Denitrifying bioreactors convert nitrate-nitrogen (NO-N) to di-nitrogen and protect water quality. Herein, the performance of a pilot-scale bioreactor (10 m long, 5 m wide, 2 m deep) containing seven alternating cells filled with either sandy loam soil or lodgepole pine woodchip and with a novel "zig-zag" flow pattern was investigated. The influent water had an average NO-N concentration of 25 mg L. The performance of the bioreactor was evaluated in two scenarios. In Scenario 1, only NO-N removal was evaluated; in Scenario 2, NO-N removal, ammonium-N (NH-N), and dissolved reactive phosphorus (DRP) generation was considered. These data were used to generate a sustainability index (SI), which evaluated the overall performance taking these parameters into account. In Scenario 1, the bioreactor was a net reducer of contaminants, but it transformed into a net producer of contaminants in Scenario 2. Inquisition of the data using these scenarios meant that an optimum bioreactor design could be identified. This would involve reduction to two cells: a single sandy loam soil cell followed by a woodchip cell, which would remove NO-N and reduce greenhouse gas (GHG) emissions and DRP losses. An additional post-bed chamber containing media to eliminate NH-N and surface capping to reduce GHG emissions further is advised. Scenario modeling, such as that proposed in this paper, should ideally include GHG in the SI, but because different countries have different emission targets, future work should concentrate on the development of geographically appropriate weightings to facilitate the incorporation of GHG into a SI.

/pdf/holistic-evaluation-of-field-scale-denitrifying-bioreactors-3ebsgqvaaf.pdf

Holistic Evaluation of Field-Scale Denitrifying Bioreactors as a Basis to Improve Environmental Sustainability.

Nutrient dynamics in a peatland forest riparian buffer zone and implications for the establishment of planted saplings

Forest clearfelling effects on dissolved oxygen and metabolism in peatland streams

Throughout the European Union (EU), agricultural soils with high phosphorus (P) status due to surplus fertiliser input have been identifi ed as a landscape pressure impacting on water quality. In Republic of Ireland, approximately 80% of agricultural land is devoted to grass, 11% to rough grazing, and 9% to arable cereal and crop production. Consequently, the majority of erosion research has focused on quantifying nutrient and sediment losses from grassland. Tillage soils are, however, more susceptible to erosion than grassland soils and, in general, have higher levels of soil P. This paper reviews the current state of research and the regulatory regime relating to diffuse P and sediment loss for tillage soils. It identifi es the key threats to soil quality associated with cultivated soils, and proposes the targeting and remediation of critical source areas for effective mitigation of P losses from tillage soils. A multiscaled approach is recommended, in which catchment and fi eld-scale monitoring is complemented with controlled laboratory and small plot-scale rainfall simulation experiments to identify areas where P loss and soil erosion are at critical levels and may pose a threat to water quality. Catchment scale research will help to link critical source areas of sediment and P loss with hydrological pathways to surface waters in the catchment area. These areas can then be targeted for remediation in the river basin management plans.

/pdf/a-review-of-phosphorus-and-sediment-release-from-irish-aw9orkn69h.pdf

A review of phosphorus and sediment release from irish tillage soils, the methods used to quantify losses and the current state of mitigation practice

Implications of applied best management practice for peatland forest harvesting

To assist in the status assessment of waterbodies in Ireland, new biological classification systems have been developed for seven biological element descriptors. These classification systems have been intercalibrated to ensure comparability of results across EU member states. Boundaries between high and good status and between good and moderate status have been established for each biological element parameter, all of which are consistent with the definitions in the Water Framework Directive. New standards developed for physico-chemical parameters, 16 relevant pollutants and 46 priority substances, which will replace existing standards, are set out.

New Water Framework Directive environmental quality standards and biological and hydromorphological classification systems for surface waters in Ireland.

J. Bowman

Papers

New Water Framework Directive environmental quality standards and biological and hydromorphological classification systems for surface waters in Ireland.