红树林湿地多环芳烃的微生物降解

Advances in microbial degradation of polycyclic aromatic hydrocarbons in mangrove wetlands

摘要:

红树林（mangrove）是海陆交汇带重要的湿地生态系统，也是环境污染物蓄积与转化的热区。多环芳烃（polycyclic aromatic hydrocarbons，PAHs）因其环境蓄积特点在红树林生境中广泛分布，威胁生态系统健康，其降解转化是近年的研究重点。本文聚焦红树林湿地多环芳烃的微生物降解研究现状，从红树林生境的PAHs生物降解规律、降解功能微生物、降解影响因素等角度综述了国内外最新的研究进展。总结发现，红树林中的PAHs含量高于林外光滩，集中于垂向10—20 cm深的沉积物中。PAHs厌氧降解相应的电子受体中，以SO₄^2–浓度最高，且渗入泥层更深，是红树林沉积物的主要电子受体；其次是NO₃^–、CO₂、Fe （Ⅲ）和Mn （Ⅳ）。PAHs降解菌多样性高，其中以Sphingomonas、Bacillus、Novosphingobium和Sphingobium报道最多。红树林生境中好氧-厌氧交替的独特环境、湿地植物根际泌氧和分泌物以及外源生物刺激因子是影响PAHs生物降解的主要因素。目前多数结果都是基于室内实验，而红树林生境复杂，建议未来面向PAHs污染修复的实际需求，针对红树林的环境特点挖掘相应的PAHs降解功能微生物种质资源，并从应用工艺等方面开展深入的研究。

关键词:红树林;沉积物;多环芳烃降解;电子受体;微生物

Abstract:

Mangrove forest is an important ecosystem in the sea-land interface zone and a hot zone for pollutant accumulation and transformation. Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants widely distributed in mangrove wetlands, threatening ecosystem health. The degradation and transformation of PAHs have attracted increasing attention of researchers in recent years. This paper reviews the available studies about microbial degradation of PAHs in mangrove wetlands from the perspectives of biodegradation rules, functional microorganisms, and influencing factors of PAH degradation in mangrove habitats. We found that the PAHs in mangrove forests had higher content than those in the beach outside the forests, and they accumulated in the sediments at a depth of 10-20 cm. Sulfates were the main electron acceptors (EAs) for anaerobic degradation of PAHs, as they had the highest concentration and infiltrated deeper into the sediments. EAs nitrate, bicarbonate, Fe(III), and Mn(IV) were also distributed in mangrove sediments and played roles on PAH-degradation. PAH-degrading bacteria had high diversity, among which Sphingomonas, Bacillus, Novosphingobium, and Sphingobium were reported frequently. The aerobic-anaerobic alternation condition, radial oxygen loss, root exudates, and exogenous biostimulators were the main factors affecting the biodegradation of PAHs in mangrove habitats. We suggest that researchers can focus on the application technologies of PAH-degrading microorganisms to meet the actual needs of wetland remediation.

Key words:mangroves;sediments;PAH degradation;electron acceptors;microorganism