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| Titel |
Indications of human activity from amino acid and amino sugar analyses on Holocene sediments from lake Lonar, central India |
| VerfasserIn |
P. Menzel, B. Gaye, M. Wiesner, S. Prasad, N. Basavaiah, M. Stebich, A. Anoop, N. Riedel, A. Brauer |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062142
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| Zusammenfassung |
| The DFG funded HIMPAC (Himalaya: Modern and Past Climates) programme aims to
reconstruct Holocene Indian Monsoon climate using a multi-proxy and multi-archive
approach. First investigations made on sediments from a ca. 10 m long core covering the
whole Holocene taken from the lake Lonar in central India’s state Maharashtra, Buldhana
District, serve to identify changes in sedimentation, lake chemistry, local vegetation and
regional to supra-regional climate patterns.
Lake Lonar occupies the floor of an impact crater that formed on the ~ 65 Ma old basalt
flows of the Deccan Traps. It covers an area of ca. 1 km2 and is situated in India’s core
monsoon area. The modern lake has a maximum depth of about 5 m, is highly
alkaline, and hyposaline, grouped in the Na-Cl-CO3 subtype of saline lakes. No
out-flowing stream is present and only three small streams feed the lake, resulting in a
lake level highly sensitive to precipitation and evaporation. The lake is eutrophic
and stratified throughout most of the year with sub- to anoxic waters below 2 m
depth.
In this study the core sediments were analysed for their total amino acid (AA) and amino
sugar (AS) content, the amino acid bound C and N percentage of organic C and
total N in the sediment and the distribution of individual amino acids. The results
roughly show three zones within the core separated by distinct changes in their AA
content and distribution. (i) The bottom part of the core from ca. 12000 cal a BP to
11400 cal a BP with very low AA and AS percentage indicating high lithogenic
contribution, most probably related to dry conditions. (ii) From 11400 cal a BP
to 1200 cal a BP the sediments show moderate AA and AS percentages and low
values for the ratios of proteinogenic AAs to their non-proteinogenic degradation
products (e.g. ASP/β-ALA; GLU/γ-ABA). (iii) The top part of the core (< 1200 cal a
BP) is characterised by an intense increase in total AA and AS, AA-C/Corg and
AA-N/Ntotas well as in the ratio of proteinogenic to non-proteinogenic AAs. This
indicates a strong increase in aquatic production which seems to be the result of
eutrophication likely caused by human activity like forest clearance and agricultural land
use. This hypothesis is corroborated by the dating of more than 10 temple ruins
surrounding the lake, which were built in the 12thcentury, indicating early urbanisation. |
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