The Journal of Agricultural Science

Nitrogen Workshop Special Issue Papers

Permeable reactive interceptors: blocking diffuse nutrient and greenhouse gases losses in key areas of the farming landscape

O. FENTONa1 c1, M. G. HEALYa2, F. BRENNANa3, M. M. R. JAHANGIRa1, G. J. LANIGANa1, K. G. RICHARDSa1, S. F. THORNTONa4 and T. G. IBRAHIMa1

a1 Teagasc, Environmental Research Centre, Johnstown Castle, Co. Wexford, Ireland

a2 Civil Engineering, National University of Ireland, Galway, Co. Galway, Ireland

a3 Ecological Sciences Group, James Hutton Institute, UK

a4 Groundwater Protection and Restoration Group, Kroto Research Institute, University of Sheffield, Sheffield, UK

SUMMARY

Engineered remediation technologies such as denitrifying bioreactors target single contaminants along a nutrient transfer continuum. However, mixed contaminant discharges to a water body are more common from agricultural systems. Indeed, evidence presented herein indicates that pollution swapping within denitrifying bioreactor systems adds to such deleterious discharges. The present paper proposes a more holistic approach to contaminant remediation on farms, moving from the use of ‘denitrifying bioreactors’ to the concept of a ‘permeable reactive interceptor’ (PRI). Besides management changes, a PRI should contain additional remediation cells for specific contaminants in the form of solutes, particles or gases. Balance equations and case studies representing different geographic areas are presented and used to create weighting factors. Results showed that national legislation with respect to water and gaseous emissions will inform the eventual PRI design. As it will be expensive to monitor a system continuously in a holistic manner, it is suggested that developments in the field of molecular microbial ecology are essential to provide further insight in terms of element dynamics and the environmental controls on biotransformation and retention processes within PRIs. In turn, microbial and molecular fingerprinting could be used as an in-situ cost-effective tool to assess nutrient and gas balances during the operational phases of a PRI.

(Received March 13 2013)

(Revised November 14 2013)

(Accepted November 26 2013)

(Online publication January 29 2014)

Correspondence

c1 To whom all correspondence should be addressed: owen.fenton@teagasc.ie

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