模拟酸雨胁迫对赤红壤磷素形态特征的影响

通过田间小区模拟酸雨实验,研究酸雨胁迫下赤红壤不同磷素形态变化的方向和程度。结果表明,原位模拟酸雨影响下,一定强度（pH≥4.0）的酸雨胁迫能有效促进有效磷的释放,而当pH〈4.0强度酸雨胁迫时有效磷的释放随pH值降低逐渐受到抑制。随酸雨酸度的增强,土壤酸性磷酸酶和微生物量磷均呈现先升高后降低的变化趋势,可见一定强度酸雨胁迫能促进溶磷微生物和磷酸酶活性,而当高强度酸雨胁迫时土壤微生物活动逐渐受到抑制。无机磷组分中Al-P、Ca-P和Fe-P含量均随酸雨酸度的增强而降低,土壤O-P含量没有显著变化。相关分析发现,有效磷含量与微生物量磷、酸性磷酸酶呈极显著正相关,表明此时土壤有效磷变化与有机磷矿化关系最为密切。有效磷含量与各种形态无机磷（Al-P、O-P、Ca-P和Fe-P）含量之间也有较强的正相关性,表明土壤生态系统磷素转化是一个自我调节的动态平衡过程,且在一定条件下可以相互转化。     

模拟酸雨对施肥条件下赤红壤氮磷淋失特征的影响

通过土柱模拟淋洗试验,研究了施用等量有机复合肥条件下,不同酸度模拟酸雨对赤红壤氮磷淋失特征的影响。结果表明,铵态氮、硝态氮、无机氮和总氮淋失量均随酸雨pH值增大而下降;pH 2.0模拟酸雨和对照（pH 6.5）的无机氮和总氮淋失量差异不显著,但均显著高于pH 3.0、pH 4.0和pH 5.0酸雨;pH 5.0模拟酸雨无机氮和总氮淋失量均最低,表明强酸性酸雨和中性淋洗液均促进氮淋失,而酸度与土壤接近的酸雨减少氮淋失。与对照相比,模拟酸雨对DP淋失无显著影响,但显著降低PP和TP淋失;不同模拟酸雨各形态磷淋失量均无显著差异,表明酸雨对赤红壤磷淋失影响有限。酸雨对淋滤液氮磷浓度动态变化和氮磷累计淋失量动态变化等均无显著影响。     

模拟酸雨对施肥条件下赤红壤氮磷淋失特征的影响

通过土柱模拟淋洗试验,研究了施用等量有机复合肥条件下,不同酸度模拟酸雨对赤红壤氮磷淋失特征的影响。结果表明,铵态氮、硝态氮、无机氮和总氮淋失量均随酸雨pH值增大而下降;pH 2.0模拟酸雨和对照(pH 6.5)的无机氮和总氮淋失量差异不显著,但均显著高于pH 3.0、pH 4.0和pH 5.0酸雨;pH 5.0模拟酸雨无机氮和总氮淋失量均最低,表明强酸性酸雨和中性淋洗液均促进氮淋失,而酸度与土壤接近的酸雨减少氮淋失。与对照相比,模拟酸雨对DP淋失无显著影响,但显著降低PP和TP淋失;不同模拟酸雨各形态磷淋失量均无显著差异,表明酸雨对赤红壤磷淋失影响有限。酸雨对淋滤液氮磷浓度动态变化和氮磷累计淋失量动态变化等均无显著影响。     

模拟酸雨对红壤铝形态的影响

用动态淋洗试验，研究了不同ｐＨ的模拟酸雨对红壤中铝形态和性质的影响。结果表明，酸雨淋洗引起红壤中盐基离子的淋失和土壤铝的溶出。随着酸雨溶液，ＰＨ的降低，盐基淋失量和铝溶出量增加，酸雨淋洗影响土壤铝形态的转化，使红壤中交换态铝上升，吸附态羟基铝有所下降。这说明在酸雨长期作用下，羟基铝溶解，并转化为交换态铝和引起铝的溶出，使铝进入环境，危害生态系统。     

模拟酸雨对红壤稀土元素释放的影响研究

模拟酸雨作用下红壤中稀土元素的释放水平大小依次为Pr＞Ce＞Nd＞Tb＞Sm＞La＞Er＞Ho＞Gd＞Dy＞Eu＞Y＞Lu≈Yb,轻稀土元素的释放水平要高于重稀土元素.酸雨对稀土元素的释放有明显的促进作用,且不同元素的CAR1/CCK、CR2/CCK比较接近(CAR1、CAR2和CCK分别表示pH4.5的酸雨、pH3.5的酸雨和对照3种情况下淋出液中稀土元素的含量).CAR1/CCK介于1.43～1.93之间,平均为1.61;CAR2/CCK介于1.76～2.27之间,平均为2.06,经过9 150～10 650 mm的模拟酸雨淋溶以后,pH4.5的酸雨使稀土总累积释放量平均提高37.61%,pH3.5的酸雨使稀土总累积释放量平均提高78.05%.稀土总释放量与Fe、Mn的释放量相关分析表明:多数红壤稀土总释放量与Fe、Mn的释放量呈显著或极显著性相关.初步推断红壤中的稀土释放可能是由于吸附载体Fe-Mn氧化物因H 的输入而解离所致.     

模拟酸雨对红壤重金属元素释放的影响研究

经过9150～10650mm的模拟酸雨淋溶以后，与对照相比，pH4．5的酸雨使红壤Cr累积释放量增加4．02％～88．54％，Co增加-2．35%～56．14％．Ni增加5．82％～79．53％．Cu增加-3．45％～82．23％．Cd增加4．87％～83．14％．Pb增加10．64％～99．19％；pH3．5的酸雨使Cr累积释放量增加6．72％～308．42％，Co增加14．17％～134．81％，Ni增加10．06％～140．32％，Cu增加-3．11％～258．89％．Cd增加8．44％～630．84％，Pb增加17．02％～483．15％。几种重金属元素释放对酸雨的敏感性依次是：Pb和Cd释放对酸雨较敏感．其次为Cr和Cu，而Ni和Co的释放对酸雨较不敏感。红壤中Cr，Co．Ni，Cu．Cd，Pb累积释放量差别较大，但不同土壤之间其分布表现出基本一致的特点，释放量大小依次是：Pb〉Co〉Ni〉Cu〉Cr〉Cd。红壤中Cr，Co，Ni，Cu，Cd．Pb的累积释放量（Q）随淋溶量（H）的变化符合二次模型。     

施用保水剂对旱地赤红壤持水能力及氮肥淋失的影响

为探明保水剂在旱地赤红壤对水分和氮素养分的保持效果,用土柱开展旱地赤红壤施用保水剂试验。结果表明,保水剂具有明显的保水保肥效果。添加土重1‰的保水剂,土壤吸持的水量增加18%～50%。保水剂的吸水能力在土壤水分处于饱和状态时为64～71g/g,在田间持水量状态时为112～115g/g,当土壤水分处于较低的供给水平时,保水剂的保水效果更明显。相比保水剂在不受土壤颗粒约束(无空间限制)的条件下,对0.01%～0.1%NaCl溶液及去离子水235～539g/g吸水能力的表现,表明土壤固相的限制和土壤盐分或电解质的影响,妨碍了保水剂吸水能力的发挥。保水剂的保肥效果也值得关注,在10mm/d的灌水强度下经过35d淋溶,施用保水剂的处理0-30cm土层的氮肥淋失率从26.2%降至17.1%,氮肥淋失减少了34.7%。     

模拟酸雨多次淋溶对红壤入渗特性的影响

采用蒸馏水稀释硫酸溶液获得不同浓度硫酸溶液来模拟不同pH值酸雨,并利用硫酸溶液进行多次积水淋溶红壤试验,揭示多次酸雨淋溶过程中红壤物理特征及入渗特性演变规律。试验结果表明:与对照处理组(蒸馏水)相比较,pH=2的硫酸溶液各次入渗速度平均降低了106%,且随着淋溶次数(x)的增加,平均入渗耗时增加百分比(y)也增加,其关系可用对数函数y=70.94ln(x)+28.53(R2=0.994)描述;pH=3硫酸溶液入渗速度平均降低了20%,随着淋溶次数增加入渗速度衰减;pH=5硫酸溶液各次入渗速度基本保持稳定,且平均入渗速度比对照组快。与初始土壤容重相比较,对照组多次淋溶处理后土壤上层容重减小,下层增大,其他处理各组土壤容重却平均增大了6%,但各处理组的上层土壤容重比下层的小。红壤经不同溶液多次淋溶处理后,其水分入渗速度、扩散度大小关系为:硫酸溶液(pH=5)蒸馏水硫酸溶液(pH=3)硫酸溶液(pH=2)。     

自然降雨对广西赤红壤坡地土壤侵蚀特征的影响

[目的]探讨自然降雨对赤红壤坡地土壤侵蚀特征的影响,为赤红壤地区水土保持综合治理提供理论依据。[方法]基于野外径流小区原位观测试验,测定2020年5—10月次降雨下广西壮族自治区赤红壤坡耕地(蔗地)、撂荒地和裸地的产流产沙量,结合降雨特征分析,探讨降雨特征及分布对赤红壤坡地土壤侵蚀特征的影响。[结果](1)2020年5—10月,坡面径流和侵蚀量整体上表现为：裸地>蔗地>撂荒地,不同处理下坡面径流和侵蚀均主要集中在8月,其中撂荒地径流和侵蚀各月差异相对较小。(2)不同处理次降雨降雨量与坡面径流量和侵蚀量呈极显著的正相关关系,降雨历时显著影响蔗地和撂荒地坡面径流量。中雨和暴雨降雨等级占观测期内侵蚀性降雨总量的70.9%,其产生的径流量占蔗地、裸地和撂荒地处理坡面径流量的68.2%,78.6%和67.8%;暴雨降雨等级是坡面侵蚀量的主要来源,占不同处理下总侵蚀量的63.8%～83.4%。[结论]在广西壮族自治区的赤红壤坡地区域,与裸地相比,蔗地和撂荒地能够有效减小坡面产流产沙量,且撂荒地的降低效果更为明显;降雨量是影响坡面产流产沙最关键的因子,中雨和暴雨降雨等级是坡面径流和侵蚀的...     

Determination of soil microbial biomass phosphorus in acid red soils from southern China

A CHCl₃ fumigation and 0.03 M NH₄F-0.025 M HCl extraction procedure was used to measure microbial biomass P (P_mic) in 11 acid red soils (pH <6.0) from southern China and the results compared to those obtained by the commonly-used CHCl₃ fumigation and 0.5 M NaHCO₃ extraction method. Extraction with NH₄F-HCl was found to be more effective and accurate than NaHCO₃ extraction for detecting the increase of P from microbial biomass P following chloroform fumigation due to its higher efficiency in extracting both native labile phosphate and added phosphate (³²P) in the soils. This was confirmed by the recovery of ³²P from in situ ³²P-labeled soil microbial biomass following fumigation and extraction by the NH₄F-HCl solution. Soil microbial biomass P, measured by the NH₄F-HCl extraction method, was more comparable with soil microbial biomass C (with a more narrow C:P ratio range of 4.3 to 22.3 and a mean of 15.6 in the microbial biomass), than that obtained by NaHCO₃ solution (with a mean C:P ratio of 30.7 and a wide range of 14.9 to 48.9). K_p, the fraction of soil microbial biomass P extracted after CHCl₃ fumigation, by the NH₄F-HCl solution was 0.34. The amount of microbial biomass P determined (using K_p =0.34) was 3–400% (mean 131%) higher than that obtained by the NaHCO₃ extraction (using K_p =0.40) for the 11 red soils studied. The results suggest that the CHCl₃ fumigation and NH₄F-HCl extraction method is more reliable for measuring microbial biomass P than the NaHCO₃ extraction method in acid red soils.     

酸雨对土壤有机碳氮潜在矿化的影响

Acid rain is a serious environmental problem worldwide. In this study, a pot experiment using forest soils planted with the seedlings of four woody species was performed with weekly treatments of pH 4.40, 4.00, 3.52, and 3.05 simulated acid rain （SAR） for 42 months compared to a control ofpH 5.00 lake water. The cumulative amounts of C and N mineralization in the five treated soils were determined after incubation at 25 ℃ for 65 d to examine the effects of SAR treatments. For all five treatments, cumulative CO2-C production ranged from 20.24 to 27.81 mg kg^-1 dry soil, net production of available N from 17.37 to 48.95 mg kg^-1 dry soil, and net production of NO3-N from 9.09 to 46.23 mg kg^-1 dry soil. SAR treatments generally enhanced the emission of CO2-C from the soils; however, SAR with pH 3.05 inhibited the emission. SAR treatments decreased the net production of available N and NO3-N. The cumulative CH4 and N2O productions from the soils increased with increasing amount of simulated acid rain. The cumulative CO2-C production and the net production of available N of the soil under Acmena acuminatissima were significantly higher （P 〈 0.05） than those under Schima superba and Cryptocarya concinna. The mineralization of soil organic C was related to the contents of soil organic C and N, but was not related to soil pH. However, the overall effect of acid rain on the storage of soil organic matter and the cycling of important nutrients depended on the amount of acid deposition and the types of forests.     

PH对红壤微生物生物量碳和生物量磷的影响

The impact of pH changes on microbial biomass carbon (Cmic) and microbial biomass phosphorus (Pmic) were examined for 3 red soils under citrus production with different lengths of cultivation. Soil pH significantly affected Cmic and Pmic. The Cmie and Pmic changes, as a function of soil pH, appeared to follow a normal distribution with the original soil pH value at the apex and as pH increased or decreased compared to the original soil pH, Cmic and Pmic declined. Moreover, there were critical pH values at both extremes (3.0 on the acidic side and 8.0 to 8.5 on the alkaline side), beyond which most of microorganisms could never survive. The effect of pH on Cmic and Pmic was also related to the original soil pH. The higher the original soil pH was, the less Cmic or Pmic were affected by pH change. It is suggested that soil microorganisms that grow in a soil environment with a more neutral soil pH range (i.e. pH 5.5-7.5) may have a greater tolerance to pH changes than those growing in more acidic or more alkaline soil pH conditions.     

离子强度和三氧化物对土壤吸附Bt毒素的影响

Chemical reactions and fate of the toxins of Bacillus thuringiensis(Bt) in the soil environment are causing increasing concerns due to the large-scale cultivation of transgenic Bt plants.In this study,the effect of ionic strength(0-1 000 mmol kg 1) adjusted by NaCl or CaCl 2 on adsorption of Bt toxin by a lateritic red soil,a paddy soil and these soils after chemical removal of organic-bound or free Fe and Al oxides,as well as by pure minerals(goethite,hematite and gibbsite) which are widespread in these soils,were studied.The results indicated that when the supporting electrolyte was NaCl,the adsorption of Bt toxin by the lateritic red soil and paddy soil increased rapidly until the ionic strength reached 250 mmol kg 1 and then gradually slowed down with the increase of ionic strength;while in case the supporting electrolyte was CaCl 2,the adsorption of Bt toxin enhanced significantly at low ionic strength(< 10 mmol kg 1) and then decreased as the ionic strength increased.The adsorption of Bt toxin by the tested minerals and soils after the removal of organic-bound or free Fe and Al oxides also increased with increasing ionic strength controlled by NaCl.Removing organic-bound Fe and Al oxides obviously increased the adsorption of Bt toxin in the tested soils.Differently,removing free Fe and Al oxides increased the Bt adsorption by the paddy soil,but decreased the adsorption by the lateritic red soil.The study indicated that the varieties of ionic strength and the presence of Fe and Al oxides affected the adsorption of Bt toxin by the soils,which would contribute to the further understanding of the fate of Bt toxin in the soil environment and provide references for the ecological risk assessment of transgenic Bt plants.     

模拟酸雨对龙眼落果及果实品质的影响研究

试验研究模拟酸雨对 8年生龙眼落果及果实品质的影响结果表明 ,pH≤ 3 5的酸雨处理显著增加落果率 ,果实可溶性固形物、固酸比和糖酸比显著下降。pH为 2 5的酸雨处理果实出现伤斑 ,单果重和可食率显著降低。     

红壤中铝、锰和铁在酸雨作用下的释放特征

酸雨作用下红壤中Al、Mn和Fe的释放大多具有阶段性特征,旦土壤不同,其阶段性特征存在明显的差异。多数情况下同一土壤中Al和Fe的阶段性释放特征较为相似。3种元素累积释放量(Q)随淋溶量(H)的变化符合二次模型:Q=A B1H B2H2。经过9150～10650mm的酸雨淋溶以后,与对照(pH5.6)相比,pH4.5的酸雨使Al累积释放量增加8.16%～87.49%,Mn增加-4.29%～24.75%,Fe增加5.78%～86.03%;pH3.5的酸雨使Al累积释放量增加68.59%～158.60%,Mn增加26.11%～205.53%,Fe增加8.48%～138.88%。3种元素对酸雨的敏感性依次是:Al>Fe>Mn。其累积释放量在不同土壤之间表现出基本一致的特点:Al和Mn的释放量较为接近,且远远大于Fe的释放量。     

Characteristics of phosphorus fractions in the soils derived from sedimentary and serpentinite rocks in lowland tropical rain forests,Borneo

ABSTRACT

Soil organic phosphorus (P) is an important P source for biota especially in P-limited forests. Organic P has various chemical formations which differ in bioavailability and these organic P can be degraded by phosphatase enzymes. Here, we report soil P fractions inferred from solution ³¹P-NMR spectroscopy and soil phosphatase activities of two tropical rain forests on contrasting parent materials; sedimentary and ultramafic igneous (serpentinite) rocks. Compared to the sedimentary soils　and previous studies, P fractions of the serpentinite soils have distinctly high proportions of pyrophosphate and scyllo-inositol hexakisphosphate (scyllo-IP₆). The accumulation of pyrophosphate and scyllo-IP₆ may be related to strong sorptive capacity of iron oxides present in the serpentinite soils, which implies a consequent low P availability in the serpentinite soils. Mean value of soil phosphatase activities was higher in the serpentinite soils than in the sedimentary soils, suggesting that biota in these serpentinite forests depend more on soil organic P as a P source.     

镉胁迫对不同小麦品种幼苗生长以及Cd~(2+)、Zn~(2+)、Mn~(2+)吸收和积累的影响

以洛旱6号、豫麦25、豫麦18、豫农949、新麦21及许农5号为试验材料,通过营养液培养法,研究了镉胁迫对其幼苗生物量积累以及Cd2+、Zn2+与Mn2+吸收的影响。结果表明,与正常生长小麦相比,低Cd2+(≤30μmol/L)浓度下,除许农5号地上部生物量有所下降外,其余品种的地上部和地下部生物量均呈上升趋势。中、高Cd2+(≥60μmol/L)浓度下,所有品种的生物量呈下降趋势,所有小麦品种体内Cd2+的含量均随着Cd2+处理浓度的增加而不断增加,而且,根系内Cd2+的含量均明显高于地上部。随着Cd2+处理浓度的增加,所有小麦品种地上部Zn2+的含量均不断增加,地下部Zn2+含量的变化品种间存在差异。地上、地下部Mn2+的含量则随处理浓度增加而不断降低。     

小麦蚕豆间作对红壤有效磷的影响及其与根际pH值的关系

在云南红壤上采用田间小区试验,通过测定分蘖～拔节期、孕穗～抽穗期、灌浆～乳熟期不同土层深度小麦根际土壤有效磷(available phosphorus)含量和根际pH值,比较研究了小麦蚕豆间作对小麦根际土壤有效磷含量和pH值的影响,探讨了间作小麦根际pH与根际土壤有效磷之间的相互作用.结果表明,与小麦单作相比,小麦蚕豆间作显著地促进了小麦产量的提高.同时,小麦蚕豆间作促进了小麦根际土壤有效磷含量的提高,分蘖～拔节期、孕穗～抽穗期0-10 cm、10-20 cm土层单、间作差异显著;间作显著降低了分蘖～拔节期10-20 cm土层、孕穗～抽穗期0-10 cm、10-20 cm、20-30 cm土层小麦根际土壤pH.分蘖～拔节期、灌浆～乳熟期,单、间作小麦根际土壤有效磷含量与根际pH呈负相关关系.试验表明,在红壤上间作小麦根际土壤有效磷含量的提高与间作降低根际pH有密切关系.