posted on 2021-08-18, 12:04authored byMegan L. Fork, Jerker B. Fick, Alexander J. Reisinger, Emma J. Rosi
Pharmaceuticals
are commonly detected at low concentrations in
surface waters, where they disrupt biological and ecological processes.
Despite their ubiquity, the annual mass of pharmaceuticals exported
from watersheds is rarely quantified. We used liquid chromatography–mass
spectroscopy to screen for 92 pharmaceuticals in weekly samples from
an urban stream network in Baltimore, MD, USA, that lacks wastewater
treatment effluents. Across the network, we detected 37 unique compounds,
with higher concentrations and more compounds in streams with higher
population densities. We also used concentrations and stream discharge
to calculate annual pharmaceutical loads at the watershed outlet,
which range from less than 1 kg to ∼15 kg and are equivalent
to tens of thousands of human doses. By calculating annual watershed
mass balances for eight compounds, we show that ∼0.05 to ∼42%
of the pharmaceuticals consumed by humans in this watershed are released
to surface waters, with the importance of different pathways (leaking
sewage vs treated wastewater effluent) differing among compounds.
These results demonstrate the importance of developing, maintaining,
and improving sewage infrastructure to protect water resources from
pharmaceutical contamination.