https://scholarlypublications.universiteitleiden.nl/access/item%3A2978611/view

Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities.

For a large set of major world rivers we established the empirical relations existing between the observed organic carbon fluxes and the climatic, biologic, and geomorphologic patterns characterizing the river basins. These characteristics were extracted from various ecological databases. The corresponding carbon fluxes were taken from the literature. Dissolved organic carbon fluxes are mainly related to drainage intensity, basin slope, and the amount of carbon stored in soils. Particulate organic carbon fluxes are calculated as a function of sediment fluxes, which depend principally upon drainage intensity, rainfall intensity, and basin slope. Although the drainage intensity is mainly related to the amount of precipitation and to mean temperature in the basin, slope is also retained as one of the controlling factors. Our empirical models result in a total organic carbon flux to the oceans of about 0.38 Gt per year globally. About 0.21 Gt carbon (Gt C) enter the oceans in dissolved form and about 0.17 Gt C in particulate form. We further regionalize fluxes with respect to major climates, different continents, and different ocean basins. About 45 % of the organic carbon is discharged from tropical wet regions. The major part of the dissolved organic carbon is discharged into the Atlantic Ocean, while the bulk of the particulate organic carbon is discharged into the Indian and Pacific Oceans.

Predicting the oceanic input of organic carbon by continental erosion

This paper examines the linkages between the carbon cycle and sedimentary processes on land. Available data suggest that sedimentation on land can bury vast quantities of organic carbon, roughly 1015 g C yr−1. To evaluate the relative roles of various classes of processes in the burial of carbon on land, terrestrial sedimentation was modeled as a series of 864 scenarios. Each scenario represents a unique choice of intensities for seven classes of processes and two different global wetland distributions. Comparison was made with presumed preagricultural conditions. The classes of processes were divided into two major component parts: clastic sedimentation of soil-derived carbon and organic sedimentation of autochthonous carbon. For clastic sedimentation, masses of sediment were considered for burial as reservoir sediment, lake sediment, and combined colluvium, alluvium, and aeolian deposits. When the ensemble of models is examined, the human-induced burial of 0.6-1.5·1015 g yr−1 of carbon on land is entirely plausible. This sink reaches its maximum strength between 30° and 50° N. Paddy lands stand out as a type of land use that warrants future study, but the many faces of rice agriculture limit generalization. In an extreme scenario, paddy lands alone could be made to bury about 1·1015 g C yr−1. Arguing that terrestrial sedimentation processes could be much of the sink for the so called “missing carbon” is reasonable. Such a hypothesis, however, requires major redesign of how the carbon cycle is modeled. Unlike ecosystem processes that are amenable to satellite monitoring and parallel modeling, many aspects of terrestrial sedimentation are hidden from space.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/98GB00741

Terrestrial sedimentation and the carbon cycle: Coupling weathering and erosion to carbon burial

https://www.meas.ncsu.edu/sealevel/publications/Liu_Yangtze_2007_Geomorphology.pdf

Flux and fate of Yangtze River sediment delivered to the East China Sea

50,000 dams later: Erosion of the Yangtze River and its delta

Transport and deposition of river sediment in the Changjiang estuary and adjacent continental shelf

Modern Huanghe-derived muds on the outer shelf of the East China Sea: identification and potential transport mechanisms

The Yangtze River transports 12 million tons of particulate organic carbon (POC) to the oceans annually, with a computed yield of 6 t km/sup -2/ of drainage basin area. Concentrations of POC can exceed 80 mg/L in near bottom waters but generally range from 4 to 40 mg/L throughout the water column. Most POC percentages (in suspended matter) vary from 1.7 to 4.0 percent, the percentage decreasing with increasing suspended matter concentration although at lesser gradient than that predicted by Meybeck. The divergence from Meybeck's world curve may be related to the high degree of human activity in the Yangtze drainage basin, or it may reflect lack of data from large rivers with high suspended loads. If the Yangtze values are representative of other turbid Asian rivers, present global estimates of fluvially-derived POC may be as much as 50% too low. 17 references, 8 figures, 1 table.

Transfer of particulate organic carbon and nitrogen from the Yangtze River to the ocean

The Yangtze River, fourth largest in the world in terms of sediment discharge, contributes about 500 × 106 t annually to the East China Sea. A disproportionate part of the load is carried after pea...

Transfer of Water and Sediment from the Yangtze River to the East China Sea, June 1980

Seasonal distributions of suspended matter and their sedimentary effect on the Changjiang Estuary mud area of the East China Sea were discussed, based on three cruise data of total suspended matter, temperature and salinity collected from the Changjiang Estuary and its adjacent area in summer and winter. The results show that the basic pattern of distributions of suspended matter in the study area is almost the same in winter and in summer. Sediments from Changjiang (Yangtze River) to the sea are chiefly trapped to the west of 123°15’E due to a strong obstruction of the Taiwan Warm Current. This suggests that these sediments are mainly transported and deposited in the inner shelf. The sediment supply, Taiwan Warm Current, and Zhejiang Coastal Current show a strong seasonal variation, which results in a strong seasonal variation of the sedimentary effect on this mud area. This mud area is a “sink” of the Changjiang’s sediment discharge to the sea and its sedimentation is stronger in summer and weaker in winter.

Yang Zuo-sheng

Papers

Transport and deposition of river sediment in the Changjiang estuary and adjacent continental shelf

Modern Huanghe-derived muds on the outer shelf of the East China Sea: identification and potential transport mechanisms

Transfer of particulate organic carbon and nitrogen from the Yangtze River to the ocean

Transfer of Water and Sediment from the Yangtze River to the East China Sea, June 1980

Seasonal variation of sedimentation in the Changjiang Estuary mud area