兰州大学机构库 >生态学院
微塑料对玉米栽培土壤的化学、生物学特性及玉米生长的影响
Alternative TitleEffect of microplastics on the chemical and biological properties of maize cultivated soil and maize growth
尚耘旭
Subtype硕士
Thesis Advisor全占军 ; 李文金
2023-05-22
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学硕士
Degree Discipline生态学
Keyword微塑料 Microplastics 根际土壤 rhizosphere soil 细菌 bacteria 真菌 fungi 玉米 maize
Abstract

2016年第二届联合国环境大会上,微塑料污染被列入环境与生态科学研究领域的第二大科学问题。由于人类活动的引入和环境介质的传输,使得土壤成为微塑料最大的贮藏库。近年来,微塑料对土壤生态系统的威胁引起国内外学者的广泛关注,农田土壤微塑料污染情况及微塑料对土壤性质的改变、微生物及动植物的影响已经成为研究热点。本研究在野外调查包头市农田土壤中微塑料赋存情况的基础上,开展短期盆栽实验,通过外源添加不同浓度梯度的微塑料颗粒模拟不同程度的农田土壤微塑料污染,探究微塑料对土壤化学、生物学指标、微生物群落及玉米生长的影响。主要研究结果见下:

1. 采样点农田土壤微塑料赋存浓度为24666.67±12950.76 n/kg耕层土壤,样地土壤中以粒径<100μm的微塑料为主,占比超过90%,微塑料组分以聚酰胺PA(67.56%)和聚乙烯PE(10.68%)为主。

2. 微塑料对土壤化学及生物学特性带来复杂影响。微塑料显著影响土壤化学性质,除土壤有机质与微塑料浓度显著正相关外(各浓度处理组与0%浓度对照组相比分别提高2.80%、30.37%、88.10%、118.22%、126.52%),微塑料在一定程度上抑制土壤全氮、硝态氮、铵态氮、有效磷、溶解性有机氮和溶解性有机碳,最高浓度处理与对照组相比分别下降31.14%、22.75%、12.50%、43.85%、36.24%和6.25%,土壤pH在一定浓度区间被抑制,而后被促进。微塑料对微生物量与土壤酶活性也带来复杂影响。土壤微生物量在微塑料添加处理组中均表现为低浓度(0.5%)抑制,而高浓度(5%-10%)促进的趋势。微塑料处理组下土壤酶活性普遍高于对照组,多数土壤酶活性在低-中(0.5%-2.5%)浓度组与微塑料浓度正相关,而在高浓度组下降,且根际土壤酶活性较非根际土壤酶活性具有更强的微塑料浓度敏感性。

3. 短期盆栽实验中,微塑料会对根际和非根际土壤细菌和真菌群落带来极大改变。群落结构变化和差异性分析结果表明:根际土壤中细菌在属水平与门水平上优势物种数量高于非根际土壤;根际土壤真菌目水平群落结构与混合土壤更相似。此外,不同浓度微塑料处理组内,根际与非根际土壤中细菌群落的差异较真菌群落更显著。微生物群落多样性分析结果表明,土壤细菌、真菌群落α多样性的变化趋势相近,不同浓度微塑料处理组之间的微生物群落差异显著且分组良好;根际土壤与非根际土壤之间差异显著。共生网络表明微塑料对根际土壤细菌的影响大于非根际土壤,可能根际土壤更能代表整体的土壤的细菌共生关系。微塑料同时影响土壤真菌共生网络,且根际土壤与非根际土壤之间真菌共生网络差异较大。本研究中,根际土壤在探究微塑料对土壤微生物群落和生态功能的影响方面具有重要作用,未来土壤微塑料相关研究需要进一步重视根际土壤监测。

4. 微塑料对玉米(Zea mays L.)生长发育和生物量积累带来负效应。微塑料污染对玉米单株生物量积累带来显著影响,微塑料处理组的生物量与对照组相比分别下降53.60%、52.95%、46.39%、38.20%和47.54%。玉米株高及叶面积短期内(0-7天)没有显现出微塑料影响的显著差异,而第14天开始在微塑料添加处理组内,玉米株高和叶面积随微塑料浓度增加呈现先促进后抑制的趋势。相关性分析表明,微塑料会通过影响土壤化学生物学特性进而间接影响玉米生长。

综上所述,基于土壤化学、生物学特性、微生物群落和植物生长等多方面的综合评估,微塑料污染可能对农田土壤生态系统带来不可逆转的负面影响,且有强烈的浓度依赖效应。本研究为农田土壤微塑料赋存情况及风险评估提供了新的证据,为农田生态系统对微塑料污染的响应机制提出了新的见解。

Other Abstract

Microplastics pollution has been ranked as the second most significant scientific issue in the field of environmental and ecological research, at the 2nd United Nations Environment Assembly in 2016. Due to human activities and the transportation of environmental media, soil has become the largest repository for microplastics. In recent years, the threat of microplastics to soil ecosystems has attracted widespread attention from scholars both domestically and internationally. The contamination of microplastics in agricultural soil, its effects on soil properties, microorganisms, and plants and animals, has become a research hotspot. This study conducted a short-term pot experiment building upon a field investigation of the presence of microplastics in farmland soil in Baotou city. By externally adding microplastics particles with different concentration gradients, simulating varying degrees of microplastics pollution in farmland soil, the study aimed to investigate the impact of microplastics on soil chemical and biological indicators, soil microbial communities and maize growth. The main findings of the study are presented below:

1. The concentration of microplastics in agricultural soils at sampling points was found to be 24666.67±12950.76 n/kg in the plow layer. Microplastics with particle sizes below 100 μm were predominant, accounting for over 90% of the total microplastics content. Polyamide (PA) and polyethylene (PE) were identified as the main microplastics components, representing 67.56% and 10.68% of the total microplastics content, respectively.

2. Microplastics have complex impacts on both chemical and biological characteristics of soil. Microplastics significantly affect soil chemical properties, with a significant positive correlation found between soil organic matter and microplastics concentration (increases of 2.80%, 30.37%, 88.10%, 118.22%, and 126.52% observed in each concentration treatment group compared to the control group). Microplastics were found to suppress soil total nitrogen, nitrate nitrogen, ammonium nitrogen, available phosphorus, dissolved organic nitrogen, and dissolved organic carbon to some extent. The highest concentration treatment decreased these parameters by 31.14%, 22.75%, 12.50%, 43.85%, 36.24%, and 6.25%, respectively. Soil pH was inhibited within a certain concentration range before being promoted. The effects of microplastics on soil microbial biomass and soil enzyme activities were complex. Soil microbial biomass in the microplastics-added treatment groups were suppressed at low concentrations (0.5%) and promoted at high concentrations (5%-10%). Soil enzyme activity in the microplastics treatment group was generally higher than that in the control group. Most soil enzyme activities were positively correlated with microplastics concentration in the low-to-medium concentration range (0.5%-2.5%), but decreased in the high concentration range. Moreover, soil enzyme activity in the rhizosphere was found to be more sensitive to microplastics concentration than that in the bulk soil.

3. In short-term pot experiments, microplastics have a significant impact on the bacterial and fungal communities in both rhizosphere and non-rhizosphere soils. The analysis of community structure and diversity showed that the number of dominant bacterial species of the genus and phylum levels was higher in rhizosphere soils than in bulk soils, and the fungal community structure at the order level in rhizosphere soils was more similar to that in mixed soils. Moreover, the differences in bacterial community between rhizosphere and bulk soils were more significant than those in fungal community, particularly in different concentration microplastics treatments. Analysis of microbial community diversity showed that the trends of changes in α-diversity of bacterial and fungal communities were similar, and the microbial community differences between different concentration microplastics treatments were significant and well-grouped, with significant differences between rhizosphere and bulk soils. The co-occurrence network showed that microplastics had a greater impact on the bacterial community in the rhizosphere soil than in the bulk soil, and the fungal co-occurrence network in rhizosphere and bulk soils differed significantly. This study highlights the important role of rhizosphere soil in investigating the impact of microplastics on soil microbial communities and ecological functions, and further attention should be paid to the monitoring of rhizosphere soil in future research on soil microplastics.

4. Microplastics pollution has negative effects on the growth, development, and biomass accumulation of maize (Zea mays L.). The results of the study showed that microplastics treatment significantly affected the biomass accumulation of individual maize plants, with a reduction of 53.60%, 52.95%, 46.39%, 38.20%, and 47.54% compared to the control group. In the short term (0-7 days), there were no significant differences in maize height and leaf area due to microplastics exposure. However, at day 14, there was a trend of promotion followed by inhibition of maize height and leaf area with increasing microplastics concentration in the treatment group. Correlation analysis showed that microplastics pollution affected maize growth by affecting the chemical and biological characteristics of the soil indirectly.

In conclusion, based on a comprehensive assessment of soil chemical and biological characteristics, microbial communities, and plant growth, microplastics pollution may have irreversible negative effects on agroecosystems and exhibit a strong concentration-dependent effect. This study provides new evidence for the presence and risk assessment of microplastics in agricultural soils and sheds new light on the response mechanisms of agroecosystems to microplastics pollution.

Subject Area生态系统生态学、微塑料污染与生态毒理学
MOST Discipline Catalogue理学 - 生态学
URL查看原文
Language中文
Other Code262010_220200929880
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/536318
Collection生态学院
Affiliation
兰州大学生态学院
Recommended Citation
GB/T 7714
尚耘旭. 微塑料对玉米栽培土壤的化学、生物学特性及玉米生长的影响[D]. 兰州. 兰州大学,2023.
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