Hot Spots and Hot Moments in Riparian Zones: Potential for Improved Water Quality Management¹

Abstract

Vidon, Philippe, Craig Allan, Douglas Burns, Tim P. Duval, Noel Gurwick, Shreeram Inamdar, Richard Lowrance, Judy Okay, Durelle Scott, and Steve Sebestyen, 2010. Hot Spots and Hot Moments in Riparian Zones: Potential for Improved Water Quality Management. Journal of the American Water Resources Association (JAWRA) 46(2):278‐298. DOI: 10.1111/j.1752‐1688.2010.00420.x Abstract: Biogeochemical and hydrological processes in riparian zones regulate contaminant movement to receiving waters and often mitigate the impact of upland sources of contaminants on water quality. These heterogeneous processes have recently been conceptualized as “hot spots and moments” of retention, degradation, or production. Nevertheless, studies investigating the importance of hot phenomena (spots and moments) in riparian zones have thus far largely focused on nitrogen (N) despite compelling evidence that a variety of elements, chemicals, and particulate contaminant cycles are subject to the influence of both biogeochemical and transport hot spots and moments. In addition to N, this review summarizes current knowledge for phosphorus, organic matter, pesticides, and mercury across riparian zones, identifies variables controlling the occurrence and magnitude of hot phenomena in riparian zones for these contaminants, and discusses the implications for riparian zone management of recognizing the importance of hot phenomena in annual solute budgets at the watershed scale. Examples are presented to show that biogeochemical process‐driven hot spots and moments occur along the stream/riparian zone/upland interface for a wide variety of constituents. A basic understanding of the possible co‐occurrence of hot spots and moments for a variety of contaminants in riparian systems will increase our understanding of the influence of riparian zones on water quality and guide management strategies to enhance nutrient or pollutant removal at the landscape scale.

Spatial distribution of archaeal and bacterial ammonia oxidizers in the littoral buffer zone of a nitrogen-rich lake

“…The littoral buffer zones as the hot spots of N cycling has been well recognized for decades (Wang et al, 2006;Vidon et al, 2010). However, nitrification as the rate a The rate of ammonia oxidized per ammonia-oxidizing bacteria (AOB) or ammonia-oxidizing archaea (AOA) cell was calculated by dividing the potential nitrification rates mentioned before, assuming each cell has equal activity and soil nitrate produced is solely from either AOB or AOA alone, and each genome of AOB and AOA contains 2.5 and 1.0 amoA gene copies, respectively.…”

“…Enhanced fluxes of nitrogen (N) in littoral buffer zones, such as disproportionately high nitrous oxide (N 2 O) emission coupled with nitrate (NO 3 − ) removal, has been recognized for decades (Verhoeven et al, 2006;Wang et al, 2006;Van den Heuvel et al, 2009;Vidon et al, 2010). The rate of N transformation in littoral buffer zones is affected by many factors, including soil moisture, temperature and carbon availability (Tiedje, 1988).…”

Land cover controls on summer discharge and runoff solution chemistry of semi-arid urban catchments

“…Studies show that ephemeral streams concentrate solutes and runoff in space and time, leading to extended periods of high soil moisture and biogeochemical activity (e.g. McClain et al, 2003;Vidon et al, 2010). Therefore, solute flushing from ephemeral waterways may be of equal or greater importance than solute sourcing form the uplands, particularly as percent impervious cover increases.…”

Soil temperature responses to climate change along a gradient of upland–riparian transect in boreal forest

“…Riparian zones are the primary regulators of water quality in the snow-dominated temperate and boreal forest (Blume and Van Meerveld 2015;McClain et al 2003;Luke et al 2007;Vidon et al 2010). How this might shift under changing climate and/or forest management is a subject of ongoing debate (Grillakis et al 2016;Oni et al 2015).…”

“…Understanding the riparian-upland connection is important for water quality management (Jencso et al 2010;Vidon et al 2010). The riparian zone is the transition point between upland and aquatic ecosystems; it controls hydrologic connectivity both laterally along hillslopes and vertically down the soil profile (Grabs et al 2012;Ledesma et al 2015) as well as retention and transport of solutes (Luke et al 2007).…”