Question $3(24$ Marks$)$ Estimation of Contaminant Effects

A golf course uses a pond on its grounds to raise trout for the golf club

restaurant. The golf course uses $2,4$ dichlorophenoxyacetic acid $(2,4-D)$ as a

herbicide to reduce weed growth.

During a recent herbicide application on the golf course, $100g$ of $2,4-$D was

accidentally sprayed in the pond. The estimated volume of the pond is $1\mathrm{.}5$

million litres. It is assumed that there is significant sediment on the bottom

surface of the pond.

The following properties for $2,4-$D n$-$butyl ester were obtained from the US EPA

property estimation program, EPIWIN:

Molecular weight: $221\mathrm{.}04\frac{g}{m}ol$

Log Kow: $2\mathrm{.}41$

Maximum water solubility: $336\mathrm{.}2m\frac{g}{L}(25C)$

Lethal dose that kills $50\%$ of a life form in a given time $(L{D}_{50})$: $590mo\frac{l}{L}$

The following are estimates of properties of the pond:

Organic solids concentration in suspended sediment: $50m\frac{g}{k}g$ water

Biota concentration: $75g$ per $100m^3$ water

Soil sorption coefficient: $150kg$ in soil $\frac{?}{kg}$ in water

Equations $3-1$ and $3-2$ are proposed estimation relationships:

$L{C}_{50}$ for guppies :$log(\frac{1}{L{C}_{50}})=0\mathrm{.}871log{K}_{ow}-4\mathrm{.}87$

$logBCF=0\mathrm{.}79(log{K}_{ow})-0\mathrm{.}40$

Eq$.3-1$

Eq$.3-2$

$[3]($a$)$ Explain in your own words the meaning of bioaccumulation potential, also

known as bioconcentration factor $($BCF$).$

$[2]($b$)$ What data from the EPIWIN estimated data set can you use estimate the

bioaccumulation potential for $2,4-$D and why?

$[3]($c$)$ What is your estimation of the bioaccumulation potential for $2,4-$D$?$

$[2]($d$)$ Determine the $L{D}_{50}$ for trout in this pond, using guppies as a surrogate fish

for the trout.

$[2]($e$)$ Was the $L{C}_{50}$ exceeded after the recent herbicide contamination in the

pond?

$[12]($f$)$ Estimate the amount of $2,4$D that would be ingested if a golfer were to

consume $0\mathrm{.}25kg$ of trout fish tacos made at the golf club with fist from this

pond, after the herbicide application. State your assumptions that apply to your

calculations.