Generational Toxicity and Incomplete Recovery from Spent Lithium-Ion Battery Leachate in an Aquatic Microinvertebrate Brachionus asplanchnoidis

Spent lithium-ion batteries (LIBs) are a rapidly growing
solid
waste; mismanagement generates metal-rich leachate that threatens
aquatic environments. We evaluated the molecule-to-population responses
of the zooplankton Brachionus asplanchnoidis to leachate from retired 18650 cells across single-generation exposure,
postexposure recovery, and multigenerational propagation and tested
whether monosodium glutamate (MSG) accelerates recovery. Rotifers
were exposed to 5% (volume/volume, v/v) leachate and assessed for
morphological, feeding, life-history, population, metabolomic, biochemical,
and gene-expression end points. Chemical profiling confirmed elevated
Li, Fe, Al, Co, Ni, and Mn above seawater background. Leachate suppressed
growth and feeding within and across generations, and poststress recovery
was asynchronous, with feeding rebounding faster than body size and
life-history traits. In multigenerational assays, the exposure lineage
collapsed by F4, whereas recovery lineages showed progressive
improvement, approaching control levels by ∼F6 in
the transgenerational lineage and by ∼F4 with MSG
supplementation. Metabolomics revealed 189 differential metabolites
and distinct exposure–recovery signatures centered on amino
acid and energy metabolism. Gene expression supported metallothionein-mediated
detoxification under the measured metal burden. By integrating short-
and long-term perspectives, this study demonstrates multilevel toxicity,
incomplete and phased recovery, and the potential of targeted nutritional
support to enhance resilience and poststress performance, informing
mixture-aware environmental risk assessment of LIB leachate.