Abstract:

In recent years, many studies have found that small mountainous rivers have instantaneous enormous flux, strong response to extreme climate events, and rapid sediment transport. However, the effects of mountainous rivers on global sediment transport have been underestimated due to the lack of adequate monitoring data and system summary. There are still inadequate studies on the mountainous rivers with different river-ocean and weathering-transportation from the mega-river systems. Revealing the sediment transport characteristics of different climates in the common natural and anthropogenic influence would help to understand the Earth’s surface processes and the global land-sea interactions. This paper summarizes the global soil carbon content, as well as meteorological, hydrologic, and mineralogical data of mountainous rivers of the different climatic zone in the coastal China region. We summarized that: (1) Soil organic carbon content of the mountainous river basins is high in China, and the primary productivity of the tropical mountainous river basins is higher than that in the temperate basins, thus the soil organic carbon content of the former is also higher. Among the tropical basins, the river relief in Taiwan, China is the highest, hence its soil organic carbon content is very high in China. In addition, the rapid sediment transport to the estuary and coastal zone by mountainous rivers has greatly improved the burial efficiency of organic carbon, therefore it represents a significant component of the global organic carbon source and sink; (2) Regardless temperate or tropical climatic zone, the mountainous rivers have strong response to extreme climate. Furthermore, the smaller the watershed area and the steeper the river terrain, the stronger the river responds to extreme climatic events; (3) Regardless of the tectonic activity intensity, the mineralogical characteristics of the mountainous rivers can accurately indicate the source information in sediments. Moreover, sediments from the rivers in low-relief and tectonic stable zone can record more detailed climatic characteristics; (4) Sediments in mountainous rivers are very sensitive to human activities, while the sedimentary environment influence from existing human activities is far lower than in the mega-river basins.

Key words: mountainous rivers, soil organic carbon content, sediment transport, extreme climate event