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1.
【目的】为探讨土壤丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)对污染土壤-作物系统Cd迁移行为的影响。【方法】采用云南兰坪铅锌矿周边重金属污染的土壤,开展室内试验,施杀真菌剂 (苯菌灵) 特异性抑制土壤土著AMF,研究抑制AMF对玉米生长、Cd含量与累积量、土壤Cd淋溶流失的影响。【结果】结果表明:(1)施苯菌灵显著抑制土壤AMF生长,导致AMF侵染率、孢子数、土壤球囊霉素相关蛋白(Glomalin related soil protein,GRSP)含量显著降低;并显著影响玉米生长与矿质营养,导致玉米地上部生物量、叶绿素与磷含量增加,而地上部氮钾含量降低。(2)施苯菌灵促进Cd向玉米根部和地上部迁移,主要富集在玉米地上部,导致玉米地上部的Cd含量和累积量显著增加。(3)施苯菌灵导致10 cm和20 cm壤中流的Cd浓度显著增加。此外,土壤GRSP含量与玉米地上部Cd累积量和壤中流的Cd流失浓度均呈极显著负相关。【结论】研究结果表明,土壤土著AMF有助于抑制土壤Cd向植株地上部迁移,减少壤中流Cd的流失浓度,降低污染土壤-作物系统Cd的环境迁移。 相似文献
2.
Heavy metal(HM) contamination in soils is an environmental issue worldwide that threatens the quality and safety of crops and human health. A greenhouse experiment was carried out to investigate the growth, mycorrhizal colonization, and Pb and Cd accumulation of pakchoi(Brassica chinensis L. cv. Suzhou) in response to inoculation with three arbuscular mycorrhizal(AM) fungi(AMF), Funneliformis mosseae, Glomus versiforme, and Rhizophagus intraradices, aimed at exploring how AMF inoculation affected safe crop production by altering plant-soil interaction. The symbiotic relationship was well established between pakchoi and three AMF inocula even under Pb or Cd stress, where the colonization rates in the roots ranged from 24.5% to 38.5%. Compared with the non-inoculated plants, the shoot biomass of the inoculated plants increased by 8.7%–22.1% and 9.2%–24.3% in Pb and Cd addition treatments, respectively. Both glomalin-related soil protein(GRSP) and polyphosphate concentrations reduced as Pb or Cd concentration increased. Arbuscular mycorrhizal fungi inoculation significantly enhanced total absorbed Pb and Cd(except for a few samples) and increased the distribution ratio(root/shoot) in pakchoi at each Pb or Cd addition level. However, the three inocula significantly decreased Pb concentration in pakchoi shoots by 20.6%–67.5% in Pb addition treatments, and significantly reduced Cd concentration in the shoots of pakchoi in the Cd addition treatments(14.3%–54.1%), compared to the non-inoculated plants.Concentrations of Pb and Cd in the shoots of inoculated pakchois were all below the allowable limits of Chinese Food Safety Standard.The translocation factor of Pb or Cd increased significantly with increasing Pb or Cd addition levels, while there was no significant difference among the three AMF inocula at each metal addition level. Meanwhile, compared with the non-inoculated plants, AMF inocula significantly increased soil p H, electrical conductivity, and Pb or Cd concentrations in soil organic matter in the soils at the highest Pb or Cd dose after harvest of pakchoi, whereas the proportion of bioavailable Pb or Cd fraction declined in the AMF inoculated soil. Our study provided the first evidence that AM fungi colonized the roots of pakchoi and indicated the potential application of AMF in the safe production of vegetables in Pb or Cd contaminated soils. 相似文献
3.
菌根对紫色土上间作玉米生长及磷素累积的影响 总被引：4，自引：2，他引：4
丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)在土壤与植物系统的磷素循环中发挥着关键的作用。本文通过盆栽模拟试验研究了不同AMF接种状况[不接种(NM)、接种Glomus mosseae(GM)、接种G.etunicatum(GE)]和玉米/大豆间作体系不同根系分隔方式(不分隔、尼龙网分隔、塑料膜分隔)对间作玉米植株生长及磷素吸收累积的影响。研究结果表明:GM处理下的间作玉米根系侵染率在不同根系分隔方式之间的差异不显著,而GE处理则在塑料膜分隔处理下对玉米的侵染率最高。接种不同AMF对间作玉米促生效果不同,GM和GE处理在不同根系分隔情况下表现出各自的优势,与未接种处理相比,GM处理能使玉米生物量、株高有一定程度增加并在根系不分隔处理下玉米磷吸收较多、生长较好;GE处理能使植株生物量有一定程度增加并在尼龙网分隔处理下的玉米磷吸收较多、生长较好。间作体系不同根系分隔方式对玉米的影响也不同,其中玉米地上部生物量在根系分隔处理下普遍小于不分隔处理,但根系生物量的大小情况则刚好相反。另外,无论何种接种状况,玉米根系磷含量及吸收量均以尼龙网分隔处理显著较高。而根系磷吸收效率则以接种G.mosseae且不分隔根系处理显著高于分隔处理。所有复合处理中,以接种G.etunicatum与尼龙网分隔根系组合处理对间作玉米的生长及磷素累积的促进作用最好,若应用于滇池流域,可望有效控制坡耕地土壤磷素的迁移。 相似文献
4.
《Pedobiologia》2014,57(4-6):223-233
Mycorrhizal fungi and earthworms can individually or interactively influence plant growth and heavy metal uptake. The influence of earthworms and arbuscular mycorrhizal (AM) fungi either alone or in combination on maize (Zea mays L.) growth and cadmium (Cd) uptake was investigated in a calcareous soil artificially spiked with Cd. Soils were contaminated with Cd (10 and 20 mg Cd kg−1), inoculated or un-inoculated with the epigeic earthworm Lumbricus rubellus and two AM fungal species (Rhizophagus irregularis and Funneliformis mosseae) for two months of growth under greenhouse conditions. Generally, earthworms alone increased both shoot P uptake and biomass but decreased shoot Cd concentration and root Cd uptake. AM fungi individually often increased total maize P uptake, declined shoot Cd concentration, and consequently produced higher total biomass. However, R. irregularis enhanced shoot Cd uptake at low Cd level and root Cd uptake at high Cd level. In plants inoculated with F. mosseae species, earthworms increased shoot biomass and Cd uptake, decreased root biomass and Cd uptake at all Cd levels, and increased shoot Cd concentration at low Cd level. In plants colonized by R. irregularis species, however, earthworm addition decreased maize biomass only at high Cd level and root Cd concentration and total maize Cd uptake at both Cd levels. Earthworm activity decreased Cd transfer from the soil to maize roots at low Cd level, but this was counterbalanced in the presence of F. mosseae. Mycorrhizal symbiosis significantly reduced the transfer of Cd from roots to shoots, independence of earthworm effect. Overall, it is concluded that L. rubellus and AM fungi, in particular F. mosseae isolate, improved maize tolerance to Cd toxicity both individually and interactively by increasing plant growth and P nutrition, and restricting Cd transfer to the aboveground biomass. Consequently, the single and interactive effects of the two soil organisms might potentially be important not only in protecting maize plants against Cd toxicity, but also in Cd phytostabilization in soils polluted by this highly toxic metal. 相似文献
5.
Huan Ll Xiaolin Li Zhengxia Dou Junling Zhang Chong Wang 《Biology and Fertility of Soils》2012,48(1):75-85
The interactive impacts of arbuscular mycorrhizal fungi (AMF, Glomus intraradices) and earthworms (Aporrectodea trapezoides) on maize (Zea mays L.) growth and nutrient uptake were studied under near natural conditions with pots buried in the soil of a maize field.
Treatments included maize plants inoculated vs. not inoculated with AMF, treated or not treated with earthworms, at low (25 mg kg−1) or high (175 mg kg−1) P fertilization rate. Wheat straw was added as feed for earthworms. Root colonization, mycorrhiza structure, plant biomass
and N and P contents of shoots and roots, soil available P and NO3−–N concentrations, and soil microbial biomass C and N were measured at harvest. Results indicated that mycorrhizal colonization
increased markedly in maize inoculated with AMF especially at low P rate, which was further enhanced by the addition of earthworms.
AMF and earthworms interactively increased maize shoot and root biomass as well as N and P uptake but decreased soil NO3−–N and available P concentrations at harvest. Earthworm and AMF interaction also increased soil microbial biomass C, which
probably improved root N and P contents and indirectly increased the shoot N and P uptake. At low P rate, soil N mobilization
by earthworms might have reduced potential N competition by arbuscular mycorrhizal hyphae, resulting in greater plant shoot
and root biomass. Earthworms and AMF interactively enhanced soil N and P availability, leading to greater nutrient uptake
and plant growth. 相似文献
6.
不同坡度下玉米生长期紫色土坡面径流及其 总被引：2，自引：0，他引：2
为探明紫色土横垄坡面径流与可溶性有机碳流失对不同坡度的响应特征,通过径流小区和野外人工模拟降雨相结合的方法,探讨了不同坡度条件下玉米各生育期地表径流、壤中流及其可溶性有机碳（DOC）流失特征。结果表明：玉米各生育期同一降雨时间段地表径流量均表现为20° > 15° > 10°,壤中流径流量却表现为10° > 15° > 20°。不同坡度下,玉米生育期地表径流量大小总体表现为苗期 > 成熟期 > 拔节期 > 抽雄期,壤中流量整体表现为抽雄期 > 拔节期 > 苗期 > 成熟期。玉米各生育期地表径流DOC质量浓度均表现为20° > 15° > 10°,不同坡度下玉米生育期地表径流DOC质量浓度表现为苗期 > 拔节期 > 成熟期 > 抽雄期。苗期、拔节期和成熟期壤中流DOC质量浓度大小表现为10° > 15° > 20°,不同坡度下玉米生育期壤中流DOC质量浓度的总体表现为苗期最大,抽雄期最小。玉米各生育期地表径流DOC迁移通量大小均表现为20° > 15° > 10°,不同坡度地表径流DOC迁移通量均表现为苗期 > 成熟期 > 拔节期 > 抽雄期;玉米各生育期壤中流DOC迁移通量大小均表现为10° > 15° > 20°,不同坡度下壤中流DOC迁移通量与地表径流一致。研究结果可为不同坡度条件下玉米生长期坡面径流损失和有机碳流失调控提供理论依据。 相似文献
7.
X. H. Zhang Y. -G. Zhu B. D. Chen A. J. Lin S. E. Smith F. A. Smith 《Journal of plant nutrition》2013,36(12):2065-2077
A greenhouse pot experiment was conducted to investigate heavy metal [copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd)] uptake by two upland rice cultivars, ‘91B3’ and ‘277’, grown in a sterilized field soil contaminated by a mixture of Cu, Zn, Pb, and Cd. Rice plants were inoculated with each of three arbuscular mycorrhizal fungi (AMF), Glomus versiforme (GV), Glomus mosseae (GM), and Glomus diaphanum (GD), or remained noninoculated (NM). Both rice cultivars could be colonized by the three AMF used in this experiment. The percentage of mycorrhizal colonization by the three AMFs on the two rice cultivars ranged from 30% to 70%. Mycorrhizal colonization of both upland rice cultivars had a large influence on plant growth by increasing the shoot and root biomass compared with non-inoculated (NM) plants. The results indicate that mycorrhiza exert some protective effects against the combined toxicity of Cu, Zn, Pb, and Cd in the contaminated soil. This conclusion is supported by the partitioning of heavy metals (HMs) in the two cultivars. In the two cultivars, colonization by AMF reduced the translocation of HMs from root to shoot (except that the colonization of AMF increased the Cu translocation of HMs in cultivar ‘277’). Immobilization of the HMs in roots can alleviate the potential toxicity to shoots induced by the mixture of Cu, Zn, Pb, and Cd. The two rice cultivars showed significant differences in uptake of Cu, Zn, Pb, and Cd when uninoculated. GM inoculation gave the most protective effects on the two cultivars under the combined soil contamination. 相似文献
8.
9.
铅锌矿区分离丛枝菌根真菌对万寿菊生长与吸镉的影响 总被引：3，自引：0，他引：3
盆栽试验研究了土壤不同施Cd水平(0、20、50 mg kg-1)下,接种矿区污染土壤中丛枝菌根真菌对万寿菊根系侵染率、植株生物量及Cd吸收与分配的影响。结果表明:接种丛枝菌根真菌显著提高了Cd胁迫下万寿菊的根系侵染率和植株生物量;随着施Cd水平提高,各处理植株Cd浓度和Cd吸收量显著增加。各施Cd水平下万寿菊地上部Cd吸收量远远高于根系Cd吸收量,尤其在20 mg kg-1施Cd水平下,接种处理地上部Cd吸收量是根系的3.90倍,对照处理地上部Cd吸收量是根系的2.33倍;同一施Cd水平下接种处理地上部Cd吸收量要显著高于对照。总体上,试验条件下污染土壤中分离的丛枝菌根真菌促进了万寿菊对土壤中Cd的吸收,并增加了Cd向地上部分的运转,表现出植物提取的应用潜力。 相似文献
10.
为探明黄壤坡耕地不同耕作措施下径流及可溶性有机碳(dissolved organic carbon,DOC)迁移途径与流失特征。以顺坡垄作、平作和横坡垄作措施下玉米种植坡耕地为研究对象,采用野外径流小区监测与室内分析相结合的方式,探讨自然降雨条件下坡耕地地表径流、壤中流及其DOC流失特征。结果表明:(1)种植玉米坡耕地径流量及DOC通量均受雨量等级影响显著,随雨量等级增大而增大,且玉米成熟期流失量均最大。(2)地表径流、0-20 cm壤中流和20-40 cm壤中流分别占总径流量的78.98%,9.05%,11.97%,DOC流失通量分别占总通量的74.90%,11.97%,13.13%。(3)横坡垄作DOC流失量显著小于顺坡垄作,横坡垄作径流量分别是平作的0.93倍,是顺坡垄作的0.86倍;横坡垄作DOC通量是平作的0.85倍,是顺坡垄作的0.79倍。雨量等级增加将显著加剧玉米种植坡耕地径流及DOC流失,研究区玉米成熟期径流及DOC流失最为严重,地表径流是坡面径流及DOC流失的主要途径,横坡垄作措施可以有效减少坡面径流及DOC流失。 相似文献
11.
Huang H Zhang S Chen BD Wu N Shan XQ Christy P 《Journal of agricultural and food chemistry》2006,54(25):9377-9382
A greenhouse pot experiment was carried out to investigate the effect of the arbuscular mycorrhizal fungus Glomus etunicatum on the uptake of atrazine (ATR) and cadmium (Cd) from soil by maize (Zea mays L.). Mycorrhizal colonization led to an increase in the accumulation of Cd and ATR in maize roots but a decrease in the shoots. Atrazine alleviated the adverse effects of Cd on maize growth, and this was more pronounced in the inoculated plants. An increase in Cd accumulation by maize roots was observed when ATR was also present. After harvest, the residual ATR concentration in the soil decreased markedly. With mycorrhizal inoculation the amount of residual ATR decreased more in the bulk soil but less in the rhizosphere soil compared to the noninoculated controls. Cadmium application significantly decreased the ATR residual concentrations in both the rhizosphere and bulk soils irrespective of inoculation treatment. 相似文献
12.
玉米成熟期黄壤坡耕地径流及其氮素流失特征研究 总被引：4，自引：4，他引：4
以顺坡垄作、平作、横坡垄作坡面为研究对象,研究自然降雨条件下,黄壤坡耕地地表径流、壤中流及其氮素流失特征,以期为研究区氮素流失预测和有效防控提供科学依据。结果表明:自然降雨条件下,玉米成熟期平均地表径流量分别为0—20,20—40cm壤中流量的7.96,8.22倍。不同耕作措施间地表径流量和氮素流失量差异显著,地表径流量和氮素流失量均表现为顺坡垄作平作横坡垄作,顺坡垄作坡面地表径流量分别是平作和横坡垄作的1.20,2.07倍,顺坡垄作坡面氮素流失量分别是平作和横坡垄作的1.35,2.06倍。在0—20,20—40cm壤中流中横坡垄作径流量和氮素流失量则明显高于其他耕作措施坡面,在0—20cm壤中流中横坡垄作氮素流失量分别是顺坡垄作和平作的2.45,1.90倍;在20—40cm壤中流中横坡垄作氮素流失量分别是顺坡垄作和平作的2.34,1.79倍。地表径流为氮素流失的主要途径,可溶态氮为氮素流失的主要形式,占总氮流失量的63.84%～72.61%;硝态氮是坡耕地无机氮流失的主要成分,占总氮流失量的16.47%～59.17%。氮素流失量与径流量和降雨量均呈显著线性正相关关系。研究区自然降雨条件下,横坡垄作能有效减少氮素流失,合理的耕作措施有助于防治研究区水土资源和氮素流失。 相似文献
13.
为揭示自然降雨条件下夏玉米生育期内黄壤坡耕地径流及磷素流失规律,采用野外径流小区观测试验与室内分析相结合的方法,探讨了自然降雨条件下地表径流、壤中流及其总磷的流失特征。结果表明：(1)顺坡垄作径流量显著高于其余两种耕作措施,其径流量分别为平作和横坡垄作的1.13倍和1.17倍。横坡垄作径流磷素流失总量显著低于其余两种耕作措施,其总磷流失量分别为平作和顺坡垄作的0.79倍和0.75倍。(2)随着玉米生育期的推进,径流量呈增加的变化趋势,表现为成熟期>抽雄期>拔节期、苗期。相较于苗期,成熟期径流量增加了9.35倍,径流磷素流失量增加了12.58倍。(3)地表径流、0—20 cm土层壤中流和20—40 cm土层壤中流量分别占径流总量的78.36%,10.20%,11.44%,其磷素流失量分别占径流磷素流失量的75.10%,9.90%,15.00%。综上,研究区以地表径流为磷素流失的主要途径,且在玉米成熟期达到最大值,横坡垄作措施对于坡面产流及磷素流失具有较好的控制效果。 相似文献
14.
通过人工模拟降雨-径流小区监测的试验方法,设不施肥对照(CK)、基肥穴施(G1)、基肥穴施+追肥面施(G2)、基肥穴施+追肥穴施(G3)4种处理,研究辽宁省浑河流域不同施肥方式下农田氮素随地表径流与壤中流的流失规律,分析不同施肥方式对氮素流失量的影响。结果表明:(1)不同施肥方式下农田地表径流与壤中流产流过程差异显著,地表径流产流时间先于壤中流,同时径流量高于壤中流,是农田主要径流输出方式。G2减少地表径流,G3增大壤中流。(2)地表径流TN平均浓度中G2显著高于其他施肥方式,达到59.00mg/L,其他施肥方式差异较小;壤中流TN平均浓度以G3最高。(3)4种施肥处理,氮素总流失量为385～814mg,各施肥处理的总流失量呈G2>G3>G1>CK,追肥对氮素流失有显著影响。与G2相比,G3在减少地表氮素流失的同时,不会显著增大壤中流氮素流失。 相似文献
15.
Qiang-Sheng Wu A.K. Srivastava Ming-Qin Cao Jing Wang 《Archives of Agronomy and Soil Science》2013,59(6):813-825
Arbuscular mycorrhizal fungi (AMF) influence soil aggregate stability through their hyphae, roots, and glomalin-related soil protein (GRSP); however, the individual effect of these factors is difficult to distinguish. Pots separated by a 37-μm mesh bag buried in the middle of each pot was used to establish root zone (root + hyphae) and hyphae zone (roots free), where the Poncirus trifoliata seedlings were colonized by Funneliformis mosseae or Paraglomus occultum in root zone. AMF inoculation significantly increased shoot, root, and plant’s total biomass, soil organic carbon, GRSP fractions, 2–4 and 1–2 mm size water-stable aggregates, and mean weight diameter (MWD) in root or hyphae zone. Within root zone, root colonization and biomass presented stronger relationship with MWD than GRSP fractions. While, within hyphae zone, total of GRSP fraction was significantly correlated with MWD. The study, suggested further that root biomass and colonization were the main mechanisms in root zone for improving aggregate stability, whereas total of GRSP fractions was of paramount importance in hyphae zone. Mycorrhizal effect on aggregate stability was observed to be contrastingly different between root zone and hyphae zone. 相似文献
16.
紫色土是长江上游最重要的土地资源之一,严重的水土流失引发了一系列问题。在对紫色土坡面产流特征进行分析的基础上,研究紫色土坡面产流特征对水土流失的作用机制以及紫色土坡耕地水土流失防治对策。结果表明:紫色土坡耕地产流模式以蓄满产流为主,壤中流在坡面径流总量中所占比例较大;紫色土坡耕地土壤侵蚀导致土壤粗骨沙化,土壤养分流失途径与营养元素的溶解性有关,易溶的N、K主要以溶解态流失,易被土壤固定的P主要随土壤颗粒流失;壤中流是紫色土坡耕地水土流失的重要外营力之一,进行水土流失治理必须对其加以干预。提出长江上游紫色土坡耕地水土流失治理策略与"增渗防冲、排水保土,先排后蓄、蓄以为用"的治理措施。 相似文献
17.
A comprehensive knowledge on the relationship between soil salinity and arbuscular mycorrhizal fungi (AMF) is vital for a deeper understanding of ecosystem functioning under salt stress conditions. The objective of this study was to determine the effects of soil salinity on AMF root colonization, spore count, glomalin related soil protein (GRSP) and community structure in Saemangeum reclaimed land, South Korea. Soil samples were collected and grouped into five distinct salt classes based on the electrical conductivity of soil saturation extracts (ECse). Mycorrhizal root colonization, spore count and GRSP were measured under different salinity levels. AMF community structure was studied through three complementary methods; spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE). Results revealed that root colonization (P < 0.01), spore count (P < 0.01) and GRSP (P < 0.01) were affected negatively by soil salinity. Spore morphology and T-RFLP data showed predominance of AMF genus Glomus in Saemangeum reclaimed land. T-RFLP and DGGE analysis revealed significant changes in diversity indices between non (ECse < 2 dS/m) and extremely (ECse > 16 dS/m) saline soil and confirmed dominance of Glomus caledonium only in soils with ECse < 8 dS/m. However, ribotypes of Glomus mosseae and Glomus proliferum were ubiquitous in all salt classes. Combining spore morphology, T-RFLP and DGGE analysis, we could show a pronounced effect in AMF community across salt classes. The result of this study improve our understanding on AMF activity and dominant species present in different salt classes and will substantially expand our knowledge on AMF diversity in reclaimed lands. 相似文献
18.
Maize roots are colonized by arbuscular mycorrhizal fungi, but less mycorrhizal symbiosis is expected as the plant-available phosphorus (P) concentration of soil increases, based on greenhouse and growth bench experiments. The objective of this study was to evaluate maize root colonization by arbuscular mycorrhizal fungi in a sandy loam soil with a gradient of plant-available P concentrations resulting from P fertilizer inputs. The field experiment received inorganic and organic P fertilizers for 3 years, and this created a 20-fold difference in the plant-available P concentration, from 12 to 204 mg Mehlich-3 extractable P kg−1. The proportion of maize roots colonized with arbuscular mycorrhizal fungi increased from 26 ± 2% during vegetative growth (V8 and VT growth stages) to 46 ± 2% in the reproductive R2 and R6 stages. The P fertilizer input did not affect maize root colonization by arbuscular mycorrhizal fungi. More arbuscular mycorrhizal fungi colonization of maize roots occurred in soil with increasing plant-available P concentrations (r = .12, p = .05, n = 237), and this was associated with greater P uptake in the maize shoots (r = .53, p < .001, n = 240). We conclude that the root-mycorrhizal symbiosis was more strongly related to maize growth than the plant-available P concentration under field conditions. 相似文献
19.
研究紫色土区坡耕地玉米全生育期细沟侵蚀阶段水土及氮素流失规律,以期为研究区氮素流失有效防控提供科学依据。采用人工模拟降雨与野外径流小区相结合的方法,开展降雨强度为1.5mm/min条件下玉米全生育期细沟侵蚀阶段地表径流、壤中流和侵蚀泥沙中氮素流失特征的研究。结果表明:细沟侵蚀阶段,玉米各生育期地表径流量、壤中流量和侵蚀产沙量总体表现为随降雨时间延长呈先增加后平稳的变化趋势。地表径流中总氮、可溶性总氮、硝态氮和侵蚀泥沙中总氮流失量总体呈现先增加后平稳的趋势,而地表径流中铵态氮流失量变化趋势在降雨前期呈现波动性变化,降雨后期逐渐平稳。壤中流中总氮、可溶性总氮、硝态氮、铵态氮流失量则随着降雨时间延长呈现平稳的变化趋势。细沟侵蚀阶段地表径流中氮素流失总量在玉米苗期最大,为628.77mg/m2;壤中流中氮素流失总量在拔节期和抽雄期最大;侵蚀泥沙中氮素流失总量在苗期最大,为144.95mg/m2。壤中流为氮素流失主要途径,硝态氮为氮素流失主要形态。 相似文献
20.
Glomalin is a metal-sorbing glycoprotein excreted by arbuscular mycorrhizal fungi (AMF). One method of estimating glomalin in soils is as glomalin-related soil protein (GRSP). In this study the role of GRSP in sequestering Pb and Cd was investigated in an in situ field experiment. The effect of metal sequestration on the subsequent decomposition of GRSP was also investigated. GRSP was determined using the Bradford method as total glomalin-related soil protein (T-GRSP) and as easily extractable glomalin-related soil protein (EE-GRSP). After 140 days, GRSP bound Pb accounted for 0.21–1.78% of the total Pb, and GRSP bound Cd accounted for 0.38–0.98% of the total Cd content in the soil. However when compared on a soil organic matter (SOM) basis, only 4% of the Pb or Cd was bound to the GRSP fraction of the SOM compared with 40–54% of the Pb or Cd bound to the humin and fulvic acids in the SOM fraction. In soils contaminated with the highest levels of Pb and Cd, the T-GRSP (EE-GRSP) decomposition after 140 days was reduced by 8.0 (6.6)% and 7.0 (7.5)%, respectively, when compared with the controls. In the high Pb or Cd treatment groups we found that the fraction of metal bound to GRSP increased even though the total GRSP content declined over time. The mass ratio between Pb and GRSP-carbon changed from 2.3 to 271.4 mg (100 g)−1 in all Pb levels soil, while with the high-Cd treatment group the mass ratio between Cd and GRSP-carbon (0.36 mg (100 g)−1) was higher than the mass ratio seen with Cd-bound humic acid fractions. Our in situ field study shows that while GRSP does bind Pb and Cd, in the soils we investigated, the levels are insignificant compared to soil organic matter such as humic and fulvic acids. 相似文献