Movement and release of phosphorus from streambank soils into Lake Champlain

PERILLO, V.L.; BALLING, C.; ROSS, D.S.; WEMPLE, B.C.

Orford, Québec

Conferencia; GLEON 16; 2014

GLOBAL LAKE ENVIRONMENTAL OBSERVATORY NETWORK

The growth of algal blooms is limited by the amount of bioavailable phosphorus (P) present in lakes and other freshwater bodies. This nutrient is released into the streams feeding a lake by soil erosion and anthropogenic activities such as farming and fertilization. Lake Champlain (located in between the states of Vermont and New York in the United States and the province of Québec in Canada) is known to have algae blooms between June and September. Soil samples were collected in the Missisquoi Bay Watershed (MBW) and Mad River Watershed (MRW) (summers 2012-2013) in corn and hay fields, and in the riparian buffer and streambank of each site. Preliminary results show that soils sampled in the MBW have a higher amount of total and available P at near-surface depths (0-15 and 15-30 cm), due to more intensive agricultural practices, than MRW. While potentially presenting a higher risk of available P runoff in extreme weather events, the presence of a riparian buffer could be protecting the stream from P runoff. Since streambank erosion is a not-sufficiently characterized source of P to the lake, we will next study the delivery mechanisms of bioavailable P originating from this type of erosion. Sampling and testing will be employed to determine the organic P fraction and its speciation, the effect of stream buffer width and land-use on P fractions in streambank soils and the transformation rate of organic P to inorganic P when this soil is submerged. P transport mechanisms will be examined by flowpath modeling.