title: (210)Pb and composition data of near-surface sediments and interstitial waters evidencing anthropogenic inputs in Amazon River mouth, Macapá, Brazil.
abstract: Activity profiles of excess (210)Pb determined in three sediment cores from Amazon River mouth, Macapá city, Brazil, provided the evaluation of sedimentation rates, contributing to a better knowledge of the hydrological conditions in the site that is the capital of Amapá State and is drained by the waters of the huge Amazon River. Chemical data were also determined in the sediments, allowing identify signatures coupled to anthropogenic inputs held in the past in Amapá State. Significant direct relationships between LOI (loss on ignition) and organic matter were found for all sediments profiles. Silica was found to be inversely related to organic matter in the three profiles; its decrease accompanied an increase on the specific surface of the sediments. This relationship was confirmed by a great number of inverse significant correlations among silica and oxides Na(2)O, K(2)O, CaO, MgO, Al(2)O(3), P(2)O(5), Fe(2)O(3) and MnO. It was possible to identify the role of organic matter on adsorption of several oxides in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to values between 450 and 2510 mg cm(-2)yr(-1) were obtained, and are compatible with the results of others studies. The (210)Pb activities in one sampling point suggested the occurrence of anthropogenic inputs related to the initial period of the mining activities conducted in Serra do Navio, Amapá State, for the commercialization of Mn ores. This was reinforced by the abrupt fluctuations in chemical data obtained for the sediments and composition of the interstitial waters occurring there. The Atlantic hurricane activity also appeared to affect the sedimentation rates in the area, as two different values were recorded in each profile.
authors.affiliation: Universidade Federal do Amapá (UNIFAP), Campus Marco Zero, Rodovia Juscelino Kubitschek, km 2, CEP 68902-280, Macapá, Amapá, Brazil. jrnery@unifap.br
authors.forename: José Reinaldo Cardoso
authors.initials: JR
authors.lastname: Nery
authors.forename: Daniel Marcos
authors.initials: DM
authors.lastname: Bonotto
mesh_terms: D001938:Brazil; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data*; D019015:Geologic Sediments / Q000737:chemistry*; D007856:Lead Radioisotopes / Q000032:analysis*; D008906:Mining; D010087:Oxides / Q000032:analysis; D011848:Radioactive Pollutants / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D012822:Silicon Dioxide / Q000032:analysis; D013052:Spectrometry, X-Ray Emission; D014887:Weather
chemical_list: D007856:Lead Radioisotopes; D010087:Oxides; D011848:Radioactive Pollutants; D012822:Silicon Dioxide