Herbicide Interchange between a Stream and the Adjacent Alluvial Aquifer

Abstract

Herbicide interchange between a stream and the adjacent alluvial aquifer and quantification of herbicide bank storage during high streamflow were investigated at a research site on the Cedar River flood plain, 10 km southeast of Cedar Rapids, Iowa. During high streamflow in March 1990, alachlor, atrazine, and metolachlor were detected at concentrations above background in water from wells as distant as 20, 50, and 10 m from the river's edge, respectively. During high streamflow in May 1990, alachlor, atrazine, cyanazine, and metolachlor were detected at concentrations above background as distant as 20, 50, 10, and 20 m from the river's edge, respectively. Herbicide bank storage took place during high streamflow when hydraulic gradients were from the river to the alluvial aquifer and the laterally infiltrating river water contained herbicide concentrations larger than background concentrations in the aquifer. The herbicide bank storage can be quantified by multiplying herbicide concentration by the "effective area" that a well represented and an assumed porosity of 0.25. During March 1990, herbicide bank storage values were calculated to be 1.7,79, and 4.0 mg/m for alachlor, atrazine, and metolachlor, respectively. During May 1990, values were 7.1, 54, 11, and 19 mg/m for alachlor, atrazine, cyanazine, and metolachlor, respectively.

Herbicide Transport to Surface Waters at Field and Watershed Scales in a Mediterranean Vineyard Area

“…This is consistent with the fact that baseflow arises from the drainage of the ground water. Other studies already showed a similar discharge of herbicides from the alluvial aquifer to the river (Frank and Sirons, 1979; Wang and Squillace, 1994; Fisher et al, 1995; Garmouna et al, 1997). Second, herbicide concentrations in the ground water were one or more orders of magnitude less than those in storm flow up to November 1997.…”

Degradation of herbicides in shallow Danish aquifers: an integrated laboratory and field study

“…The sources and transport routes of pesticides to groundwater are multifaceted 16–18. They can include non‐point sources such as agriculture, where the pesticides leach from top soil via matrix‐flow in sandy aquifers, via preferential flow19, 20 or macropore flow in eg tills, or surface water recharge of groundwater occurring through ‘leaky streams’ 21–25. Aquifers may also be contaminated from point sources such as accidental spillage near well‐heads or spillage near vulnerable soil areas, use of non‐approved soakaways, inappropriate disposal of waste washings from farmyard equipment, improper installation and maintenance of groundwater and irrigation wells and leakage from agricultural chemical dealerships and industrial manufacturing plants 26.…”

Occurrence, Characteristics, Transport, and Fate of Pesticides, Pharmaceuticals, Industrial Products, and Personal Care Products at Riverbank Filtration Sites

“…In some cases, the presence of numerous herbicides and other organic compounds in groundwater has been attributed to surface water that was contaminated with herbicides by periodic flooding, bank storage of river water, artificial recharge by impoundments, and induced infiltration (Exner, 1990;Duncan et al, 1991;Thurman et al, 1991;Taylor, 1994;Wang and Squillace, 1994;Frycklund, 1998;Burkart et al, 1999a;Verstraeten et al, 1999b;Lange et al, 2000;Mazounie et al, 2000;Verstraeten et al, in press). In other cases, pesticides have been identified in surface water during base-flow conditions and have been attributed to inflow from contaminated groundwater (Barbash and Resek, 1996).…”