根分泌物对根际重金属动态的影响

介绍了采用上，下分根试验，使水稻根系下部生长在不同浓度铁营养液中，研究不同供铁处理对不同品种水稻吸收生金属和微量元素及其在体内转移和运输的影响。结果表明缺铁处理时常优８７－８８品种的植株地下部铁含量仅为正常供铁处理的５８％，而Ｃｄ，Ｚｎ的含量却比正常供的植株高１．４倍；缺铁时远诱一号和科长８９－１１３两个品种植株地上部含铁量也比正常供铁时低，但差异不如常优８７－８８明显，Ｃｄ，Ｚｎ含量比正常供铁时     

Effects of butachlor on microbial enzyme activities in paddy soil

This paper reports the influences of the herbicide butachlor(n-butoxymethl-chloro-2‘,6‘-diethylacetnilide)on microbial respiration,nitrogen fixation and nitrification,and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil.The results showed that after application of butachlor with concentrations of 5.5μg/g dried soil,11.0μg/g dried soil and 22.0μg/g dried soil,the application of butachlor enhanced the activity of dehydrogenase at increasing concentrations.The soil dehydrogenase showed the highest activity on the 16th day after application of 22.0μg/g dried soil of butachlor.The hydrogen peroxidase could be stimulated by cutachlor.The soil respiration was depressed within a period from several days to more than 20 days,depending on concentrations of butachlor applied.Both the nitrogen fixation and nitrification were stimulated in the beginning but reduced greatly afterwards in paddy soil.     

Salinity elevates Cd bioaccumulation of sea rice cultured under co-exposure of cadmium and salt

Salt-tolerant rice (sea rice) is a key cultivar for increasing rice yields in salinity soil. The co-existence of salinity and cadmium (Cd) toxicities in the plant-soil system has become a great challenge for sustainable agriculture, especially in some estuaries and coastal areas. However, little information is available on the Cd accumulating features of sea rice under the co-stress of Cd and salinity. In this work, a hydroponic experiment with combined Cd (0, 0.2, 0.8 mg/L Cd²⁺) and saline (0, 0.6%, and 1.2% NaCl, W/V) levels and a pot experiment were set to evaluate the Cd toxic risks of sea rice. The hydroponic results showed that more Cd accumulated in sea rice than that in the reported high-Cd-accumulating rice, Chang Xianggu. It indicated an interesting synergistic effect between Cd and Na levels in sea rice, and the Cd level rose significantly with a concomitant increase in Na level in both shoot (r = 0.54, p < 0.01) and root (r = 0.66, p < 0.01) of sea rice. Lower MDA content was found in sea rice, implying that the salt addition probably triggered the defensive ability against oxidative stress. The pot experiment indicated that the coexistent Cd and salinity stress further inhibited the rice growth and rice yield, and the Cd concentration in rice grain was below 0.2 mg/kg. Collectively, this work provides a general understanding of the co-stress of Cd and salinity on the growth and Cd accumulation of sea rice. Additional work is required to precisely identify the phytoremediation potential of sea rice in Cd-polluted saline soil.     

Response of peroxidase and catalase to acid rain stress during seed germination of rice, wheat, and rape

Seed germination of plants with various acid-resistance display different responses to acid rain. To understand the reason why such differences occur, the effects of simulated acid rain (pH 2.5–5.0) on the activities of peroxidase (POD) and catalase (CAT) during seed germination of rice (O. sativa), wheat (T. aestivum), and rape (B. chinensis var. oleifera) were investigated. Results indicated that the maximum change in activities of CAT and POD by acid rain treatment with different acidity and time in relation to the referent treatment without acid rain, was in the order: rice (28.8%, 31.7%) < wheat (34.7%, 48.3%) < rape (79.3%, 50.0%). The pH level for which the treatment with acid rain did not cause significant difference (p < 0.05) was in the order: rice (3.5).wheat (4.0).rape (5.0). Moreover, the change in activity of POD was higher than that of CAT, which showed that POD was more sensitive to acid rain stress than CAT. The difference in the ability of POD and CAT in removing free radicals was one reason why the germination indexes of these three species behaved differently. __________ Translated from Environmental Science, 2005, 26(6): 123–125 [译自: 环境科学]     

稻壳灰中温热处理稳固化垃圾飞灰重金属

利用稻壳灰与某垃圾电厂产生的飞灰为原料,对飞灰和稻壳灰与飞灰的混合物进行中温热处理,探究热处理工艺参数对稻壳灰稳固化垃圾飞灰重金属的影响.在一定温度范围内,反应主要产物为CSSF（即Ca₁₀（SiO₄）₃（SO₄）₃F₂）、Ca₃SiO₅等硅酸盐结晶相,这些物质会包覆重金属,同时,飞灰重金属Pb、Zn、Cu、Cd中相对不稳定的酸溶态和可还原态向更稳定的可氧化态或残渣态转变,使Pb、Zn、Cu、Cd的浸出浓度显著降低;热处理时间延长,稻壳灰添加量增加,会使热处理样中硅酸盐种类增多,结晶度提高,导致重金属的浸出浓度逐渐降低;稻壳灰添加量在2%~4%范围内,经中温热处理样品的重金属浸出浓度较低,添加量过高时（超过6%时）,重金属浸出浓度逐渐升高.     

水分管理和外源硒对水稻吸收累积铅的影响

通过盆栽试验,研究了不同水分管理和外源亚硒酸盐的添加对水稻根际铅的动态变化和水稻吸收累积铅的影响.结果表明,淹水显著增加了根表铁膜对铅的吸附和根系对铅的吸收,淹水下苗期和成熟期水稻根系铅含量分别是非淹水处理时的4.2~8.5和1.4~1.5倍;淹水降低了地上部的铅分配,在苗期和成熟期分别降低85.9%~86.7%和51.8%~74.0%.加硒降低了土壤溶液、苗期水稻根系和地上部的铅含量以及成熟期水稻根表铁膜、根系和茎中的铅含量.与对照相比,淹水和非淹水下加硒处理使苗期水稻根系铅含量分别降低了5.4%~24.3%和2.7%~61.7%,使成熟期水稻根系铅含量分别降低了56.1%~64.1%和53.8%~63.2%.水稻籽粒中的铅含量在不同处理间无显著差异.因此,水分管理和外源硒的添加显著影响了水稻根系对铅的吸收,而对水稻籽粒对铅的累积无显著影响.     

超声波辅助离子液体-盐酸溶液预处理稻秆的研究

为研究超声波对离子液体-盐酸溶液预处理木质纤维素的影响,采用氯化-1-丁基-3-甲基咪唑和氯化-1-烯丙基-3-甲基咪唑的盐酸溶液在超声辅助下对稻秆于30~70℃进行预处理,探讨了温度、酸度和处理时间对酶解产糖量的影响,并在最佳条件下通过酶解糖化、成分分析、表面形貌、结晶度及化学结构的变化对有无超声辅助下预处理的效果进行考察.结果表明,温度、酸度及处理时间对酶解产糖量具有显著影响,在超声波辅助下,产糖量、纤维转化率及脱木质素率分别提高20.13%~28.96%、31.69%~35.23%和18.06%~19.33%.扫描电镜、X-射线衍射及傅里叶变换红外光谱分析表明,超声波辅助离子液体-盐酸溶液预处理能够促进对稻秆表面形貌和化学结构的破坏,并降低纤维素的结晶度.     

低积累水稻品种联合腐殖酸、海泡石保障重镉污染稻田安全生产的潜力

以某铅锌矿开采区周边重镉污染稻田(全Cd含量为2.52 mg·kg~(-1))以及Cd低积累型晚粳稻品种嘉33为对象,研究了Cd低积累水稻嘉33与改良剂腐殖酸、海泡石联合对重镉污染稻田的农产品安全输出的保障潜力.结果表明,重镉污染稻田上嘉33仍表现出良好的低镉积累特性,改良剂腐殖酸、海泡石单独或联合投加,可降低水稻各器官中Cd的积累,以及茎对根吸收的Cd和精米对茎中Cd的转运系数,且降低量随着改良剂施用量的增加而增加.当施用5.250 t·hm~(-2)的腐殖酸、或6.750 t·hm~(-2)的海泡石、或1.125 t·hm~(-2)的腐殖酸和3.375 t·hm~(-2)的海泡石搭配施用均可使嘉33精米中Cd含量低于国家的限量指标(GB 2762~(-2)012),其精米中Cd含量分别为(0.171±0.01)、(0.184±0.01)和(0.181±0.01)mg·kg~(-1).腐殖酸单施、海泡石单施以及腐殖酸与海泡石配施均能促进土壤Cd向残渣态、铁锰氧化物结合态转化,显著降低土壤中有效Cd含量,降低Cd的生物有效性,进而降低了水稻各器官中Cd含量.其中海泡石单施、腐殖酸与海泡石配施降低土壤中有效Cd含量效果优于腐殖酸单施.同时,相比于腐殖酸单施、海泡石单施,腐殖酸和海泡石搭配施用对土壤养分的影响更趋友好,除了土壤碱解氮含量无明显性变化外,对应的土壤速效磷、速效钾及有机质含量均随改良剂施用量增加而升高.综上结果,意味着在重镉污染土壤上,低Cd积累水稻品种联合腐殖酸和海泡石配施是实现重镉污染土壤安全生产的优选措施.     

米糠与氧化钙、过磷酸钙联用钝化Pb污染土壤

研究了生物质材料米糠及其与氧化钙、过磷酸钙联用对土壤中重金属Pb的钝化作用.结果表明,向土壤中加入米糠可增大土壤pH值,增加土壤中重金属Pb的稳定性.米糠投加量每增加2%,土壤pH值增大约0.3.米糠投加量增大,Pb稳定效率也随之增大,6%米糠投加量60 d时,Pb稳定化效率达到38.06%,弱酸提取态降低28.90%.6%米糠+2%氧化钙联用、6%米糠+0.6%过磷酸钙联用均可对土壤中Pb产生较好的钝化效果,60 d时的稳定效果分别为47.36%、44.85%.6%米糠+2%氧化钙对Pb污染土壤有较好的钝化调节作用,可增大土壤pH,从而促进酸可提取态Pb向其他稳定形态转变.     

稻壳生物炭对污染土壤中稀土元素生物有效性的影响

利用农业秸秆制备了污染土壤修复材料稻壳生物炭和稻壳灰,在模拟稀土（REE）污染的酸性土壤中,添加0、5%和10%的稻壳灰（RHA）稻壳生物炭（RHB）,通过栽培实验考察RHA和RHB对REEs的形态和生物有效性的影响.春秋两季的盆栽实验结果表明,RHA和RHB的添加有效的降低了稀土的弱酸可提取态,随着添加量的增加效果越明显,10% RHA和10% RHB土壤中REEs的弱酸（乙酸）提取态较对照组分别降低了31.65%、19.915%,弱酸可提取态转化为了可还原态,与对照组相比,RHA和RHB的土壤中稀土元素的可还原态分别增加了26.367%、10.321%.两种修复材料显著降低了胡萝卜和茼蒿对稀土元素的富集,10% RHA处理组胡萝卜和茼蒿REEs含量分别较对照组降低了98.08%、93.41%,10% RHB胡萝卜和茼蒿REEs含量分别较对照组降低了68.61%、66.75%.研究结果表明,稻壳生物炭和稻壳灰的施用,能够有效的改善污染土壤的理化性质,降低稀土元素生物可利用态的含量,从而遏制植物对稀土元素的富集.