Manganese occurs naturally in sediment, yet anthropogenic sources, such as industrial wastewater and mining, increases Mn concentration. However, the environmental risk of bioavailable Mn is often overlooked and infrequently addressed. A probabilistic risk assessment was conducted to determine the effects of bioavailable Mn in river sediments on reproduction in model organism Caenorhabditis elegans using in utero egg counts and germline apoptosis as biomarkers. The lowest-observed-adverse-effect level (LOAEL) of sediment Mn that decreases in utero egg counts or increases germline apoptosis in C. elegans was 50 or 10 mg of Mn(II) per kg of dry weight sediment, respectively. Effect and exposure analyses were conducted using Hill model-simulated concentration-response curves and Mn concentrations of Laojie River sediment. Risk quotients (RQs) and exceedance risk (ER) analyses showed that bioavailable levels of Mn in Laojie River sediments from downstream sites collected during the dry season elevate reproductive risk as measured by germline apoptosis. These findings suggest that bioavailable levels of Mn in sediment exert negative impacts, and germline apoptosis is a sensitive biomarker for reproductive risk assessment. Our results also suggest that the anthropogenic Mn pollution in river sediment and spatial-seasonal bioavailability of Mn should be considered to improve sediment quality control.

锰天然存在于沉积物中，但人为来源，如工业废水和采矿，会增加锰的浓度。然而，生物可利用锰的环境风险经常被忽视并且很少被提及。进行了概率风险评估，以确定河流沉积物中生物可利用的锰对模型生物秀丽隐杆线虫繁殖的影响，使用子宫内卵数和生殖细胞凋亡作为生物标志物。沉积物 Mn 的最低观察到不良反应水平 (LOAEL) 会减少子宫内卵子数量或增加线虫中的生殖细胞凋亡分别为每千克干重沉积物 50 或 10 毫克 Mn(II)。使用希尔模型模拟的浓度-响应曲线和老街河沉积物的锰浓度进行了影响和暴露分析​​。风险商数 (RQ) 和超标风险 (ER) 分析表明，旱季收集的下游地点的老街河沉积物中锰的生物可利用水平提高了生殖风险，如生殖细胞凋亡所测量的那样。这些发现表明沉积物中锰的生物可利用水平会产生负面影响，生殖细胞凋亡是评估生殖风险的敏感生物标志物。我们的研究结果还表明，应考虑河流沉积物中的人为锰污染和锰的空间季节性生物有效性，以改善沉积物质量控制。