Land-Coastal Ocean Interactions In The Tropics And Subtropics: Hawaii As An Example

The culture, subsistence, and welfare of tropical and subtropical Pacific Island Nation people are all in some way tied to the interactions between the land and the adjacent and surrounding coastal waters. Land use plays an important role in the relative chemical species distribution and concentrations of particulate and dissolved nutrients that reach coastal waters by riverine, groundwater, and atmosphere. Some key human activities on land that affect coastal waters through land-sea connections and interactions are: (1) the application of nitrogenous and phosphorus-bearing fertilizers and biocides to the landscape and subsequent leaching of significant proportions of these materials into water courses, (2) the release of sewage into aquatic systems, including directly into coastal ocean waters, (3) the diversion of water flows through channelized structures and dams resulting in changes in retention times of water, nutrients and sediments and also in riparian communities on land and hence changes in water, nutrient and suspended sediment fluxes to the coastal ocean, (4) deforestation and/or conversion of land type from, for example, agricultural use to urban housing, (5) the fallout of nitrogen from the atmosphere derived from combustion sources on land and its ultimate transport into aquatic systems, (6) CO2 emissions from fossil fuel and land-use activities (e.g., deforestation) and absorption of some of this CO2 by coastal and open ocean waters, and (7) atmospheric nitrogen emissions from combustion sources on land that ultimately fall directly on the ocean surface, and especially that of the coastal ocean. Grant/cooperative agreement no. NA09OAR4170060

热带及亚热带太平洋岛国民众的文化、生计与福祉，均在不同程度上与陆地及其邻近、周边近岸海域的相互作用息息相关。土地利用方式对通过河流、地下水与大气途径输入近岸海域的颗粒态与溶解态营养盐的相对化学形态分布及浓度水平具有重要影响。若干通过陆海连通与相互作用影响近岸海域的关键陆地人类活动包括：（1）向地表施用含氮、含磷肥料与生物杀灭剂，随后其中相当比例的此类物质经淋溶作用进入河道水体；（2）将污水排放至水生生态系统，包括直接排入近岸海域；（3）通过渠化构筑物与大坝调控水流，改变水、营养盐与沉积物的滞留时间，同时改变陆地河岸带群落结构，进而改变输入近岸海域的水、营养盐与悬浮沉积物通量；（4）森林砍伐及/或土地利用类型转换，例如将农业用地转为城市住宅用地；（5）陆地燃烧源产生的大气氮沉降，最终通过大气过程进入水生生态系统；（6）化石燃料燃烧与土地利用活动（如森林砍伐）产生的二氧化碳排放，以及近岸海域与开阔大洋对部分二氧化碳的吸收；（7）陆地燃烧源产生的大气氮排放，最终直接沉降至海洋表面，尤其是近岸海域。资助/合作协议编号：NA09OAR4170060