[Distribution and controlling factors of nitric oxide concentrations in surface seawater of Jiaozhou Bay and adjacent waters].

Distribution of nitric oxide (NO) concentrations in surface seawater of Jiaozhou Bay and adjacent waters was studied adopting the chemiluminescence method during February and March 2011. Based on the data of NO concentrations and related environmental parameters in hydrology, chemistry and biology, the distribution and controlling factors were discussed. The results showed that the range and the mean of NO concentrations in surface seawater of Jiaozhou Bay were 0.080-0.493 nmol x L(-1) and (0.292 +/- 0.146) nmol x L(-1), respectively. The concentrations of NO ranged from below detection limit to 0.435 nmol x L(-1) in adjacent waters of Jiaozhou Bay, with the mean of (0.160 +/- 0.130) nmol x L(-1). The concentrations of NO showed a gradually decreasing trend from inside to outside of Jiaozhou Bay, which was possibly due to the effect of terrestrial runoff and human activities. The NO concentration of surface seawater in Jiaozhou Bay and adjacent waters was one order of magnitude higher than that in the open sea. The concentrations of NO in the surface seawater exhibited an obvious diurnal variation. The highest concentration of NO appeared at 15:00, which was presumably due to the effect of illumination intensity. The influencing factors of NO concentration and distribution were complex, including nitrite, pH, light intensity and so on. The present study showed that Jiaozhou Bay and adjacent waters was a source of atmosphere NO in spring,and F(NO) was about 1.09 x 10(-15)mol x (cm2 x s) (-1).