模拟酸雨对我国亚热带森林土壤有机碳矿化的影响研究

酸雨污染已成为威胁土壤和植物健康的全球性环境问题。为探究酸雨对我国亚热带森林土壤有机碳矿化的影响，选取南京紫金山区域酸碱性不同的森林土壤，通过室内培养试验，以仅添加纯水（CK）和纯水+凋落叶（T0）为对照，模拟凋落叶添加后，pH分别为1.65 （T1）、3.67 （T2）、5.55 （T3）的酸雨对土壤有机碳矿化的影响。结果表明，碱性土壤条件下，各处理CO₂累积排放量为1.67~3.35 g·kg^-1，表现为T3>T2>T1>T0>CK；而在酸性土壤中，CO₂累积排放量为0.99~3.90 g·kg^-1，表现为T3>T0>T2>CK>T1。与CK相比，添加凋落叶（T0）后，酸性、碱性土壤CO₂累积排放量分别增加了41.20%和71.72%。轻度酸雨（T3）能促进CO₂排放，加快凋落叶的分解；重度酸雨（T1）会显著抑制酸性土壤有机碳和凋落叶的矿化（P<0.05），但加速了碱性土壤有机碳和凋落叶的矿化；而中度酸雨（T2）对两类土壤的土壤呼吸、凋落叶分解的抑制或促进作用均未达显著水平。凋落叶的添加会显著增加碱性土壤的CO₂排放，但对酸性土壤CO₂排放的影响因模拟酸雨pH的差异而不同。总体而言，不同强度的酸雨对碱性土壤有机碳矿化有促进作用；而在酸性土壤中，除轻度酸雨外，其他强度的酸雨均抑制了土壤有机碳矿化。

Effects of simulated acid rain on soil organic carbon mineralization in the subtropical forests of China

Acid rain, one of the major global environmental problems, is severely endangering soil health and plant growth. To explore the effects of acid rain on soil organic carbon mineralization in the subtropical forests of China, in this study, two forest soils with different acidity were selected from the Zijin Mountain in Nanjing, only distilled water(CK) and distilled water + litters(T0) as controls, and incubated in microcosms to investigate the effects of simulated acid rain with the gradient pH levels of 1.65(T1), 3.67(T2), and 5.55(T3) on soil organic carbon mineralization under the addition of litters. The results showed that, CO₂ emission from the alkaline soil was 1.67~3.35 g·kg^-1, with the trend:T3>T2>T1>T0>CK; while in the acid soil, CO₂ emission was 0.99~3.90 g·kg^-1, and changed with:T3>T0>T2> CK>T1. The cumulative CO₂ emission of T0 treatment increased by 41.20% and 71.72% in the acid and alkaline soil, respectively compared with that of CK. High pH-simulated acid rain(T3) enhanced carbon dioxide(CO₂) emission and accelerated litter decomposition. Severe simulated acid rain(T1) with lower pH significantly inhibited organic carbon mineralization and litter decomposition in the acidic soil(P<0.05), and reduced CO₂ emissions; while enhanced the decomposition rates of organic carbon and litter in the alkaline soils. However, the effects of moderate simulated acid rain(T2) on soil respiration and litter decomposition in both two soils were not statistically significant. Leaf litter addition significantly increased CO₂ emissions from the alkaline while CO₂ emissions from the acidic soils were varied with the pH of stimulated acid rain. In summary, simulated acid rain with different pH stimulated organic carbon mineralization in alkaline soil; albeit with an inhibition effect in acid soil except the treatment of high pH acid rain.