Wilske Burkhard, Bai Mo, Lindenstruth Beate, Bach Martin, Rezaie Zahra, Frede Hans-Georg, Breuer Lutz
Institute for Landscape Ecology and Resources Management (ILR), Justus Liebig University, Giessen, Germany,
Environ Sci Pollut Res Int. 2014;21(16):9453-60. doi: 10.1007/s11356-013-2103-1. Epub 2013 Sep 14.
Superabsorbent polymers (SAP) are used, inter alia, as soil amendment to increase the water holding capacity of soils. Biodegradability of soil conditioners has become a desired key characteristic to protect soil and groundwater resources. The present study characterized the biodegradability of one acrylate based SAP in four agricultural soils and at three temperatures. Mineralisation was measured as the (13)CO₂ efflux from (13)C-labelled SAP in soil incubations. The SAP was either single-labelled in the carboxyl C-atom or triple-labelled including additionally the two C-atoms interlinked in the SAP backbone. The dual labelling allowed estimating the degradation of the polyacrylate main chain. The (13)CO₂ efflux from samples was measured using an automated system including wavelength-scanned cavity ring-down spectroscopy. Based on single-labelled SAP, the mean degradation after 24 weeks varied between 0.45% in loamy sand and 0.82% in loam. However, the differences between degradation rates in different soils were not significant due to a large intra-replicate variability. Similarly, mean degradation did not differ significantly between effective temperature regimes of 20° and 30 °C after 12 weeks. Results from the triple-labelled SAP were lower as compared to their single-labelled variant. Detailed results suggest that the polyacrylate main chain degraded in the soils, if at all, at rates of 0.12-0.24 % per 6 months.
高吸水性聚合物（SAP）尤其可用作土壤改良剂，以提高土壤的持水能力。土壤改良剂的生物降解性已成为保护土壤和地下水资源的一个重要特性。本研究对一种丙烯酸酯基SAP在四种农业土壤和三种温度下的生物降解性进行了表征。矿化作用通过土壤培养中（13）C标记的SAP释放的（13）CO₂来测量。SAP要么在羧基碳原子上进行单标记，要么进行三标记，另外还包括在SAP主链中相互连接的两个碳原子。双重标记有助于估计聚丙烯酸酯主链的降解情况。使用包括波长扫描腔衰荡光谱的自动化系统测量样品中（13）CO₂的流出量。基于单标记的SAP，24周后的平均降解率在壤质砂土中为0.45%，在壤土中为0.82%。然而，由于重复实验中的较大变异性，不同土壤中降解率的差异并不显著。同样，在12周后，20℃和30℃的有效温度条件下，平均降解率也没有显著差异。三标记SAP的结果比其单标记变体的结果要低。详细结果表明，聚丙烯酸酯主链在土壤中的降解（如果有的话）速率为每6个月0.12 - 0.24%。
