Environmental changes in the southeastern Pampa plain (southeastern South America) during the last millennium based on multiple lacustrine indicators and historical records
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引用次数: 0
Abstract
Paleoenvironmental analyses have been widely used to infer the fluctuations in past environmental conditions of lakes and reservoirs due to either anthropogenic and/or climatic influences. The Siete Lomas shallow lake (37° 08′ S, 57° 38′ W) is located in an area with a long history of anthropogenic impacts in the Pampa plain, southeastern Argentina. Our aim was to reconstruct the paleoenvironmental history of the Siete Lomas shallow lake and to identify the main forcings of change during the last 1000 years. A multi-proxy analysis was performed including pollen and non-pollen palynomorphs, diatoms, fossil pigments, plant macrofossils and the associated fauna, Total Phosphorus (TP) and organic matter. Two main environmental stages (the latter including two substages) throughout the history of the Siete Lomas lake were recognized as a result of the action of natural variability and anthropogenic drivers. Stage I (1100–1880/1900 AD) recorded a pre-agricultural period when human impacts were negligible, and was considered as reference conditions. In this stage, a temporary, brackish and oligotrophic lake was inferred. Stage II was composed by two substages. Substage II-1 (1900–1945 AD) suggested the establishment of a permanent freshwater lake with higher pelagic primary production and an incipient eutrophication process, associated to increased anthropogenic activity and higher precipitation. Nutrient load and eutrophication processes controlled Substage II-2 (1945–2021), as a productive lake subject to increased eutrophication as a consequence of nutrient loadings from the surrounding catchment was identified. In particular, a highly productive, turbid-hypereutrophic and permanent lake related to the increase in agricultural activities was recognized for the period 2005–2021 AD. Overall, during the early period of the lake history, changes in dominant communities were mainly controlled by climate whereas after 1900 AD anthropogenic and natural forcing synergistically promoted the generalized degradation of the water quality of the Siete Lomas shallow lake.
期刊介绍:
The realization that a historical perspective is often useful, if not essential, to the understanding of most limnological processes has resulted in the recent surge of interest in paleolimnology. The main aim of the Journal of Paleolimnology is the provision of a vehicle for the rapid dissemination of original scientific work dealing with the reconstruction of lake histories. Although the majority of papers deal with lakes, paleoenvironmental studies of river, wetland, peatland and estuary systems are also eligible for publication.
The Journal of Paleolimnology, like the subject itself, is multidisciplinary in nature, and papers are published that are concerned with all aspects (e.g. biological, chemical, physical, geological, etc.) of the reconstruction and interpretation of lake histories. Both applied and more theoretical papers are equally encouraged. The Journal of Paleolimnology will continue to be a major repository for papers dealing with climatic change, as well as other pressing topics, such as global environmental change, lake acidification, eutrophication, long-term monitoring, and other aspects of lake ontogeny. Taxonomic and methodological papers are also acceptable provided they are of relatively broad interest. New equipment designs are frequently featured. In addition to original data and ideas, the Journal of Paleolimnology also publishes review articles, commentaries and program announcements. A relevant Book Review Section is also featured.