The effects of simulated acid rain and cadmium-containing atmospheric fine particulate matter on the pakchoi (Brassica campestris. L) seedlings growth and physiology

ABSTRACT Acid rain (AR) and atmospheric particulate matter (APM) are important environmental issues that often occur simultaneously in agricultural regions, the combined pollution of AR and atmospheric fine particles (PM2.5) containing heavy metals has negatively affected the growth of seedlings and has become a hot research topic. In this paper, we established exposure scenarios to simulate the AR and the cadmium-containing PM2.5 (PM2.5-Cd) pollutions. Under the scenarios, hazardous impacts of AR and PM2.5-Cd on growth, physiological and biochemical characteristics of pakchoi were evaluated. After being exposed simulated AR and PM2.5-Cd for 21 days, our results indicate that: single treatment with either AR (pH 5.5) or PM2.5-Cd, or a combined treatment of AR (pH 5.5) and PM2.5-Cd (150, 300 μg·m−3) increased the growth of pack hoi seedlings. Combined treatments with low-acidity AR (pH 3.5) and PM2.5-Cd (500 μg·m−3), significantly decreased the growth and the Soil and Plant Analyzer Development (SPAD) of pakchoi, and it also induced a significantly increase in foliar MDA content and catalase (CAT) activity, while decreasing peroxidase (POD) and superoxide dismutase (SOD) activity. The Cd concentration of leaves increased with an increasing PM2.5-Cd concentration. Correlation analysis indicated that the growth and SPAD of pakchoi were highly correlated with the foliar MDA content and enzyme activities under the combined treatments with AR and PM2.5-Cd treatment. Our results might serve as a guide to increase agricultural production and food crop safety in areas with high levels of AR and PM2.5 pollution.