미국동부해안에서 강우가 해양 클로로필 농도에 미치는 영향

Abstract

Precipitation over the ocean surface in the vicinity of industrialized and populated coastlines can increase the ocean nitrate concentration and consequently enhance ocean primary productivity. Using satellite data and a meteorological reanalysis product, we evaluated the impact of precipitation events on the chlorophyll-a concentration in coastal and offshore waters located downwind of the eastern United States. We found that in low-nutrient areas (defined as having nitrate concentrations < 1 &micro M) precipitation events were associated with increased levels of chlorophyll-a (up to approximately 15%), but in high-nutrient areas (nitrate concentrations > 1 &micro M) they were associated with decreased levels. These contrasting responses of chlorophyll-a concentration to precipitation were attributed to the correlation of precipitation with wind speed and to other factors (nutrients and light) limiting phytoplankton growth. Our results indicate that an increase in wind speed accompanied by precipitation events was a major contributor to the observed changes in chlorophyll-a concentration during wet days, whereas the wet deposition of pollutant nitrogen slightly increased the chlorophyll-a concentration (< 5%) only in nutrient-depleted areasalysis product, we evaluated the impact of precipitation events on the chlorophyll-a concentration in coastal and offshore waters located downwind of the eastern United States. We found that in low-nutrient areas (defined as having nitrate concentrations < 1 &micro M) precipitation events were associated with increased levels of chlorophyll-a (up to approximately 15%), but in high-nutrient areas (nitrate concentrations > 1 &micro M) they were associated with decreased levels. These contrasting responses of chlorophyll-a concentration to precipitation were attributed to the correlation of precipitation with wind speed and to other factors (nutrients and light) limiting phytoplankton growth. Our results indicate that an increase in wind speed accompanied by precipitation events was a major contributor to the observed changes in chlorophyll-a concentration during wet days, whereas the wet deposition of pollutant nitrogen slightly increased the chlorophyll-a concentration (< 5%) only in nutrient-depleted areas