Modeling the Impact of Salinity Variations on Aquatic Environments: Including Negative and Positive Effects in Life Cycle Assessment

Salinity is changing
in aquatic systems due to anthropogenic activities
(like irrigation or dam management) and climate change. Although there
are studies on the effects of salinity variations on individual species,
little is known about the effects on overall ecosystems, these impacts
being more uncertain in transitional waters such as estuaries or fiords.
The few works that do address this topic have considered these impacts
using ecotoxicity models. However, these models state that an increase
in the concentration of a pollutant generates an increase in the impacts,
disregarding the effects of water freshening. The present research
work introduces a general framework to address the impacts of salinity
variations, including emission-related positive effects. We validated
this framework by applying it to an estuarine area in Galicia (northwestern
Spain), where sharp drops in the salt concentration have caused mass
mortalities of shellfish in recent decades. This research work addresses
for the first time the potential effects on the environment derived
from a decrease in the concentration of essential substances, where
the effects of an emission can also generate positive impacts. Moreover,
it is expected that the framework can also be applied to model the
environmental impacts of other essential substances in life cycle
assessment (LCA), such as metals and macronutrients.