GEOREVIEW: Scientific Annals of Stefan cel Mare University of Suceava. Geography Series, 2016
Significant changes in available moisture have occurred in the hyperarid Atacama Desert throughou... more Significant changes in available moisture have occurred in the hyperarid Atacama Desert throughout the late Quaternary. Paleorecords show that areas in the adjacent high Andes and western Altiplano have experienced significant increases in rainfall, likely the result of intensified summer systems associated with the South American Summer Monsoon, tropical Pacific sea-surface temperature gradients and the mean position of the Intertropical Convergence Zone
Understanding the variables that balance bacterial network gathering in normal soils is a longsta... more Understanding the variables that balance bacterial network gathering in normal soils is a longstanding test in microbial network biology. In this work, we thought about two microbial co-event systems speaking to bacterial soil networks from two unique areas of a pH, temperature and stickiness inclination happening along a western slant of the Andes in the Atacama Desert. In doing as such, a topological diagram arrangement of co-event systems was utilized to decide the effect of a move in ecological factors on OTUs ordered sythesis and their connections. We saw that a small amount of affiliation designs recognized in the co-event systems are relentless in spite of huge natural variety. This evident versatility is by all accounts because of: an extent of OTUs that endure over the angle and keep up comparative affiliation designs inside the network and bacterial network biological adjustments, where a significant division of the OTUs come to fill the environmental jobs of different OTU...
The Laguna del Maule (LdM) volcanic field is one of the most seismically and volcanically active ... more The Laguna del Maule (LdM) volcanic field is one of the most seismically and volcanically active areas in the central-southern Andes, with intense postglacial and Holocene activity. We performed a seismic survey and collected a transect of sediment cores to study the depositional evolution of the lake located in the LdM caldera. This new high-resolution centennial-scale multi-proxy record provides insight into environmental and eruptive dynamics over the last 13.0 ka BP. Up to 18 ash and 5 lapilli layers mark volcanic events, which mostly cluster in the early and late Holocene with an extensive volcanic event at ~ 4.0 ka. Sedimentary facies and geochemical indicators (TOC, C/N, Br/Ti and Fe/Mn) are used to infer higher (lower) organic productivity during early and mid-Holocene (late Holocene) associated to lower (higher) water levels and dominant anoxic (oxic) conditions at the bottom of the lake. We attribute decreased lake levels between ~ 8.0 and 5.0 ka in part to lowered winter precipitation, which is coeval with a southward shift in the Southern Westerly Winds documented in other records, and a strengthening of the Pacific Subtropical High. Higher fluctuations in lake levels after 4.0¿3.0 ka BP are indicative of increased ENSO variability. Several important global climate transitions (LIA, 4.0, 8.0 and 11 ka) are well represented in the LdM sequence showing the importance of this record for reconstructing regional paleohydrology. Finally, periods of higher lake productivity during early and mid-Holocene were synchronous with elevated frequencies of volcanic events suggesting a climatic-volcanic synergy in limnological processes.Peer Reviewe
ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but ... more ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but well-preserved fossil remains from well-dated sites are scarce in the Atacama Desert and adjacent arid Andes. Here we report on a partially complete skeleton (46%) of a single young (ca. 3–4 years old) extinct horse discovered in the Salar de Surire, a salt flat located on the Andean altiplano of northern Chile (4,250 m asl). Comparative and osteometric morphological analyses identify the specimen as a South American endemic horse Hippidion saldiasi Roth, 1899. A direct AMS radiocarbon date on bone collagen yielded a calibrated age of 13,170 cal yr BP (2σ range: 13,300–13,060 cal yr BP) indicating that it lived near the end of the last glaciation. The body mass of the individual was calculated at approximately 326.4 kg, close to the upper limit of the larger sizes reported for the genus. Stable isotope evidence shows that the Salar de Surire horse relied on an almost 100% C3 diet that is mostly consistent with Hippidion specimens from other environments that also consumed either mixed C3/C4 or fully C3 diets. This finding is now the southernmost high-elevation record for this species and provides further evidence for the broad geographic and ecological distribution of this genus throughout southern South America.
The hyperarid Atacama Desert coast receives scarce moisture inputs mainly from the Pacific Ocean ... more The hyperarid Atacama Desert coast receives scarce moisture inputs mainly from the Pacific Ocean in the form of marine advective fog. The collected moisture supports highly specialized ecosystems, where the bromeliad Tillandsia landbeckii is the dominant species. The fog and low clouds (FLCs) on which these ecosystems depend are affected in their interannual variability and spatial distribution by global phenomena, such as ENSO. Yet, there is a lack of understanding of how ENSO influences recent FLCs spatial changes and their interconnections and how these variations can affect existing Tillandsia stands. In this study, we analyze FLCs occurrence, its trends and the influence of ENSO on the interannual variations of FLCs presence by processing GOES satellite images (1995–2017). Our results show that ENSO exerts a significant influence over FLCs interannual variability in the Atacama at ~ 20°S. Linear regression analyses reveal a relation between ENSO3.4 anomalies and FLCs with oppos...
Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Cha... more Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Changes (LUCCs) since the industrial revolution and especially during the Great Acceleration (1950 CE). Yet, the impact of such activities on terrestrial and aquatic ecosystems above their ecological baselines are not well known, especially when considering the response of these systems to the intensity of LUCCs on nutrient cycles. Here, we used a multiproxy approach (sedimentological, geochemical and isotopic analyses, historical records, climate data, and satellite images) to evaluate the role that LUCCs have on Nitrogen (N) cycling in a coastal mediterranean watershed system of central Chile over the last two centuries. Despite long-term anthropogenic use (agriculture, cattle grazing) in the Matanzas watershed– lake system, these LUCC appear to have had little impact on nutrient and organic matter transfer since the Spanish Colonial period. In contrast, the largest changes in N dynamics ...
A key concern regarding current and future climate change is the possibility of sustained drought... more A key concern regarding current and future climate change is the possibility of sustained droughts that can have profound impacts on societies. As such, multiple paleoclimatic proxies are needed to identify megadroughts, the synoptic climatology responsible for these droughts, and their impacts on past and future societies. In the hyperarid Atacama Desert of northern Chile, many streams are characterized by perennial flow and support dense in-stream wetlands. These streams possess sequences of wetland deposits as fluvial terraces that record past changes in the water table. We mapped and radiocarbon dated a well-preserved sequence of in-stream wetland deposits along a 4.3-km reach of the Río San Salvador in the Calama basin to determine the relationship between regional climate change and the incision of in-stream wetlands. The Río San Salvador supported dense wetlands from 11.1 to 9.8, 6.4 to 3.5, 2.8 to 1.3, and 1.0 to 0.5 ka and incised at the end of each of these intervals. Comp...
GEOREVIEW: Scientific Annals of Stefan cel Mare University of Suceava. Geography Series, 2016
Significant changes in available moisture have occurred in the hyperarid Atacama Desert throughou... more Significant changes in available moisture have occurred in the hyperarid Atacama Desert throughout the late Quaternary. Paleorecords show that areas in the adjacent high Andes and western Altiplano have experienced significant increases in rainfall, likely the result of intensified summer systems associated with the South American Summer Monsoon, tropical Pacific sea-surface temperature gradients and the mean position of the Intertropical Convergence Zone
Understanding the variables that balance bacterial network gathering in normal soils is a longsta... more Understanding the variables that balance bacterial network gathering in normal soils is a longstanding test in microbial network biology. In this work, we thought about two microbial co-event systems speaking to bacterial soil networks from two unique areas of a pH, temperature and stickiness inclination happening along a western slant of the Andes in the Atacama Desert. In doing as such, a topological diagram arrangement of co-event systems was utilized to decide the effect of a move in ecological factors on OTUs ordered sythesis and their connections. We saw that a small amount of affiliation designs recognized in the co-event systems are relentless in spite of huge natural variety. This evident versatility is by all accounts because of: an extent of OTUs that endure over the angle and keep up comparative affiliation designs inside the network and bacterial network biological adjustments, where a significant division of the OTUs come to fill the environmental jobs of different OTU...
The Laguna del Maule (LdM) volcanic field is one of the most seismically and volcanically active ... more The Laguna del Maule (LdM) volcanic field is one of the most seismically and volcanically active areas in the central-southern Andes, with intense postglacial and Holocene activity. We performed a seismic survey and collected a transect of sediment cores to study the depositional evolution of the lake located in the LdM caldera. This new high-resolution centennial-scale multi-proxy record provides insight into environmental and eruptive dynamics over the last 13.0 ka BP. Up to 18 ash and 5 lapilli layers mark volcanic events, which mostly cluster in the early and late Holocene with an extensive volcanic event at ~ 4.0 ka. Sedimentary facies and geochemical indicators (TOC, C/N, Br/Ti and Fe/Mn) are used to infer higher (lower) organic productivity during early and mid-Holocene (late Holocene) associated to lower (higher) water levels and dominant anoxic (oxic) conditions at the bottom of the lake. We attribute decreased lake levels between ~ 8.0 and 5.0 ka in part to lowered winter precipitation, which is coeval with a southward shift in the Southern Westerly Winds documented in other records, and a strengthening of the Pacific Subtropical High. Higher fluctuations in lake levels after 4.0¿3.0 ka BP are indicative of increased ENSO variability. Several important global climate transitions (LIA, 4.0, 8.0 and 11 ka) are well represented in the LdM sequence showing the importance of this record for reconstructing regional paleohydrology. Finally, periods of higher lake productivity during early and mid-Holocene were synchronous with elevated frequencies of volcanic events suggesting a climatic-volcanic synergy in limnological processes.Peer Reviewe
ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but ... more ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but well-preserved fossil remains from well-dated sites are scarce in the Atacama Desert and adjacent arid Andes. Here we report on a partially complete skeleton (46%) of a single young (ca. 3–4 years old) extinct horse discovered in the Salar de Surire, a salt flat located on the Andean altiplano of northern Chile (4,250 m asl). Comparative and osteometric morphological analyses identify the specimen as a South American endemic horse Hippidion saldiasi Roth, 1899. A direct AMS radiocarbon date on bone collagen yielded a calibrated age of 13,170 cal yr BP (2σ range: 13,300–13,060 cal yr BP) indicating that it lived near the end of the last glaciation. The body mass of the individual was calculated at approximately 326.4 kg, close to the upper limit of the larger sizes reported for the genus. Stable isotope evidence shows that the Salar de Surire horse relied on an almost 100% C3 diet that is mostly consistent with Hippidion specimens from other environments that also consumed either mixed C3/C4 or fully C3 diets. This finding is now the southernmost high-elevation record for this species and provides further evidence for the broad geographic and ecological distribution of this genus throughout southern South America.
The hyperarid Atacama Desert coast receives scarce moisture inputs mainly from the Pacific Ocean ... more The hyperarid Atacama Desert coast receives scarce moisture inputs mainly from the Pacific Ocean in the form of marine advective fog. The collected moisture supports highly specialized ecosystems, where the bromeliad Tillandsia landbeckii is the dominant species. The fog and low clouds (FLCs) on which these ecosystems depend are affected in their interannual variability and spatial distribution by global phenomena, such as ENSO. Yet, there is a lack of understanding of how ENSO influences recent FLCs spatial changes and their interconnections and how these variations can affect existing Tillandsia stands. In this study, we analyze FLCs occurrence, its trends and the influence of ENSO on the interannual variations of FLCs presence by processing GOES satellite images (1995–2017). Our results show that ENSO exerts a significant influence over FLCs interannual variability in the Atacama at ~ 20°S. Linear regression analyses reveal a relation between ENSO3.4 anomalies and FLCs with oppos...
Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Cha... more Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Changes (LUCCs) since the industrial revolution and especially during the Great Acceleration (1950 CE). Yet, the impact of such activities on terrestrial and aquatic ecosystems above their ecological baselines are not well known, especially when considering the response of these systems to the intensity of LUCCs on nutrient cycles. Here, we used a multiproxy approach (sedimentological, geochemical and isotopic analyses, historical records, climate data, and satellite images) to evaluate the role that LUCCs have on Nitrogen (N) cycling in a coastal mediterranean watershed system of central Chile over the last two centuries. Despite long-term anthropogenic use (agriculture, cattle grazing) in the Matanzas watershed– lake system, these LUCC appear to have had little impact on nutrient and organic matter transfer since the Spanish Colonial period. In contrast, the largest changes in N dynamics ...
A key concern regarding current and future climate change is the possibility of sustained drought... more A key concern regarding current and future climate change is the possibility of sustained droughts that can have profound impacts on societies. As such, multiple paleoclimatic proxies are needed to identify megadroughts, the synoptic climatology responsible for these droughts, and their impacts on past and future societies. In the hyperarid Atacama Desert of northern Chile, many streams are characterized by perennial flow and support dense in-stream wetlands. These streams possess sequences of wetland deposits as fluvial terraces that record past changes in the water table. We mapped and radiocarbon dated a well-preserved sequence of in-stream wetland deposits along a 4.3-km reach of the Río San Salvador in the Calama basin to determine the relationship between regional climate change and the incision of in-stream wetlands. The Río San Salvador supported dense wetlands from 11.1 to 9.8, 6.4 to 3.5, 2.8 to 1.3, and 1.0 to 0.5 ka and incised at the end of each of these intervals. Comp...
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