Data from: How common road salts and organic additives alter freshwater food webs: in search of safer alternatives

The application of deicing road salts began in the 1940s and has increased
drastically in regions where snow and ice removal is critical for
transportation safety. The most commonly applied road salt is sodium
chloride (NaCl). However, the increased costs of NaCl, its negative
effects on human health, and the degradation of roadside habitats has
driven transportation agencies to seek alternative road salts and organic
additives to reduce the application rate of NaCl or increase its
effectiveness. Few studies have examined the effects of NaCl in aquatic
ecosystems, but none have explored the potential impacts of road salt
alternatives or additives on aquatic food webs. We assessed the effects of
three road salts (NaCl, MgCl2 and ClearLane™) and two road salts mixed
with organic additives (GeoMelt™ and Magic Salt™) on food webs in
experimental aquatic communities, with environmentally relevant
concentrations, standardized by chloride concentration. We found that NaCl
had few effects on aquatic communities. However, the microbial breakdown
of organic additives initially reduced dissolved oxygen. Additionally,
microbial activity likely transformed unusable phosphorus from the organic
additives to usable phosphorus for algae, which increased algal growth.
The increase in algal growth led to an increase in zooplankton abundance.
Finally, MgCl2 – a common alternative to NaCl – reduced compositional
differences of zooplankton, and at low concentrations increased the
abundance of amphipods. Synthesis and applications. Our results indicate
that alternative road salts (to NaCl), and road salt additives can alter
the abundance and composition of organisms in freshwater food webs at
multiple trophic levels, even at low concentrations. Consequently, road
salt alternatives and additives might alter ecosystem function and
ecosystem services. Therefore, transportation agencies should use caution
in applying road salt alternatives and additives. A comprehensive
investigation of road salt alternatives and road salt additives should be
conducted before wide-scale use is implemented. Further research is also
needed to determine the impacts of salt additives and alternatives on
higher trophic levels, such as amphibians and fish.