PRELIMINARY RESULTS OF MAGNETIC MEASUREMENTS ON STREAM-SEDIMENTS FROM BUENOS AIRES PROVINCE, ARGENTINA

M.A.E. CHAPARRO; J.C. BIDEGAIN; A.M. SINITO; C.S.G. GOGORZA; S. JURADO

Studia geophysica et geodaetica

StudiaGeo s.r.o.

Lugar: Praga; Año: 2003 vol. 47 p. 53 - 77

0039-3169

ABSTRACTA wide urban area in the Northeast of Buenos Aires Province (Argentina) is exposedto anthropogenic influence, mainly due to industrial and urban activity. In this area twostreams were chosen, Del Gato and El Pescado streams. They have similarcharacteristics, although the first one runs through the built-up area and the other onethrough a rural area; consequently, Del Gato stream has a higher input of pollutants(fluvial effluents, fly ashes, solid wastes, etc.) than El Pescado stream.Magnetic measurements and geochemical studies were carried out on five sedimentcores taken out from both streams with the aim of establishing a link betweenconcentration of ferrimagnetic materials and contents of heavy metals. In order toinvestigate concentration of magnetic carriers and its intrinsic features (present magneticminerals and grain size distribution) several magnetic parameters were measured andrelations between them were analyzed.The magnetic characteristics for both sites indicate the presence of magnetically softminerals in both streams, predominantly in Del Gato stream and with the additionalpresence of relatively hard minerals in El Pescado stream. Besides, a higherconcentration of secondary ferrimagnetic minerals was found in Del Gato stream than inEl Pescado stream.Chemical studies show (in some cases) a high concentration of some heavy metals(lead, copper, zinc, nickel and iron) on the upper 22-cm. Magnetic parameters, especiallyanhysteric remanent magnetization and contents of some heavy metals, showed a verygood correlation.Keywo rds: magnetism, heavy metals, sediment core, and pollution.