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Review of magnetism and heavy metal pollution studies of various environments in Argentina
Earth, Planets and Space volume 58, pages1411–1422(2006)
In recent years, the number of studies of pollution and magnetic proxies for environmental pollution in developed countries, especially European and North American countries, has gradually increased from the 80’s to date. Despite this trend that shows a positive interest in taking care of the environment and researching into the environmental impact of several human activities, pollution studies in Latin American countries have been reducing in number. Moreover, studies of magnetic proxies for pollution are scarce; in particular, studies of this nature has been carried out in Argentina over the past few years by Chaparro and coworkers. Studies of magnetic enhancement in soils due to the burning mechanism are discussed and the results of burnt soils affected by fires of different nature and natural soils are compared, taking into account their magnetic carriers. Nevertheless, this article deals mainly with the first studies of magnetic proxies for pollution conducted in a province in Argentina. Soils, lagoon and stream sediments from three areas were studied. These areas comprise La Plata, Chascomús, and Tandil districts. The influence of pollution was investigated in Tandil and La Plata, revealing magnetic enhancement and the presence of pollutants only in Tandil soils. On the other hand, stream and lagoon sediments were studied in La Plata and Chascomús. Magnetic carriers and the contents of some heavy metals were identified and investigated in both areas separately. Magnetic parameters show distinctive points and wide areas affected by pollution. Furthermore, this magnetic inference is supported by high contents of heavy metals, especially lead and zinc. Finally, a new statistical study of multiple correlation analysis concerning data from La Plata and Chascomús areas was tried in order to investigate the existence of a linear relation between sets of several magnetic parameters and several chemical variables.
Acevedo-Figueroa, D., Comparative analyses of heavy metals in sediment and water from two coastal lagoons in Puerto Rico, MS thesis, University of Puerto Rico, 160 pp., 2001.
Acevedo-Figueroa, D., B. D. Jiménez, and C. J. Rodríguez-Sierra, Trace metals in sediments of two estuarine lagoons from Puerto Rico, Environ. Pollut., 141(2), 336–342, 2006.
Alzuet, P., E. Gaspes, and A. Ronco, Mutagenecy of environmental samples from an industrialised area of the Río de La Plata Estuary using the Salmonella-Microsomal Assay, Environ. Toxicology and Water Quality, 11, 1231–1236., 1996.
Anderson, T. W., An Introduction to Multivariate Statistical Analysis, Wiley. New York (USA), 1958.
APHA, AWWA, WEF, Standard Methods for the Examination of Water and Wastewater. 20th Edition, 1998.
Bartington Instruments Ltd., Operation manual, Environmental magnetic susceptibility—Using the Bartington MS2 system, Chi Publishing, UK, 54 pp., 1994.
Beckwith, P., J. Ellis, D. Revitt, and F. Oldfield, Heavy metal and magnetic relationships for urban source sediments, Phys. Earth Planet. Int., 42, 67–75, 1986.
Bianchi, M. M., Fire history in Patagonia: Post-Glacial and Holocene charcoal record of Lago Escondido (41°S—72°W). In Spanish, Revista Cuaternario y Ciencias Ambientales. CADINCUA, COMINCUA. Asociación Geológica Argentina. Publicación Especial 4, vol. 1, 23–29, 2000.
Bilos, C., J. C. Colombo, C. N. Skorupka, and M. J. Rodriguez Presa, Sources, distributions and variability of airborne trace metals in La Plata city area, Argentina, Environ. Pollut., 111, 149–158, 2001.
Bityukova, L., R. Scholger, and M. Birke, Magnetic susceptibility as indicator of environmental pollution of soils in Tallin, Phys. Chem. Earth (A), 24(9), 829–835, 1999.
Boyko, T., S. Höll, R. Scholger, and MagProx Team, Anthropogenic and geogenic impacts on magnetic susceptibility anomalies of forest top-soil in Austria, Extended abstract for the International Symposium on Fundamental Rock Magnetism and Environmental Applications, Erice, Italy, n. 26: 11, 2002.
Boyko, T, R. Scholger, H. Stanjek, and MAGPROX TEAM, Topsoil magnetic susceptibility mapping as a tool for pollution monitoring: repeatability of in-situ measurements, J. Appl. Geophys., 55(3–4), 249–259, 2004.
Cabral, M. G., M. A. Hurtado, J. E. Giménez, C. A. Sánchez, D. Muntz, and M. da Silva, Indices de afectación territorial en la planificación estratégica del partido de La Plata, Provincia de Buenos Aires, Argentina. V, Jornadas Geológicas and Geofísicas Bonaerenses, 20 pp., 2002.
Chan, L. S., S. L. Ng, A. M. Davis, W. W. S. Yim, and C. H. Yeung, Magnetic properties and heavy-metal contents of contaminated seabed sediments of Penny’s bay, Hong Kong, Mar, Pollution Bull., 42(7), 569–583, 2001.
Chaparro, M. A. E., Caracterización magnética de distintos tipos de suelos—Aplicaciones, Tesis de licenciatura en Ciencias Físicas, Facultad de Ciencias Exactas. UNCPBA, 101 pp., 1999.
Chaparro, M. A. E., C. S. Gogorza, Sinito, and J. M. Lirio, “Aumento Magnetico” en Suelos Incendiados. Resumen expandido, Actas de Trabajos XX Reunión Científica de Geofísica and Geodesia, 166–170, 2000.
Chaparro, M. A. E., C. S. Gogorza, A. Lavat, S. Pazos, and A. M. Sinito, Preliminary Results of Magnetic Characterisation of Different Soils in Tandil Region (Argentina) Affected by the Pollution of Metallurgical Factory, Eur. J. Environ. Eng. Geophys., 7, 35–58, 2002a.
Chaparro, M. A. E., J. C. Bidegain, A. M. Sinito, C. S. Gogorza, and S. Jurado, Comparison of Magnetic Studies of Soils and Stream-Sediments from Buenos Aires Province (Argentina) Applied to Pollution Analysis. Extended abstract for the International Symposium on Fundamental Rock Magnetism and Environmental Applications. Erice, Italy, n. 26: 25–27, 2002b.
Chaparro, M. A. E., J. C. Bidegain, A. M. Sinito, C. S. Gogorza, and S. Jurado, Preliminary Results of Magnetic Measurements on Stream-Sediments from Buenos Aires province, Argentina, Stud. Geophys. Geod., 47(1), 121–145, 2003.
Chaparro, M. A. E., J. C. Bidegain, A. M. Sinito, C. S. Gogorza, and S. Jurado, Magnetic Studies Applied to Different Environments (Soils and Stream-Sediments) from a Relatively Polluted Area in Buenos Aires Province, Argentina, Environ. Geol., 45(5): 654–664, 2004a.
Chaparro, M. A. E., J. C. Bidegain, A. M. Sinito, S. Jurado, and C. S. Gogorza, Relevant Magnetic Parameters and Heavy Metals from Relatively Polluted Stream-sediments —Spatial Distribution along a Cross-city Stream in Buenos Aires Province, Argentina, Stud. Geophys. Geod., 48(3), 615–636, 2004b.
Chaparro, M. A. E. and A. M. Sinito, An Alternative Experimental Method to Discriminate Magnetic Phases Using IRM Acquisition Curves and Magnetic Demagnetisation by Alternating Field. Brazilian J. Geophys., 22(1): 17–32, 2004.
Chaparro, M. A. E., J. M. Lirio, H. Nunez, C. S. G. Gogorza, and A. M. Sinito, Preliminary Magnetic Studies of Lagoon and Stream Sediments from Chascomus Area (Argentina)—Magnetic Parameters as Pollution Indicators and Some Results of Using an Experimental Method to Separate Magnetic Phases, Environ. Geol., 49(1), 30–43, 2005.
Chaparro, M. A. E., Estudio de Parámetros Magneticos de Distintos Ambientes Relativamente Contaminados en Argentina y Antártida, MONOGRAFIAS, Geofísica UNAM, Monografía No. 7, 107 pp., 2006.
Chirinos, L., N. L. Rose, R. Urrutia, P. Munoz, F. Torrejón, L. Torres, F. Cruces, A. Araneda, and C. Zaror, Environmental evidence of fossil fuel pollution in Laguna Chica de San Pedro lake sediments (Central Chile), Environ. Pollut., 141(2), 247–256, 2006.
Colombo, J. C., C. Bilos, and P. Landoni, Sources, distributions and variability of airborne particles and Hydrocarbons in La Plata city area, Argentina, Environ. Pollut., 104, 305–314, 1999.
Colombo, J. C., N. Cappelletti, A. Barreda, M. C. Migoya, and C. N. Skorupka, Vertical fluxes and accumulation of PCBs in coastal sediments of the Río de la Plata estuary, Argentina, Chemosphere, 61(9), 1345–1357, 2005.
Dangavs, N. V., A. M. Blasi, and D. M. Merlo, Geolimnología de laguna Chascomús, Provincia de Buenos Aires, Argentina, Revista Museo La Plata (NS), Geología, XI(112), 157–166, 1996.
Das, B. K., Environmental pollution impact on water and sediments of Kumaun lakes, Lesser Himalaya, India: a comparative study, Environ. Geol., 49(2), 230–239, 2005.
Desenfant, F., E. Petrovský, and P. Rochette, Magnetic signature of industrial pollution of stream sediments and correlation with heavy metals: case study from South France, Water, Air and Soil Pollut., 152(1), 297–312, 2004.
Durza, O., Heavy contamination and magnetic susceptibility in soils around metallurgical plant, Phys. Chem. Earth (A), 24(6), 541–543, 1999.
Dunlop, D. J. and Ö. Özdemir, Rock magnetism. Fundamentals and frontiers, Cambridge University Press, Cambridge, 573 pp., 1997.
Environmental Protection Agency, EPA SW-846, Method 3050 Acid digestion of sediments, sludges and soils, Chapter 3: Metallic analysis, volume one, section A, part 1 of test methods for evaluating solid waste, Washington D.C., 1986.
Evans, M. E. and F. Heller, Environmental magnetism, Principles and applications of enviromagnetics, Academic Press. An imprint of Elsevier Science (USA). 299 pp., 2003.
Fakayode, S. O. and B. I. Olu-Owolabi, Heavy metal contamination of roadside topsoil in Osogbo, Nigeria: its relationship to traffic density and proximity to highways, Environ. Geol., 44, 150–157, 2003.
Fidalgo, F. and O. Martinez, Algunas caracterïsticas geomorfologicas dentro del partido de La Plata, Provincia de Buenos Aires, Revista de la Asociaciön Geolögica Argentina, Buenos Aires, 38(2), 263–273, 1983.
Flanders, P. J., Collection, measurement, and analysis of airborne magnetic particulates from pollution in the environment, J. Appl. Phys., 75(10), 5931–5936, 1994.
Frink, C. R., A perspective on metals in soils, J. Soil Contamination, 5(4), 329–359, 1996.
Gautam, P., U. Blaha, and E. Appel, Integration of magnetic properties and heavy metal chemistry to quantify environmental pollution in urban soils, Kathmandu, Nepal, Himalayan J. Sci., 2(4), 140–141, 2004a.
Gautam, P., U. Blaha, E. Appel, and G. Neupane, Environmental magnetic approach towards the quantification of pollution in Kathmandu urban area, Nepal, Phys. Chem. Earth, 29(13–14), 973–984, 2004b.
Gautam, P., U. Blahab, and E. Appel, Magnetic susceptibility of dust-loaded leaves as a proxy of traffic-related heavy metal pollution in Kathmandu city, Nepal, Atmospheric Environ., 39, 2201–2211, 2005.
Georgeaud, V. M., P. Rochette, J. P. Ambrosi, D. Vandamme, and D. Williamson, Relationship between heavy metals and magnetic properties in a large polluted catchment: the Etang de Berre (South of France), Phys Chem. Earth, 22(1–2), 211–214, 1997.
Gioia, S. M. C. L., M. M. Pimentel, M. Tessler, E. L. Dantas, J. E. G. Campos, E. M. Guimaraes, M. T. S. Maruokaa, and E. L. C. Nascimento, Sources of anthropogenic lead in sediments from an artificial lake in Brasília—central Brazil, Sci. Tot. Environ., 356(1–3), 125–142, 2006.
Goddu, S. R., E. Appel, D. Jordanova, and F Wehland, Magnetic properties of road dust from Visakhapatnam (India)—Relationship to industrial pollution and road traffic, Phys. Chem. Earth., 29, 985–995, 2004.
Hanesch, M. and R. Scholger, Mapping of heavy metal loadings in soils by means of magnetic susceptibility measurements, Environ. Geol., 42, 857–870, 2002.
Heller, F., Z. Strzyszcz, and T. Magiera, Magnetic record of industrial pollution in soils of Upper Silesia, Poland, J. Geophys. Res., 103(B8), 17767–17774, 1998.
Hoffmann, V., M. Knab, and E. Appel, Magnetic susceptibility mapping of roadside pollution, J. Geochem. Int., 66(1–2), 313–326, 1999.
Hu, S., Y. Wang, E. Appel, Y. Zhu, V. Hoffmann, C. Shi, and Y. Yu, Magnetic responses to acidification in Lake Yangzonghai, SW China, Phys. Chem. Earth, 28, 711–717, 2003.
Hunt, A., J. Jones, and F Oldfield, Magnetic measurements and heavy metals in atmospheric particulates of anthropogenic origin, Sci. Total Environ., 33, 129–139, 1984.
Johnson, R. A. and D. W. Wichern, Applied Multivariate Statistical Analysis, Third edition, Prentice-Hall, Inc, New Jersey (USA), 642 pp., 1992.
Jordanova, N. V., D. V. Jordanova, L. Veneva, K. Andorova, and E. Petrovský, Magnetic response of soils and vegetation to heavy metal pollution—A case of study, Environ. Sci. Tech., 37, 4417–4424, 2003a.
Jordanova, D. V., L. Veneva, and V. Hoffmann, Magnetic susceptibility screening of anthropogenic impact on the Danube river sediments in Northwestern Bulgaria—preliminary results, Studia Geophys. Geod., 47, 403–418, 2003b.
Jordanova, D. V., V. Hoffmann, and K. Thomas Fehr, Mineral magnetic characterization of anthropogenic magnetic phases in the Danube river sediments (Bulgarian part), Earth and Planet. Sci. Lett., 221, 71–89, 2004.
Jung, H-B., S-T. Yun, B. Mayer, S-O. Kim, S-S. Park, and P-K. Lee, Transport and sediment—water partitioning of trace metals in acid mine drainage: an example from the abandoned Kwangyang Au—Ag mine area, South Korea, Environ. Geol., 48(4–5), 437–449, 2005.
Kapicka, A., E. Petrovský, S. Ustjak, and K. Machacková, Proxy mapping of fly-ash pollution of soils around a coal-burning power plant: a case study in Czech Republic, J. Geochem. Explor., 66, 291–297, 1999.
King, J., S. K. Banerjee, J. Marvin, and Özdemir, Ö., A comparison of different magnetic methods for determining the relative grain size of magnetite in natural materials: Some results from lake sediments, Earth Planet. Sci. Lett., 59, 404–419, 1982.
Knab, M., E. Appel, and V. Hoffmann, Separation of the anthropogenic portion of heavy metal contents along a highway by means of magnetic susceptibility and fuzzy c-means cluster analysis, Eur J. Environ. Eng. Geophys., 6, 125–140, 2001.
Knab, M., V. Hoffmann, E. Petrovsky, A. Kapicka, N. Jordanova, and E. Appel, Surveying the anthropogenic impact of the Moldau river sediments and nearby soils using magnetic susceptibility, Environ. Geol., 49, 527–535, 2006.
Kukier, U., C. Fauziah Ishak, M. E. Summer, and W. P. Miller, Composition and element solubility of magnetic and non-magnetic fly ash fractions, Environ. Pollut., 123, 255–266, 2003.
Le Borgne, E., Susceptibilité magnetique anormale du sol superficiel, Ann. Géophys., II, 399–419, 1955.
Lecoanet, H., F. Léveque, and J.-P. Ambrosi, Combination of magnetic parameters: an efficient way to discriminate soil-contamination sources (south France), Environ. Pollut., 122, 229–234, 2003.
Maher, B. A., Characterisation of soil by mineral magnetic measurements, Phys. Earth Planet. Int., 42, 76–92, 1986.
Maher, B. A., R. Thompson, and M. W. Hounslow, Introduction, in Quaternary Climate, Environments and Magnetism, edited by B. A. Maher and R. Thompson, pp. 1–48, Cambridge University Press, Cambridge, 1999.
Magiera, T. and Z. Strzyszcz, Ferrimagnetic minerals of anthropogenic origin in soils of some Polish national parks, Water, Air Soil Pollut., 124, 37–48, 1999.
Magiera, T., Z. Strzyszcz, A. Kapicka, E. Petrovsky, and MAGPROX TEAM, Discrimination of lithogenic and anthropogenic influences on topsoil magnetic susceptibility in Central Europe, Geoderma, 130, 299–311, 2006.
Manassero, M., C. Camillon, and A. Ronco, Sedimentologia and geoquim-ica de metales pesados de fondo de arroyos de la vertiente del Río de La Plata, Provincia de Buenos Aires, VII Reunión Argentina de Sedimentología—Actas, pp. 69–78, 1998.
Mardia, K., Multivariate Analysis, Academic Press, Inc., New York (USA), 1980.
Matzka, J. and B. A. Maher, Magnetic biomonitoring of roadside tree leaves: identification of spatial and temporal variations in vehicle-derived particulates, Atm. Environ., 33, 4565–4569, 1999.
Mazzeo, N. A., L. E. Venegas, and H. Choren, Analysis of NO, NO2, O3 and NOx concentrations measured at a green area of Buenos Aires City during wintertime, Atm. Environ., 39, 3055–3068, 2005.
Morris, W. A., J. K. Versteeg, C. H. Marvin, B. E. McCarry, and N. A. Rukavina, Preliminary comparisons between magnetic susceptibility and polycyclic aromatic hydrocarbons content in sediments from Hamilton Harbour, western Lake Ontario, Sci. Total Environ., 152, 153–160, 1994.
Mullins, C. E. and M. S. Tite, Magnetic viscosity, quadrature susceptibility and frequency dependence of susceptibility in single-domain assemblages of magnetite and maghaemite, J. Geophys. Res., 78, 804–809, 1973.
Mullins, C. E., Magnetic susceptibility of the soil and its significance in Soil Science: a review, J. Soil Sci., 28, 223–246, 1977.
Park, S-S., S-O. Kim, S-T. Yun, G-T. Chae, S-Y Yu, S. Kim, and Y. Kim, Effects of land use on the spatial distribution of trace metals and volatile organic compounds in urban groundwater, Seoul, Korea, Environ. Geol., 48(8), 1116–1131, 2005.
Petrovský, E., A. Kapicka, K. Zapletal, E. Sebestová, T. Spanilá, M. J. Dekkers, and P. Rochette, Correlation between magnetic properties and chemical composition of lake sediments from northern Bohemia, Preliminary study, Phys. Chem. Earth (A), 23(9–10), 1123–1126, 1998.
Petrovský E. and B. Elwood, Magnetic monitoring of air, land and water pollution, In Quaternary Climates, Environment and Magnetism, edited by B. A. Maher and R. Thompson, Cambridge University Press, pp. 279–322, 1999.
Petrovský, E., A. Kapicka, N. Jordanoa, M. Knob, and V. Hoffmann, Low field susceptibility: a proxy method of estimating increased pollution of different environmental systems, Environ. Geol., 39(3–4), 312–318, 2000.
Pozza, M. R., J. I. Boyce, and W. A. Morris, Lake-based magnetic mapping of contaminated sediment distribution, Hamilton Harbour, Ontario, Canada, J. Applied Geophys., 57, 23–41, 2004.
Quaranta, N., C. Grasselli, and J. Ferrante, Federal network of environmental monitoring in Argentina, in Air Pollution X., edited by C. A. Brebbia and J. F. Martin-Duque, pp. 361–369, ISBN 1-85312-916-X, 2002.
Ronco, A., C. Sobrero, G. Bulus Rosini, P. Alzuet, and B. Dutka, Screening for sediment toxicity in the Río Santiago Basin: a baseline study, Environ. Toxicology and Water Quality, 10, 35–39, 1995.
Ronco, A., C. Camilon, and M. Manassero, Geochemistry of heavy metals in bottom sediments from streams of the western coast of the Río de la Plata estuary, Argentina, Environ. Geochem. and Health, 23, 89–103, 2001.
Rosales Hoz, L., A. Carranza Edwards, S. Santiago Perez, and E. Morales De La Garza, Spatial trends in the geochemical composition of sediments in the Panuco River discharge area, Gulf of Mexico, Environ. Geol., 48, 496–506, 2005.
SAGyP-INTA, Mapa de Suelos de la Provincia de Buenos Aires. Escala 1:500.000, Buenos Aires.—Proyecto PNUD ARG 85/019. 527 pp., 1989.
Schibler, L., T. Boyko, M. Ferdyn, B. Gajda, S. Höll, N. Jordanova, W. Rösler, and the Magprox team, Topsoil magnetic susceptibility mapping: data reproducibility and compatibility, measurement strategy, Stud. Geophys. Geod., 46, 43–57, 2002.
Scholger, R., Heavy metal pollution monitoring by magnetic susceptibility measurements applied to sediments of the river Mur (Styria, Austria), Eur. J. Environ. Eng. Geophys., 3, 25–37, 1998.
Spiteri, C., V. Kalinski, W. Rösler, V. Hoffmann, E. Appel, and MAGPROX team, Magnetic screening of a pollution hotspot in the Lausitz area, Eastern Germany: correlation analysis between magnetic proxies and heavy metal contamination in soils, Environ. Geol., 49, 1–9, 2005.
STATISTICA, STATISTICA for Windows (volumen III): Statistics 2nd edition, StatSoft(R), Tulsa (USA). 782 pp., 1995.
Strzyscz, Z., Magnetic susceptibility of soils in the areas influenced by industrial emission, in Soil Monitoring, pp. 255–269., Basel, Monte Verita, Birkhauser Veralg, 1993.
Strzyszcz, Z., T. Magiera, and F Heller, The influence of industrial im-misions on the magnetic susceptibility of soils in Upper Silesia, Stud. Geoph. Geod., 40, 276–286, 1996.
Szczucinski, W., P. Niedzielski, G. Rachlewicz, T. Sobczynski, A. Ziola, A. Kowalski, S. Lorena, and J. Siepak, Contamination of tsunami sediments in a coastal zone inundated by the 26 December 2004 tsunami in Thailand, Environ. Geol., 49(2), 321–331, 2005.
Thompson, R., J. Bloemendal, J. Dearing, F. Oldfield, J. Rummery, J. Stober, and G. Turner, Environmental applications of magnetic measurements, Science, 207(4430), 481–486, 1980.
Thompson, R. and F Oldfield, Environmental Magnetism, Allen & Unwin (Publishers) Ltd. 225 pp., 1986.
Tite, M. and R. Linington, Effect of climate on the magnetic susceptibility of soils, Nature, 256, 565–566, 1975.
Vadiunina, A. F and V. F. Babanin, Magnetic susceptibility of some soils in the U.S.S.R. Soviet, Soil Sci., 6, 106–110, 1972.
Vassilev, S. V., Phase mineralogy studies of solid waste products from coal burning at some Bulgarian thermoelectric power plants, Fuel, 71, 625–633, 1992.
Versteeg, J. K., W A. Morris, and N. A. Rukavina, The utility of magnetic properties as a proxy for mapping contamination in Hamilton Harbour, J. Great Lakes Res., 21, 71–83, 1995.
Wang, X-S. and Y. Qin, Correlation between magnetic susceptibility and heavy metals in urban topsoil: a case study from the city of Xuzhou, China, Environ. Geol., 49(1), 10–18, 2005.
Wang, X-S. and Y. Qin, Magnetic properties of urban topsoils and correlation with heavy metals: a case study from the city of Xuzhou, China, Environ. Geol., 49, 897–904, 2006a.
Wang, X-S. and Y. Qin, Spatial distribution of metals in urban topsoils of Xuzhou (China): controlling factors and environmental implications, Environ. Geol., 49, 905–914, 2006b.
Yuce, G., A. Pinarbasi, S. Ozcelik, and D. Ugurluoglu, Soil and water pollution derived from anthropogenic activities in the Porsuk River Basin, Turkey, Environ. Geol., 49, 359–375, 2006.
Zhang, W. and L. Yu, Relationships between magnetic properties and heavy metals in inter-tidal sediments of the Yangtze Estuary, China, Extended abstract for the International Symposium on Fundamental Rock Magnetism and Environmental Applications, Erice, Italy, 195–197, 2002.
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Chaparro, M.A.E., Gogorza, C.S.G., Chaparro, M.A.E. et al. Review of magnetism and heavy metal pollution studies of various environments in Argentina. Earth Planet Sp 58, 1411–1422 (2006). https://doi.org/10.1186/BF03352637
- magnetic enhancement
- stream sediments