PLIERS: Pesticide Losses in Erosion and Runoff Simulator

Water Pollution Simulation and Health Risk Assessment Through a Refined Contaminant Transport Model

“…À FA a f p LAI ð Þ W waÀs ¼ W pÀc R cr 1 À exp À1n2 t t 1=2 ! P wa0 ¼ W waÀc þ W waÀs Martin et al 1978;Willis et al 1986;Kenimer et al 1989;Chen et al 2003aChen et al , b, 2001b Pesticide adsorptiondesorption Wauchope and Leonard 1980;Leonard et al 1987;Novotny and Olem 1994;Chen et al 2003b Pesticide availability for runoff Knisel 1980;Mackay et al 1986;Sauer 1998;Chen et al 2003b Erosion and Sedimentation C se ¼ C r K d R en ln R en ð Þ ¼ 2 þ 0:2ln C ev =A Chen et al 2003bChen et al , 2004Smith 1992;USDA 1995 Where Δt is time step of the routing (day); A a is the application area (km 2 ); a c is the unit conversion factor; a sb is an empirical constant (=0.0058; unitless); C av is the pesticide concentration available in the soil for runoff (mg/kg); C ev is the soil loss (kg); CN is the SCS runoff curve number (unitless); C r is the solution-phase pesticide concentration (mg/L); C se is the concentration of pesticide in sediment (mg/kg); C sn is the degree-day snowmelt factor, which is the daily decrease of snow depth per degree day (m/°C day); F is volatilization flux of pesticide from canopy (kg/m 2 s); f p is the fraction of leaf area contacted by pesticide (%); f sc is the soil cover factor (%); F t is the daily emission factor of pesticide (%); I is the initial abstraction (m); I 1 and I 2 are inflows to the reach at the beginning and the end of time steps, respectively (m 3 /s); K d is the soil-water partitioning coefficient (m 3 /kg); K e is the pesticide equilibrium constant (unitless); K er is the soil erodability factor (unitless); K ex is the extraction coefficient (m 3 /kg); K OC is the organic carbon sorption coefficient (m 3 /kg); k wf is the wash off rate constant (unitless); LAI is the leaf area index, which is defined as the onesided area of leaves per unit ground area (unitless); LS is the length-slope factor (unitless); N cell is the number of cells; O 1 and O 2 are outflows from the reach at the beginning and the end of time steps, respectively (m 3 /s); OC is the percent organic carbon (%); OM is the percent organic matter (%); P is the volume of precipitation (m); P c is the conservation practice factor (unitless); P cell(i, t) is the pesticide amount generated within a cell at the ith cell at time t (kg); P in(i, t) is the sum of all pesticides entering a cell from other cells through runoff at the ith cell at time t (kg); P out(i, t) is the amount of pesticide leaving a cell through runoff at the ith cell at time t (kg); P wa is the change in pesticide content in wash off water (kg); P wa0 is the initial pesticide loading in wash off water (kg); Q is the volume of runoff (m 3 ); Q p is the peak runoff rate (m/s); S 1 and S 2 are storages in the reach at the begi...…”

Modelling of Atrazine Loss in Surface Runoff from Agricultural Watershed

“…This equation is used due to its ability to adequately predict observed wash-off data reported by Martin et al (1978) and Willis et al (1986). The change in pesticide content in wash-off water, P wa , with respect to the cumulative volume of intercepted rainfall, V r , is described as (Kenimer et al 1989):…”

“…The adsorption of pesticides by soil particles is a reversible process. In order to describe the adsorption/desorption processes, the Freundlich equation was used in some models like ARM (Donigian et al 1977) or PLI-ERS (Kenimer et al 1989). In CREAMS (Leonard et al 1987) a constant partition coefficient was assumed between the adsorbed and the solution phase, which means that the active ingredient of pesticide reaches an instant equilibrium between the soil mass and the overland flow in the zone of interaction.…”

Concentration enrichment of sparingly soluble contaminants (U, Th and Pb) by erosion and by soil adhesion to plants and skin

“…SER can also be computed from the ratio of the solid/liquid partition coefficients, KdS, for the clay and the residual soils, as done in the PLIERS code (Kenimer et al, 1989) and by van Hoof and Andren (1989), but measurement of Ka is rather involved.…”