INVESTIGADORES
LECOMTE Karina Leticia
artículos
Título:
Magnetic studies of river sediments and its variation with different physiographic regions of Bharathapuzha River, southwestern India. Palabras clave: magnetic parameters, major and trace elements, multivariate statistical, analysis, radionuclides, river
Autor/es:
CHAPARRO M.A.E.; KRISHNAMOORTHY N; CHAPARRO M.A.E.; LECOMTE K.L.; MULLAINATHAN S; MEHRA R; SINITO AM
Revista:
STUDIA GEOPHYSICA ET GEODAETICA
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2015 vol. 59 p. 1 - 23
ISSN:
0039-3169
Resumen:
Bharathapuzha River is the second longest river in southwest India, where three
physiographic regions show a distinctive spatial variation and their bed sediments can be
considered environmental hosts for end-products generated by human activities and
natural radionuclide components. Thus, the study of this river sediments in SW India is
important not only because they are recorders of adverse human impacts (e.g., intense
agricultural activities and urban pollution), but also because of their potential health
hazards due to their common use as construction materials. Magnetic (e.g., magnetic
susceptibility, anhysteretic remanent magnetisation and isothermal remanent
magnetisation), radionuclide (226Ra, 232Th and 40K) and chemical (trace and major
elements) measurements were carried out in bed sediment samples along 33 sites from the
uppermost catchment downstream. Magnetic measurements show the dominance of
ferrimagnetic minerals; their concentration ranges widely along the river and between
regions, showing up to 7-fold higher values for concentration-dependent magnetic
parameters, e.g., mean values of saturation of isothermal remanent magnetisation
acquisition are 67.9 and 9.4 10 3 Am2 kg 1 for highland and lowland regions,
respectively. Multivariate statistical analyses show the existence of relationships between
magnetic, radioactivity and chemical variables. In particular, magnetic concentrationdependent
parameters are significantly correlated with radioactivity variables 40K and
226Ra (with concentrations about 20% higher than the worldwide mean values), as well as
with some elements: Fe, Ca and P. Such analyses also show differences between
physiographic regions where samples from the highland (and lowland) region are well
grouped showing higher (lower) magnetic concentrations and lower (higher) coercivity
minerals. The spatial variation of magnetic parameters along the river can be related to
the influence of both natural sources and human activities, i.e. urbanisation and intense
agricultural activities. In this sense, environmental magnetism data provide very useful
tools to investigate adverse human activities occurring in the riverine environment.