【作者】 贾继元；

【导师】 吴建军； 徐建明；

【作者基本信息】 浙江大学 ， 生态学， 2005， 硕士

【摘要】 随着工农业经济的发展和大量农用化学物质的使用,在农田生态系统中重金属铅和苄嘧磺隆除草剂的复合污染变得越来越普遍。但是关于二者复合污染对土壤质量影响的研究国内外报道还比较交少见。本研究采用三种不同性质的水稻土(黄筋泥田、青紫泥田、淡涂泥田),添加不同浓度的铅处理和苄嘧磺隆除草剂处理,通过实验室培养试验重点研究了铅与苄嘧磺隆除草剂复合污染条件下对苄嘧磺隆的降解以及土壤中微生物量的影响,以揭示苄嘧磺隆的降解动态以及添加重金属铅对其降解的影响,明确两种污染物对土壤中微生物量指标的影响及其随时间的变化动态,以及探索两种污染物在对微生物量影响上的交互作用。这对修复除草剂污染土壤,制定环境容量标准,改善土壤质量,保障农副产品安全,实现农业可持续发展等有着重要的理论意义和现实意义。本研究主要得到以下结论: (1) 在本研究条件下,苄嘧磺隆除草剂是一种易降解农药,半衰期为27.2～45.3天。影响苄嘧磺隆降解的主要因素是土壤的pH值和土壤中微生物的数量。土壤中加入重金属铅后,使土壤微生物量下降而显著抑制苄嘧磺隆的降解,使其降解半衰期延长;铅的浓度越高,对苄嘧磺降除草剂降解的抑制效应就越强,三种供试土壤中均是如此。在相同处理条件下,苄嘧磺隆除草剂在土壤中的降解半衰期与土壤的pH值呈正相关,土壤pH值越高,其在士壤中消失的就越慢,半衰期就越长。供试三种土壤的半衰期次序为:淡涂泥田(pH=7.38)>青紫泥田(pH=6.10)>黄筋泥田(pH=4.96)。 (2) 铅与苄嘧磺隆除草剂复合污染在整个培养期间(180天)都对土壤中微生物量碳和氮的含量产生显著的抑制效应。添加污染物后,土壤微生物量碳和氮的含量明显下降;污染物的浓度越高,微生物量碳和氮的含量下降就越多,在整个培养过程中三种土壤均表现出相似的结果。从整个培养期间的动态变化上来看,两个指标随时间的变化趋势都表现为先降低后升高,在培养的第7-14天,下降到最低值,其后略有回升趋于平稳,但仍然低于对照,三种土壤均是如此。 (3) 两种污染物复合污染对微生物量碳氮比值的影响则表现出与微生物量碳、氮相反的趋势。添加污染物后,微生物量碳氮比值比对照有所上升,污染物更多还原

【Abstract】 With the rapid development of industry and agriculture and excess application of agricultural chemicals, combined pollution of lead and bensulfuron-methyl in agricultural ecosystems has become more and more popular. However, study on the effects of the combined pollution on soil quality was neglected. In this research, three different paddy soils (paddy field on quaternary red soil, blue clayey paddy soil, paddy field on desalting muddy polder) were used. The soils were treated with different concentrations of lead (0,100,300,500,800mg/kg), bensulfuron-methyl (0, 5.10mg/kg) and their combinations, and incubated to study the effects of combined pollution of lead and bensulfuron-methyl herbicide on the degradation of bensulfuron-methyl, the size of the microbial biomass in soils and the dynamics of Cmic, Nmic and Cmic/Nmic ratio with time. The interactive effects of lead and bensulfuron-methyl on microbial biomass were also evaluated. The study is important for the remediation of soils contaminated by herbicides, establishment of criteria of soil environmental capacity, improvement of soil quality, safety of agricultural products, and sustainable development of agriculture. The main results were summarized as follows:1. In this research, bensulfuron-methyl was an easily degradable herbicide. Its half-life of degradation was 27.2-45.3 days. The degradation was mainly affected by soil pH and the size of soil microbial biomass. In all three soils, the degradation of bensulfuron-methyl herbicide was significantly inhibited by addition of lead. The more lead was added, the longer the half-life of degradation of bensulfuron-methyl herbicide was. Under the same treatment, the half-life of bensulfuron-methyl herbicide degradation showed significant difference because of different pH values among the soils. The higher the pH value was, the longer the half-life of degradation was: with the order of paddy field on desalting muddy polder (pH=7.38)> blueclayey paddy soil (pH=6.10) > paddy field on quaternary red soil (pH=4.96).2. The results indicted that the soil Cmic and Nmic were decreased significantly with the treatments of combined pollution of lead and bensulfuron-methyl during the whole incubation period (180d). Similar patterns of decrease were observed for Cmic and Nmic. Low Cmic or Nmic was observed in the treatments of high lead or bensulfuron-methyl concentration. The inhibitory effects on Cmic and Nmic were strong during the initial 7-14 days and then became less strong after 30 days.3. In the soils, the combined pollution of lead and bensulfuron-methyl resulted in an increase of the Cmic/Nmic ratios during the initial 7-14 days. However, the differences were not significant for most treatments. After 30 days, no differences were found between the treatments and the check.4. Statistical results indicated that the interactive effects of lead and bensulfuron-methyl on the Cmic and Nm;c were significant in most sampling days, being synergistic inhibitory effects on Cmic and Nmic.更多还原