Well thank you and thanks @WillMelling for the clarification. It's funny how with all tripods and lenses I have at home that photo was taken on a little point and shoot balanced precariously on the brick edge of the canal. It was green algae being blown upstream with a 20 second time exposure. It took quite a few takes, and I left quite light headed from a choking cloud of diesel exhaust fumes from a canal boat generator lingering under the bridge.
So the theme this week, #oil
By that I was thinking of the Burtynsky series, our unhealthy reliance on it, its cycle, its bi-products, however you see fit.