Nitrate Concentration Trends in Iowa's Rivers, 1998 to 2012: What Challenges Await Nutrient Reduction Initiatives?

摘要: Nitrate-nitrogen (NO-N) concentrations threaten water supplies and contribute to impairments of surface resources. In this study, we analyzed concentration trends at 60 ambient river monitoring sites in Iowa for the years 1998 2012 assess presence linear NO-N data using a time-series method that accounted temporal correlation combined trend information from individual into an assessment state-wide rate change concentrations. Forty-six had sufficient records analysis. Study results indicated 37 out 46 (80%) did not have statistically significant over period ( > 0.1). Six western increasing < 0.05), three additional located southern showed nominally The increases ranged 0.15 0.33 mg L yr. Aggregated across state, overall rivers is increasing, with average median 0.05 0.03 yr, respectively. Increasing likely associated fertilizer sales animal production, but better tracking needed establish definitive relation. Reducing conservation practices major focus recently proposed Nutrient Reduction Strategy, our study provides important milestone preceding implementation strategy.