Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
Chemosphere. 2013 Feb;90(6):1767-78. doi: 10.1016/j.chemosphere.2012.07.048. Epub 2012 Aug 22.
Carbonaceous soil amendments are applied to contaminated soils and sediments to strongly sorb hydrophobic organic contaminants (HOCs) and reduce their freely dissolved concentrations. This limits biouptake and toxicity, but also biodegradation. To investigate whether HOCs sorbed to such amendments can be degraded at all, the desorption and biodegradation of low concentrations of (14)C-labelled phenanthrene (≤5 μg L(-1)) freshly sorbed to suspensions of the pure soil amendments activated carbon (AC), biochar (charcoal) and compost were compared. Firstly, the maximum abiotic desorption of phenanthrene from soil amendment suspensions in water, minimal salts medium (MSM) or tryptic soy broth (TSB) into a dominating silicone sink were measured. Highest fractions remained sorbed to AC (84±2.3%, 87±4.1%, and 53±1.2% for water, MSM and TSB, respectively), followed by charcoal (35±2.2%, 32±1.7%, and 12±0.3%, respectively) and compost (1.3±0.21%, similar for all media). Secondly, the mineralization of phenanthrene sorbed to AC, charcoal and compost by Sphingomonas sp. 10-1 (DSM 12247) was determined. In contrast to the amounts desorbed, phenanthrene mineralization was similar for all the soil amendments at about 56±11% of the initially applied radioactivity. Furthermore, HPLC analyses showed only minor amounts (<5%) of residual phenanthrene remaining in the suspensions, indicating almost complete biodegradation. Fitting the data to a coupled desorption and biodegradation model revealed that desorption did not limit biodegradation for any of the amendments, and that degradation could proceed due to the high numbers of bacteria and/or the production of biosurfactants or biofilms. Therefore, reduced desorption of phenanthrene from AC or charcoal did not inhibit its biodegradation, which implies that under the experimental conditions these amendments can reduce freely dissolved concentration without hindering biodegradation. In contrast, phenanthrene sorbed to compost was fully desorbed and biodegraded.
向污染土壤和沉积物中添加碳素土壤改良剂，以强烈吸附疏水性有机污染物（HOC）并降低其自由溶解浓度。这限制了生物摄取和毒性，但也限制了生物降解。为了研究吸附到这种改良剂上的 HOC 是否可以被降解，比较了新鲜吸附到纯土壤改良剂活性炭（AC）、生物炭（木炭）和堆肥悬浮液中的低浓度（14）C 标记的菲（≤5μg L（-1））的解吸和生物降解。首先，测量了水、最小盐培养基（MSM）或胰蛋白酶大豆肉汤（TSB）中土壤改良剂悬浮液中菲的最大非生物解吸到主导硅脂阱中的分数。AC 吸附的菲分数最高（水、MSM 和 TSB 中分别为 84±2.3%、87±4.1%和 53±1.2%），其次是木炭（35±2.2%、32±1.7%和 12±0.3%，分别）和堆肥（1.3±0.21%，所有介质相似）。其次，确定 Sphingomonas sp. 10-1（DSM 12247）吸附到 AC、木炭和堆肥上的菲矿化。与解吸的量相比，所有土壤改良剂的菲矿化率相似，约为初始放射性的 56±11%。此外，HPLC 分析表明，悬浮液中残留的菲仅占少量（<5%），表明几乎完全生物降解。将数据拟合到偶联解吸和生物降解模型中表明，对于任何一种改良剂，解吸都没有限制生物降解，并且由于细菌数量多和/或生物表面活性剂或生物膜的产生，降解可以进行。因此，AC 或木炭中菲的解吸减少并没有抑制其生物降解，这意味着在实验条件下，这些改良剂可以降低自由溶解浓度而不阻碍生物降解。相比之下，吸附到堆肥上的菲完全解吸并被生物降解。
