Organic enrichment may deeply affect benthic nitrogen (N) cycling in macrophyte meadows, either promoting N loss or its recycling. This depends upon the plasticity of plants and of the associated microbial communities, as those surrounding the rhizosphere. Rates of denitrification, dissolved inorganic N fluxes and N uptake were measured in sediments vegetated by the submerged macrophyte Vallisneria spiralis L. under increasing organic matter loads. The aim was to investigate how the combined N assimilation and denitrification, which subtract N via temporary retention and permanent removal, respectively, do vary along the gradient. Results showed that V. spiralis meadows act as regulators of benthic N cycling even in organic enriched sediments, with negative feedbacks for eutrophication. A moderate organic load stimulates N uptake and denitrification coupled to nitrification in the rhizosphere. This is due to a combination of weakened competition between macrophytes and N cycling bacteria and enhanced radial oxygen loss by roots. An elevated organic enrichment affects N uptake due to hostile conditions in pore water and plant stress and impairs N mineralisation and its removal via denitrification coupled to nitrification. However, the loss of plant performance is almost completely compensated by increased denitrification of water column nitrate, resulting in a shift between the relative relevance of temporary and permanent N removal processes

Benthic nitrogen metabolism in a macrophyte meadow (Vallisneria spiralis L.) under increasing sedimentary organic matter loads / Soana, Elisa; Naldi, Mariachiara; Bonaglia, Stefano; Racchetti, Erica; Castaldelli, Giuseppe; Bruchert, Volker; Viaroli, Pierluigi; Bartoli, Marco. - In: BIOGEOCHEMISTRY. - ISSN 0168-2563. - 124:1-3(2015), pp. 387-404. [10.1007/s10533-015-0104-5]

Benthic nitrogen metabolism in a macrophyte meadow (Vallisneria spiralis L.) under increasing sedimentary organic matter loads

SOANA, Elisa
;
NALDI, Mariachiara;RACCHETTI, Erica;VIAROLI, Pierluigi;BARTOLI, Marco
2015-01-01

Abstract

Organic enrichment may deeply affect benthic nitrogen (N) cycling in macrophyte meadows, either promoting N loss or its recycling. This depends upon the plasticity of plants and of the associated microbial communities, as those surrounding the rhizosphere. Rates of denitrification, dissolved inorganic N fluxes and N uptake were measured in sediments vegetated by the submerged macrophyte Vallisneria spiralis L. under increasing organic matter loads. The aim was to investigate how the combined N assimilation and denitrification, which subtract N via temporary retention and permanent removal, respectively, do vary along the gradient. Results showed that V. spiralis meadows act as regulators of benthic N cycling even in organic enriched sediments, with negative feedbacks for eutrophication. A moderate organic load stimulates N uptake and denitrification coupled to nitrification in the rhizosphere. This is due to a combination of weakened competition between macrophytes and N cycling bacteria and enhanced radial oxygen loss by roots. An elevated organic enrichment affects N uptake due to hostile conditions in pore water and plant stress and impairs N mineralisation and its removal via denitrification coupled to nitrification. However, the loss of plant performance is almost completely compensated by increased denitrification of water column nitrate, resulting in a shift between the relative relevance of temporary and permanent N removal processes
Benthic nitrogen metabolism in a macrophyte meadow (Vallisneria spiralis L.) under increasing sedimentary organic matter loads / Soana, Elisa; Naldi, Mariachiara; Bonaglia, Stefano; Racchetti, Erica; Castaldelli, Giuseppe; Bruchert, Volker; Viaroli, Pierluigi; Bartoli, Marco. - In: BIOGEOCHEMISTRY. - ISSN 0168-2563. - 124:1-3(2015), pp. 387-404. [10.1007/s10533-015-0104-5]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2798925
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