Nutrient retention in agricultural headwater stream: artificial manipulation of main-channel morphology and hydrologic condition.

Abstract

To make up for the deficiency of transient storage and nutrient retention capacity of some headwater streams, some effective artificial measures have been developed to improve the stream ecosystem functions. But few studies have focused on the effects of artificial manipulation on nutrient retention in hydrologic and non-hydrologic processes of streams. In response, we selected an agricultural headwater stream in the Banqiao River tributary of Chaohu Lake Basin, artificially altered the flow pattern in the main-channel by introducing barriers which were composed of soil, coarse sand, and stones, and used the tracer experiment and OTIS (one-dimensional transport with inflow and storage) model to assess the transient storage potential of stream and the nutrient retention of hydrologic and non-hydrologic processes. Compared with the control, the retention capacity of ammonium (NH4+) and phosphate (PO43-) and the transient storage potential were increased after introducing barriers. In addition, the total retention (TR), hydrologic retention (HR), and non-hydrologic retention (NHR) of NH4+ and PO43- were significantly increased after manipulation.