Exposure and distribution of Microplastics (WP1)
We have conducted two intensive monitoring campaigns in farming case studies in Canada and Spain, collecting several hundreds of samples, including sludge (used as soil amending agent), soil, sediments, fresh water, and runoff samples. We have characterized different potential sources including wastewater effluents.
In Spain we focused on assessing emissions of microplastics (MPs) and exposure in surface waters in the watershed of Henares River (Province of Madrid). Close collaboration with international partners (IMDEA, NIVA, Trent University and Windsor University) ensured consistent sampling techniques (mesh sizes, sampling depths, etc.) between case studies.
Three sampling stations for river water and sediments were selected, representative of different levels of human impact:
i) low impact from all sources;
ii) high agricultural impact;
iii) high mixed impact (urban, agricultural, industrial) at the watershed outlet.
In addition, a runoff experiment was performed to evaluate the contribution of MPs from runoff on agricultural soils. Special devices for runoff collection were placed on three plots with comparable soil characteristics but different MPs treatments:
(i) soil never treated with sludge (control),
(ii) soil treated with sludge in the past (in 2013), and
(iii) soil treated with sludge at the start of the experiment (in November 2017). Sludge was applied according to standard agricultural practices.
In Canada, monitoring of MPs was undertaken in three catchments within Lake Simcoe; Beaverton and Orillia, which have a history of biosolids applications on agricultural lands, and a control site within the Innisfil region. The aim was to assess contributions of MPs from a range of sources (wastewater, biosolids, stormwater), their transport (via runoff, soil erosion, and stream flow), and fate (in soils and stream sediment).
Over 3000 samples were collected throughout the catchments. Samples were taken before, during and after the application of biosolids to soils, with higher frequency sampling conducted during heavy rainfall events. Runoff plots were constructed to analyse MP transport from soils into streams during rainfall events.
Samples collected in Spain and Canada were transferred to NIVA in Norway for the MP analysis. The lack of validated methods for the analysis of MPs in soil, sediments and sludge samples, called for an urgent and significant effort to fill this gap. We have developed the first full validation study of a method for this type of analysis and published it in one of the top journals in the field.
This study includes, for the first time, a direct assessment of analytical recovery for different type of MPs with results that enormously increase credibility and trust on the data we are delivering.
The analytical effort in analyzing MP has been so far tremendous. We have individually identified and chemically analyzed 5988 individual particles across all analyzed samples. MPs detection is a laborious, and to a large extent still manual, operation.
Results will be disseminated through this site after they will be published on peer-reviewed scientific journals.