Estuarine microbiome exposed to copper oxide nanoparticles

Nanomaterials usages are increasing in multiple fields. With a large spectrum of applications, the impact of nanomaterials on natural ecosystems is a growing concern in environmental science and management. Methods for nanomaterials removal from wastewaters are yet developing and currently a significant fraction of nanomaterials escapes treatment plants. As a result estuaries are becoming the final repository for nanomaterials. The implications of this towards biota have been assessed, but usually at higher concentrations than the environmentally-predicted. Moreover, the impact of nanoparticles towards ecosystem services has seldom been reported. The aim of this project was to ascertain whether deposition of copper oxide nanoparticles (Cu NPs) in estuarine sediments will change metal speciation and bioavailability, which will in turn impact the composition and functionality of the estuarine microbial communities. For this project we selected the Douro River estuary (North Atlantic), which is of major importance in its geographical area as its watershed drains 17 % of the Iberian Peninsula. We performed a series of microcosms enrichment experiments exposing estuarine sediments to Cu NPs, of size <50 nm, at a concentration of 10 ng/g, tested for 4 h, 7h and 24 h. The microcosms pH and dissolved oxygen was monitored, as well as concentrations of nitrate, nitrite and ammonium. DNA was extracted from the sediment and sequencing was performed using Illumina Hiseq Xten to acquire 150 bp paired-end sequences. This generated 18 Gbp per sample, after filtering adaptor sequences, contamination and low-quality reads. Links were identified between the microbial community and ecosystems services they might provide, namely the service of removing fixed nitrogen, which is critical in eutrophic ecosystems.