Browsing by Autor "Rienk H. Smittenberg"

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Polychlorinated Alkane Profiles and Concentrations in Bolivian Andes Soils Point to a Long-Range Transport Influence
(American Chemical Society, 2026) Bo Yuan; Cheng Wu; Cynthia A. de Wit; Claudia Mohr; Marcos Andrade; Isabel Moreno; Volker Brüchert; Rienk H. Smittenberg; Matthew MacLeod
High-altitude terrain may intersect the upper atmospheric boundary layer and exhibit distinct environmental dynamics. We investigated the anthropogenic pollutants polychlorinated alkanes (PCAs, also known as chlorinated paraffins) in surface soils along a transect from the La Paz-El Alto metropolitan area in Bolivia (3200-4100 masl) to the upper slopes of Mount Chacaltaya (>5200 masl), around 16 km away. Concentrations of PCAs in urban soils (750-5,230 ng/g organic carbon [OC]) decreased exponentially with increasing distance from the urban boundary, declining to ∼150 ng/g OC at elevations below 4,700 masl. Beyond 4,700 masl concentrations increased again, reaching levels comparable to those in the urban area, 1,670-4,300 ng/g OC, above 5,000 masl. Given that pollutant concentrations typically decline with distance from their source, this altitudinal trend, together with a pronounced shift in PCA forensic fingerprints near 4,700 masl, strongly suggests contributions from sources beyond the local metropolitan area. Carbon and nitrogen isotope signatures in organic carbon further support long-range transport as a source, consistent with previous modeling and observations that the upper slopes of Mount Chacaltaya predominantly receive air masses and organic carbon from distant regions via transport in the free troposphere. Our observation that pollutant levels in high-altitude areas are comparable to those in the metropolis of 1.8-million inhabitants underscores the efficiency of long-range atmospheric transport.
The impact of soil chemistry, moisture and temperature on branched and isoprenoid GDGTs in soils: A study using six globally distributed elevation transects
(Elsevier BV, 2023) Cindy De Jonge; Jingjing Guo; Petter Hällberg; Marco Griepentrog; Hamdi Rifai; Andreas Richter; Edson Ramírez; Xinbao Zhang; Rienk H. Smittenberg; Francien Peterse
Using biomarker lipids to reconstruct soil fertility through time
(2024) Cindy De Jonge; Jingjing Guo; Petter Hällberg; Marco Griepentrog; Hamdi Rifai; Andreas Richter; Edson Ramírez; Xinbao Zhang; Rienk H. Smittenberg; Francien Peterse
Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous membrane-spanning lipids with a wide environmental distribution. In soils, branched GDGTs are produced by a possibly large diversity of bacteria. The relative abundance of methyl groups attached to the central alkyl chains forms the basis of the paleotemperature proxy MBT&#8217;5ME. However, MBT&#8217;5ME values in soils can also be directly influenced by pH (De Jonge et al., 2021). A second group of compounds, the isoprenoid GDGTs, are produced by archaea. They have been used only sparsely as environmental proxies in soils, although they are at the base of the marine paleotemperature proxy TEX86. In soils, a compilation by Yang et al. (2016) illustrates that the temperature dependency of TEX86 is sometimes present, but potentially influenced by other soil (chemistry) parameters.In addition to temperature, other soil parameters are expected to vary with time, even on a Holocene timescale. For instance, soil mineral fertility (specifically, the concentration of exchangeable cations) will vary following ongoing soil formation influenced by climate, vegetation and/or land use changes. As soil mineral fertility will impact the soil nutrient status for vegetation and impact the soil capacity to store organic carbon (von Fromm et al., 2021), it is a relevant parameter to reconstruct over time. However, as soil fertility of surface soils will decrease during erosion or burial, this parameter can currently not be reconstructed quantitatively.To investigate the potential of GDGTs as soil fertility proxies, branched and isoprenoid GDGTs were measured in soils from 5 elevation transects (Austria, Bolivia, China, Indonesia and Tanzania; De Jonge et al., 2024) that cover a large gradient in mean annual temperature (0-28 &#8451;), seasonality, and soil chemical parameters. Supplemented with temperature and precipitation data, we evaluate both changes in absolute concentration and relative distribution of the GDGTs. Of the chemical parameters, exchangeable calcium and exchangeable iron are shown to correlate with the absolute abundance of several branched (6 methyl brGDGTs) and isoprenoid (crenarchaeol isomer) GDGT compounds. Based on these relations we have developed ratios as proxies for calcium (and summed bases) and iron (and summed metals) [r2=0.61-0.68, p