last time posted person got answer wrong

A 2005 chemical spill occurred in northern China that released benzene into the Songhua river with a cross-sectional area of 3m2 and a linear velocity of 0.3m/s. The concentration of benzene in the river at the spill site was 100mg/L. Benzene is lost from the river by transfer to the air with a "reaction" rate of 0.2d1 and benzene is biodegraded by bacteria in the river sediments with a half-life of 1.7d. Much of the concern centered on the major city of Harbin, 377km downstream of the spill, which draws drinking water from the river. Estimate the benzene concentration at that point in the river. Would it exceed the drinking water limit of 0.005mg/L