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Potential Efficiency of Riparian Vegetated Buffer Strips in Intercepting Soluble Compounds in the Presence of Subsurface Preferential Flows.

Allaire SE, Sylvain C, Lange SF, Thériault G, Lafrance P - PLoS ONE (2015)

Bottom Line: However, such strips do not intercept all contaminants, particularly soluble ones.Our results demonstrate that the risk of water contamination by soluble contaminants is high in such systems, even when a well-vegetated buffer strip is used.The design of buffer strips should be modified to account for underground bypass, either by using plants that have deep, fine roots that do not favour PF or by adding a filter extending deep underground that can be regularly changed.

View Article: PubMed Central - PubMed

Affiliation: Département des sols et de génie agroalimentaire, Université Laval, Québec City, Quebec, Canada.

ABSTRACT
Buffer strips have been widely recognized as to promote infiltration, deposition and sorption of contaminants for protecting surface water against agricultural contamination. However, such strips do not intercept all contaminants, particularly soluble ones. Although preferential flow (PF) has been suggested as one factor among several decreasing the efficiency of buffer strips, the mechanisms involved are not well understood. This project examines buffer strip efficiency at intercepting solutes when subsurface PF occurs. Two soluble sorbed tracers, FD&C Blue #1 and rhodamine WT, were applied on an agricultural sandy loam soil to evaluate the ability of a naturally vegetated buffer strip to intercept soluble contaminants. Rhodamine was applied about 15 m from the creek, while the Blue was applied 15 m to 165 m from the creek. Tracer concentration was measured over a two-year period in both the creek and the buffer strip through soil and water samples. Although the tracers traveled via different pathways, they both quickly moved toward the creek, passing beneath the buffer strip through the soil matrix. Our results demonstrate that the risk of water contamination by soluble contaminants is high in such systems, even when a well-vegetated buffer strip is used. The design of buffer strips should be modified to account for underground bypass, either by using plants that have deep, fine roots that do not favour PF or by adding a filter extending deep underground that can be regularly changed.

No MeSH data available.


Schematic representation of the experimental set up and installation of the lysimeter plates (not scaled).The plots were not protected after tracer application, and the farm maintained its normal production routine. It is important to keep in mind, however, that the tracers were applied after fall soil tillage and the plots were sampled later that fall.
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pone.0131840.g002: Schematic representation of the experimental set up and installation of the lysimeter plates (not scaled).The plots were not protected after tracer application, and the farm maintained its normal production routine. It is important to keep in mind, however, that the tracers were applied after fall soil tillage and the plots were sampled later that fall.

Mentions: Four 2- x 2-m plots were established in the field. Three were aligned along distinct parts of the catena at 15 m (plot B), 60 m (plot C), and 165 m (plot D) from the creek (Fig 2). The fourth (plot A) was placed 15 m from the creek at the footslope, about 30 m away from plot B (Fig 2). Thus, A and B were along the creek at the footslope, while C was at the backslope and D was at the shoulder. Two tracers were homogeneously applied by hand at the soil surface using 20 L of water (Fig 1C). The tracer FD&C Blue #1 (Warner-Jenkinson Company) was applied at a rate of 125 g m-2 on all plots on 8 October 2010, while rhodamine WT (Sigma, San Diego, CA, USA) was applied at a rate of 2.5 g m-2 on the same day using the same solution and method, but only on plots A and B (close to the buffer strip). The tracers were chosen to represent weakly sorbed (Blue) and more sorbed (rhodamine) solutes. The Blue mimics phosphate [24] or atrazine [25], and rhodamine represents medium-sorbed pesticides [26] in low-sorbing soils. Tracer selection and application rates were based on detection limits, toxicity, and because they were used in previous researches [27–28]. They were never reapplied.


Potential Efficiency of Riparian Vegetated Buffer Strips in Intercepting Soluble Compounds in the Presence of Subsurface Preferential Flows.

Allaire SE, Sylvain C, Lange SF, Thériault G, Lafrance P - PLoS ONE (2015)

Schematic representation of the experimental set up and installation of the lysimeter plates (not scaled).The plots were not protected after tracer application, and the farm maintained its normal production routine. It is important to keep in mind, however, that the tracers were applied after fall soil tillage and the plots were sampled later that fall.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492607&req=5

pone.0131840.g002: Schematic representation of the experimental set up and installation of the lysimeter plates (not scaled).The plots were not protected after tracer application, and the farm maintained its normal production routine. It is important to keep in mind, however, that the tracers were applied after fall soil tillage and the plots were sampled later that fall.
Mentions: Four 2- x 2-m plots were established in the field. Three were aligned along distinct parts of the catena at 15 m (plot B), 60 m (plot C), and 165 m (plot D) from the creek (Fig 2). The fourth (plot A) was placed 15 m from the creek at the footslope, about 30 m away from plot B (Fig 2). Thus, A and B were along the creek at the footslope, while C was at the backslope and D was at the shoulder. Two tracers were homogeneously applied by hand at the soil surface using 20 L of water (Fig 1C). The tracer FD&C Blue #1 (Warner-Jenkinson Company) was applied at a rate of 125 g m-2 on all plots on 8 October 2010, while rhodamine WT (Sigma, San Diego, CA, USA) was applied at a rate of 2.5 g m-2 on the same day using the same solution and method, but only on plots A and B (close to the buffer strip). The tracers were chosen to represent weakly sorbed (Blue) and more sorbed (rhodamine) solutes. The Blue mimics phosphate [24] or atrazine [25], and rhodamine represents medium-sorbed pesticides [26] in low-sorbing soils. Tracer selection and application rates were based on detection limits, toxicity, and because they were used in previous researches [27–28]. They were never reapplied.

Bottom Line: However, such strips do not intercept all contaminants, particularly soluble ones.Our results demonstrate that the risk of water contamination by soluble contaminants is high in such systems, even when a well-vegetated buffer strip is used.The design of buffer strips should be modified to account for underground bypass, either by using plants that have deep, fine roots that do not favour PF or by adding a filter extending deep underground that can be regularly changed.

View Article: PubMed Central - PubMed

Affiliation: Département des sols et de génie agroalimentaire, Université Laval, Québec City, Quebec, Canada.

ABSTRACT
Buffer strips have been widely recognized as to promote infiltration, deposition and sorption of contaminants for protecting surface water against agricultural contamination. However, such strips do not intercept all contaminants, particularly soluble ones. Although preferential flow (PF) has been suggested as one factor among several decreasing the efficiency of buffer strips, the mechanisms involved are not well understood. This project examines buffer strip efficiency at intercepting solutes when subsurface PF occurs. Two soluble sorbed tracers, FD&C Blue #1 and rhodamine WT, were applied on an agricultural sandy loam soil to evaluate the ability of a naturally vegetated buffer strip to intercept soluble contaminants. Rhodamine was applied about 15 m from the creek, while the Blue was applied 15 m to 165 m from the creek. Tracer concentration was measured over a two-year period in both the creek and the buffer strip through soil and water samples. Although the tracers traveled via different pathways, they both quickly moved toward the creek, passing beneath the buffer strip through the soil matrix. Our results demonstrate that the risk of water contamination by soluble contaminants is high in such systems, even when a well-vegetated buffer strip is used. The design of buffer strips should be modified to account for underground bypass, either by using plants that have deep, fine roots that do not favour PF or by adding a filter extending deep underground that can be regularly changed.

No MeSH data available.