Institute for Energy Security and Environmental Safety, Centre for Energy Research, Hungarian Academy of Sciences, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary.
Budapest Sewage Works Pte Ltd., South-Pest Wastewater Treatment Plant, H-1238, Meddőhányó utca 1, Budapest, Hungary.
Sci Total Environ. 2018 May 1;622-623:1009-1015. doi: 10.1016/j.scitotenv.2017.12.065. Epub 2017 Dec 13.
Numerous studies have been published on the radiolysis of sulfonamide antibiotic solutions but little effort has been made to monitor the biological properties of degradation products. A complex approach should also clarify the changes in antibacterial activity and biodegradability, besides the usual screening of toxicity. To fill this gap, the ionizing radiation induced degradation of four sulfonamide antibiotics was investigated in dilute aqueous solutions, with emphasis on the biological assessment of decomposition products. Complete removal of sulfonamides was achieved by a low absorbed dose (1.5kGy). 2-2.5kGy dose was needed to transform the persistent initial molecules to substances biodegradable in both river water and activated sludge. The ratio of the biological and chemical oxygen demand increased from <0.21 to at least 0.59, but values as high as 0.80 were also measured. It was demonstrated that antibacterial activity is due to the initial molecules, as it disappeared when the sulfamethoxazole concentration decreased below the minimal inhibitory concentration (30 μM). This means that the products have no antibacterial activity. Toxicity testing performed on test organisms from three different trophic levels and activated sludge evidenced that the toxicity depends both on the test organism and on the sulfonamide used. The degradation of initial molecules is not always enough to eliminate the environmental risk due to the toxic products formed e.g. inhibitory effects to Vibrio fischeri increased by 34% at 2.5kGy. For this reason, complex biological assessment of treated solutions has to play an important role in development and optimization of advanced treatment techniques.
已有大量研究报道了磺胺类抗生素溶液的辐射分解，但很少有人致力于监测降解产物的生物特性。除了常规的毒性筛选外，复杂的方法还应阐明抗菌活性和生物降解性的变化。为了填补这一空白，本研究在稀水溶液中研究了四种磺胺类抗生素的电离辐射诱导降解，重点是对分解产物的生物评估。通过低吸收剂量（1.5kGy）可完全去除磺胺类药物。需要 2-2.5kGy 的剂量才能将持久性的初始分子转化为可在河水和活性污泥中生物降解的物质。生物需氧量与化学需氧量之比从<0.21 增加到至少 0.59，但也测量到高达 0.80 的值。研究表明，抗菌活性归因于初始分子，因为当磺胺甲恶唑浓度降至最小抑菌浓度（30 μM）以下时，其活性消失。这意味着这些产物没有抗菌活性。对来自三个不同营养级别的测试生物和活性污泥进行的毒性测试表明，毒性取决于测试生物和使用的磺胺类药物。初始分子的降解并不总是足以消除由于形成的有毒产物而产生的环境风险，例如在 2.5kGy 时，对发光菌的抑制作用增加了 34%。因此，处理后溶液的复杂生物评估必须在开发和优化高级处理技术中发挥重要作用。
