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Cadmium sorption and desorption behaviour of hydroxy-Alinterlayered montmorillonite (pillared) was compared with unpillared montmorillonite. Characteristic properties of themontmorillonite, whose interlayer cations were replaced byhydroxy-Al polymers, are its thermal stability up to ～500 °C and increased surface area of about 300 × 103 m2 kg-1. The cation exchange capacity was reduced by ～30% after interlayering withpositively charged hydroxy-Al polymers.Cadmium sorption data for the two montmorillonites fitted verywell (R2 = 0.98 to 0.99) to the Freundlich equation. Inthe concentration range (0.89–17.79 μM Cd L-1) used for the experiment, the unpillared montmorillonite sorbed moreCd than the pillared montmorillonite. Cadmium is possibly retained by electrostatic and chemisorption mechanisms by thepillared montmorillonite whereas electrostatic attraction ismainly responsible for Cd sorption by unpillared montmorillonite. After 5 extractions with 0.01 M NaNO3the amount of Cd desorbed varied between 30–47 and 34–59% for unpillared and pillared montmorillonites, respectively. At lower concentrations of initially sorbed Cd, the amount ofCd desorbed was nearly equal for the two samples. 相似文献
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Lili Ye Marta Camps-Arbestain Qinhua Shen Johannes Lehmann Balwant Singh Muhammad Sabir 《Soil Use and Management》2020,36(1):2-18
The added value of biochar when applied along with fertilizers, beyond that of the fertilizers themselves, has not been summarized. Focusing on direct comparisons between biochar additions (≤20 t ha−1) – separately considering the addition or not of inorganic fertilizers (IF) and/or organic amendments (OA) along with biochar – and two different controls (with and without the addition of IF and/or OA), we carried out a meta-analysis to explain short-term (1-year) field responses in crop yield across different climates, soils, biochars and management practices worldwide. Compared with the non-fertilized control, a 26% (CI: 15%–40%) increase in yield was observed with the use of IF only, whereas that of biochar along with IF caused a 48% (CI: 30%–70%) increase. Compared with the use of IF only, the addition of biochar along with IF caused a 15% (CI: 11%–19%) increase in yield, indicating that biochar was as effective as fertilizers in increasing crop yields when added in combination. The use of biochar alone did not increase crop yield regardless of the control considered. Whereas in the short term, liming may have partly contributed to the beneficial effect of biochar (>90% was plant-derived) when added along with IF, a separate meta-analysis – using those studies that reported crop yields for different years after a single biochar application – showed a 31% (CI: 17%–49%) increase in crop yield over time (≥ 3 years), which denotes the influence of biochar properties other than liming (i.e. an increase in CEC). Our results also suggest that biochar application rates > 10 t ha−1 do not contribute to greater crop yield (at least in the short term). Data limitations precluded identification of the influence of feedstock, production conditions or climatic conditions without bias. As the response of crop yield to biochar addition was less a result of climatic zones or soil type than fertilizer use (chiefly N additions), the choice of nutrient addition along with biochar should be priorities for future research and development regardless of the region. 相似文献
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Soil warming and liming impacts on the recovery of 15N in an acidic soil under soybean cropping 
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下载免费PDF全文 Liming has important implications for N dynamics in acidic soils planted with legumes that are not fully understood. We used a 15N tracer (K15NO3) to examine N dynamics in a Chromic Luvisol planted with soybean with and without lime in environmentally‐controlled chambers set at 20°C and 30°C (full factorial design). Liming increased total N and 15N recovery in soybean, but had no effect on microbial recovery. Elevated temperature, increased total plant N, decreased 15N recovery in soybean and microbes, and increased loss of N through leaching. Our results show enhanced uptake of soil mineral N by soybean with liming, thereby reducing N loss from soil, while an increase in temperature from 20°C to 30°C may enhance N loss in these systems. 相似文献
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采用盆栽模拟试验,研究了澳大利亚蕨类植物粉叶蕨对砷的耐性及吸收富集砷的特征,同时比较了澳大利亚粉叶蕨(Pityrogramma calomelanos(L.)Link var.austroamericana(Domin)Farw)和中国蜈蚣草(Pteris vit-tats L.)在澳大利亚的Kurosol土壤上对As的吸收积累差异及植物修复效率.研究结果表明,在As投加浓度为2 400 μmol/kg时,虽然粉叶蕨的生长受到一定抑制,但仍维持了较高的地上部生物量;地上部As含量达到2438.33 mg/kg DW时,超过了砷超积累植物的临界含量标准(1 000 mg/kg);地上部As积累量为21.6 mg/株DW时,地上部对As的生物富集系数为18.6,地上部As含量大于根系As含量,基本符合As超积累植物的基本特征.与As超积累植物蜈蚣草相比较,暴露在As浓度为2 400 μmol/kg环境时,中国蜈蚣草对砷的耐性、地上部As含量及生物富集等方面均明显优于澳大利亚粉叶蕨,其地上部As含量和积累量分别为2 936.13 mg/kgDW和41.1 mg/株DW. 相似文献
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1998年进行旱地秋植甘蔗的田间试验,研究了15个早熟、中迟熟甘蔗品种的生理特性,结果表明,中迟熟甘蔗品种B0128的甘蔗产量超过其它品种,收获时蔗汁的蔗糖分最高,而且九月份的叶面积指数,叶片叶绿素a、b含量和脯氨酸含量也最高。六、九月份的叶面积指数,一月中旬的叶绿素a、b含量和蔗汁蔗糖分都与甘蔗产量极显著正相关。脯氨酸含量与甘蔗产量之间也有正的关系。因此,在选育耐旱甘蔗品种时就应该考虑这些生理特性。 相似文献
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Heavy Metals Contamination in Vegetables Grown in Urban and Metal Smelter Contaminated Sites in Australia 总被引：1，自引：0，他引：1
Dietary exposure to heavy metals, namely cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu), has been identified as a risk to human health through the consumption of vegetable crops. This study investigates the source and magnitude of heavy metal contamination in soil and vegetable samples at 46 sites across four vegetable growing regions in New South Wales, Australia. The four regions Boolaroo, Port Kembla, Cowra and the Sydney Basin were a mix of commercial and residential vegetable growing areas. The extent of metal contamination in soils sampled was greatest in regions located in the vicinity of smelters, such as in Boolaroo and Port Kembla. Soil metal concentrations decreased with depth at these two sites, suggesting contamination due to anthropogenic activities. Cadmium, Pb and Zn contamination was greatest in vegetables from Boolaroo, and Cu concentrations were greatest in vegetables sampled from Port Kembla. At Boolaroo, nearly all the samples exceeded the Australian Food Standards maximum level (ML) (0.01 mg kg?1 fresh weight) of Cd and Pb in vegetables. Over 63% of samples exceeded international food standard guidelines set by the Commission of the European Communities and the Codex Alimentarius Commission. All vegetables sampled from Cowra, which is a relatively pristine site had Cd and Pb levels below the Australian and international food standards guideline values. This study suggests that the Australian guideline values are more conservative in defining the ML for Cd and Pb in vegetable crops. This investigation highlights the increased danger of growing vegetables in the vicinity of smelters. 相似文献
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Soil organic carbon(SOC) is the largest terrestrial carbon(C) stock, and the capacity of soils to preserve organic C(OC) varies with many factors,including land use, soil type, and soil depth. We investigated the effect of land use change on soil particulate organic matter(POM) and mineral-associated organic matter(MOM). Surface(0–10 cm) and subsurface(60–70 cm) samples were collected from paired sites(native and cropped) of four contrasting soils.Bulk soils were separated into POM and MOM fract... 相似文献
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Shailesh Pandey Balwant Singh J. Kumar 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(4):847-862
Bacterial leaf blight caused (BLB) by Xanthomonas oryzae pv. oryzae (Xoo) is the most serious biotic constraint of rice in Udham Singh Nagar (U.S. Nagar), India. We have experienced severe BLB outbreaks, causing total crop failure during 2007–2010. The severity of losses incurred due to BLB in U.S. Nagar necessitates the development of an ecology-conscious, effective and durable management strategy. Our interests here were focused to obtain information on the haplotypic and pathogenic variability of Xoo to develop effective breeding strategy for BLB resistance. Our results indicate that the currently existing population of Xoo in U.S. Nagar is highly virulent and genetically diverse. Twenty one haplotypes were detected among a collection of 193 strains by each of the PCR technique used i.e. rep-PCR and IS-PCR. The high value of total haplotypic diversity (HT =0.79) reflected the genetic heterogeneity of Xoo population infecting popular varieties. Strains responsible for severe BLB outbreaks were grouped into eight distinct lineages with significant bootstrap values (p?>?75). Virulence assay revealed the presence of 11 pathotypes. The interaction of lines with strains was found significant (p?<?0.01) confirming the pathogenic specialization of Xoo in U.S. Nagar. Most of the single major resistance genes used in rice breeding program at International Rice research Institute (IRRI) was defeated by Xoo strains, at the same time; effectiveness of Xa21 to all the pathotypes is encouraging. The potential of Xa21 alone or in combination with xa13 and xa5 could be exploited for pyramiding into well-adapted rice cultivars for the effective management of the pathogen in this region. This is the first report on the population structure of Xoo in U.S. Nagar, India. 相似文献