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Magnetic susceptibility (MS) represents a high resolution environmental and lithological (LITHO) proxy tool, which is successfully used for the study of recent sediments in freshwater or marine aquatic environments. The studies that we have achieved in the last 40 years in the Danube – Danube Delta – Black Sea hydrosedimentary system have revealed strong connections between the characteristics of sedimentary environment, sediment quality and their magnetic properties. In the present paper are discussed results concerning several lakes from Gorgova − Uzlina Depression (Danube Delta), which are added to the lately published magneto-lithological data for sedimentary environments of Meşteru − Fortuna and Matiţa − Merhei depressions. This work, which represents the first part of a composite paper, is particularly focused on the sediment cores collected in the lakes Gorgova, Cuibeda, Uzlina and Isacova. Their MS characterization, not neglecting the lithological support, defined by the three main components, namely the SILiciclastic/ minerogenic fraction – SIL, Total Organic Matter – TOM and CARbonates – CAR, is approached. Several lithological units are identified, based upon the macroscopic characteristics, magnetic properties and lithological composition. It is interesting to note that although the study area is included in the fluvial delta plain, the recent lacustrine sediments are very thin in some sectors and the short cores (under 60 cm) stop at a level of marine clays (L. Cuibeda). The second part of this study, regarding the surficial sediments from the above-mentioned lakes, and more other ones is published inside of a similar magneto-lithogenetic context. All these data give new evidences for demonstrating the availabilities of the method used to identify the environmental influences on the magnetic susceptibility of lake sediments, and hence to assess the geoecological state of the deltaic area under attention., {"references":["Catianis, I., Rădan, S., Grosu, D. (2013) − Distribution of lithological components of recent sediments from some lakes in the Danube Delta; environmental significance, Carpath. J. Earth Environ. Sci., 8, 2, 55-68.","Catianis, I., Rădan, S., Grosu, D. (2014) − Loss of ignition as a proxy indicator for assessing the lithological composition of the recent sediments accumulated in some freshwater lakes from the Danube Delta, Romania, Inter. J. Innov. Appl. St., ISSN 2028-9324, 9, 1, 260-278.","Dean, W.E. (1974) − Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: comparison with other methods, Journal of Sedimentary Petrology, 44, 242-248.","Egli, R. (2003) − Environmental influences on the magnetic properties of lake sediments, PhD Thesis, Swiss Federal Institute of Technology, Zurich, 328p. (with an Appendix). Rădan, S.-C., Rădan, S. (2007a) − A magnetic susceptibility scale for lake sediments; inferences from the Danube Delta and the Razim - Sinoie lagoonal Complex (Romania), Geo-Eco-Marina, 13, Bucureşti - Constanţa, 61-74.","Rădan, S.-C., Rădan, S. (2007b) − The magnetic signature of present environmental changes in lake sediments induced by hydrotechnical works; a case study from the Danube Delta (Romania), the XXIVth IUGG General Assemby, \"Earth: Our changing planet\", July 2 – 13, 2007, Abstracts, IAGA, Inter-Association Symposia and Workshops, published by Umbria Sci. Meet. Ass. (USMA), Perugia, Italy, December, 2007, Abstract 3104, p. 156. http://www.iugg- 2007perugia.it/iuggProc/A.pdf","Rădan, S.-C., Rădan, S. (2007c) − Modern Sediments as Enviromagnetic Archives. A Case Study: Danube Delta and Northwestern Black Sea, EOS Transactions, American Geophysical Union, 88 (52), Fall Meet. Suppl., 10 - 14 December, 2007, San Francisco, USA, Abstract GP53B-1220.","Rădan, S.-C., Rădan, S. (2010a) – The use of the magnetic susceptibility to study hydrosedimentary environments and processes in Danube Delta, Geo-Eco-Marina, 16, Bucureşti - Constanţa, 37-46.","Rădan, S.-C., Rădan, S. (2010b) – Lake sediments fingerprinting in the Danube Delta, using composite magneto-lithological signatures; an environmental approach, Travaux Géophysiques, XXXIX, Abstracts of the 12th \"Castle Meeting − New Trends in Geomagnetism. Palaeo, Rock and Environmental Magnetism\", Castle of Nové Hrady, Czech Republic, August 29 - September 4, 2010, 68-69.","Rădan, S.-C., Rădan, S. (2011) − Recent sediments as enviromagnetic archives. A brief overview, Geo-Eco-Marina, 17, Bucureşti - Constanţa, 103-122.","Rădan, S.-C., Rădan, S., Catianis, I. (2013) − The use of the magnetic susceptibility record as a proxy signature for the lithological composition of lake sediments: Evidences from Danube Delta short cores in the Meşteru − Fortuna Depression (Danube Delta), Geo- Eco-Marina, 19, Bucureşti - Constanţa, Romania, 77-105.","Rădan, S.-C., Rădan, S., Catianis, I. (2014a) − Relationship between the magnetic susceptibility and lithological composition in sediment cores from lakes of Matiţa − Merhei Depression (Danube Delta, Romania): Towards a proxy method of sedimentological and environmental fingerprinting, Geo-Eco-Marina, 20, Bucureşti - Constanţa, ISSN: 2248–2776 ISSN-L: 1224–6808, 45-86.","Rădan, S.-C., Rădan, S., Catianis, I., Scrieciu, A. (2014b) − Magnetosusceptibility and lithological fingerprints of the marine clays recovered from sediment cores taken in the Danube Delta (Romania), p. 30. In: L Török (Ed.) − \"Deltas and Wetlands\" (Book of abstracts), vol. 2, Conference \"BSB Net-Eco − Deltas and Wetlands.\"Environmental aspects and available scientific tools for Black Sea Basin protection\" (Tulcea, Romania, 15 - 17 September, 2014), Danube Delta Technological Information Center Publishing House, Tulcea, Romania, ISSN 2344-3766; DOI: 10.14592/DDI.D. W.02. 2014, 48p.","Rădan, S.-C., Rădan, S., Catianis, I., Scrieciu, A. (2014c) − Composite enviromagnetic and lithological signatures retrieved from recent sediments in the Danube Delta (Romania), with a special view to the couples of lakes, 14th Castle Meeting \"New Trends on Paleo, Rock and Environmental Magnetism\", 31st August - 6th September 2014, Évora, Portugal. https://www.fc.ul.pt/sites/default/ files/fcul/public/14Castle_meeting/Radan1_Castle%20Meeting_ Portugal_Abstract-Paper%201_Danube-Delta_Radan-etal_ Romania.pdf.","Rădan, S.-C., Rădan, S., Catianis, I., Scrieciu, A. (2014d) − Towards assessing the potential for stratigraphic studies in the Danube Delta geo-environments by using magnetosusceptibility and lithological records retrieved from Recent sediments, 127- 128, 203 (Appendix 10/Fig. A11). In: A.V. Borodin, E.A. Markova, T.V. Strukova (Eds.) − \"The Quaternary of the Urals: Global trends and Pan-European Quaternary records\", International Conference, INQUA- SEQS 2014 (Ekaterinburg, Russia, September 10 - 16, 2014), Ekaterinburg, UrFU, ISBN 978-5-321-02398-3, 228p.","Rădan, S.-C., Rădan, S., Scrieciu, A. (2015)− Environmental influences on the magnetic susceptibility of recent sediments in Danube Delta, in geoecological context: insights from lakes of Gorgova − Uzlina Depression, p. 29, In: Török L. (ed.), \"Deltas and Wetlands\" (Book of abstracts), vol. 3, Danube Delta Technological Information Center Publishing House, Tulcea, Romania, ISSN 2344-3766; DOI: 10.14592/ DDI.D.W.03.2015, 45 p.","Rădan, S.C., Rădan, S., Catianis, I., Grosu, D., Pojar I., Scrieciu, A. (2016) − An environmental magneto-lithogenetic study in the lakes of the Gorgova − Uzlina Depression (Danube Delta, Romania). II. Insights from surficial sediments, Geo-Eco-Marina, 22, Bucureşti - Constanţa (this volume).","Trodahl, M. I. (2010) − Late Holocene Sediment Deposition in Lake Wairarapa, M.Sc. Thesis, submitted to Victoria University of Wellington, New Zealand, 114p."]}

Magnetic susceptibility (MS) represents a high resolution environmental and lithological (LITHO) proxy tool, which is successfully used for the study of recent sediments in freshwater or marine aquatic environments. The studies that we have achieved in the last 40 years in the Danube – Danube Delta – Black Sea hydrosedimentary system have revealed strong connections between the characteristics of sedimentary environment, sediment quality and their magnetic properties. In the present paper are discussed results concerning several lakes from Gorgova − Uzlina Depression (Danube Delta), which are added to the lately published magneto-lithological data for sedimentary environments of Meşteru − Fortuna and Matiţa − Merhei depressions. This work, which represents the first part of a composite paper, is particularly focused on the sediment cores collected in the lakes Gorgova, Cuibeda, Uzlina and Isacova. Their MS characterization, not neglecting the lithological support, defined by the three main components, namely the SILiciclastic/ minerogenic fraction – SIL, Total Organic Matter – TOM and CARbonates – CAR, is approached. Several lithological units are identified, based upon the macroscopic characteristics, magnetic properties and lithological composition. It is interesting to note that although the study area is included in the fluvial delta plain, the recent lacustrine sediments are very thin in some sectors and the short cores (under 60 cm) stop at a level of marine clays (L. Cuibeda). The second part of this study, regarding the surficial sediments from the above-mentioned lakes, and more other ones is published inside of a similar magneto-lithogenetic context. All these data give new evidences for demonstrating the availabilities of the method used to identify the environmental influences on the magnetic susceptibility of lake sediments, and hence to assess the geoecological state of the deltaic area under attention., {"references":["Catianis, I., Rădan, S., Grosu, D. (2014) − Loss of ignition as a proxy indicator for assessing the lithological composition of the recent sediments accumulated in some freshwater lakes from the Danube Delta, Romania, Inter. J. of Innov. and Appl. St., ISSN 2028- 9324, 9, 1, 260-278.","Dean, W.E. (1974) − Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: comparison with other methods, Journal of Sedimentary Petrology, 44, 242-248.","Dekkers, M.J. (1997) − Environmental magnetism: an introduction, Geol. Mijn., 76, 163-182.","Evans, M.E., Heller, F. (2003) − Environmental Magnetism. Principles and Applications of Enviromagnetics, Academic Press, Elsevier Science, USA, 299p.","Oldfield, F. (1991) − Environmental magnetism – a personal perspective, Quater. Sci. Rev., 10, 73-85.","Egli, R. (2003) − Environmental influences on the magnetic properties of lake sediments, PhD Thesis, Swiss Federal Institute of Technology, Zurich, 328p. (with an Appendix).","Ishii, Y., Kazuaki Hori, K. (2016) − Formation and infilling of oxbow lakes in the Ishikari lowland, northern Japan, Quaternary International, 397, 136-146.","Rădan, S. (2015) − Field campaign for monitoring, review and completion in the master areas from the Danube Delta, the Razim - Sinoie Lagoon Complex, and the marginal lakes, \"Phase no. 22\" Report (PN 09-41 03 04 Project), 50 p., GeoEcoMar, Bucharest, Romania (unpublished Scientific Report; in Romanian).","Rădan, S.-C. (1981) – Magnetometric and petromagnetic researches in the lacustrine area, Bul. Inf. Ştiinţ. Tehn., I, 1, Inst. Geol. Geofiz., Bucureşti, 9-11 (in Romanian).","Rădan, S.-C. (2008) – The direct problem and the inverse problem in Petromagnetology and Palaeomagnetology; a discussion, with exemplification in Geophysics, Geology and Geoecology, Geo- Eco-Marina, 14, Suppl. no. 1, Bucureşti - Constanţa, 201-215 (with 3 plates) (in Romanian).","Rădan, S.-C. Rădan, S. (2003) – Magneto-susceptibilimetric models drawn up for bottom sediments sampled in different phases from lakes of the Gorgova – Uzlina Depression, in S.C. Rădan and S. Rădan (2003) – The elaboration of an enviromagnetic method to characterize the sedimentary systems in areas covered by water. Experimentation in the Danube Delta and the Razelm (Razim) - Sinoie Lagoon Complex. Phase II (\"CERES\" Project), G.I.R. – GeoEcoMar Archives, Bucharest, Romania (unpublished Scientific Report; in Romanian).","Rădan, S.-C., Rădan, S. (2006a) – 30 years of magnetic susceptibility measurements on the Danube Delta lake sediments (Romania, 1976 - 2006). Sedimentologic applications to Environmental Magnetism, 10th Castle Meeting \"New Trends in Geomagnetism – Palaeo, Rock and Environmental Magnetism\", September 3 – 8, 2006, Castle of Valtice, Czech Republic; Abstract, Travaux Géophysiques, XXXVIII, 2006, ISSN 0231-5548, Geophysical Institute, Academy of Sciences of the Czech Republic, Prague, 94-95.","Rădan, S.-C., Rădan, S. (2006b) – A magnetic susceptibility scale with a lithological support originated in the lake sediments from the Danube Delta and the Razim – Sinoie Lagoonal Complex (Romania). An environmental and geoecological approach, 10th Castle Meeting \"New Trends in Geomagnetism – Palaeo, Rock and Environmental Magnetism\", September 3 – 8, 2006, Castle of Valtice, Czech Republic; Abstract, Travaux Géophysiques, XXXVIII, 2006, ISSN 0231-5548, Geophysical Institute, Academy of Sciences of the Czech Republic, Prague, 96-97.","Rădan, S.-C., Rădan, S. (2007a) – A magnetic susceptibility scale for lake sediments; inferences from the Danube Delta and the Razim – Sinoie Lagoonal Complex (Romania), Geo-Eco-Marina, 13, Bucureşti - Constanţa, 61-74.","Rădan, S.-C., Rădan, S. (2007b) – Modern Sediments as Enviromagnetic Archives. A Case Study: Danube Delta and Northwestern Black Sea, American Geophysical Union Fall Meeting, 10 – 14 December, 2007, San Francisco, USA (Poster Presentation); EOS Transactions, American Geophysical Union, 88 (52), Fall Meet. Suppl., San Francisco, USA, Abstract GP53B-1220.","Rădan, S.-C., Rădan, S. (2009) – Integrated magnetic susceptibility and lithological studies on lacustrine recent sediments from the Danube Delta, Geo-Eco-Marina, 15, Bucureşti - Constanţa, 177-197.","Rădan, S.-C., Rădan, S. (2010a) – The use of the magnetic susceptibility to study hydrosedimentary environments and processes in Danube Delta, Geo-Eco-Marina, 16, Bucureşti - Constanţa, 37-46.","Rădan, S.-C., Rădan, S. (2010b) – Lake sediments fingerprinting in the Danube Delta, using composite magneto-lithological signatures; an environmental approach, Travaux Géophysiques, XXXIX, Abstracts of the \"12th Castle Meeting − New Trends in Geomagnetism. Palaeo, Rock and Environmental Magnetism\", Castle of Nové Hrady, Czech Republic, August 29 - September 4, 2010, 68-69.","Rădan, S.-C., Rădan, S. (2011) – Recent sediments as enviromagnetic archives. A brief overview, Geo-Eco-Marina, 17, Bucureşti-Constanţa, 103-122 (with a double plate).","Rădan, S.-C., Rădan, M., Rădan, S. (1978) – Magnetic susceptibility of bottom sediments. In: N. Mihăilescu et al. (1978) – The geological and geophysical study of the Danube Delta to assess its economical potential (Goloviţa L. – Sinoe L. sector), Archives of Institute of Geology and Geophysics (in present, Geological Institute of Romania), Bucharest, Romania (unpublished Scientific Report; in Romanian).","Rădan, S.C., Rădan, M., Rădan, S. (1980) − Petromagnetic characteristics of the bottom sediments. In: Mihăilescu, N. et al. (1980) – The geological and geophysical study of the Danube Delta in order to evaluate its economical potential (Gorgova – Uzlina – Isacova sector), Archives of Institute of Geology and Geophysics (in present, Geological Institute of Romania), Bucharest, Romania (unpublished Scientific Report; in Romanian).","Rădan, S.-C., Rădan, S., Catianis, I. (2013) − The use of the magnetic susceptibility record as a proxy signature for the lithological composition of lake sediments: Evidences from Danube Delta short cores in the Meşteru − Fortuna Depression (Danube Delta), Geo- Eco-Marina, 19, Bucureşti - Constanţa, Romania, 77-105.","Rădan, S.-C., Rădan, S., Catianis, I. (2014) − Relationship between the magnetic susceptibility and lithological composition in sediment cores from lakes of Matiţa − Merhei Depression (Danube Delta, Romania): Towards a proxy method of sedimentological and environmental fingerprinting, Geo-Eco-Marina, 20, Bucureşti - Constanţa, ISSN: 2248–2776 ISSN-L: 1224–6808, 45-86.","Rădan, S.-C., Rădan, S., Catianis, I., Grosu, D., Scrieciu, A., Pojar, I. (2016) − An environmental magneto-lithogenetic study in the lakes of the Gorgova – Uzlina Depression (Danube Delta, Romania). I. Insights from short sediment cores, Geo-Eco-Marina, 22, Bucureşti - Constanţa, ISSN: 2248–2776 ISSN-L: 1224–6808 (this volume).","Rădan, S.-C., Rădan, S., Scrieciu, A. (2015) − Environmental influences on the magnetic susceptibility of recent sediments in Danube Delta, in geoecological context: insights from lakes of Gorgova − Uzlina Depression, Abstract, p. 29, in L. Török (ed.) − 2015 Deltas and Wetlands (Book of abstracts), vol. 3, 45 p., Danube Delta Technological Information Center Publishing House, Tulcea, Romania, ISSN 2344-3766.DOI:10.14592/DDI.D.W.03.2015","Thompson, R., Battarbee, R.W., O'Sullivan, P.E., Oldfield, F. (1975) − Magnetic susceptibility of lake sediments, Limnol. Oceanogr., 20, 5, 687-698.","Verosub, K.L., Roberts, A.P. (1995) − Environmental magnetism: Past, present, future, J.Geophys. Res., 100, 82, 2175-2192."]}

In the framework of the Danube Delta geosystem spatial evolution study, new results achieved for sediment cores − this time collected from the Matiţa − Merhei Depression lakes − are added up to the data which were previously published with regard to the Meşteru − Fortuna Depression. Actually, it is the second part of the series of papers dedicated to the magneto − lithological investigation of sediment columns, taken out from various aquatic environments, in both the Fluvial and Marine Delta Plains. Vertical profiles of magnetic susceptibility (MS) and contents of siliciclastic/minerogenic/detrital fraction (SIL), total organic matter (TOM) and carbonate (CAR) are carried out for 9 cores (not longer than 55.5 cm), collected from four lakes (Babina, Matiţa, Polideanca and Bogdaproste), a swamp (Polideanca − Lopatna) and a canal (Lopatna − Polideanca). These records are based on MS (k) measurements (with a Kappabridge KLY-2), and respectively, on lithological component contents analyses (by the “Loss on Ignition”/LOI method), performed on sediment samples obtained by core slicing, at 1-3 cm intervals. MS, SIL, TOM and CAR maps are carried out for surficial sediments, as well, in order to describe the magneto-lithological background which characterizes each of the lakes from where the short sediment cores were extracted. The MS calibration of the lake sediments (core and grab samples) is carried out by using a k scale with 5 classes. The correlation coefficient (r) is calculated for all 6 possible pairs of above specified parameters (SIL vs. k, TOM vs. k, CAR vs. k, SIL vs. TOM, SIL vs. CAR and TOM vs. CAR). To evaluate the correlation size, a scale with 6 steps is used. Positive/direct and negative/reversed correlations have always been obtained for SIL vs. k, and TOM vs. k, respectively. Therefore, new proofs are added to assign the magnetic parameter proxy quality as environmental and sedimentological fingerprinting tool. Another important result of the present study is the detection of some marine clays located very close below the water/sediment interface, intercepted, particularly, at the lower/basal part of two cores from the Babina Lake, two from Matiţa Lake, and another one from the Lopatna − Polideanca Canal. These marine deposits (with macroscopically identified specific fauna) are characterized by clearly different magnetic and lithological signatures (high MS values and SIL contents, low TOM contents), as compared with the fingerprints recovered from the overlying muds (sampled at the upper part of the cores). The presence of a marine episode revealed by some of the sediment cores collected from lakes of the Matiţa − Merhei Depression, which is a part of the Fluvial Delta Plain, is very interesting and can represent a contribution to the better knowledge of the deltaic system temporal and spatial evolution.

The paper analyses the enviromagnetic results obtained on short cores collected from Danube Delta lakes and channels. A Hydro-Bios type core sampler was used to investigate sediments up to ca. 60 - 80 cm depth from various sedimentary environments located both in the Fluvial Delta Plain (e.g., Lungu L., Cuteţchi L., Fortuna L., Crânjală Canal, Băclăneşti L., Matiţa L., Babina L., Bogdaproste L., Gorgova L., Uzlina L., Isacova L.) and the Fluvio-Marine Delta Plain (e.g., Puiu L. and Roşu L.). In this article, the results achieved for the sediment cores taken in the Meşteru - Fortuna Depression, during the 2010 - 2013 interval, are presented. The data make possible to compare, in some cases, the magnetic susceptibility (k; MS) characterisation of the bottom sediments (sampled with the grab sampler) with the MS data associated with the first 10-30 cm of sediments collected from the upper half of the cores, taken out from the same places within a lake. More interesting are the variations in the magnetic susceptibility regime along the cores. In many cases, the enviromagnetic parameter “intensity” increased from the upper part towards the core base, but also some well-defined maximum and minimum k anomalies were detected. A clearly higher MS regime was identified along the whole short cores collected from the Crânjală mid-channel. The data demonstrate the capability of the MS parameter as a sedimentogenetic indicator, being possible to correlate the higher k values with the interception of a silted up zone or of two different sediment sequences within a core as a result of the hydrological regime changes occurred during the time. As regards the lower k values measured at the upper part of the cores, they are usually related to the muds rich in fine vegetal (organic) detritus and/or rich in shell fragments. Based on the values of the enviromagnetic parameter (k) and of the contents of the lithological components along the cores, several correlation coefficients (r) were calculated, taking into consideration all the possible pairs of magnetic and/or lithological parameters. The vertical distribution of the magnetic susceptibility associated with the cores clearly illustrates the particular characteristics of the “confined sedimentary environments” versus the “dynamic sedimentary environments”.

This tentative synopsis mainly focusses on the aspects of dating the loess - palaeosol sequences in the Romanian Plain and Dobrogea. The approach - placed in a historical framework - is defined by two characteristics. The first part is a short review of important achievements concerning the estimation or evaluation of the loess age, starting ca 120 years ago and ending in 1961. The second part continues with the loess dating history in a comprehensive table systematising significant contributions of the last half-century. Actually, this article has been generated by another paper (under review), dedicated to a conceptual sedimentary model of the loess in the Lower Danube Basin (Jipa, in press). The table emphasizes the interest for the loess dating during the last 50 years, and follows the chronological order of contributions. Implicitly, it is remarked the way passed through time in order to know the loess age, i.e. from the classic stratigraphy/pedostratigraphy to magnetostratigraphy, astronomically tuned ciclostratigraphy, magnetoclimatology, and up to the multi-proxy approach and optical/luminescence dating. In most of the sections, ages up to 781 ka are determined (the loess - palaeosol horizons are assigned to the Brunhes Chron of the ATNTS20004/ATNTS2012), but the synopsis includes a section from Dobrogea (analysed by the Infrared Stimulated Luminescence/IRSL dating method; Bălescu et al., 2003), wherefore the ”estimated geological age“ of 800 ka and the Marine Isotope Stage 20 are mentioned. Moreover, a recent result (Rădan, 2000, updated in 2012 - references therein) for a loess - palaeosol borehole profile (ca 30m thick) from the Romanian Plain points out, according to the palaeomagnetic investigation of the basal part and to the magnetic susceptibility vertical variation along the sampled borehole (40m depth), the possible identification of the Matuyama/Brunhes boundary (0.781 Ma), located at the base of the MIS 19. This subject has generated a dispute in the scientific literature on both the Chinese and the European loess. A tentative discussion on the ”observed MBB“ (within the loess horizon L8) and the ”corrected/true MBB“ (placed within the palaeosol S7) is done, by comparing our results from the Romanian Plain with data from the Chinese Loess Plateau.

A vast enviromagnetic archive has been recovered from the recent sediments of the Danube Delta (DD), Razim (Razelm) – Sinoie Lagoonal Complex (RSLC), Black Sea Littoral Zone (BSLZ) and Northwestern Black Sea (NWBS), which have been sampled over ca 35 years. The identified magnetic signatures can be used to characterize and differentiate the depositional environments inside an extended, diversified, and, at the same time, unitary complex of fluvial, lacustrine, littoral and marine ecosystems. The presence of the anthropogenic influence on some zones from these aquatic areas is clearly demonstrated by the modified magnetic fingerprints recovered from the bottom sediments and cores, at different time intervals. The most extended enviromagnetic archive belongs to the DD and RSLC. This is based on thousands of (sub)samples collected during numerous cruises carried out during the 1976 – 2011 period. To calibrate the modern sediments of the various aquatic environments and compare the different magnetic fingerprints, a Magnetic Susceptibility Scale (Rădan & Rădan, 2006a, 2007) is successfuly used.

Modern sediments have been sampled from the most important wetlands in the southeastern Romania, i.e. Danube Delta, Razim (Razelm) – Sinoie Lagoonal Complex and the Black Sea Littoral Zone. Composite models are illustrated and the correlations between the magnetic susceptibility (MS; k) values and the main lithological components (i.e. total organic matter/TOM, carbonate/CAR and mineral-siliciclastic/SIL, respectively) are analysed. The quality of proxy environmental parameter of the magnetic susceptibility to reveal distinguishing features for different lithological characters is discussed. Besides, the data show the connection with the distinct position of the lakes related to the fluvial supplies, to the hydrodynamic context or to the specific source-areas. Moreover, it is analysed how the changes of the ecohydrological conditions in the Western Meşteru – Fortuna Depression (by digging a new canal) or along a Danube Delta distributary (by cutting-off its meanders) are reflected by the enviromagnetic fingerprints recovered from the bottom sediments.

The paper is focused on some results obtained during the interval 2006 – 2009,concerning the bottom sediments fingerprinting in 10 mainlakes of the Danube Delta (DD), using a composite magnetic susceptibility (MS; k)-lithological tracer. However, some remarks to the previous data obtainedwithin the last three decades are also done. The bottom sediments were collected with “van Veen”-type grab samplers. “Confined” vs “dynamic” vs“intermediate” deltaicenvironments are compared and defined by particular magnetic ingerprints recovered from lake sediments. The “dynamic environments”,usually placed lose to the influx points of the master canals or connected by relatively short canals to the main DD branches, are reflected by intermediateand high MS values, which are assigned to k classes III, IV and V of the MS scale achieved by theauthors (Rădan & Rădan, 2007). The “confinedenvironments”, situated far from the Danubian supplies and from the direct riverine inputs, are characterisedby a low intensity MS fingerprint, that is assignedto the lower k classes I and II, whereas the “intermediate” category is defined by k classes II and III. A distribution model points out the compositionchanges of the DD lake sediments, as the distance related to the Danubian source increases: the greater the distance to the source, the richer the sedimentsin organic matter and poorer in detrital mineral material. Several correlation coefficients (r) were calculated, .g. related to k vs TOM (Organic matter), kvs CAR (Carbonate fraction), k vs (TOM+CAR) and k vs SIL (siliciclastic/mineral fraction). In addition to all thesedata, the diagrams showing the verticaldistribution of the MS values for our sediment cores taken from three DD lakes are presented. The resultsdemonstrate the abilities of the magnetic susceptibilityas a lake sediments fingerprinting tool used for integrated lithological, hydrosedimentaryand environmental-geoecological studies in deltaic lakes.

The present paper is the first of a series of three, focused on the results of the integrated magnetic susceptibility and lithological studies carried out in several lacustrine areas of the Danube Delta, the Razim (Razelm) - Sinoie lagoonal Complex and the Black Sea Littoral Zone. Enviromagnetic fingerprints are recovered from the bottom sediments sampled in dynamic and confined aquatic environments and their intensities are evaluated and compared. Distinguishing features identified between different lakes are clearly reflected by the investigated enviromagnetic parameter (MS). The connection between the MS regime recorded within the lake sediments and the ternary diagrams showing their lithological classification (i.e. mineral-siliciclastic fraction, carbonate fraction and organic matter) is discussed, as well. Besides, several composite models illustrate the correlations between the k values and the main lithological components (i.e. organic/TOC, carbonate/CAR and mineral- iliciclastic/SIL, respectively). On the basis of the magneto-lithological data base obtained for the lake sediments sampled in the 2006 cruises, several correlation coefficients (r) were calculated, e.g. related to k vs TOC, k vs CAR, k vs (TOC+CAR) and k vs SIL. The graphical correlation is also taken into consideration to show and interpret the connection between the enviromagnetic parameter and the lithological characters. Generally, positive (direct) correlations characterise the magnetic susceptibility (MS) vs mineral component (SIL), whereas negative (reverse) correlations define MS vs TOC, as well as MS vs (TOC+CAR). The modern sediments sampled in various deltaic environments stand for high fidelity enviromagnetic archives, which are deciphered within the presented case studies.

The magnetic susceptibility (MS) research carried out in Romania, since 1977, on thousands of bottom sediment samples collected from various environments of the Danube River – Danube Delta – Black Sea geosystem, have demonstrated that the MS (k) values mainly reflect the lithological variations of the deposits. On the other hand, the results have shown that the k values can reveal the metallic contamination levels in the finer sediments; the most important of these are clearly evidenced by high magnetic susceptibilities. Taking into consideration the noticeable connections between the MS values and the lithological characteristics of the bottom sediment samples, a data sorting based on several susceptibility classes was quite feasible. It must be emphasized that for the Danube Delta and the Razim – Sinoie Lagoonal Complex (RSLC) area, more than 2000 k values have been measured and analysed. Five MS (k) categories related to certain lithological types of bottom sediments have been identified, the last one (Vth class) being subdivided into 4 sub-classes: Va, Vb, Vc and Vd. They subsequently became “magnetic susceptibility classes”. The version in use of the scale extends between k values lower than 10x10-6 SI u. (negative values included) and k values higher than 1000x10-6 SI u. The lower classes (i.e. I and II) correspond to the fine sediments, usually rich in organic material and/or carbonates, the intermediate class III is characteristic for the fine clayey up to silty sediments, and the higher classes (i.e. IV and V) are commonly recorded for the coarser silts and sands. A series of examples are given in the paper, where the patterns integrate – through the MS classes – all the k values that have been used for the MS characterisation of the bottom sediments in the Danube Delta, its main branches, as well as in the RSLC. A comparative analysis of the percentage weight distribution of the MS values that characterise the sedimentary deposits from the deltaic, fluvial-deltaic and the lagoonal aquatic environments is done. The presented cases exemplify the way the elaborated and experimented “k scale” works. The correlation to the Environment Quality Scale is pointed out. To conclude, the Danube Delta lake sediments provided a high resolution enviromagnetic instrument, a Magnetic Susceptibility Scale with a genuine lithological support.

The sedimentogenetic study of the Dacian Basin has been a scientific adventure for several decades. The first presentation of the general features of the Basin was made a couple of years ago, with a book in the Romanian language (Jipa, ed., 2007). The present publication on Dacian Basin expands and develops the main aspects presented in the Romanian book. Some chapters have been dropped, some chapters have been rewritten and new chapters added. At the present time, the Dacian Basin investigation is far from being complete. The sedimentogenetic information we have in this book refers especially to the outcropping deposits (the littoral zone of the Basin). The deposits in the central and southern part of the Dacian Basin are not treated comprehensively enough, as our subsurface information is fragmented, scarce or non-existent. The authors’ team is made of two scientists from different generations, giving hope that the Dacian Basin sedimentological study will be continued and enhanced by future researchers. The authors are grateful to Radu Olteanu (Geological Institute of Romania), Sorin C. Radan (Geological Institute of Romania), Liviu Maţenco (Vrije Universiteit, Amsterdam) and Cristina Poenaru (GeoEcoMar, Bucharest) for their expert contributions in the chapter regarding the Dacian Basin presentation. Several colleagues read parts of the manuscript and suggested significant improvements. They are W. Anthony (Tony) Nicholas (School of Earth and Environmental Sciences, University of Wollongong, Australia), Ion Andreescu (Geological Institute of Romania), Claudia Sliwinski (Peachtree, Georgia, US), Gabriela Maximov (GeoEcoMar, Bucharest) and Camelia Cazacu (GeoEcoMar, Bucharest). Our Dacian Basin understanding was influenced by stimulating and challenging discussions we had in front of the outcrops with Ron Steel (University of Texas at Austin), Henk Weerts (National Service for Archeology, Utrecht), Liviu Maţenco (Vrje Universiteit, Amsterdam), Radu Olteanu (Geological Institute of Romania), Marius Stoica (University of Bucharest), Victoria Lubenescu. (Prospectiuni S.A., Bucharest) and Ion Andreescu (Geological Institute of Romania). We wish to acknowledge the help of Viorela Anastasiu (atlas author) and Dan Dumitru (editor), who permitted the use of the Editura Didactica Printing House maps as basis for some of our figures. Dorina Tambrea (Danubian Energy Consulting, Bucharest) and Corneliu Dinu (University of Bucharest) kindly allowed use of some of their Black Sea figures. The senior author is deeply indebted to Joe Gencarelli (Lynchburg, Virginia, US). Joe’s support and constant encouragement were important for the achievement of the present book. He read the entire manuscript and improved the English language of the book. Special thanks go to the „task force” represented by Sorin Rădan, Cristina Poenaru, Joe Gencarelli and Carmen Biriş for their patience and commitment in the final, long phase of manuscript correction. The senior author acknowledges the basic support for publishing this book from the National Authority for Scientific Research – Romania. Part of the data presented in the book comes from the scientific projects developed within the Romanian National Research and Development Plan CERES 4-246/2004 (“Global factors influence on the evolution of the Dacian Basin”) and IDEI 144/2007 (“The effect of the Messinian desiccation on the evolution of the Dacian Basin”).