Navegando por Assunto "Tintas anti-incrustantes"

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Acesso aberto (Open Access)
Assinatura isotópica de Pb em sedimentos da margem leste da Baía do Guajará (orla de Belém) e rio Maguari
(Universidade Federal do Pará, 2020-10-05) BARRA, Ingledir Suely Silva; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645
Estuarine sediments provide a long-term record of the accumulation of trace metals from riverside, atmospheric and anthropogenic sources. The release of trace metals from point sources is largely controlled by the natural processes of physical and chemical weathering of rocks, in addition to anthropogenic disturbances that can occur on a large scale. In addition to diffuse anthropogenic sources, estuarine sediments can be enriched in trace metals by antifouling paints, with high contents of metals (Cu, Zn, Pb), which are applied to ship hulls and many submerged structures to prevent the growth of fouling organisms such as bacteria, macroalgae, mussels, bivalves, and invertebrates. Pb isotopic signatures are useful tools to investigate the sources and mobility of trace metals in estuarine systems and allow to distinguish between geogenic and anthropogenic source contributions. In recent years, several isotopic Pb studies for this purpose have been conducted in the hydrographic system of Belém. The aim of this work is the application of Pb isotope geochemistry in bottom sediments, suspended particulate matter (MPS), and fragments of vessels with antifouling paint of several shipyards in Guajará Bay and the Maguari River, in the metropolitan area of Belém-PA. It is intended to verify whether the paints used in the shipyards can be considered a point source of contamination by Pb. Bottom sediment samples were collected at 9 stations along the northern and southern waterfront of Belém, at the right margin of the Guajará Bay, and 3 on the Maguari River near shipyards, 6 samples of suspended particulate matter and 4 samples of vessel hull fragments. Samples of bottom sediments at the mouth of the Una Channel (3 samples) and Paracui River (1 sample) were also collected. Finally, a sample of bottom sediments was also sampled on Barra island, in the middle of Guajará Bay, as a reference to the geogenic background. Chemical analyzes of bioavailable Pb were carried out on the bottom sediment samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and Pb isotopic analyzes on all samples by inductively coupled plasma mass spectrometry with magnetic sector and multiple collectors (ICP-MS). In the bottom sediment samples from the shipyards of the Belém waterfront and the Maguari River, important variations of Pb concentrations of the bioavailable fraction occur, from a value similar to the reference point (11 mg kg-1) up to contents of 25 mg kg-1. These variations suggest incipient processes of anthropic action. Even so, the levels are within the range of concentrations found so far and do not show evidence of a significant contribution of Pb linked to the proximity of the shipyards. The similar ranges of bioavailable Pb concentration between the various sectors studied (northern and southern sectors of the waterfront Belém and Maguari River) show that there is no clear pattern of distribution of Pb levels in the sectors studied. These concentrations were shown to be systematically lower than the reference values TEL (35 mg kg-1) and PEL (91.3 mg kg-1), thus indicating that Pb is not causing harmful effects to biota in these areas of the Guajará Bay system. In the northern sector of the waterfront Belém and along the Maguari River, the variations in 206Pb/207Pb isotopic ratios are within the range of the Barra island reference point and the values considered geogenic in previous works (1.189 – 1.197). Only the point identified as “vessel graveyard” presented a lower ratio (206Pb/207Pb= 1.183) and may indicate an increase in Pb anthropogenic contribution due to the deterioration of abandoned vessels and the working shipyard. In the southern sector of the Belém shore, practically all the sediments from the shipyards and the mouth of the Una canal presented lower 206Pb/207Pb isotopic ratios (1.163 and 1.178), indicating an anthropogenic contribution. This diffuse anthropogenic contribution is apparently related to the Una channel and also to the greater concentration of shipyards and other possible sources of metals. In addition, the comparison of the Pb isotopic composition of the sediments at the mouth of the drainage channels in the northern and southern sectors of the Belém waterfront suggests the existence of a relationship between anthropogenic contribution and the size of the drainage basins, population density, and urban activities. No correlation was found between the 206Pb/207Pb isotopic ratios of the bottom sediments and corresponding MPS, however, all points fit a trend line, confirming the mixture between two different sources of Pb for both sediments and suspended material. The isotopic signatures of the hull + paint fragments are positioned along the same trend line established between a geogenic end-member and an anthropogenic end-member (aerosols), for the hydrographic system of Belém, making it impossible to identify a specific anthropogenic source of Pb from the shipyards. The comparison of these signatures of the fragments with the bottom sediments of the shipyards indicates that this possible anthropogenic source enters as one of the subordinate components of the diffuse anthropogenic contribution of Guajará Bay. Finally, based on the data from this study and the works already developed in the hydrographic system of Belém, it is proposed to extend the range of 206Pb/207Pb ratio of the geogenic Pb to 1.189 – 1.204 for the hydrographic system of Belém, as a whole.
Acesso aberto (Open Access)
Avaliação da contaminação por metais pesados em sedimentos por atividades de estaleiros na Baia do Guajará e no canal do Rio Maguari
(Universidade Federal do Pará, 2021-12-17) GUIMARÃES, Robledo Hideki Ebata; WALLNER-KERSANACH, Mônica; http://lattes.cnpq.br/7960214506412584; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
Antifouling paints applied on ships contain high concentrations of metals in their composition, mainly copper and zinc, with concentrations above 50% and 20%, respectively. Despite being essential elements for living beings, in high concentrations it causes problems in cell growth and reproduction of organisms. In the city of Belém, State of Pará, a significant amount of industrial and domestic effluents is released into the Bay of Guajará, one of which is related to activities in shipyards. Previous studies have shown evidence of metal contamination in the sediments in the edge of Belém estuary, however, no work has highlighted contamination from shipyards. Therefore, the objective of this work is to evaluate sediment contamination by activities in shipyards and abandonment of vessels in the edge of Belém city. The three samples of sediments were collected in 5 shipyards in Belém, two of which were collected in the less rainy period (September 2017 and November 2019) and one in the rainy season in May 2018. The sediment was collected up to 10 cm deep, and samples of paint fragments and fragments of the hulls of abandoned vessels were collected. The in situ pH of the interstitial sediment water was measured. In the laboratory, the sediment samples were placed in an oven at 60°C to dry, disaggregated and then sieved (< 63μm). The samples of paint fragments and the hulls of abandoned boats were washed with deionized water and dried in an oven at 60°C, macerated, mixed with the sprayed white area and reserved. A sample of the commercial paint most commonly used in shipyards was placed on a cellulose nitrate membrane in a hood, after which part of the sample was removed and macerated. An aliquot of the sediment samples from each shipyard was used for particle size analysis, using a laser particle analyzer. The mineralogical composition of the sediment samples was determined by X-ray diffraction, powder method. The clay minerals were determined by X-ray diffraction, following Stokes' Law and according to the methodology proposed by Moore & Reynolds Jr (2002). For the determination of total organic carbon, a TOC - VCPH analyzer with a combustion detector was used. To determine the concentrations of Cu, Zn, Pb, Ni, Cr, Ba, V, Li, Fe and Al contained in sediment, commercial paint, paint fragments and hull fragments of abandoned ships, the samples were subjected to chemical extraction with aqua regia and determined through Optical Emission Spectrometry with Inductively Coupled Plasma (ICP-OES). For statistical treatment of the data, Spearman's correlation was applied to determine the relationship between the parameters, and the Principal Component Analysis test to determine the relationship of metals with shipyards, control station and diffuse anthropogenic source station. The Wilcoxon test was also applied to verify if there were significant differences in the metal concentrations of the sediments collected in front of the shipyard with the sediments collected that were in contact with the abandoned vessel. To assess the level of contamination by metals, the geoaccumulation index proposed by Muller (1969) was applied. The sediment granulometry of the Belem shore presents a higher proportion of sand and silt. The sediments are composed of muscovite, illite, kaolinite, quartz and plagioclase. The clay minerals identified were: smectite, kaolinite, illite and quartz. The pH values of the interstitial water of the sediment samples from Baía do Guajará and Furo do Maguari were around 5.2 – 6.7. The total organic carbon of the sediment was around 0.6% to 2.2%. The commercial paint analyzed presented the following concentrations: Fe (21.2%), Cu (18,497 mg kg-1), Zn (16,589 mg kg-1) and Al (1.59%). The highest concentrations found in the composition of paint fragments and in the fragments of the hulls of abandoned vessels were: Fe (69.2 %), Ba (29,583 mg kg-1), Zn (9,350 mg kg-1), Pb (1,406 mg kg-1), Cu (697 mg kg-1) and Cr (548.7 mg kg-1). This result revealed that abandonment of vessels is the biggest source of contamination in shipyard areas in the city of Belém. According to the Sediment Quality Guidelines for Metals in Freshwater Ecosystems by Buchman (2008), only the average concentration of Cu, with 41.0 mg kg-1, in the sediment reached values above the Threshold Effects Level for the amphipod, Hyallela azteca (28.0 mg kg-1) in the ABSS shipyard. The other shipyards had copper averages ranging between 13.3 – 28.3 mg kg-1. The other metals had mean concentrations always below the Threshold Effects Level value. Spatially, the sediments that were collected in front of the ABSS shipyard for most metals had higher concentrations compared to the sediments that were in contact with the hull of the abandoned ship, of this shipyard. However, the sediments that were collected in front of the MS shipyard in general had lower concentrations compared to the sediments that were in direct contact with the abandoned vessel. Those that presented with concentrations of Cu (39.0 mg kg-1), Zn (120.0 mg kg-1) and Cr (32.0 mg kg-1) that exceed the value of Threshold Effects Level for the amphipod. However, the Wilcoxon Rank statistical test did not attest significant differences in the sediment collected in front of the shipyards with the sediment that was in contact with the abandoned vessels. The main elements that make up the antifouling paints: Cu, Zn had a strong positive correlation (r = 0.80; p<0.05). The Principal Component Analysis confirmed contamination by the metals Cu, Zn, Pb, Ni, Li, Fe and Al and has a stronger relationship with shipyard activities and ship abandonment than with diffuse geogenic or anthropogenic sources The geoaccumulation index classified the sediments close to the IS and ABSS shipyards as moderately polluted for copper with indices of 2.0 and 2.5, respectively. The other metals Zn, Ba, Fe and Al in the studied shipyards show an anthropogenic contribution by activities in shipyards and abandonment of vessels, classifying one or more shipyards as being in a situation close to a polluted environment, for one or more studied metals, with geoaccumulation index close to 2. The results can support additional studies of metal contamination through activities in shipyards and abandonment of vessels, and it can assist in the application of waste management in shipyards and ship cemeteries around the world.