Mn, V, Zn, Cr, Co, Ni, Cu, As, Mo, Cd, Sb, Tl, Pb, and Hg) and total organic matter of 61 topsoil samples were analyzed, and then, the results were used to assess the environmental factors controlling the concentrations of potentially toxic elements (PTE) in the region. The results showed that most of the elements including Fe, Mn, V, Cr, Co, Ni, Cu, As, and Sb reflected the natural state, but several PTE (Zn, Mo, Hg, Cd, Pb, and Tl) had been influenced by anthropogenic factors. Among these, Zn, Mo, Hg, and Cd were significantly correlated with the organic matter content, which suggests that agricultural soils will accumulate more PTE. From the calculations for the human risk assessment of anthropogenically derived PTE (Zn, Mo, Hg, Cd, Pb, and Tl), the risks for ingestion in this region were found to be higher than those for inhalation and dermal absorption; however, the results also suggested there are no non-carcinogenic risks for all anthropogenically influenced PTE in the current state.     

Vertical and Horizontal Distributions of Zn,Cd, Pb,Cu, and Hg in Uncultivated Soil in the Vicinity of a Zinc Smelter at Odda,Norway

In the present work the extent and variation of Zn, Cd, Pb, Cu, and Hg loading in undisturbed surface soil (0–5 cm) and the vertical transport of the metals in soil profiles are studied in the vicinity of a zinc smelter in Norway. Three major controlling factors on the metal concentrations in soil have been assessed: 1) distance from the anthropogenic point source; 2) organic matter content (O.M.); and 3) the prevailing wind directions. Moreover metal distributions in proximal soil profiles in 1972 and 2003 are compared. Current concentrations of Zn, Cd, Pb, Cu, and Hg in surface soil reach 14000, 60, 980, 430, and 7.0 mg·kg ^{? 1} , respectively, near the smelter and decrease regularly with distance in the northerly direction according to the regression model (y = ax^{? b} ). The Zn concentrations are significantly different from the background range up to 30 km from the smelter, whereas the other metals approach background at only 10 km distance. Subsurface concentration peaks of Pb, Cu, and Hg are found at greater depth in soil profiles than peaks of Zn and Cd. Levels of Zn, Cd, and Pb in surface soil seem to have decreased from 1972 to 2003, whereas for Cu the levels appear not to be significantly different.     

山东省部分水岸带土壤重金属含量及污染评价

为了解山东省水岸带土壤重金属的含量特征和污染状况,于2010年9月—10月采集了39个水岸带土壤样品,分析了土壤中Cr、Co、Ni、Cu、Zn、Cd、Pb和Hg的含量以及土壤的pH值、粒度和有机质,采用单因子指数法、综合指数法和潜在生态危害指数法对水岸带土壤重金属污染进行了评价,并利用相关分析和聚类分析对其来源进行了初步的解析。结果表明：水岸带土壤的pH值为5.67—8.66,主要呈碱性;有机质的平均含量为9.39 g/kg,土壤粒度主要以砂粒和粉粒为主,其平均体积百分比分别为50.33%和38.48%,平均粒径为89.69 μm;Cr、Co、Ni、Cu、Zn、Cd、Pb和Hg的平均含量为53.03 mg/kg、10.33 mg/kg、24.96 mg/kg、18.38 mg/kg、56.13 mg/kg、0.142 mg/kg、22.48 mg/kg和0.020 mg/kg。各水岸带土壤重金属的含量均符合《土壤环境质量标准》（GB15618-1995）二级标准。以山东省土壤元素背景值为评价标准,水岸带土壤重金属总体表现为轻度污染和轻微生态风险,其中Cd和Hg是主要的污染因子,其对潜在生态危害指数的平均贡献率分别为46.8% 和33.6%。洙赵新河、廖河、门楼水库和东平湖水岸带土壤重金属污染及潜在生态危害明显高于其他水源地。源解析的结果表明：水岸带土壤重金属的含量受自然源和人为源的双重影响,人为源主要包括地表径流、工业废气、垃圾和交通运输等。     

龙胜县丘陵山区土壤与罗汉果重金属含量及潜在生态危害评价——以宝赠村为例

桂林市龙胜县作为罗汉果的三大主产区之一,种植区土壤重金属含量及罗汉果质量影响到该区罗汉果产业的健康发展.为探索龙胜县丘陵山区典型贫困村罗汉果园的安全性,该文研究了宝赠村典型罗汉果园土壤及罗汉果果实中砷、铜、锌、铅、镉、铬、汞7种重金属含量,并采用Hankanson指数法分析了其潜在生态风险.结果表明:(1)龙胜丘陵山区...     

Manure Application and Cannabis Cultivation Influence on Speciation of Lead and Cadmium by Selective Sequential Extraction

The contamination of agricultural soils by heavy metals is a worldwide problem. Degradation of organic matter (OM) from organic amendments used in the remediation of metal-contaminated soils leads to changes in soil chemical properties shortly after their addition, which may affect the soil metal distribution. The effects of four differing organic amendments on chemical forms of Pb and Cd in a contaminated soil were investigated in a pot experiment of control unamended soil and soils amended with dry cow and poultry manures (20 g CM or PM kg^?1 soil), and cow and poultry manure extracts (2 g CME or PME kg^?1 soil) cultured with cannabis sativa. After eight weeks, a sequential extraction scheme was used to fractionate soil Pb and Cd into soluble-exchangeable (Sol-Exch), organic matter associated (AOM), and carbonates associated (ACar) forms. The addition of animal manures and their extracts increased the DTPA-extractable Pb and Cd in soil significantly. Soil Pb and Cd in Sol-Exch fraction were increased by manure applications. Both Pb and Cd in AOM fraction were increased by application of manures and their extracts. This increase was more obvious for Pb in application of cow and poultry manure extracts. The ACar chemical forms of Pb and Cd were also increased by application of manures and their extracts. The increases of Pb and Cd in Acar fraction was noticeable in soils treated with cow manure. Soil cultivation with cannabis sativa increased available, Sol-Exch, and AOM chemical forms of Pb in soil significantly compared to control soil. However, soil Pb and Cd in ACar fraction were decreased significantly by cannabis cultivation. The effect of cannabis cultivation on all of the Cd chemical forms (except on Sol-Exch) was similar to the results of Pb chemical forms. Plant cultivation had no significant effect on Cd in Sol-Exch chemical form.     

基于GIS和地统计学的稻田土壤养分与重金属空间变异

以湖南省长沙县北山镇3.56 hm²的水稻田为研究区域,基于网格法(25 m×25 m)等距离取样,采用GIS和地统计学相结合的方法,对研究区土壤耕作层(0～20 cm)的pH值、有机质、全氮、速效磷、阳离子交换量(CEC)与3种典型重金属元素Cd、As、Pb的空间变异特征进行了定量分析.结果表明: 研究区内土壤pH值和Pb含量表现为弱变异,其他各项指标均表现出中等强度变异,变异顺序的大小为:速效磷＞Cd＞全氮＞有机质＞CEC＞As＞Pb＞pH.半方差检验结果表明,有机质、速效磷、As的半方差函数的最佳拟合模型为指数模型;pH、全氮、CEC、Cd和Pb的最佳拟合模型为球状模型;除CEC呈中等空间相关外,其余指标均表现出强烈的空间相关.克里格插值分析表明: pH、全氮、CEC、Pb呈斑块状分布;有机质、速效磷、Cd、As呈块状和带状分布.植被、地形和人类活动是造成研究区土壤养分与重金属格局差异的主要因素.相关性分析表明,部分土壤养分与重金属含量的相关性达到显著水平,其中pH与有机质、Cd与Pb的相关性达到了极显著相关水平.     

新疆焉耆盆地辣椒地土壤重金属污染及生态风险预警

从新疆加工辣椒主产地(焉耆盆地)采集105个辣椒地典型土壤样品,测定其中As、Cd、Cr、Cu、Mn、Ni、Pb和Zn等8种重金属元素的含量。采用污染负荷指数(Pollution load index,PLI)、潜在生态风险指数(Potential ecological risk index,RI)和生态风险预警指数(Ecological risk warning index,I_(ER))对辣椒地土壤重金属污染及生态风险进行评价。结果表明:(1)焉耆盆地辣椒地土壤Cd、Cr、Ni、Pb和Zn含量的平均值分别超出新疆灌耕土背景值的1.65、1.40、1.32、3.21、6.42倍。辣椒地土壤Pb和Zn呈现重度污染,Cd、Cr和Ni轻度污染,As、Mn和Cu无污染。(2)土壤PLI平均值为1.40,呈现轻度污染。各重金属元素单项生态风险指数从大到小依次为:Cd、Ni、As、Cu、Pb、Cr、Zn。土壤RI平均值为18.40,属于轻微生态风险态势,IER平均值为-4.78,属于无警态势;博湖县辣椒地污染水平、潜在生态风险程度与生态风险预警等级最高,焉耆县污染水平、潜在生态风险程度与生态风险预警等级最低。(3)辣椒地土壤As、Cd、Pb与Zn主要受到人类活动的影响,Cr、Cu、Mn和Ni主要受到土壤地球化学作用的控制。Cd是焉耆盆地辣椒地生态风险等级最高的重金属元素,研究区农业生产过程中要防范Cd的污染风险。     

Soil Nitrogen Fertilization Effects on Phytoextraction of Cadmium and Lead by Tobacco (Nicotiana tabacum L.)

A greenhouse experiment using 24 plastic pots filled with 6 kg of Pb- and Cd-contaminated soil was carried out. In all 24 pots, soils were heavy metal–contaminated with 10 mg Cd kg^?1 soil and 500 mg of Pb kg^?1 soil by using CdCl and PbNO₃. Two-month-old tobacco (Nicotiana tabacum L.) plants were used to extract these heavy metals. Results showed that tobacco is able to remove Cd and Pb from contaminated soils and concentrate them in its harvestable part, that is, it could be very useful in phytoextraction of these heavy metals. Increasing additions of ammonium nitrate to soil (50, 100, and 150 mg N kg^?1 soil) significantly (p ≤ .05) increased aboveground Cd and Pb accumulation during a 50-day experimental period, whereas increasing additions of urea to soil (50 and 100 mg N kg^?1 soil) did not show these effects at the same significance levels. Increasing additions of ammonium nitrate to soil shows as dry matter increases, both accumulated Cd and accumulated Pb also increase when tobacco plants are growing under Pb- and Cd-contaminated soil conditions. Higher Pb concentrations depress Cd/Pb ratios for concentrations and accumulations, suggesting that Pb negatively affects Cd concentration and/or accumulation.     

金毛狗对重金属的富集特性的研究

为探讨金毛狗[Cibotium barometz(L.) J. Sm.]对重金属的富集能力,在广东省选取6个样点(南岭、南昆山、白云山、大岭山、梧桐山、西樵山)采集金毛狗的叶片、根状茎和根际土壤,采用ICP-MS测定9种重金属元素(Cr、Mn、Ni、Cu、Zn、As、Cd、Hg、Pb)的含量。结果表明,样地土壤已受到不同程度的重金属污染,土壤中Cd和Hg含量均高于广东省土壤背景值,分别为背景值的1.61~4.82倍和4.74~11.79倍。西樵山土壤中Cd含量最大,南岭土壤中Hg含量最大。在9种元素中,金毛狗对Hg的转运系数最高,达4.8,对Cd的富集系数最高,达2.2,Cu和Cd元素的转运系数和富集系数均大于1。这说明金毛狗对重金属元素的富集能力较弱而转运能力较强。     

Association of Soil Aggregation with the Distribution and Quality of Organic Carbon in Soil along an Elevation Gradient on Wuyi Mountain in China

Forest soils play a critical role in the sequestration of atmospheric CO₂ and subsequent attenuation of global warming. The nature and properties of organic matter in soils have an influence on the sequestration of carbon. In this study, soils were collected from representative forestlands, including a subtropical evergreen broad-leaved forest (EBF), a coniferous forest (CF), a subalpine dwarf forest (DF), and alpine meadow (AM) along an elevation gradient on Wuyi Mountain, which is located in a subtropical area of southeastern China. These soil samples were analyzed in the laboratory to examine the distribution and speciation of organic carbon (OC) within different size fractions of water-stable soil aggregates, and subsequently to determine effects on carbon sequestration. Soil aggregation rate increased with increasing elevation. Soil aggregation rate, rather than soil temperature, moisture or clay content, showed the strongest correlation with OC in bulk soil, indicating soil structure was the critical factor in carbon sequestration of Wuyi Mountain. The content of coarse particulate organic matter fraction, rather than the silt and clay particles, represented OC stock in bulk soil and different soil aggregate fractions. With increasing soil aggregation rate, more carbon was accumulated within the macroaggregates, particularly within the coarse particulate organic matter fraction (250–2000 μm), rather than within the microaggregates (53–250μm) or silt and clay particles (< 53μm). In consideration of the high instability of macroaggregates and the liability of SOC within them, further research is needed to verify whether highly-aggregated soils at higher altitudes are more likely to lose SOC under warmer conditions.     

Leaching of Zinc,Cadmium, and Lead in a Sandy Soil Due to Application of Poultry Litter

Dissolved organic matter in poultry litter could contribute organic ligands to form complexes with heavy metals in soil. The soluble complexes with heavy metals can be transported downward and possibly deteriorate groundwater quality. To better understand metal mobilization by soluble organic ligands in poultry litter, soil columns were employed to investigate the movement of zinc (Zn), cadmium (Cd), and lead (Pb). Uncontaminated soil was amended with Zn, Cd, and Pb at rates of 400, 8, and 200 mg kg ^{? 1} soil, respectively. Glass tubes, 4.9-cm-diameter and 40-cm-long, were packed with either natural or metal-amended soil. The resulting 20-cm-long column of soils had bulk density of about 1.58 g cm ^{? 3} . Columns repacked with natural or amended soil were leached with distilled water, 0.01 M EDTA, 0.01 M CaCl ₂ , or poultry litter extract (PLE) solutions. Low amounts of Zn, Cd, and Pb were leached from natural soil with the solutions. Leaching of Zn, Cd, or Pb was negligible with distilled water. In the metal-amended soil, EDTA solubilized more Zn, Cd, and Pb than CaCl ₂ and PLE. The breakthrough curves of Zn and Pb in the PLE and CaCl ₂ were similar, indicating they have similar ability to displace Zn and Pb from soils. Compared with Zn and Cd the PLE had a small ability to solubilize Pb from metal-amended soil. Thus, the application of poultry litter on metal-contaminated soils might enhance the mobility of Zn and Cd.     

An Investigation of the Soil Property Changes and Heavy Metal Accumulation in Relation to Long-term Wastewater Irrigation in the Semi-arid Region of Iran

Concentrations and spatial distribution of Zn, Cu, Cd, and Pb along two landscapes including a wastewater-irrigated area and a control area were determined to assess the impact of long-term wastewater irrigation and landscape properties on heavy metal contamination. Some disturbed and undisturbed soil samples were taken from soil trenches and soil cores, located on three main landscape positions (upper slope, midslope, and lower slope) in northwestern Iran. The investigation showed that the mean concentration of the heavy metals followed the order Zn > Cu > Pb > Cd in the wastewater-irrigated soil and Pb > Zn > Cu > Cd in the control soils. On average, compared to similar positions in the control region, the wastewater-irrigated regions contained 3.0 (midslope) to 4.9 (lower slope), 2.7 (midslope) to 4.6 (lower slope), 3.3 (upper slope) to 4.1 (lower slope), and 1.7 (upper slope) to 2.6 (lower slope) times higher amounts of Zn, Cu, Cd, and Pb, respectively. Significant positive relationships (P < 0.05) were recorded between the heavy metals concentration with <0.002 mm particle-size fraction and organic matter content, the fractions linked to runoff and soil erosion. It is believed that the two soil fractions play a crucial role in the distribution of the metals along the wastewater-irrigated landscape. Despite the significant increase of heavy metals (P < 0.05) in the wastewater-irrigated soils compared with control soils, the concentration of all evaluated metals was below the maximum accepted limits (Zn < 300 mg/kg, Cu < 100 mg/kg, Cd < 5 mg/kg, and Pb < 100 mg/kg), and grouped as “not-enriched” to “moderately-enriched” categories regarding the topsoil enrichment index. Overall, the lower slope was shown to be more contaminated with the heavy metals compared to the other positions.     

Bioaccumulation of mercury,arsenic, cadmium,and lead in plants grown on coal mine soil

Mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) are the major toxic metals released by coal mining activities in the surrounding environment. These metals get accumulated in the soils. The plants grown on the contaminated soil uptake these toxic metals in their roots and aerial parts. This study monitored the bioaccumulation of Hg and other three toxic metals in coal mine soil. The pot study of Hg accumulation in Brassica juncea showed that the extent of Hg uptake by roots and shoots of the plants grown on was high in the mature plant and Hg content in root was higher than the shoot. In the soil of unreclaimed overburden (OB) dump, the toxic metal content was higher than that of reclaimed OB dump which posed high ecological risk in the soil of unreclaimed OB dump. Bioaccumulation coefficient (BAC) value showed that Hg was not accumulated in the leaves of Dalbergia sissoo L., Gmelina arborea, Peltaphorum inerme L., Cassia seamea L, and Acacia mangium L grown on coal mine soil.     

不同粒径红壤胶体颗粒对DNA的吸附特性

采用平衡法研究了含有机质粗粘粒、去有机质粗粘粒、含有机质细粘粒和去有机质细粘粒4种红壤胶粒对DNA的吸附特征及其热力学特性.结果表明: 4种红壤胶粒对DNA的吸附是快反应过程,Langmuir吸附方程可较好地描述4种红壤胶体对DNA的等温吸附,相应拟合的相关系数r²分别为0.974、0.991、0.958和0.975.最大吸附量表现为含有机质细粘粒>去有机质细粘粒>含有机质粗粘粒>去有机质粗粘粒.电解质浓度和种类及吸附体系pH是影响红壤胶体对DNA吸附的重要因子,一定电解质浓度范围(NaCl<60 mmol·L^-1,CaCl₂<10 mmol·L^-1)内,DNA在红壤胶体表面的吸附量随电解质浓度的增大而显著增加,其中钙离子的促进作用大于钠离子,但随着吸附体系pH的上升而显著降低.含有机质胶粒对DNA的吸附过程是吸热反应,而去有机质胶粒对DNA的吸附过程是放热反应,红壤胶粒对DNA的吸附反应过程是一个熵增过程.     

Phytostabilization of Acidic Soils with Heavy Metal Contamination Using Three Forage Grasses in Combination with Organic and Inorganic Amendments

Two experiments were conducted to investigate the effects of organic and inorganic amendments on metal stabilization and the potential of three forage grasses, i.e., Pennisetum americanum × Pennisetum, Euchlaena mexicana, and Sorghum dochna, for phytostabilization of acidic heavy metal-contaminated soils. The three grasses died 5 days after transplanting into the contaminated soils. Organic fertilizer (pig slurry and plant ash) only or combined with lime, NPK fertilizer, and sewage sludge resulted in adequate grass growth in the contaminated soils through a significant increase in the soil pH, N, P, K, and organic matter contents, and a decrease in the metal concentrations. The shoot biomass of P. americanum×P. purpureum and S. dochna was 1.92 and 2.00 times higher than that of E. Mexicana. The solubility of Cd, Pb, and Zn strongly depends on organic matter, while the solubility of Cu strongly depends on both soil organic matter and pH. The concentrations of Cd, Pb, and Zn in plant shoots growing in soil with a mixed amendment were significantly lower than plants growing in soil amended with an organic fertilizer only, whereas the Cu concentrations in plant shoots exhibited the opposite trend. The results indicated that 5% organic fertilizer only or combined with 5% sewage sludge were appropriate amendments and S. dochna and P. americanum × Pennisetum are suitable plants for phytostabilization of acidic heavy metal-polluted soils.     

广州市花都城区绿地土壤肥力与重金属污染分析

在对广州市花都城区绿地土壤取样调查的基础上,采用全国第二次土壤普查养分分级标准和内梅罗污染指数法等对其土壤肥力和重金属污染情况进行分析评价,揭示花都城区绿地土壤存在的问题。结果表明,花都城区绿地土壤容重变幅在1.25～1.75 g·cm^–3之间,孔隙度变幅在30.81%～47.42%之间,pH在6.16～7.68之间,有机质含量在四级及以下标准,严重缺乏氮素和磷素。不同绿地类型中,厂区路旁绿地土壤重金属污染最严重,其次为主干道两侧绿地;研究区As污染最严重,Pb次之,未受Zn污染,存在不同程度的Cu、Cd、Cr、Ni、Hg污染。相关性分析表明,土壤pH与全钾、碱解氮含量极显著相关,有机质与全氮极显著相关,全氮、全磷分别与碱解氮、有效磷显著正相关,全钾与碱解氮显著负相关;重金属元素中,Cu与Zn、Cr、Ni极显著相关,Zn与Cu、Pb、Cd、Cr、Ni极显著相关,Pb与Zn、Cd极显著相关,Cr与Cu、Zn、Ni极显著相关,As和Hg与其他重金属元素均无显著相关性。