Chen Juan, Zhou Hai Chao, Pan Ying, Shyla Farzana Shazia, Tam Nora Fung-Yee
Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China; State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China.
Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China; State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China.
Sci Total Environ. 2016 May 15;553:60-70. doi: 10.1016/j.scitotenv.2016.02.052. Epub 2016 Feb 20.
Little is known about polybrominated diphenyl ethers (PBDEs) and planting affect biogeochemical processes, and their impact on microbial nitrogen (N) transformation in soil. A 12-month microcosm experiment was conducted to understand the effects of a mixture of PBDEs at two contamination levels, 2 and 20 mg kg(-1)dry weight representing low and high soil contamination, respectively, using two mangrove plant species, namely Kandelia obovata (Ko) and Bruguiera gymnorrhiza (Bg), on nitrification, denitrification and anammox in mangrove soils. No significant changes in these N transformation processes were found at month 3 and at a low level of PBDEs in both plant species, suggesting that short-term exposure to 2 mg kg(-1) contamination did not affect microbial N transformation. At month 12, a high level of PBDE contamination significantly decreased the nitrification potential activity and the copy numbers of archaeal amoA and bacterial amoA gene in Ko soil, but such inhibitory effect was not significant in Bg soil. On the contrary, the denitrification-related parameters, including the activities of nitrate reductase and nitrite reductase, potential denitrification activity and copy numbers of nirK, nirS and nosZ gene, were stimulated by a high level of PBDE contamination in both Ko and Bg soils, and the stimulation was higher in the more anaerobic Bg soil. Different from denitrification, a high level of PBDE contamination decreased the copy numbers of anammox bacterial 16S rRNA gene in Bg soil but not in Ko soil; this was possibly related to the lower nitrate concentration in Bg soil that might inhibit the growth of anammox bacteria. These results indicated that the effects of PBDEs on microbial N transformation were plant species-specific, with the nitrifying microorganisms in Ko soil more susceptible to PBDE contamination, while denitrification and anammox in Bg soil were more sensitive.
关于多溴二苯醚（PBDEs）及其对生物地球化学过程的影响，以及它们对土壤中微生物氮（N）转化的影响，人们所知甚少。进行了一项为期12个月的微观实验，以了解两种污染水平（分别为2和20 mg kg(-1)干重，代表低和高土壤污染）的PBDEs混合物对两种红树林植物，即秋茄（Ko）和木榄（Bg），对红树林土壤中硝化作用、反硝化作用和厌氧氨氧化的影响。在第3个月以及两种植物中PBDEs含量较低时，这些N转化过程没有显著变化，这表明短期暴露于2 mg kg(-1)的污染水平不会影响微生物N转化。在第12个月时，高浓度的PBDE污染显著降低了秋茄土壤中的硝化潜力活性以及古菌amoA和细菌amoA基因的拷贝数，但这种抑制作用在木榄土壤中不显著。相反，在秋茄和木榄土壤中，高浓度的PBDE污染均刺激了与反硝化作用相关的参数，包括硝酸还原酶和亚硝酸还原酶的活性、潜在反硝化活性以及nirK、nirS和nosZ基因的拷贝数，并且在厌氧性更强的木榄土壤中刺激作用更大。与反硝化作用不同，高浓度的PBDE污染降低了木榄土壤中厌氧氨氧化细菌16S rRNA基因的拷贝数，但在秋茄土壤中没有；这可能与木榄土壤中较低的硝酸盐浓度有关，该浓度可能抑制了厌氧氨氧化细菌的生长。这些结果表明，PBDEs对微生物N转化的影响具有植物物种特异性，秋茄土壤中的硝化微生物对PBDE污染更敏感，而木榄土壤中的反硝化作用和厌氧氨氧化更敏感。
