College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China; Center for Ecological and Environmental Sciences, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.
Chemosphere. 2018 Apr;196:214-222. doi: 10.1016/j.chemosphere.2017.12.170. Epub 2017 Dec 28.
Both elevated temperature and heavy metal contamination can have profound effects on microbial function and soil biogeochemical cycling. However, the interactive effects of heavy metal toxicity and temperature on microbial activity have been poorly understood. The aim of this study was to quantify the effect of temperature and cadmium (Cd) toxicity on alkaline phosphatase (ALP) produced by microbes to acquire phosphorus. To determine whether these effects were dependent on soil properties, we utilized 11 soil types from cropland throughout China. We measured ALP activities and kinetics across a temperature (17, 27, 37, and 47 °C) and Cd concentration gradient (0, 0.6, 5, 25, 50, 100, 200, 300, and 500 mg kg). We found that the half saturation constant (K) and the velocity constant (k) of ALP increased nonlinearly with temperature across all soil types. However, the maximum reaction velocity (V) increased linearly with temperature. Regardless of soil type and temperature, Cd had a non-competitive inhibitory mechanism. Soil pH, TOC, and clay content were the major factors controlling the affinity of ALP for Cd (K). The ecology dose (ED) for V and k, and K were negatively related to temperature, indicating that the toxicity of Cd on ALP is temperature-dependent. Additionally, higher temperatures led to more inhibition of Cd on ALP activity in alkaline soils than that in acidic and neutral soils. Our results suggest that global warming might accelerate the deficiency of available phosphorus in Cd contaminated soils due to higher inhibition of Cd on ALP activity, particularly in alkaline soils.
高温和重金属污染都可能对微生物功能和土壤生物地球化学循环产生深远影响。然而，重金属毒性和温度对微生物活性的交互影响还知之甚少。本研究旨在量化温度和镉（Cd）毒性对微生物产生的碱性磷酸酶（ALP）获取磷的影响。为了确定这些影响是否依赖于土壤性质，我们利用了来自中国农田的 11 种土壤类型。我们在温度（17、27、37 和 47°C）和 Cd 浓度梯度（0、0.6、5、25、50、100、200、300 和 500mgkg）下测量了 ALP 活性和动力学。我们发现，所有土壤类型的 ALP 的半饱和常数（K）和速度常数（k）随温度呈非线性增加。然而，最大反应速度（V）随温度呈线性增加。无论土壤类型和温度如何，Cd 都具有非竞争性抑制机制。土壤 pH、TOC 和粘粒含量是控制 ALP 对 Cd（K）亲和力的主要因素。V、k 和 K 的生态剂量（ED）与温度呈负相关，表明 Cd 对 ALP 的毒性是温度依赖性的。此外，较高的温度导致 Cd 对碱性土壤中 ALP 活性的抑制作用大于酸性和中性土壤。我们的研究结果表明，全球变暖可能会由于 Cd 对 ALP 活性的更高抑制作用，加速 Cd 污染土壤中有效磷的缺乏，尤其是在碱性土壤中。
