Nutrients in the wet deposition of Shanghai and ecological impacts

Nutrients from wet deposition are often neglected compared with other pollution sources. However recent studies reveal that they may be important. Nutrients in wet deposition were monitored at two typical sites that represent rural and downtown area of Shanghai from July 2007 to July 2008. No significant difference of the nutrient loads in wet deposition is found between these two sites. Averaged nutrient concentrations in wet deposition for NH4+–N, NO3-–N, TN, PO43-–P and TP are 1.33 mg L−1, 0.53 mg L−1, 2.43 mg L−1, 0.016 mg L−1, and 0.030 mg L−1, respectively. Antecedent dry period is found positively correlated with nutrient concentrations while rainfall volume is negatively correlated. Phytoplankton growth in a small enclosed lake with little external pollution load discharge was monitored at the same period of time to investigate the ecological impact of the nutrient from wet deposition. The results indicate that nutrients from wet deposition could stimulate phytoplankton growth and Chl-a concentration increased by 30.6% in succeeding days on average for the monitored 85 rainfall events.