Ecotoxicological implications of leachates from concrete demolition debris on oligochaetes: survival and oxidative stress status.

Urbanization and population growth demand the construction of structures to facilitate the need for space, and old infrastructures must make space for new ones leading to demolition and concrete debris. In addition to demolition, aging and weather are factors leading to concrete deterioration and, thus, a new challenge as an environmental pollutant. Studies on how concrete debris and leachate affect biota in the environment are limited. The present study aimed to understand the effects of leachate from various sizes of concrete debris on the three oligochaete species Enchytraeus crypticus, Tubifex, and Lumbriculus variegatus. Acute toxicity testing was carried out to determine the adverse effects over time. The oligochaetes' survival was monitored as well as the activity of the biotransformation enzyme glutathione S-transferase and the antioxidative enzyme catalase as indicators of the oxidative stress status. Leachate from the smallest concrete particle size (<1 mm) was found to be the most toxic as it caused, on average, 6-fold increased oligochaete mortality compared to the larger pieces (2-5 cm) after 96 h of exposure, potentially due to the larger surface area facilitating the release of toxicants. Substrate buffered the toxic effect of the leachate with 42 ± 12% fewer mortalities and reduced adverse effects on the enzymes. Of the three oligochaetes, E. crypticus was the most resilient to the concrete leachate. The study is the first to investigate the effects of concrete leachate on oligochaetes.