Solar Output Controls Periodicity in Lake Productivity and Wetness at Southernmost South America

Abstract

Cyclic changes in total solar irradiance (TSI) during the Holocene are known to affect global climatic conditions and cause cyclic climatic oscillations, e.g., Bond events and related changes of environmental conditions. However, the processes how changes in TSI affect climate and environment of the Southern Hemisphere, especially in southernmost South America, a key area for the global climate, are still poorly resolved. Here we show that highly sensitive proxies for aquatic productivity derived from sediments of a lake near the Chilean South Atlantic coast (53 °S) strongly match the cyclic changes in TSI throughout the Holocene. Intra-lake productivity variations show a periodicity of ~200–240 years coherent with the time series of TSI-controlled cosmogenic nuclide 10Be production. In addition TSI dependent periodicity of Bond events (~1500 years) appear to control wetness at the LH site indicated by mineral matter erosion from the catchment to the lake assumingly through shifts of the position of the southern westerly wind belt. Thus, both intra-lake productivity and wetness at the southernmost South America are directly or indirectly controlled by TSI.

Solar irradiance and primary productivity controlled mercury accumulation in sediments of a remote lake in the Southern Hemisphere during the past 4000 years

“…% [median ± standard deviation] ∼ 70 wt. % OM) interrupted by more mineral matter‐rich layers related to periodic changes in wetter and dryer conditions (Hermanns et al ; Pérez‐Rodríguez et al ) and a tephra layer at 4250 cal. BP (Mt.…”

“…Further discussion of the FTIR data will be confined to the use of one principal component (PCA‐Cp9) extracted by PCA from the FTIR data from a previous study of LH ( see Pérez‐Rodríguez et al for full details). In brief, PCA was performed on the FTIR data to identify the main geochemical signals of the lake core and relate them to the underlying environmental processes in the lake and its catchment.…”

“…The spectral analysis (REDFIT, Schulz and Mudelsee ) providing periodicities of PCA‐Cp9 (an algaenan signal), HI, Hg, and Cu concentrations and accumulation were performed using the Past software (Hammer et al ). PCA‐Cp9 and HI spectral analysis are from Pérez‐Rodríguez et al ().…”

“…In this study, we supplemented data from a previous investigation (Hermanns et al ) on the importance of algal scavenging and catchment processes (terrestrial OM fluxes) on Hg accumulation in a small lake (Lago Hambre [LH]) located at the Strait of Magellan (53°S) by spectroscopic Fourier transform infrared spectroscopy (FTIR) characterization of the lake's sediments and compared it to the 10 Be record (a proxy for TSI). Pérez‐Rodríguez et al () demonstrated that the application of principal component analysis (PCA) to the LH FTIR data allows sensitive detection of in‐lake productivity signals, the latter showing a strong correlation with TSI changes throughout the Holocene. Based on this previous result, we present a reevaluation of the 4.0 kyr Hg sediment record of this small, pristine lake in Patagonia (Fig.…”

“…). We use a combination of geochemical and spectroscopic proxies discussed in previous studies (Hermanns and Biester ; Hermanns et al ; Pérez‐Rodríguez et al ) to determine the influence of solar‐induced lake productivity changes on mercury accumulation in sediments.…”