Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture/Tianjin Key Laboratory of Agro-environment and Safe-product, Tianjin 300191, China.
Institute of Hanjiang, Hubei University of Arts and Science, Xiangyang 441053, China.
Int J Environ Res Public Health. 2019 Sep 19;16(18):3489. doi: 10.3390/ijerph16183489.
Phthalate acid esters (PAEs) are the most frequently utilized synthetic chemical compounds worldwide. They are typical emergent contaminants and are currently attracting considerable concern due to their risks to plants, animals, and public health. Determining the vital environmental factors that affect the toxicity of target pollutants in soil is important for vegetable production and the maintenance and control of soil productivity. We investigated the influence of di--butyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) under different soil conditions on physiological changes in water spinach ( Forsk.) seedlings and the rhizosphere soil microbial community. Supported by our former experiments in which we determined the representative concentrations that caused the most pronounced toxic effects, three experimental concentrations were studied including control soils without PAEs and spiked soils with either 20 mg DBP or DEHP kg soil. The soil at all the three PAE concentrations was then adjusted to test two soil pH values, three levels of soil organic matter (SOM) content, and three levels of soil moisture content; thus, we completed 12 treatments or conditions simulating different soil environment conditions in greenhouses. After 30 days of cultivation, we analyzed the toxicity effects of two target PAEs on plant growth and physiological factors, and on soil microbial community characteristics. The toxicity of soil DBP and DEHP to the physiology of water spinach was found to be most affected by the soil pH value, then by SOM content, and least of all by soil moisture. The results of the 454 high-throughput sequencing analysis of the soil microbial community indicated that the toxicity of target PAEs to soil microorganisms was most affected by SOM content and then by soil moisture, and no clear relationship was found with soil pH. Under different soil conditions, declines in leaf biomass, chlorophyll a content, and carotenoid content-as well as increases in free amino acid (FAA) content, superoxide anion free radical activity, and hydroxyl radical activity-occurred in response to DBP or DEHP. Heavy use of chemical fertilizer, organic fertilizer, and high humidity led to the special environmental conditions of greenhouse soil, constituting the main conditions considered in this study. The results indicate that under the special highly intensive production systems of greenhouses, soil conditions may directly influence the effects of pollutant phytotoxicity and may thus endanger the yield, nutrient content, and food safety of vegetables. The combined studies of the impacts on plants and rhizosphere microorganisms give a more detailed picture of the toxic effects of the pollutants under different soil conditions.
邻苯二甲酸酯（PAEs）是全球应用最广泛的合成化学物质。它们是典型的新兴污染物，由于对植物、动物和公众健康的危害，目前受到了极大关注。确定影响土壤中目标污染物毒性的重要环境因素对于蔬菜生产以及土壤生产力的维持和控制非常重要。我们研究了不同土壤条件下邻苯二甲酸二丁酯（DBP）和邻苯二甲酸二（2-乙基己基）酯（DEHP）对蕹菜（ Forsk.）幼苗生理变化和根际土壤微生物群落的影响。在我们之前的实验中，我们确定了导致最明显毒性效应的代表性浓度，研究了三个实验浓度，包括不含 PAEs 的对照土壤和添加 20mgDBP 或 DEHPkg 土壤的添加土壤。然后，将所有三种 PAE 浓度的土壤调整为测试两种土壤 pH 值、三个水平的土壤有机质（SOM）含量和三个水平的土壤水分含量；因此，我们完成了 12 种处理或条件，模拟了温室中不同的土壤环境条件。在 30 天的培养后，我们分析了两种目标 PAE 对植物生长和生理因素以及土壤微生物群落特征的毒性效应。发现土壤 DBP 和 DEHP 对蕹菜生理的毒性受土壤 pH 值影响最大，其次是 SOM 含量，受土壤水分影响最小。土壤微生物群落的 454 高通量测序分析结果表明，目标 PAE 对土壤微生物的毒性受 SOM 含量影响最大，其次是土壤水分，与土壤 pH 值无明显关系。在不同的土壤条件下，叶片生物量、叶绿素 a 含量和类胡萝卜素含量下降，游离氨基酸（FAA）含量、超氧阴离子自由基活性和羟基自由基活性增加，均是由于 DBP 或 DEHP 所致。大量使用化肥、有机肥和高湿度导致温室土壤的特殊环境条件，这是本研究中主要考虑的条件。结果表明，在温室高度集约化的生产系统下，土壤条件可能直接影响污染物的植物毒性效应，从而危及蔬菜的产量、营养成分和食品安全。对植物和根际微生物的综合研究更详细地描述了不同土壤条件下污染物的毒性效应。
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