摘要:多环芳烃作为环境污染物中一类极为重要的物质，探索它的去除方法吸引了全球环境****及政府的高度重视。大气氮沉降在过去几十年不断增加，已影响到陆地生态系统氮循环过程。但目前，氮沉降与多环芳烃降解之间的关系尚不明确。通过在新疆克拉玛依市石油化工厂附近的荒漠草地上，模拟氮沉降实验，通过在4氮添加梯度（CK=0；N1=10；N2=30；N3=90 kg N hm^-2 a^-1）上调查土壤中16种优先控制多环芳烃的含量和总量（∑PAHs），以及它们与生物非生物环境因子（土壤环境因子、土壤酶活性和土壤微生物功能多样性）之间的关系，旨在揭示氮沉降对多环芳烃降解的影响。结果表明：除苊烯（Acenaphthylene）和苊（Acenaphthene）两种多环芳烃在4个N添加梯度上未检测到含量外，∑PAHs和其他14种优先控制多环芳烃在土壤中的含量均随氮添加量增加显著减小（N2 ≤ N3 < N1 < CK）（P < 0.01）；对照样地（CK）在施氮前后，低高分子多环芳烃含量的比值 > 1.00，且0.40 < 荧蒽（Fluoranthene）/[（荧蒽（Fluoranthene）+芘（Pyrene）] < 0.50，石油污染物是当地土壤中多环芳烃的主要来源；9月份克拉玛依市荒漠草地土壤中∑PAHs约（28.91±2.32）mg/kg，属于多环芳烃重污染土壤；广义线性混合效应模型结果显示，在大多数情况下，∑PAHs和14种多环芳烃的含量与土壤有机质、铵态氮、硝态氮、总氮、有效磷和脲酶活性显著相关（P < 0.05），但其与生物非生物环境因子之间的回归关系在不同种类多环芳烃之间差异较大。综上可知，土壤中多环芳烃的降解是一个非常复杂的过程，它是自身属性、植物根系和土壤微生物等多重因子相互共同作用的结果。在干旱区荒漠草地中，氮添加能提升土壤中营养物质的可利用性、植物根系和土壤微生物的活性，有利于降解土壤多环芳烃。



Abstract:As a critical environmental pollutant, the development of contamination control methods for polycyclic aromatic hydrocarbons (PAHs) has generated great concern worldwide. Atmospheric nitrogen (N) deposition has increased over the last few decades, which in turn has made available N increase in terrestrial ecological systems. However, relationship between PAHs degradation and N deposition remains unclear. In this study, four amounts of N fertilization, i.e., low (N1), middle (N2), and high (N3) N additions (10, 30, and 90 kg N hm^-2 a^-1, respectively) and an unfertilized control (CK; 0 kg N hm^-2 a^-1), were conducted in the desert grassland of Karamay, Xinjiang, in northwest China. Then, the amounts of 16 priority USEPA PAHs, the total amount of PAHs (∑PAHs), and three biotic-abiotic factors, including soil environmental factors, enzyme activities, and microbial functional diversity, were investigated to demonstrate the effects of N fertilization on PAHs degradation in the desert grassland. The results showed that, the amounts of ∑PAHs and 14 priority USEPA PAHs significantly decreased along the gradient of N addition (N2 ≤ N3 < N1 < CK)(P < 0.01), except for undetected acenaphthylene and acenaphthene, in all N additions treatments. This suggested N fertilization was advantageous to the decrease of soil PAHs in arid desert grassland. Low molecular weight PAHs/heavy molecular weight PAHs > 1.00, whereas 0.40 < fluoranthene/(fluoranthene+pyrene) < 0.50 in CK plots in both April and September, suggesting that PAHs mainly originated from a petroleum pollutant. ∑PAHs in the desert grassland soil equaled to (28.91±2.32) mg/kg in September in Karamay, indicating that the local soil had a heavy pollution level of PAHs. In most situations, the amounts of ∑PAHs and 14 priority USEPA PAHs had a significant regression relationship with soil organic matter, ammonium nitrogen, nitrate nitrogen, total nitrogen, available phosphorus, and urease activity in the generalized linear mixed models (GLMMs) (P < 0.05). The regression function of PAHs to biotic-abiotic factors varied among PAH types. Overall, our results showed that PAH degradation was a complex process in desert grassland soil, which was interactively determined by their own characteristics, plant roots, and microorganisms. N deposition might improve nutritional availability, with positive interactions with plant roots, microorganisms, and PAHs degradation, and the subsequent decrease in PAHs concentration along an N addition gradient.





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