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Mineral aerosols profoundly impact global climate. Modeling of the dust cycle is the main tool used to gauge this effect. However, the scarcity of in situ modern dust flux measurements is the main reason why validation of existing models is hampered. We present the first long-term (14-year) record of dust flux in the Pampas, southern South America, home to the largest loess deposit in the Southern Hemisphere. Measured 14-year mean deposition (40 g m−2 year−1) and horizontal (362 g m−2 year−1) fluxes imply that current models underestimate the power of the central Pampas as a dust sink. Based on cross-spectral analysis, both wet and, to a lesser extent, dry deposition are found to play significant roles in atmospheric dust extraction. Dust is sourced regionally from the South American Arid Diagonal and from the shores of Mar Chiquita lake (~260 km), which we find to be the main contributor of dust particles >30 µm. Cross-spectral and satellite image analyses show that surface wind speed and precipitation at the Puna-Altiplano Plateau are controlling factors for horizontal dust flux in the Pampas. El Niño Southern Oscillation probably plays a role in controlling interannual horizontal dust flux periodicities. Finally, preliminary comparisons between modern vertical dust fluxes and loess accumulation rates point to the Pampas as a more powerful dust sink during the last deglaciation and Antarctic Cold Reversal (18–12.5 ka). [ABSTRACT FROM AUTHOR]

Summary: River discharge time series in southern South America (between ∼15° and ∼50°S) show dissimilar historical trends. In the Río de la Plata drainage basin (RPDB) the record shows a runoff trend change from decreasing to increasing, around the mid 20th century. Independently of the seasonal variation, currently-observed discharge change in the region is mainly accounted for by increased discharge during low-flow periods. In contrast, most Patagonian rivers show a negative discharge trend, which mainly occurs in some austral summer months and is particularly significant in the Negro River. When considering the historical discharge variability in the southern part of South America, the spectral analysis produced evidence of interannual, quasi-decadal, and quasi-bidecadal periodicities. Most rivers in the region show El Niño-like interannual periodicities with the exceptions of the Bermejo and Pilcomayo rivers. In the RPDB, during the 20th century, interannual periodicity changed from the ∼2 to ∼5-year band to the ∼5 to ∼7-year band between ∼1935 and ∼1970. In Patagonia, the interannual oscillation showed maximum power ∼1930 and ∼1980 in the Colorado, whereas further south (Negro and Chubut rivers), maximum power appears ∼1950. The quasi-decadal signal is strong in the RPDB, in general, and particularly in Patagonia’s Colorado, which runs close to the so-called Arid Diagonal and bears this signal presumably due to the influence of the low-level jets (LLJs). This periodicity is conspicuously absent in other Patagonian rivers. Finally, a quasi-bidecadal signature appears to be restricted to the Bermejo and Iguaçu rivers, in the RPDB, and in Patagonia’s Colorado and Santa Cruz rivers. [Copyright &y& Elsevier]