稻壳基生物炭对生菜Cd吸收及土壤养分的影响

探讨稻壳基生物炭对Cd污染土壤上叶菜吸收Cd和土壤Cd形态的影响作用,明确稻壳基生物炭对土壤Cd污染的调控效应,可为合理利用稻壳基生物炭降低叶菜Cd含量提供参考。采用盆栽试验,研究了稻壳基生物炭在不同用量水平下对2茬生菜地上部Cd含量、土壤养分含量及Cd赋存形态的影响。结果表明,在5~25 g-kg-1用量范围内,稻壳基生物炭显著降低了2茬生菜地上部和根系Cd含量,且在最大用量25 g-kg-1时效果最好,地上部Cd含量分别比未施稻壳基生物炭的对照处理降低了19.6%和45.8%,根系Cd含量分别降低了36.8%和28.0%。在25 g-kg-1用量水平下,稻壳基生物炭对土壤p H、有效磷、速效钾及有机质含量提升效果明显,但显著降低了土壤碱解氮含量。施加稻壳基生物炭对土壤有效态Cd含量及Cd化学形态也有不同影响。随着稻壳基生物炭用量的增加,土壤NH4OAc提取态Cd含量和弱酸提取态Cd含量显著降低,在用量为25 g-kg-1时,分别比对照降低17.9%和10.4%,可还原态Cd含量无显著变化,可氧化态Cd含量呈减低趋势,残渣态Cd含量增加17.6%。因此推测,提升土壤p H、降低土壤有效态Cd含量、增加残渣态Cd含量可能是稻壳基生物炭降低生菜体内Cd含量的主要原因。稻壳基生物炭可以作为土壤改良剂,抑制Cd污染土壤上叶菜对Cd的吸收,改善土壤养分状况。     

改良剂对镉污染酸性水稻土的修复效应与机理研究

为探明田间条件下施用石灰、钙镁磷肥、海泡石和腐殖酸等改良剂对Cd污染酸性水稻土的修复效应和作用机理, 通过在Cd污染区建立田间小区试验, 研究了改良剂单施和与石灰配施对Cd污染酸性水稻土中Cd作物有效性的影响。结果表明, 施用改良剂有效地改变了土壤中Cd的存在形态, 除腐殖酸外, 其他改良剂均使土壤酸提取态Cd不同程度地转化为可还原态Cd和残渣态Cd; 施用改良剂可使0.1 mol·L^-1 NaNO₃和 0.01 mol·L^-1CaCl₂提取态Cd 降低26%~97%, 降低效果为石灰+海泡石>海泡石>石灰+钙镁磷肥>钙镁磷肥>石灰>石灰+腐殖酸>腐殖酸; 改良剂使水稻地上部分的Cd吸收量降低6%~49%。试验结果还显示, 施用改良剂提高土壤pH是引起土壤中Cd作物有效性降低的主要原因之一。根据田间试验的结果, 海泡石可推荐作为Cd污染酸性水稻土的改良剂, 而腐殖酸则不宜使用。     

Efficiency of KOH-modified rice straw-derived biochar for reducing cadmium mobility, bioaccessibility and bioavailability risk index in red soil

Cadmium (Cd) pollution in agricultural soils has exerted a serious threat due to continuous application of pesticides, fertilizers, and wastewater irrigation. The present study aimed to test the efficiency of KOH-modified and non-modified rice straw-derived biochar (KBC and BC, respectively) for reducing Cd solubility and bioavailability in Cd-contaminated soil. Cadmium-contaminated soil was incubated for 60 d with 15 and 30 g kg^-1 BC and KBC. At the end of incubation, Cd mobility was estimated by the European Community Bureau of Reference sequential extraction and toxicity characteristic leaching procedure (TCLP), while bioavailability was determined using 1 mol L^-1 NH₄NO₃ extraction. The bioavailability risk index and bioaccessibility, assessed by a simple bioaccessibility extraction test, of Cd were used to examine the potential effects of Cd on living organisms. The results indicated that application of both KBC and BC significantly increased soil pH, cation exchange capacity, nutrients, and organic carbon. The soluble fraction of Cd was significantly decreased by 30.3% and 27.4%, respectively, with the addition of KBC and BC at 30 g kg^-1 compared to the control (without biochar addition). Similarly, the bioaccessible Cd was significantly decreased by 32.4% and 25.2%, respectively, with the addition of KBC and BC at 30 g kg^-1 compared to the control. In addition, both KBC and BC significantly reduced Cd leaching in the TCLP and NH₄NO₃-extractable Cd in the amended soil compared to the control. The reduction in Cd solubility and bioaccessibility by KBC and BC may be due to significant increases in soil pH and surface complexation. Overall, KBC at an application rate of 30 g kg^-1 demonstrated positive results as soil amendment for Cd immobilization, and reduced bioaccessible Cd in contaminated soil.     

Sorption-desorption behaviors of heavy metals by biochar-compost amendment with different ratios in contaminated wetland soil

Purpose

Heavy metal pollution in soils has become a global environmental concern. The combination of biochar and compost has already been proved to be an attractive method in contaminated soil. The objective was to study the sorption-desorption characteristics of Cd, Cu, and Zn onto soil amended with combined biochar-compost.

Materials and methods

In this study, the soil was amended with combinations of biochar and compost with different ratios at 10% (w/w). To determine the sorption-desorption behaviors of heavy metals by biochar-compost amendment with different ratios, we determine the effects of different ratios on soil properties and use batch experiments to investigate sorption-desorption behaviors of Cd, Cu, and Zn.

Results and discussion

The results show that the Langmuir and Freundlich model can well describe the adsorption isotherm of Cd, Cu, and Zn in the soils with or without biochar-compost combinations. The incorporation of amendment combinations into soil significantly promotes the sorption affinity of soil on metals. The sorption capacity of Cd and Zn was improved as the compost percentage rose in biochar-compost more likely due to the increase of organic matter and available phosphorus, while that of Cu was stronger with 10 and 20% biochar addition in biochar-compost combinations likely as the result of the formation of new specific adsorption sites and the mobile Cu adsorption in compost after adding a certain amount of biochar in amendment mixtures. Additionally, a certain proportion of biochar applied into amendment mixtures could suppress desorption of Cd and Cu by pH change, and the Zn desorption rate gradually decreased as the compost ratio increased in amendment mixtures.

Conclusions

The results indicated that the various ratios between biochar and compost have a significant effect on sorption-desorption of metals in soil, which helps us consider the effective combination of biochar and compost in soil.

     

菌渣生物炭对镉污染土壤性质及小白菜吸收镉的影响

为探讨以菌渣为原料制备的生物炭修复重金属镉污染土壤的可行性。采用盆栽试验,以香菇菌渣生物炭(SC)和平菇菌渣生物炭(PC)为研究对象,设置0.5%,1%,2%的生物炭施用量(w/w,%),研究其对镉污染土壤理化性质、土壤各形态镉分布、小白菜生长及镉吸收的影响。结果表明:施用SC和PC均能显著提高土壤pH和有机质(SOM)含量。与对照相比,2%的生物炭处理,土壤pH分别提高1.05和1.10个单位,SOM含量分别提高80.6%和61.2%。施用SC和PC使土壤可交换态镉降低,而提高残渣态镉含量。相关分析表明,土壤可交换态镉与pH、SOM和蔗糖酶呈显著负相关。与对照相比,2%处理下SC和PC显著降低小白菜镉含量,分别降低57.5%和54.1%;1%用量下小白菜产量分别提高53.4%和41.6%,表明高投加量菌渣生物炭对小白菜生长有不利影响。总体看来,SC和PC均有利于改善土壤性质,减轻镉对植物的毒害,促进小白菜生长。     

生物炭对铜矿区污染土壤微生物活性及香根草富集铜、镉、铅的影响

矿区土壤易发生重金属污染,是土地资源利用和维护的一大难题。以铜矿区污染土壤为研究对象,按质量比添加0,1%,2%,4%,10% (w/w)的生物炭,进行香根草室内盆栽试验。研究添加生物炭对土壤pH和微生物活性、香根草富集与转运重金属的影响,探明重金属形态含量与生物炭、微生物活性的相关性,旨在为生物炭与香根草联合修复矿区重金属污染土壤提供理论参考。结果表明:生物炭的添加能提高土壤pH,显著提高土壤FDA水解酶、蔗糖酶和脲酶活性,显著促进土壤基础呼吸,但对土壤微生物量碳无显著影响;生物炭的添加使香根草生物量显著增大,降低土壤Cu和Pb的有效态占比,Cd的变化与此相反;添加生物炭促进香根草对Cd和Pb的富集,降低香根草对Cu的富集,减少Cu、Cd和Pb在香根草体内的转运,因此香根草可作为Cu、Cd和Pb的稳定化植物。土壤蔗糖酶活性与香根草叶片Cu、Cd和Pb含量、有效态和残渣态Cu含量呈显著正相关,土壤基础呼吸与叶片Cu、Cd和Pb含量、有效态Cu、Pb含量呈显著负相关,而与有效态Cd含量呈显著正相关。总之,生物炭可减弱矿区土壤重金属对香根草生长的毒害作用,并促进香根草对重金属的富集,两者结合可改善铜矿区污染土壤的理化性质和微生物活性,有利于重金属污染土壤修复,改善土壤质量。     

Evaluation of fly ash,apatite and rice straw derived-biochar in varying combinations for in situ remediation of soils contaminated with multiple heavy metals

ABSTRACT

In

-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.     

Contribution of arbuscular mycorrhizal fungi and soil amendments to remediation of a heavy metal-contaminated soil using sweet sorghum

Owing to their potential advantages such as waste reduction,recycling,and economic attributes,fast-growing bioenergy crops have the capacity to e?ectively phytoremediate heavy metal-contaminated soils.However,little is known about the role of microbial and chemical amendments in phytoremediation using bioenergy crops.Here,we studied the contributions of inoculation with the arbuscular mycorrhizal fungus (AMF) Acaulospora mellea ZZ and three soil amendments,i.e.,hydroxyapatite (HAP),manure,and bi...     

含磷材料及生物炭对复合重金属污染土壤修复效果与修复机理

选取含磷材料（胛）、牛粪生物炭（DM）和水稻秸秆生物炭（Rs）实施Pb、Zn、Cd复合污染土壤化学稳定修复,进而评价修复效果,并分析影响因素;借助BCR连续提取法和x射线衍射光谱（XRD）探讨可能存在的修复机理。经过56d的化学稳定修复,修复材料均能显著降低TCLP提取态Pb、zn、cd,修复效果均为：Pb〉Zn〉Cd。三种修复材料对Pb、cd的修复效果为Er〉DM〉RS,对zn的修复效果基本相同。胛处理使土壤TCLP提取态的Pb、zn、cd分别降低了77．6％、31．5％、27．9％;DM处理使TCLP提取态的Pb、zn、cd分别降低了56．0％、26．1％、10．O％;RS处理使TCLP提取态的Pb、zn、cd分别降低了35．8％,25．0％和4．4％。三种修复材料均可促进Pb、cd从不稳定态向稳定状态转化。胛对Ph的固定机理主要是溶解一沉淀,XRD证明有Ca2Pb8（PO4）6（OH）2和Pb10（PO4）6（OH）2沉淀生成;DM固定Pb包括沉淀、吸附、离子交换等,XRD证明有Ca2Pb8（PO4）6（OH）2生成;Rs固定Pb主要为吸附、离子交换。研究结果表明,含磷材料和牛粪生物炭可作为理想的土壤Pb、zn、cd的修复材料。     

Assessment of compost and three biochars associated with Ailanthus altissima (Miller) Swingle for lead and arsenic stabilization in a post-mining Technosol

The elevated presence of metal(loid)s in the environment significantly impacts ecosystems and human health and is generally largely due to industrial and mining activities. Thus, in the current study, we investigated and proposed an environmentally friendly method (phytomanagement) aimed at reducing the negative impacts associated with metal(loid) pollution through the use of soil amendments (biochar and compost) to permit Ailanthus altissima growth on a highly contaminated mining Technosol, with arsenic (As) and lead (Pb) contents of 539.06 and 11 453 mg kg^-1, respectively. The objective was to examine the impacts of three biochars and compost on i) the physicochemical characteristics of soil, ii) metal(loid) immobilization in soil, and iii) A. altissima growth. We revealed that the application of biochar as a soil amendment improved soil conditions by increasing soil electrical conductivity, pH, and water-holding capacity. Moreover, concomitantly, we observed a large reduction (99%) in Pb mobility and availability following application of the hardwood biochar in combination with compost (HBCP). Thus, this combined soil amendment was most effective in promoting A. altissima growth. In addition, the HBCP treatment prevented As translocation in the upper parts of plants, although soil pore water As concentration was not diminished by amendment application.     

Biochar reduced soil extractable Cd but increased its accumulation in rice (Oryza sativa L.) cultivated on contaminated soils

Purpose

This study focused on the effects and mechanisms of biochar amendment to Cd-contaminated soil on the uptake and translocation of Cd by rice under flooding conditions.

Materials and methods

Pot and batch experiments were conducted using Cd-contaminated soil collected from a field near an ore mining area and a cultivar of Oryza sativa ssp. indica. Biochar derived from rice straw under anaerobic conditions at 500 °C for 2 h was mixed with the soil at the rate of 0, 2.5, and 5%.

Results and discussion

The application of 5% biochar reduced CaCl₂-extractable soil Cd by 34% but increased Cd concentration in brown rice by 451%. Biochar amendment decreased water-soluble Fe²⁺ in soils and formation of Fe plaques on roots and weakened the Fe²⁺-Cd²⁺ competition at adsorption sites on the root surface. Biochar increased water-soluble Cd in the soil and consequently Cd uptake by rice roots by releasing water-soluble Cl^?. Biochar application also reduced the proportion of cell wall-bound Cd in the root, which caused easier Cd translocation from the cortex to the stele in the root and up to the shoot.

Conclusions

Rice straw biochar (with high concentration of water-soluble Cl^?) reduced CaCl₂-extractable soil Cd but increased Cd concentration in rice under flooding condition.

     

木醋液对Cd污染石灰性土壤理化性质及Cd形态转化的影响

为寻找可行的强化Cd污染土壤植物修复的方法,通过室内培养试验,设置7个不同稀释梯度木醋液添加处理,研究木醋液对石灰性重金属污染土壤的理化性质、酶活性和Cd形态的影响。结果表明:随木醋液浓度升高,土壤pH逐渐降低,EC(除原液外)无明显变化。土壤有机质、碱解氮、有效磷和速效钾含量较CK分别增加0.35%~66.64%,9.74%~96.10%,31.71%~56.64%,8.34%~30.87%。稀释10~100倍土壤脲酶、蔗糖酶和过氧化氢酶活性明显增加,而稀释5倍和木醋液原液处理土壤酶活性显著被抑制(P＜0.05)。土壤可交换态Cd含量除稀释5倍处理外较CK均[JP]显著升高(P＜0.05),增加24.69%~72.40%。各处理Cd的碳酸盐结合态、铁锰氧化物态及有机物结合态含量较CK均升高,分别为6.67%~196.70%,16.24%~80.09%,31.51%~70.32%。Cd残渣态含量与CK相比均显著降低,降幅为45.88%~59.93%(P＜0.05)。综上所述,添加适宜浓度的木醋液可提高土壤养分含量和酶活性,促进残渣态Cd向其他形态转化。     

生物炭对不同酸化水平稻田土壤性质和重金属Cu、Cd有效性影响

针对南方稻田土壤酸化严重,导致养分流失有毒重金属活化,严重影响稻米质量安全的重大现实问题。以水稻秸秆和谷壳等农业废弃物为原料制备生物炭(分别记为RSC和RHC),研究不同原料生物炭对酸化土壤改良及其对重金属有效性的影响。设置3个生物炭用量(0,20,50 g/kg,分别记为CK、C1、C2),4种土壤酸化水平(pH 4.01,4.25,4.33,4.58,分别记为L1、L2、L3、L4),生物炭与重金属污染土壤共同培养60天后测定土壤pH、全氮、有机质、有效磷、速效钾和有效态Cu、Cd含量。结果表明:RSC对酸化土壤pH的改良效果明显优于RHC,且施炭量越高提高幅度越大,RSC的C2处理使4种酸度水平的土壤pH分别提高了0.68,0.97,1.29,1.71个单位。2种生物炭均能提高土壤的全氮、有效磷、速效钾和有机质含量,其中各施炭处理有机质显著提高,尤以速效钾的增幅最为显著,RSC对4种养分的提高均优于RHC。RHC对土壤有效态Cu含量无显著影响;RSC的C2较C1处理更能降低土壤中有效态Cu含量,使4种酸度水平的土壤分别降低了13.62%,6.57%,4.36%,7.88%。RHC处理的L3、L4土壤中有效态Cd含量显著降低,最大分别降低了13.79%,19.23%。RSC使4种酸度土壤有效态Cd含量最大分别降低了20.00%,25.81%,20.69%,19.23%。相关分析表明,土壤pH与有效态重金属含量呈显著负相关关系。水稻秸秆炭用于改良酸化土壤、降低重金属Cu和Cd有效性的效果更佳,且降低污染土壤中Cd的有效性较Cu好;生物炭对酸化程度越低的土壤pH和有效磷含量的提高以及有效态Cd含量的降低效果较好,而有效态Cu含量的降低效果则在酸化程度越高的土壤中表现更佳;土壤pH是生物炭调控重金属Cu、Cd有效性的主要影响因素。     

Biochar addition enhanced growth of Dactylis glomerata L. and immobilized Zn and Cd but mobilized Cu and Pb on a former sewage field soil

The mobility and bioavailability of heavy metals in soils contaminated by irrigation with wastewater increase with increasing mineralization of accumulated organic substance and decreasing pH. In laboratory experiments addition of biochar reduced heavy metal availability to plants and enhanced plant growth. However, literature from field trials is scarce. Therefore, we conducted a 2‐year field experiment with orchard grass (Dactylis glomerata L.) to study the effects of miscanthus‐derived biochar applied to sewage field soil on biomass production and concentrations of zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb) and various nutrients in plants and in the soil solution. Biochar was mixed into the contaminated topsoil (30 cm) with addition rates of 0, 1, 2.5 and 5% on a dry‐mass basis (g 100 g^?1). The soil solution was collected with suction plates installed at a depth of 30 cm. Addition of biochar increased biomass production and reduced Zn and Cd concentrations in the soil solution. Zinc concentrations were also reduced in plants. This effect seems to be attributable to an increase in pH caused by biochar addition. In contrast, Pb and Cu concentrations in the soil solution generally increased and were related to the concentrations of dissolved organic carbon (DOC). Copper concentrations also increased in the plants; however, only at the beginning of the measurement period. Our data indicate that increased concentrations of DOC, Cu and Pb in the soil solution might be a transient effect. Therefore, further research is needed to determine the long‐term effect of biochar amendment on element immobilization and leaching into groundwater.     

钝化材料复配对镉污染土壤中镉的固定效果

为探讨钝化材料不同复配处理对Cd污染土壤有效Cd含量的影响,利用土壤培养试验和盆栽试验,采用正交试验设计,研究生物炭、粉煤灰、汉白玉3种钝化材料不同复配处理对土壤pH值和Cd生物有效性的影响。结果表明,3种钝化材料不同复配处理均显著提高了土壤pH值,降低了土壤有效Cd含量。随着时间的延长,大部分处理土壤有效Cd含量呈先降低后逐渐达到平衡的趋势,平衡时间为7~15 d。同时,3种钝化材料的因素主次效应依次表现为汉白玉>生物炭>粉煤灰。添加钝化材料后小白菜可食部位的Cd含量显著降低,降幅为9.10%~24.39%,以小白菜可食部位Cd含量作为评价指标,1.5%生物炭+1.0%汉白玉、1.0%生物炭+1.0%粉煤灰+0.5%汉白玉、1.0%生物炭+0.5%粉煤灰+1.0%汉白玉为最优复配处理。本研究结果为Cd污染土壤钝化修复和作物的安全生产提供了理论依据。     

生物质炭对土壤-水稻系统中Cd迁移累积的影响

探究生物质炭添加对Cd污染土壤中Cd形态、植株对Cd的吸收分配及土壤肥力的影响,为污染稻田粮食安全提供科学依据。在湖南省长沙市Cd污染稻田进行田间定位试验,设置5个生物质炭添加量处理(0,10,20,30,40t/hm^2),分析生物质炭对Cd在土壤中形态转化和水稻器官中分配的影响。结果表明:生物质炭通过将土壤中酸溶态Cd钝化为可还原态Cd以减少在水稻器官中的累积,钝化量随着生物质炭增加而增加,土壤酸溶态Cd较CK降低3.83%～19.08%;且茎对根和糙米对茎的转运系数随生物质炭的添加分别降低4.23%～9.30%和1.39%～8.33%;土壤酸溶态Cd含量直接影响糙米中Cd含量,且受土壤pH和土壤有机碳的调控。Cd污染稻田添加生物质炭可以提高土壤肥力,降低土壤Cd生物有效性,20t/hm^2生物质炭添加量可以作为研究区周边Cd污染稻田修复的参考标准。     

生物炭与沸石混施对不同污染土壤镉形态转化的影响

采用室内培养模拟了低(1.0 mg/kg)、高(10 mg/kg)镉污染的土壤,通过向镉污染土壤中添加0.4%,2%,10%的1∶1的生物炭和沸石的混合物,探究了生物炭及沸石混施对不同程度镉污染土壤的pH和镉形态变化的影响。结果表明:2种不同程度镉污染土壤的pH均较CK有所提高,且随钝化剂用量的增加而增大。随着培养时间的延长,低污染土壤pH呈现降低趋势,而高污染土壤pH先升高后降低最后趋于稳定。培养后期,低污染和高污染土壤在混合物添加量分别为2%和10%时有效态镉降低比例最大,降低比例分别为56.78%和27.33%。各处理土壤随生物炭和沸石混合物添加量的增加交换态镉降低比例逐渐增大,培养后期,低污染土壤的交换态镉较CK分别降低8.35%,13.81%,20.65%,高污染土壤的交换态镉较CK分别降低10.02%,22.34%,33.01%。各处理的钝化剂能够明显的降低交换态镉的含量,增加碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态镉的含量,低污染土壤的有机结合态明显高于高污染土壤。由此可见,生物炭与沸石混施能够降低土壤重金属的生物有效性,为农田土壤修复奠定了理论基础。     

4种不同原料生物炭对镉污染土壤的钝化效果与稳定性比较

生物炭的性质与老化作用是影响生物炭钝化修复Cd污染土壤效果的重要因素。比较研究4种不同原料生物炭(污泥类、秸秆类、动禽粪便类和木本类)对Cd²⁺吸附作用和Cd污染土壤的钝化修复效果的差异。结果表明:施用生物炭显著提升土壤孔隙水pH(棕榈丝生物炭除外),降低孔隙水DOC和Cd浓度,从而减少水稻根系对孔隙水中Cd的吸收。同时,4种生物炭提高土壤pH,降低土壤有效态Cd、水稻根系和籽粒Cd含量。老化作用减弱稻秆生物炭的钝化效果,显著增强棕榈丝生物炭对土壤Cd的钝化作用,然而,老化作用对富含灰分的猪粪生物炭和污泥生物炭的影响较小。因此,选择生物炭钝化修复Cd污染稻田土壤时,必须考虑生物炭的原料及其老化作用。     

Sewage sludge treated with bentonite,vermiculite or biochar can improve soil properties and enhance growth of grasses

Sewage sludge treated with 15% bentonite, vermiculite or biochar was evaluated as a soil amendment in comparison to limed and untreated sludge. Seven treatments were established to two soils, an acid and an alkaline, in three replications, i.e. 2% addition of sludge treated with bentonite, vermiculite, biochar and lime and application of 2% untreated sludge, inorganic fertilization and no sludge or inorganic fertilizers (control). Then, the soil treatments were used in a pot experiment with perennial ryegrass (Lolium perenne L.) as a test plant. Sludge treated with the clay minerals or biochar improved pH of the acid soil and significantly increased organic matter and available nutrients of both soils compared to control. Although no salinity or sodicity hazard was evidenced, the initial salinity of acid and alkaline soil increased by four-eight and two-three times, respectively, upon addition of all sludge treatments, especially that of untreated sludge. Moreover, soil available zinc (Zn) increased by four-eight times. Soil application of sludge treated with the clay minerals or biochar increased the total aboveground biomass yield of ryegrass in the acid and alkaline soil by 133%–171% and 72%–88%, respectively, compared to control and enhanced nutrient uptake by plants. Furthermore the microbial metabolic quotient indicated lack of low pH and heavy metal stress with addition of sludge to the acid soil. After three harvests of ryegrass, the residual effect of sludge on pH of acid soil and salinity, available phosphorus (P), Zn and boron (B) of both soils still persisted. Thus sewage sludge treated with 15% bentonite, vermiculite or biochar could be applied to soils at a rate of 2% (≈80 Mg ha⁻¹) to serve as soil amendment and fertilizer for grasses and pasture species; however, caution is needed regarding possible P build-up, Zn phytotoxicity and salinization risks.     

稻草生物质炭对3种可变电荷土壤吸附Cd（Ⅱ）的影响

按土重的3%和5%向采自海南和广西的3种可变电荷土壤中添加由稻草制备的生物质炭,混合培养30 d后用一次平衡法研究了生物质炭对土壤吸附Cd（Ⅱ）的影响及其与土壤表面电化学性质的关系,旨在阐明生物质炭促进可变电荷土壤吸附和固定Cd（Ⅱ）的机制。结果表明,添加稻草炭显著提高了3种土壤的阳离子交换量（CEC）和土壤pH,并使土壤胶体Zeta电位向负值方向位移。因此,添加稻草炭增加了土壤表面的负电荷量,土壤表面对Cd（Ⅱ）的吸附容量增强,使3种可变电荷土壤对Cd（Ⅱ）的吸附量增加,且Cd（Ⅱ）吸附量的增幅随稻草炭添加水平的提高而增加。Freundlich方程和Langmuir方程可以拟合3种土壤对Cd（Ⅱ）的吸附等温线,但Freundlich方程拟合效果更好,该方程表征吸附容量的常数k也随着稻草炭添加水平提高而增大。研究表明在pH3.0~5.0范围内,稻草炭均增加土壤对Cd（Ⅱ）的吸附量。添加稻草炭提高土壤pH,促进Cd（Ⅱ）的吸附,因为Cd（Ⅱ）的吸附量随pH升高而增加。解吸实验表明,添加稻草炭处理Cd（Ⅱ）的解吸量高于对照处理,说明生物质炭提高了土壤对Cd（Ⅱ）的静电吸附量。