基于三七质量安全的土壤Cd和Pb风险阈值

为保障三七(Panax notoginseng)绿色种植和质量安全,探讨中国三七安全生产的土壤风险阈值。分析土壤理化性质、土壤Cd(镉)、Pb(铅)含量和有效态、三七主根Cd、Pb含量,通过线性相关分析三七主根Cd、Pb与土壤理化性质及土壤Cd、Pb总量与有效态之间的关系。利用回归模型建立土壤Cd、Pb总量有效态与三七主根Cd、Pb的回归方程,反推土壤有效态Cd、Pb阈值。结果表明,三七种植区土壤Cd、Pb样品超标率分别是83.64%和16.36%,土壤Cd污染严重,土壤Pb处于清洁水平。三七主根Pb含量未超标,Cd含量超标率为29.09%。土壤pH与三七主根Pb呈显著负相关,三七主根Cd含量与土壤Cd含量和土壤有效态Cd含量分别呈显著和极显著正相关;三七主根Pb与土壤Pb含量和土壤有效态Pb均呈极显著正相关。基于三七主根Cd、Pb限量标准推导出土壤有效态Cd阈值为0.27 mg/kg,土壤有效态Pb阈值为70.66 mg/kg。

磁性微碳球改性材料修复Pb污染土壤的影响因素与作用机理

Pb(Ⅱ)是有毒重金属,被世界卫生组织国际癌症研究机构列为一类致癌物,如何从土壤中去除Pb是土壤污染修复中的重要课题。该文采用水热合成法制备磁性陶粒负载微碳球并经聚乙二醇改性功能材料MCCSPG用于土壤Pb污染修复。结果表明,MCCSPG对土壤Pb具有很好的吸附去除效果,总Pb平均去除率为94.11%,有效态Pb去除率达95%以上。在影响土壤Pb去除率的因素中,材料投加量、作用时间和土壤Pb初始含量在吸附平衡之前与去除率均为正比关系,而pH为弱酸性时去除率大,pH为4.9时吸附量最大,材料的最大吸附容量可达48 mg/g。MCCSPG对土壤中Pb不仅存在化学吸附,还有相当数量的物理吸附,吸附过程符合Freundlich等温吸附和准一级动力学模型。吸附上升阶段持续时间长、吸附量起点低,材料投入土壤吸附Pb需要12 d以上达最大吸附量。

Spatial Variation Characteristics of Soil Available Plumbum (Pb) in Vegetable Bases in Urumqi City

[Objective] The paper was to study the spatial variation characteristics of soil available plumbum （Pb） in vegetable bases of Urumqi City. [Method] With the vegetable base in northern suburb of Urumqi city as a typical area, the structure feature of soil available Pb content in suburb of oasis city in the arid area was ana- lyzed to get the spatial distribution pattern of available Pb, the origin and pollution source of this distribution pattern were also revealed. [Result] The available Pb in vegetable base of northern suburb in Urumqi City belonged to moderate variation. Semivariance model fitting showed that available Pb content could be fit with expo- nential function, which had spatial correlation within a certain range. The spatial dis- tribution pattern of available Pb content was obtained by using optimal Kriging inter- polation, and indicated that soil available Pb content was closely related to industrial activities, sewage irrigation and atmospheric dust. [Conclusion] The study provided the scientific basis for recognition, pollution risk assessment and pollution control of Pb pollution sources in the region, which have great significance on creating safe and clean production environment and selecting reasonable vegetable planting districts.

Remediation Effects of Different Concentration of Nano-Hydroxyapatite Level on Pb-Contaminated Soil

Phosphorus-containing amendments can reduce the mobility of Pb in soil. Hydroxyapatite (HAP) is one of the most commonly used phosphorus-containing amendments. With the development of nanotechnology, nano-hydroxyapatie (n-HAP) was gradually applied to remediate soil polluted by heavy metals. Considering the concentrations of HAP/n-HAP were not more than 5% in most studies, soil polluted by Pb was artificially prepared and three different concentrations of n-HAP: 5%, 7% and 10% by weight, were added into the Pb-polluted soil separately. The mixtures of soil and n-HAP were incubated for 180 d and sampled regularly. The bioaccessibility of Pb in soil was determined using simulated gastric juices of two in-vitro digestion tests: USPM (United States Pharmacopeia Methodology) and PBET (Physiologically-Based Extraction Test). The results showed that the immobilizing efficiency of 5% n-HAP to Pb in soil was the highest in PBET. The extractable Pb from soil by USPM was not affected by concentration of n-HAP. So, the least concentration of n-HAP, i.e. 5% n-HAP treatment, was the most cost-effective in USPM. Soil pH increased with concentration of n-HAP. However concentration of n-HAP had little effects on content of soil OM. According to regression analysis, more than 50% differences of the extractable Pb from soil by PBET can be explained by soil pH, while soil pH, organic matter content and incubation time together explained nearly 85% differences of extractable Pb from soil by USPM.

Adsorption characteristic of bensulfuron-methyl at variable added Pb^(2+) concentrations on paddy soils

The combined pollution of heavy metal Pb^2＋ and bensulfuron-methyl （BSM）, originating from chemical herbicides, in agroecological environments has become commonplace in southern China. The adsorption of BSM on three paddy soils in the presence of Pb^2＋ was examined using high-performance liquid chromatograph （HPLC）. Results indicated that adsorption of BSM could accurately be described by a Freundlich isotherm equation with correlation constant （R） 〉 0.98, irrespective of the presence of spiked Pb^2＋. Of the various factors influencing BSM sorption, soil pH appeared to be the most influential. The constant Kf of Freundlich isotherm equation tended to increase with increasing Pb^2＋ concentration in soil which indicated that the spiked of Pb^2＋ in paddy soils would promote the sorption of BSM. AGo of BSM in three paddy soils was less than 40 kJ/mol in all treatments, indicating the adsorption of BSM is mainly physical in nature. The elution of soil dissolved organic matter （DOM） enhanced the adsorption of BSM in paddy soils. The mechanisms involved in the promotion effects of the spiked Pb^2＋ on BSM adsorption might be the modified surface characteristics of paddy soil solids due to the soil acidification and the increase of soil organic matter concentration because of DOM binding.

Bioavailability of crops to environmental hormone Pb in soils and its remediation

Lead (Pb), as an environmental hormone, acts as an estrogen in animal and human bodies, and its envi- ronmental pollution can result in many procreant anomalies, such as maladjustment of incretion, weakening of pro- creation function and descending of genital immunity. Experiments on pot-growth of paddies and corns in this study indicated that these crops did not show any macro-toxic symptoms in the observed contents of Pb added (0–4000 mg/kg) in soils. However, lead in soils can be easily absorbed by crops and accumulated in the different parts of plants. Statistical analysis showed that Pb contents in the crops are strongly positively correlated to the Pb contents in soils. In the crops, the Pb contents of roots are highest, tens to thousands of times those of straws and seeds. It is suggested that the root is a barrier of Pb absorbed by straws and seeds. Based on this fact, Pb pollution in soils can be gradually reduced by planting crops and subsequently removing the roots from the soil. This biotechnology may be used in environmental remediation, which embraces the quality of sustainable agricultural economy and a healthy environment.

Toxicity threshold of lead(Pb) to nitrifying microorganisms in soils determined by substrate-induced nitrification assay and prediction model

Lead （Pb） contamination has often been recorded in Chinese field soils. In recent years, efforts have been made to inves- tigate Pb toxicity thresholds in soils with plant growth and microbial assays. However, the influence of soil properties on Pb toxicity impacts on soil microbial processes is poorly understood. In this study ten soils with different properties were collected in China to investigate the relationships between thresholds of Pb toxicity to soil microbes and soil properties. The effect of soil leaching on Pb toxicity was also investigated to determine the possible influence of added anions on Pb toxicity during dose-response tests. Toxicity was inferred by measuring substrate-induced nitrification in leached and non-leached soils after Pb addition. We found that soil microbe Pb toxicity thresholds （ECx, x=10, 50） differed significantly between the soils; the 10% inhibition ratio values （ECI0） ranged from 86 to 218 mg kg-1 in non-leached soils and from 101 to 313 mg kg in leached soils. The 50% inhibition ratio values （EC50） ranged from 403 to 969 mg kg^-1 in non-leached soils and from 494 to 1 603 mg kg^-1 in leached soils. Soil leaching increased EC50 and EC50 values by an average leaching factor （LF） of 1.46 and 1.33, respectively. Stepwise multiple regression models predicting Pb toxicity to soil microbes were developed based on ECx and soil properties. Based on these models, soil pH and organic carbon are the most important soil properties af- fecting Pb toxicity thresholds （R2〉0.60）. The quantitative relationship between Pb toxicity and soil properties will be helpful for developing soil-specific guidance on Pb toxicity thresholds in Chinese field soils.

小麦秸秆生物炭对土壤中Pb污染的钝化研究

为揭示小麦秸秆生物炭不同添加比例对土壤中重金属Pb的钝化影响,本文取云南国土资源职业学院校区酸性土壤,以质量比2%、5%和10%分别添加600℃下制备的小麦秸秆生物炭,并在培养10天、30天和50天后取样分析土壤pH值和重金属Pb四种形态变化。结果表明:在相同的培养时间,添加量越大,土壤pH值越大。土壤钝化时间越长,土壤中pH值也呈现逐渐增大的趋势。生物炭添加量对土壤中Pb的钝化影响较大,显示随着T600添加比例增加,土壤中重金属Pb可交换态、可氧化态和可还原态含量呈逐渐降低趋势,当添加量在10%,培养50d时,Pb残渣态最大达69.27%,钝化效果最好。

Effect of combined pollution by heavy metals on soil enzymatic activities in areas polluted by tailings from Pb-Zn-Ag mine

Some enzymatic activities were determined in the areas polluted by tailings from Tiantai Pb-Zn-Ag Mine in Zhejiang Province of China. The results indicated the soil enzymatic activities decreased significantly with increase of concentrations of heavy metals or the distance away from mining tailing center, especially dehydrogenase and urease activities. Multivariate regression analysis between heavy metal contents and soil enzymatic activities indicated that single dehydrogenase activity was very significantly correlated to combined effect of soil heavy metals in mine area. Moreover, single urease, protease and acid phosphatase activities were significantly related to the combined effect of heavy metals. The results suggest it is feasible to use soil enzymatic activities to indicate the pollution situation by combined heavy metals in the soil of mine area.

Adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) in paddy soils cultivated for various years in the subtropical China

The adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ） on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The study showed that the organic matter content and cation exchange capacity （CEC） of the soils are important factors controlling the adsorption and desorption of Cu（Ⅱ） and Pb（Ⅱ）.The 15-Year paddy soil had the highest adsorption capacity for Pb（Ⅱ）,followed by the 35-Year paddy soil.Both the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu（Ⅱ） than the upland soil and other paddy soils.The 15-Year paddy soils exhibited the highest desorption percentage for both Cu（Ⅱ） and Pb（Ⅱ）.These results are consistent with the trend for the CEC of the soils tested.The high soil CEC contributes not only to the adsorption of Cu（Ⅱ） and Pb（Ⅱ） but also to the electrostatic adsorption of the two heavy metals by the soils.Lower desorption percentages for Cu（Ⅱ） （36.7% to 42.2%） and Pb（Ⅱ） （50.4% to 57.9%） were observed for the 85-Year paddy soil.The highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.

微生物菌剂对芦竹修复Pb污染土壤的影响

为了探明微生物菌剂对芦竹(Arundo donax Linn.)修复Pb污染土壤的影响,以ETS微生物菌剂为供试微生物菌剂,将对照组(未添加微生物菌剂和Pb)、微生物菌剂单一处理组(每个水泥池200 mL微生物菌剂)、Pb单一处理组(土壤Pb终质量浓度300 mg·kg^(-1))和微生物菌剂-Pb复合处理组(每个水泥池200 mL微生物菌剂,土壤Pb终质量浓度300 mg·kg^(-1))芦竹的生长情况和光合特性以及Pb的积累和迁移特征进行比较。结果显示:Pb单一处理组芦竹的株高、分蘖数和单丛地上部干质量显著(P<0.05)低于对照组,叶绿素相对含量、净光合速率和水分利用效率与对照组差异不显著(P>0.05),气孔导度、胞间CO_(2)浓度和蒸腾速率显著高于对照组;而微生物菌剂-Pb复合处理组芦竹的株高、分蘖数、单丛地上部干质量和水分利用效率显著高于Pb单一处理组,叶绿素相对含量和胞间CO_(2)浓度与Pb单一处理组差异不显著,净光合速率、气孔导度和蒸腾速率显著低于Pb单一处理组。Pb单一处理组芦竹根和茎的Pb含量显著高于对照组,叶的Pb含量和根的Pb富集系数与对照组差异不显著,茎和叶的Pb富集系数显著低于对照组;而微生物菌剂-Pb复合处理组芦竹根和茎的Pb含量以及根、茎和叶的Pb富集系数不显著高于Pb单一处理组,叶的Pb含量显著高于Pb单一处理组。从不同器官看,Pb单一处理组芦竹根的Pb含量和Pb富集系数最高,而微生物菌剂-Pb复合处理组芦竹叶的Pb含量和Pb富集系数最高。另外,芦竹的Pb转运系数在4个处理组间差异显著,其中,Pb单一处理组芦竹的Pb转运系数最低,微生物菌剂-Pb复合处理组芦竹的Pb转运系数显著高于Pb单一处理组。研究结果显示:微生物菌剂能够促进Pb胁迫下芦竹的生长,提高芦竹的Pb吸收和转运能力,进而增强其对Pb污染土壤的修复能力。

Determination of Pb Content in Soil Samples by Graphite Furnace Atomic Absorption Spectrometry

[ Objective] A method was established to determine trace Pb in soil by graphite furnace atomic absorption spectrometry. [ Method] The pre-treatment of soil sample was conducted by nitric acid -perchloric acid -hydrochloric acid system. Palladium nitrate was added to eliminate ma- trix interference. Digestion acid, ashing and atomization temperature of the sample were selected. The operating parameters of instrument and tem- perature-rise program of graphite furnace were optimized. National standard matter was used to verify accuracy of the method. [Result] The detec- tion limit for Pb was 0.27 μg/g by graphite furnace atomic absorption spectrometry, and the recovery rate was 91.0% -96.1%. [ Conclusion The method had rapid analysis velocity, high sensitivity, less interference and easy operation. When applied to determination of trace Pb in the soil, the method obtained satisfactory results.

A feasibility study on cleaning Pb-contaminated soil with chelating agents

In this paper, the complexing abilities of EDTA, TTHA and Cit. with lead in the Pb(2.59 mg/g) contaminated soil were compared in the laboratory. Possibilities for lead and the threeagents to develop stable complexes increased proportionally to the growth of lead complexible formwhen the PH values ranged between 4 and 6. Under acid conditions, logB_(Pb-TTHA)) valued as 28.1 wasmuch higher than logB_(Pb-EDTA), as 18.0 depending on producing Pb_2-TTHA (logK_(Pb_2-TTHA= 11 0) andPb-HTTHA (logK(Pb-HTTTHA)=8.2)). Conclusively, the complexing ability of TTHA with Pb still ex-aseded that of EDTA by about 10% even when the amount of TTHA added was only equal to onefourth of that of EDTA. Due to the lower cost and less harzn to crops, Cit. can still be taken as abetter chelating agent in acid soil although its coordinative capability with Pb was weaker thanEDTA and TTHA.

Effects of Pb on Rhizosphere Soil Enzyme Activity and Chemical Constituents of Achyranthes bidentata Blume

[Objectives]The purpose of this study was to investigate the effects of Pb on rhizosphere soil enzyme activity and chemical constituents of Achyranthes bidentata Blume.[Methods]A.bidentata Blume plants were cultivated in self-made polyvinyl chloride(PVC)pots.The soil was added with different levels of Pb(0,200,400,600,800 and 1000 mg/kg air-dried soil)to investigate the effects of Pb on dry mass,active ingredients(oleanolic acid and ecdysterone)and rhizosphere soil enzyme activity of A.bidentata Blume.[Results]The root dry mass of A.bidentata Blume cultivated in the soil with Pb level above 400 mg/kg significantly reduced.The Pb residues in the A.bidentata Blume.plants growing in the soil with Pb level below 400 mg/kg complied with national standard.The contents of oleanolic acid and ecdysterone in A.bidentata Blume growing in the soil with Pb level above 600 mg/kg declined significantly.At the Pb level of 1000 mg/kg,the activity of urease was inhibited significantly.The activity of phosphatase was inhibited in the presence of Pb in the soil.The activity of sucrase was activated in the soil with Pb level below 400 mg/kg,and was inhibited in the soil with Pb level above 400 mg/kg.[Conclusions]This study has important guiding significance for the reasonable selection of planting base for A.bidentata Blume and the guarantee of its yield and quality.

Concentrative phenomenon of relative content ratios of Cu, Pb and Zn in soils

It is discovered that there is the concentrative phenomenon of relative content ratios of Cu, Pb and Zn in soil by studying their parageneous association in soil, meteorites and rocks with the relative content ratios. This not only is helpful to understand the trends of Cu, Cd and Zn enriched and dispersed in the evolution course of earth matter, but also provides evidence for geochemical self-organization that there may be in the process of Cu, Pb and Zn translation and distribution.

Review on the Mechanism and Effect of Organic Materials on Available Pb in Soil

Heavy metal pollution and remediation of soils have drawn much attention. More and more scholars tend to remediate soil heavy metals without affecting the normal agricultural production. By analyzing the mechanism of action of organic materials to remediate Pb pollution in soil,the effect of different organic materials on the passivation of available Pb in soil was summarized,and the prospect was proposed for the future application of organic materials,in order to provide reference for the remediation of Pb and other heavy metals by organic materials.

Distribution Characteristics of Pb and Its Ecological Risk in Different Farmland Soils of Changchun Suburb

Pb in the farmland surface soil of Changchun suburb was taken as the main research object. The field research and laboratory analysis were used to investigate Pb content, spatial distribution characteristics and its ecological risk in different farmland soils. The results showed that Pb content was during 18.85 - 41.34 mg/kg in farmland soil of Changchun suburb, and was higher than the background value of Jilin Province at 90% of the sampling sites. The spatial distribution of Pb content in farmland soil had obvious geographical features, and Pb content in southwest and northeast soils was higher. The high-content areas were relatively concentrated, and Pb content gradually reduced from the high-content island- shape center to its surrounding. The soil Pb contents in paddy field, dry field and vegetable field had insignificant difference with the background value, indicating that Pb accumulations in dry field, paddy field and vegetable field were not significant. The order of Pb content in different land use types was showed as follows： vegetable field 〉 dry field 〉 paddy field. Pb pollution of all samples belonged to light pollution. The average potential ecological risk of soil Pb in different land use types presented the following order： vegetable field 〉 dry field 〉 paddy field.

Effective Sodium Metabisulfite (Na₂S₂O₅), HCl, Sulfur and Distilled Water for the Removal of Pb, Zn and Cr Contaminated Soil in the Columns Method

This paper presents an evaluation of different dose of Sodium Metabisulfite (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water for the removal of soil contaminated with Pb, Zn and Cr by the column mode. The field soil contained concentrations of Pb (307.31 mg&#8901;kg&#8722;1), Zn (207.77 mg&#8901;kg&#8722;1) and Cr (447.50 mg&#8901;kg&#8722;1). Both (0.01 M Na2S2O5), (Na2S2O5) + (0.1 HCl), and Distilled water were found to be effective on removing (Na2S2O5) Pb, Cr and Zn respectively. (Na2S2O5) + (0.1 HCl) Cr, Zn and Pb respectively. Sulfur Pb, Cr and Zn respectively. The removal rate of Pb, Zn, and Cr varied from 10.35% - 26%, 3.4% - 21.60% and 4.97% - 23.88% for (0.01 M Na2S2O5 respectively. The removal rate of Pb, Zn, and Cr varied from 16.13% - 20.07%, 8.20% - 23.48%, 5.42% - 28.93% for (0.01 M Na2S2O5 + 0.1 M HCl) respectively. The removal rate of Pb, Zn, and Cr varied from 10.20% - 25.5%, 9.55% - 25.13% and 6.04% - 25.54% for (S) respectively.

Spatial variations of Pb in the vertical zone of the soil-plant system in the Changbai Mountain National Nature Reserve

The characteristics of vertical and horizontal variations of lead element(Pb) in soil plant system of vertical zone in Changbai Mountain National Nature Reserve(CNNR) were studied. The results showed that Pb concentrations in soils of vertical zone are all above 25 mg/kg, and the average Pb concentration of each soil zone negatively correlates its degree of variation, i.e. brown coniferous forest soil zone has the lowest average Pb concentration of four soil zones, and the highest horizontal variation; however, mountain soddy forest soil has the highest average Pb concentration, and the lowest horizontal variation; the average concentration of plant Pb of each plant zone is lower than the worldwide average level of Pb in plant(Clarke), respectively, and plant Pb content order is consistent with soil Pb content order, but their horizontal variations are different from those in soil zones, the variation of mountain tundra forest zone is highest, but Betula ermanii forest zone the lowest. Vertical variation of plant Pb is obviously higher than that in soils with variation coefficient of 89.76%; the enrichment capability of plant for Pb is depended on the plant types and the different organs of plant; parent material and parent rock, pH values, soil organic matter and soil particle fraction etc. are the main factors influencing variations of Pb content in soil plant system of vertical zone in CNNR.

Effect of Crop-Straw Derived Biochars on Pb(Ⅱ) Adsorption in Two Variable Charge Soils

Two variable charge soils were incubated with biochars derived from straws of peanut, soybean, canola, and rice to investigate the effect of the biochars on their chemical properties and Pb（II） adsorption using batch experiments. The results showed soil cation exchange capacity （CEC） and pH significantly increased after 30 d of incubation with the biochars added. The incorporation of the biochars markedly increased the adsorption of Pb（II）, and both the electrostatic and non-electrostatic adsorption mechanisms contributed to Pb（II） adsorption by the variable charge soils. Adsorption isotherms illustrated legume- straw derived biochars more greatly increased Pb（II） adsorption on soils through the non-electrostatic mechanism via the formation of surface complexes between Pb（II） and acid functional groups of the biochars than did non-legume straw biochars. The adsorption capacity of Pb（II） increased, while the desorption amount slightly decreased with the increasing suspension pH for the studied soils, especially in a high suspension pH, indicating that precipitation also plays an important role in immobilizing Pb（II） to the soils.