不同污染区巨菌草生物炭内源污染物分布及其生物毒性

由于生物质原料来源广泛，缺乏生物炭内源污染物及其用量限制标准，极有可能将含有高内源污染物的生物炭用于环境修复，产生潜在的环境风险.采用清洁区、中度和重度污染区的巨菌草为原料制备生物炭，考察其内源铜（Cu）和镉（Cd）全量及其酸溶态含量和持久性自由基（PFRs）分布，并研究生物炭浸出液对小麦根伸长抑制率和抗氧化酶活性的影响.结果表明，重度污染区九牛生物炭Cu和中度污染区水泉生物炭中Cd含量分别是清洁区红壤生物炭Cu和Cd的3.73倍和4.43倍，九牛生物炭中酸溶态Cu含量分别是水泉和红壤生物炭的3.32倍和2.84倍，水泉和九牛生物炭中酸溶态Cd含量分别是红壤生物炭的7.95倍和5.11倍.3种生物炭中均含有相邻氧原子以碳为中心的PFRs，表现为：红壤>九牛>水泉.3种生物炭浸出液对小麦根伸长均表现为抑制作用，但均不同程度地提高了小麦幼苗超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性，其中九牛生物炭浸出液对小麦根伸长抑制率最高，达到27.7%.本研究表明，生物炭中内源重金属及PFRs等污染物的共同作用对小麦幼苗产生了显著的生物毒性，后期的研究需关注生物炭内源污染物的潜在环境风险，避免产生二次污染等环境问题.

Distribution and Biotoxicity of Endogenous Pollutants in Pennisetum sp. Biochar from Different Polluted Areas

Due to the wide sources of biomass raw materials and the lack of limits for the endogenous pollutants in biochar and their dosage, some biochar with high endogenous pollutants may be used for environmental remediation, which results in potential environmental risks. In this study, three biochars were prepared from the straws of Pennisetum sp. grown in clean, moderately polluted and highly polluted soils, respectively. The total endogenous copper (Cu) and cadmium (Cd), acid-soluble fraction, and persistent free radical (PFRs) distribution in biochars were investigated, and their biotoxicities were evaluated based on wheat root elongation inhibition rate and antioxidant enzyme activity. The results indicated that total Cu in Jiuniu biochar from the highly polluted soil and total Cd in Shuiquan biochar from the moderately-polluted soil were 3.73 and 4.43 times higher than that in Hongrang biochar from the clean soil, respectively. Moreover, acid-soluble Cu in Jiuniu biochar was 3.32 and 2.84 times higher than that in Shuiquan and Hongrang biochar, respectively, and acid-soluble Cd in Shuiquan and Jiuniu biochar was 7.95 and 5.11 times higher than that in Hongrang biochar, respectively. All three biochars had PFRs with adjacent oxygen atoms centered on carbon and followed the order of Hongrang>Jiuniu>Shuiquan. Three biochar leaching solutions significantly inhibited wheat root elongation but enhanced the enzyme activities of SOD, POD, and CAT for the wheat seedlings compared with that in the control. In particular, the highest inhibition rate (27.7%) was found in Jiuniu biochar. This study indicated that the interaction of endogenous heavy metals and PFRs in biochar exhibited significant biotoxicity to wheat seedlings. In the future, more attention should be paid to the potential environmental toxicity of endogenous pollutants from biochar to avoid new environmental pollution problems.