Diffuse nitrogen pollution control: Moving from riparian zone to headwater catchment approach—A tribute to the influence of Professor Geoff Petts

Abstract

A lot of attention has been given to the importance of riparian zones as a nitrogen buffer during the last 30 years. Expectations were high and have resulted often in mismanagement practices. This paper aims at revisiting during this period the main research advancement, questions generated, and the progress in understanding the role of interactions between land and water in river system functioning. We describe how the seminal papers published in the 1980s on the role of riparian zone as nitrogen buffer have triggered several fundamental and applied questions related to the mechanisms at stake or their long efficiency in different hydrological and climatic contexts. We then address how this local riparian buffer capacity can be evaluated at the small drainage basin scale. We finally touch upon the restoration and protection of riparian zones in the context of climate change and especially its potential role on local and global water fluxes and other key aquatic ecosystem functions.

Isotopic signals in an agricultural watershed suggest denitrification is locally intensive in riparian areas but extensive in upland soils

“…Further, the NO 3 − undergoing denitrification in riparian corridors is primarily sourced from upgradient cultivated soils, highlighting the central role of cultivated soils in overall N r budgets for cultivated landscapes. These findings support both calls to bolster strategic management of riparian corridors and wetlands (Cheng et al 2020) and to allocate more attention to N management in the soils of uplands and headwater catchments (Pinay and Haycock 2019). Loss of N r from cultivated soils via denitrification and leaching not only limits agricultural productivity but also has contributed to a ten-fold increase in N 2 O emissions from croplands since the 1860s (Stevens and Laughlin 1998;Tian et al 2019;Billen et al 2020).…”

Deep denitrification: Stream and groundwater biogeochemistry reveal contrasted but connected worlds above and below

“…In Brittany, as in many temperate regions, surface water is comprised of water mixing from the shallow and deep groundwater (Marçais et al 2018, Thomas and Abbott 2018. While the processes and solute concentrations in the groundwater system are highly variable, they become mixed as they enter the surface environment through riparian zones and diffuse groundwater flux to streams (Krause et al 2022, Pinay and Haycock 2019, Le Moal et al 2019, Cardenas 2015. Given the short transit times in the surface, this results in a homogenized signature; as the surface water travels farther and faster, it integrates a larger spatial scale and reflects a larger landscape patch (Abbott et al 2018a, Dupas et al 2019.…”

Professor Geoffrey Petts (1953–2018): An outstanding interdisciplinary river scientist

“…Foster et al () contribute to theme 3 (river water quality and its management) by examining sediment transfers and connectivity within a lowland agricultural catchment, where they investigate particle size of sediment deposits in small, rapidly silting reservoirs. In contrast, Pinay and Haycock () broaden the focus to encompass riparian zones and review research findings dating back to the 1980s on the role of riparian zones as nitrogen buffers, an important component of the many interactions between land and water that affect river system functioning.…”