Experiments in saturated soil columns were performed to investigate the transport and retention of 25 nm and 75 nm silver nanoparticles stabilized with polyvinylpyrrolidone (PVP-AgNPs) in two Brazilian soils (sandy and sandy-clay). The normalized concentration of the PVP-AgNPs was obtained through a flow injection analysis method based on the surface plasmon ressonance effect of the metallic nanoparticles. The use of the ultraviolet–visible spectroscopy (UV–Vis) allows a rapid and low-cost analysis. The obtained breakthrough curves (BCs) were modeled with a deterministic model of solute transport in steady conditions of water flow and considering two regions of non-physical equilibrium; this model allowed the determination of the hydrodynamic parameters. It was found that the process occurs in condition of non-equilibrium, with a low mass transfer for larger NP, and that the process is predominantly advective and affected by the pore size of the soil packed in the columns. The BCs for PVP-AgNPs obtained by UV–Vis spectroscopy were compared with the BCs obtained by ICP-MS and with BCs of the bromide anion, confirming that the nanoparticles have a low retention and few modifications when transported through the soil column. These PVP-AgNPs are highly mobile and can be transported through the studied tropical soils, representing a potential environmental problem, due to the possibility of these materials reaching groundwater. On the contrary, the conservative behavior of PVP-AgNPs in the studied tropical soils, indicates its potential use as tracers, substituting the bromide anion which has been demonstrated to be not a good tracer in the same conditions.

Mercury emissions from artisanal gold mining operations occurring in roughly 80 developing countries are a major workplace health hazard for millions of people as well as the largest contributor to global mercury pollution. There are no portable, cheap, and rapid methods able to inform workers or health practitioners of mercury exposure on site in remote locations. In this work, a proof of concept for a miniaturized mercury sampler, prepared by the direct reduction of gold into the porous nanostructures of Vycor glass (PVG), is introduced. Mercury retention on the PVG/Au sampler induces significant color changes, due to the formation of Au-Hg amalgam that affects the surface plasmon resonance characteristics of the material. The color change can potentially be quantified by the analysis of pictures obtained with a cell phone camera rapidly and onsite. Laboratory experiments showed the viability of using PVG/Au as passive sampler for monitoring of Hg°. PVG/Au samplers were then deployed in an artisanal and small-scale gold mining (ASGM) operations in Burkina Faso and it was able to indicate personal mercury exposures. The amount of mercury quantified in the samplers for all miners was higher than the current personal exposure limit set by the US Occupational Safety & Health Administration (OSHA).

Forests represent an important role in the control of atmospheric emissions through carbon capture. However, in forest fires, the carbon stored during photosynthesis is released into the atmosphere. The carbon quantification, in forest burning, is important for the development of measures for its control. The aim of this study was to quantify CO2 and CO emissions of forest fires in Western Amazonia. In this paper, results are described of forest fire experiments conducted in Cruzeiro do Sul and Rio Branco, state of Acre, and Candeias do Jamari, state of Rondonia, Brazil. These cities are located in the Western portion of the Brazilian Amazon region. The biomass content per hectare, in the virgin forest, was measured by indirect methods using formulas with parameters of forest inventories in the central hectare of the test site. The combustion completeness was estimated by randomly selecting 10% of the total logs and twelve 2 x 2 m(2) areas along three transects and examining their consumption rates by the fire. The logs were used to determine the combustion completeness of the larger materials (characteristic diameters larger than 10 cm) and the 2 x 2 m(2) areas to determine the combustion completeness of small-size materials (those with characteristic diameters lower than 10 cm) and the. The overall biomass consumption by fire was estimated to be 40.0%, 41.2% and 26.2%, in Cruzeiro do Sul, Rio Branco and Candeias do Jamari, respectively. Considering that the combustion gases of carbon in open fires contain approximately 90.0% of CO2 and 10.0% of CO in volumetric basis, the average emission rates of these gases by the burning process, in the three sites, were estimated as 191 +/- 46.7 t ha(-1) and 13.5 +/- 3.3 t ha(-1), respectively. (C) 2016 Elsevier Ltd. All rights reserved.

Fluoroquinolones are potent antibacterial agents that are active against a wide range of pathogenic organisms and are widely used in veterinary medicine. Fluoroquinolones and their metabolites may reach the soil through animal excreta or manure and may contaminate water and soils. The degree of sorption of these antimicrobials to soils varies widely, as does the mobility of these drugs. In the present study, sorption of norfloxacin in four soils of the state of São Paulo was investigated with batch equilibrium experiments. A strong matrix effect on the chromatographic determination of norfloxacin was verified. Sorption kinetics were best fit by a pseudo second-order model (r0.99), and sorption/desorption isotherms were well fit by the Freundlich model in log form (r0.97). Norfloxacin showed high affinity for soil particles, with KF sorption values ranging from 643 to 2410 μg(1-1/n)(cm(3))(1/n)g(-1) and KF desorption values ranging from 686 to 2468 μg(1-1/n)(cm(3))(1/n)g(-1). The high desorption KF values indicate that norfloxacin is highly immobile in the evaluated soils.

Mercury stored in forests can be volatilized to the atmosphere during fires. Many factors influence this process such as mercury concentration, vegetation loading and the soil temperature reached during the fire. We quantified mercury emissions from biomass and soil during a prescribed fire in Brazil using the difference in mercury burden in vegetation and soil before and after burning, and data were critically compared with those previously obtained in a similar experiment in another part of the Amazonia. The calculated mercury emission factor was 4.1±1.4gHgha-1, with the main part (78%) originating from litterfall and O-horizon, and only 14% associated with live biomass. When considering the fuel burned loading, the emission factor ranged from 40 to 53μgHgkg-1. Data were also obtained on soil temperature profile and on Hg speciation in soil in an effort to relate these parameters to Hg emissions. 2014 Elsevier Ltd.

Forest ecosystems are a sink of atmospheric mercury, trapping the metal in the canopy, and storing it in the forest floor after litter fall. Fire liberates a portion of this mercury; however, little is known about the long-term release of mercury post deforestation. We conducted two large-scale experiments to study this phenomenon. In upstate New York, gaseous mercury emissions from soil were monitored continually using a Teflon dynamic surface flux chamber for two-weeks before and after cutting of the canopy on the edge of a deciduous forest. In Brazil, gaseous mercury emissions from soil were monitored in an intact Ombrophilous Open forest and an adjacent field site both before and after the field site was cleared by burning. In the intact forest, gaseous mercury emissions from soil averaged-0.73±1.84ngm-2h-1 (24-h monitoring) at the New York site, and 0.33±0.09ngm-2h-1 (daytime-only) at the Brazil site. After deforestation, gaseous mercury emissions from soil averaged 9.13±2.08ngm-2h-1 in New York and 21.2±0.35ngm-2h-1 at the Brazil site prior to burning. Gaseous mercury emissions averaged 74.9±0.73ngm-2h-1 after burning of the cut forest in Brazil. Extrapolating our data, measured over several weeks to months, to a full year period, deforested soil is estimated to release an additional 2.30gha-1yr-1 of gaseous mercury to the atmosphere in the Brazilian experiment and 0.41gha-1yr-1 in the New York experiment. In Brazil, this represents an additional 50% of the mercury load released during the fire itself. 2014 The Authors.

In this paper, we present the results obtained for the determination of particulate-bound mercury (PHg) collected on a glass fiber filter by a combustion-AAS technique using a Direct Mercury Analyzer (DMA-80 TRICELL; Milestone Inc., Italy). The accuracy of the method was demonstrated by comparison with the U.S. EPA IO-5 method. Sampling was always performed in duplicate using two identical sampling devices arranged side by side. The limit of quantitation of the proposed method was 0.22 ng, which was in the same order as that observed for the U.S. EPA method (0.23 ng), and corresponds to 5.0 pg m-3 for a sampling flow of 30 L min-1 and a 24 h sampling period. For paired sampling filters, the precision was 10% for PHg concentrations in the range of 6.5 to 29.3 pg m-3. For triplicate filters spiked with 0.3000 and 1.000 ng Hg(ii), the recovery was (97 ± 2)% and (85 ± 9)%, respectively. The accuracy was checked by analyzing paired sampling filters by both methods (DMA and U.S. EPA) and did not show any significant difference (p 0.05). the Partner Organisations 2014.

The present speciation method reports the determination of inorganic arsenic forms, using metallic furnace hydride generation atomic absorption spectrometry. The inorganic As speciation is carried out using mild conditions for hydride formation, such as slightly acid pH media (4.50) and low tetrahydridoborate(1-) concentration (0.1% (w/v)). Limits of detection and quantification of 2.0 and 6.6 μg L-1 of iAs(III) are obtained using optimized conditions. Additionally, microwave-assisted extraction using water as solvent is carried out to provide the appropriate environment for As species extraction as well as impeding inter-conversion between species. With these analytical strategies, As was accurately determined (at 99.9% confidence level) in water and plankton samples. 2012 Elsevier B.V.

This work aims to assess a method for total Hg quantification in soil and leaf samples by using a Direct Mercury Analyzer (DMA-80 TRICELL; Milestone Inc., Italy). Standard Reference materials of tree leaves, river sediment and soil, and collected samples of soil and leaves were used to optimize and to validate the method. Given that the technique allows direct analysis of samples by combustion, aspects like effect of sample amount variation and sample granulometry were considered. Method's robustness was also assessed through the Youden test showing that for leaf sample analyses, among the seven tested factors, four were able to significantly affect the analytical results, but the soil samples results were not significantly affected by slight variations of any of the seven factors. Recoveries for reference materials ranged from 102% to 104%, and the precision (RSD) was lower than 5%. 2013 Sociedade Brasileira de Química.

OCCURRENCE, BEHAVIOR AND ENVIRONMENTAL IMPACTS CAUSED BY THE PRESENCE OF VETERINARY ANTIMICROBIALS IN SOILS. Antimicrobials, among other veterinary drugs, are used worldwide in industry and agriculture to protect animal health and prevent economic loss. In recent years, they have been detected in various environmental compartments. including soil, surface and groundwater and have become a topic of research interest. Emphasizing this class of compounds, this review presents the different pathways which veterinary drugs enter in the environment, in particular contaminate soils. Also are presented regulatory aspects and guidelines, adsorption/desorption and degradation of these compounds in soils and the consequences of its dispersal in the environment.

Several recent studies have indicated that forest fires are likely to re-emit important quantities of atmospherically deposited mercury (Hg) to the atmosphere. Although the Amazon forest accounts for approximately 25% of the world's total rainforest, few data are available about these emissions. The emissions of mercury from prescribed fires of two 4-ha plots of Amazon forest were investigated. Hg concentration and Hg burden were determined for vegetation, litter and soil before and after the fires. The data show that only Hg present in the aboveground vegetation and in the O-horizon was volatilised; no significant soil emission was observed. Before the fire, the Hg stored in the vegetation (logs, branches, leaves and litter) ranged from 3.7 to 4.0 g ha(-1) while 1.8 g ha(-1) was found in the O-horizon. The mass balance calculations of the present work indicate an average Hg emission of 3.5 g ha(-1) due to forest fires, with 1.6 ha(-1) originating from O-horizon and 1.9 from above ground vegetation. On the base of the average annual deforestation rate of the Brazilian Amazon between 2000 and 2008, an annual Hg emission of 6.7 Mg yr(-1) was estimated. Citation: Michelazzo, P. A. M., A. H. Fostier, G. Magarelli, J. C. Santos, and J. A. d. Carvalho Jr. (2010), Mercury emissions from forest burning in southern Amazon, Geophys. Res. Lett., 37, L09809, doi: 10.1029/2009GL042220.

Despite the low level of industrial activity and human density, Hg concentration in the Negro River basin is relatively high. Soil enriched with naturally high Hg concentrations and atmospheric deposition are the main sources of the metal in this watershed. Differences between invasive and evasive fluxes at the water/air and soil/air interfaces indicate Hg accumulation in the basin at a rate of 39.9 t y-1. The type of soil, which is the main source of mercury for the water bodies, the hydrological cycle with floods and dry periods, act markedly on the water redox chemistry. A complex interaction between many seasonable variables such as solar intensity, water pH, age of the naturally occurring organic matter and the hydrological cycle alter the redox characteristics of these black water bodies, thus markedly affecting the consumption of Hg0 and the degradation of methylmercury present in the water. Although methylation is favored in black waters, photodegradation counterpoints this formation, thus regulating the methylmercury burden in the water column. 2009 Sociedade Brasileira de Química.

Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO2 immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO2 concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO2 concentration of the coating solution: 10%; Fe(II): 7.0 mg l-1; solar exposure time: 120 min) were applied to natural water samples spiked with 500 μg l-1 As(III) in order to verify the influence of natural water matrix. After treatment, As(III) and total As concentrations were lower than the limit of quantitation (2 μg l-1) of the voltammetric method used, showing a removal over 99%, and giving evidence that As(III) was effectively oxidized to As(V). The results obtained demonstrated that TiO2 can be easily immobilized on a PET surface in order to perform As(III) oxidation in water and that this TiO2 immobilization, combined with coprecipitation of arsenic on Fe(III) hydroxides(oxides) could be an efficient way for inorganic arsenic removal from groundwaters. 2008 Elsevier Ltd. All rights reserved.

Here, we show a fast and sensitive method for the determination of inorganic arsenic in natural waters using differential pulse cathodic stripping voltammetry. All the arsenite determinations were done in 2.0 mol L-1 HCl + 3.15 x 10(-4) mol L-1 Cu(II) supporting electrolyte. 1 x 10(-3) mol L-1 sodium thiosulphate was used as As(V) reducing agent. The detection limit was 0.5 mu g L-1 for both species. The method has been applied to water samples collected in an arsenic-contaminated region of Brazil, in particular, to verify the efficiency of the solar oxidation and removal of arsenic process applied to these waters.

The concentrations of Total Gaseous Mercury (TGM) and Total Particulate Mercury (TPM) were monitored during the 2002-2003 rainy and dry seasons at two sampling points (industrial and residential areas) of the Campinas Metropolitan Region. No significant difference was observed between the concentrations found at the two sampling areas and the mean values were 7.0 ± 5.8 ng m -3 (TGM) and 0.4 ± 0.3 ng m-3 (TPM). The analysis of the diel variability showed higher TGM concentrations during the day, which could be related to more intense anthropogenic activity during the day. Atmospheric dispersion processes could also explain some seasonal variation observed in TGM concentrations. For TPM concentrations a decreasing trend was observed during the rainy season, which could be explained by the removal of particles by wet deposition. The concentrations of TGM and TPM found in this study were of the same order of magnitude of those recorded in some highly industrialized regions of the northern hemisphere. These data show that emissions from the most industrialized Brazilian regions, and probably from similar regions in other countries of the southern hemisphere, should also be assessed and integrated into the global anthropogenic mercury emission assessment. 2006 Sociedade Brasileira de Química.

A sampling and analysis program has been completed between 1995 and 1998 in order to determine mercury concentrations in water, sediments, soils and fish in the Piracicaba river basin, one of the most populated and industrialized regions in Brazil. In sediment, the average Hg concentrations varied between 33 ± 17 ng g-1 and 106 ± 78 ng g-1, in samples collected during the rainy and dry season, respectively. The same averages were also found for soil samples (35 ± 14 and 109 ± 61 ng g -1). In water, the total Hg concentration varied between 1.1 and 24.0 ng L-1. In piscivore fish, up to 943 μ g Hg kg-1 was found. Our results show that all compartments undergo Hg contamination, in view of the levels found in pristine environments. Water contamination seems to be due mainly to diffuse processes of soil erosion and suspension of river bed sediment during the rainy season. Also untreated wastewaters generated by industrial activities and from domestic sewage appear to be potential non-point sources in the most industrialized and populated part of the basin. On the other hand, atmospheric transport of mercury originating from the Campinas Metropolitan Region could be another source of mercury contamination, especially in the basin headwaters. Springer 2005.

An investigation of air/surface exchange of mercury, performed at the Negro River Basin, (Amazonian region) in January 2003 and January 2004, is presented. Five sites were investigated: a flooding primary forest, a non-flooding primary forest and three deforested areas. The fluxes were estimated by using a dynamic flux chamber with sampling times varying between 6 and 12 h. The average mercury flux in deforested sites (13.7±10.3 pmol m-2 h -1) was significantly higher than in forest sites (0.1±1.8 pmol m-2 h-1). Our results showed that deforestation could be responsible for significantly increasing soil Hg emissions, mainly because of the high soil temperatures reached in deforested sites. Atmospheric gaseous mercury concentrations were generally low when compared with background areas from the Northern hemisphere. The average atmospheric Hg concentrations were 1.4±0.9 and 0.4±0.2 ng m-3 for forest and deforested sites, respectively. 2005 Elsevier Ltd. All rights reserved.

Gaseous mercury sampling conditions were optimized and a dynamic flux chamber was used to measure the air/surface exchange of mercury in some areas of the Negro river basin with different vegetal coverings. At the two forest sites (flooding and non-flooding), low mercury fluxes were observed: maximum of 3 pmol m(-2) h(-1) - day and minimum of -1 pmol m(-2) h(-1) - night. At the deforested site, the mercury fluxes were higher and always positive: maximum of 26 pmol m(-2) h(-1) - day and 17 pmol m(-2) h(-1) - night. Our results showed that deforestation could be responsible for significantly increasing soil Hg emissions, mainly because of the high soil temperatures reached at deforested sites.

A monitoring project for two forest catchments was established in 2001 in Sao Paulo State, Brazil. The chosen catchments differed significantly with respect to human occupation. One catchment area, PER (23degrees39'S and 46degrees37'W), is inside the largest metropolis of South America, the city of Sao Paulo, within a Park of 549.3 ha, located about 50 km away from the ocean. The other catchment area, CUNHA (between parallels 23degrees13'18{”} and 23degrees16'10{”} South and meridians 45degrees02'53{”} and 45degrees02'53{”} West), is within a State Reserve of the Atlantic Forest, with 2850 ha, located about 15 km from the ocean, surrounded by rural areas and small villages. PER is about 798 m above sea level, while CUNHA is about 1050 m. In this work we examined the monthly litterfall trace metal (Fe, Mn, Zn, Cu, Cr, Ph, Cr, Cd, Hg) fluxes for both catchments during the 2001 dry season (may to September). Trace element concentrations were also determined in soils. CUNHA is characterized by low fluxes and low concentrations in soil, compared with PER. The same tendency was also observed for rainfall and throughfall Fe, Mn, Zn and Cu fluxes.

Studies were carried out to investigate the contamination of Piracicaba and Mogi-Guaçu River basins (São Paulo State, Southeastern, Brazil) for heavy metals (Cd and Pb), using the limnic bivalve Anodontites trapesialis as a biological monitor. The results showed that the concentrations of Pb were higher than the control group in both basins, showing the bioavailability of this non-essential element in the basins. The concentrations were higher in the Mogi-Guaçu than in the Piracicaba basin, and in the slightly contaminated sites in both basins. There was no correlation between the degree of human impact and Cd and Pb concentrations, it was not possible to infer about concentrations of these heavy metals in the bivalves based only in a broad evaluation of human impact.

This work focuses on the behaviour of mercury in lateritic soil profiles found in the Serra do Navio and Tartarugalzinho areas of the State of Amapa in Northern Brazil. The Hg contents are high in the upper horizons of the soil profiles (100-300 mug kg(-1)), and decrease to less than 100 mug kg(-1) at depths of 200 or 300 cm. The higher levels of Hg are associated with higher Fe concentrations, particularly in the ferruginous accumulations as mottles and nodules. For each horizon of the soil profile, balance calculations were used to distinguish the amount of mercury naturally accumulated from rocks through lateritic pedogenesis (lithogenic mercury) from the anthropogenic mercury introduced in the profile through atmospheric contamination. The results show that the anthropogenic contribution is significant in the upper horizons (up to 95%% of the total Hg), and decreases downward in the soil profile. Mercury burdens were calculated for soil profiles in both upslope (272 880 and 217 440 mug m(-2) for the first 70 cm) and downslope positions (118 800 and 182 160 % mug m(-2) for the first 70 cm). The loss of Hg in downslope profiles seems to be related to the natural evolution of iron duricrust into latossols, which has been brought about by climatic changes toward increasing humidity in the Amazon since the Tertiary.

The rainfall chemical composition in two Amazonian ecosystems, a “terra firme{”} forest (dense tropical rain forest) and the “cerrado{”} (savanna) are presented. Both areas are located in the northeast Brazilian Amazon (Amapa State). This study evaluated the statistical differences in the rainfall chemistry, as well as the deposition through rainfall, for each ecosystem. The chemical species evaluated in the rainwater were Na+, K+, Mg2+, Ca2+, NH4+, Cl-, NO3-, SO42-, Fe3+, Al3+, Zn2+, and Mn2+ for both ecosystems. Factor analysis for the terra fume ecosystem indicated that there is a significant difference between the dry and wet periods in the rainfall chemical composition, indicating a biomass-burning signature (K+ in association with Zn2+. High deposition of solutes, except for Mn2+ and Cl+, was also observed during the dry period. Comparison between the terra fume and cerrado rainfall chemistry showed statistical differences in concentration for the marine species (Nac and CU and for the soil dust species (Al3+, Fe3+, and Mn2+. The sea-salt and biogenic sources of chemical species in terra fume forest rainwater are equally important. The site nearer to the sea (cerrado) has rainfall chemistry dominated by species having marine origins. The terra firme forest also has rainfall chemistry dominated by marine origin species, although the biogenic and soil dust origin species are highly significant at this site. Also in the terra firme a biomass-burning signature was observed. The amount of sea salt deposited was more than 50% larger in the cerrado owing to its proximity to the shore.

Mercury (I-Ig total) fluxes were calculated for rainwater, throughfall and stream water in a small catchment located in the northeastern region of the Brazilian Amazon (Serra do Navio, Amapa State), whose upper part is covered by a natural rainforest and lower part was altered due to deforestation and activities related to manganese mining. The catchment area is 200 km from the nearest gold mining (garimpo). Minimum and maximum Hg concentrations were measured monthly from October 1996 to September 1997 and were 3.5-23.4 ng l(-1) for rainwater, 16.5-82.7 ng l(-1) for throughfall (March-August 1997) and 1.2-6.1 and 4.2-18.8 ng l(-1) for stream water, in natural and disturbed areas, respectively. In the natural area, the inputs were 18.2 mu g m(-2) year(-1) in rainwater and 72 mu g m(-2) year(-1) in throughfall. This enrichment was attributed to dry deposition. The stream output of 2.9 mu g m(-2) year(-1) indicates that Hg is being recycled within the forest as other chemical species or is being retained by the soil system, as confirmed by the cumulative Hg burden in the 0-10 cm surface layer, which was 36 480 mu g m When the disturbed area of the catchment was included, the stream output was 9.3 mu g m(-2), clearly indicating the impact of the deforestation of the lower part of the basin on the release of mercury. The Hg burden in the disturbed area was 7560 mu g m(-2) for the 0-10 cm surface layer. (C) 2000 Elsevier Science B.V. All rights reserved.

In the present work, results from a survey on mercury concentration in sediments and soils from a gold mining area along the Vila Nova river, in Amapa State, Brazil, are presented. These values were compared with those from the Igarape: Pedra Preta basin, an area unaffected by mining activities. Total mercury contents were determined in the muddy (silt+clay) fraction of the sediments and in the 2 mm fraction of the soils using radiochemical neutron activation analysis (RNAA). The detection limit of the method was 54 mu g.kg(-1) for soils and 14 mu g.kg(-1) for sediments when 200 mg of sample were analysed. The Hg results obtained from a comparison between our current method (RNAA) and CV AAS are also presented. Mercury levels showed to be very high in the soils and sediments collected in the Vila Nova river (up to 2 mg.kg(-1)) when compared to background values (0.3 mg.kg(-1)) for this region. An enrichment factor was calculated, using Al as a normalizing factor. It showed values up to 8 in sediments of the Vila Nova river basin, indicating a relatively high degree of pollution as compared to the values of about 1 for the samples of the Igarape Pedra Preta basin.

Total Hg was determined in sediment, piscivorous fish and human hair from two similar lake areas in Amapa State, Brazilian Amazon: Duas Bocas Lake (DBL), influenced by Hg releases from gold mining; and Pracuuba Lake (PL), a pristine site 15 km to the north. In DBL, Hg profiles in sediments clearly documented the evolution of Hg pollution, and Hg was significantly higher in fish and human hair than in FL. (203)Hg methylation rates in sediments and methylmercury proportions in fish suggest a high Hg bioavailability in both lakes. Average daily fish intake is approx. 200 g, and at DBL 95% of fish samples (N = 40) exceeded the 150 ng Hg g(-1) safety limit. Hg in human hair averaged 28 mu g g(-1) (N = 15), i.e. a level at which neurotoxic effects have been found. However, Hg was also high in the pristine FL, where 67-100% (N = 34) of the fish had levels that exceeded the safety limit, and 87% of hair samples (N = 15) had above 10 ng Hg g(-1). In both areas, children and pregnant women should be advised to consume nonpiscivorous and/or small fish species. Hg levels should also be investigated in other areas of the Amapa coastal plain.

An on-line microwave-assisted decomposition procedure for the determination of lead in fish is proposed. 300 mu L slurry and 400 mu L of a 6 mol L(-1) HNO3 solution were simultaneously injected, and the mixture was positioned inside a microwave oven. The decomposed sample inside the flushing solution was collected in the autosampler cup of a graphite furnace. The proposed procedure covered the 2.5 to 25 mu g L(-1) Pb range and presented a detection limit of 0.72 mu g L(-1) Pb. Precision expressed as RSD, was 10.5% (n = 20) for repeatability and 14.3% (n = 10) for reproducibility. Accuracy was assessed using standard reference material, and also by comparing the results to a nitric-perchloric decomposition procedure.

A pyrolysis chamber is described for the direct determination of mercury in sediments by atomic absorption spectrometry, The finely, ground and dried sample is weighed (2.0-60.0 mg), transferred to a quartz cup, inserted in a pyrolysis chamber and heated at 1100 degrees C for 30 s by means of three focused, infrared lamps in the presence of an air stream as-the carrier gas, Interfering substances are destroyed by a precolumn containing alumina, silica and copper(li) oxide, and the released mercury is amalgamated on to a gold-coated collector, Mercury vapour is later measured by AAS after thermal desorption, Calibration is easily performed by flow injection, in which known volumes of mercury-saturated air are introduced into the same air carrier stream, The absolute detection limit was 0.26 ng Hg and the relative standard deviation of measurements (n=12) from a typical 4.0 mg sample was about 7%, By applying a t-test, there was no significant difference at the 5% probability level between the results obtained with the proposed method and those certified or recommended for NIST materials, One analysis takes only 2 min, including sample weighing.

Lyophilized fish tissues and bottom sediments were decomposed in a microwave oven, The behavior of the inner pressure was observed for two different digestion solutions in absence of samples, by varying the number of digestion vessels, For fish analysis, effects of fat content, sample amount and volume of HNO3 were investigated, Decomposition of the sediment samples was studied by varying sample amount, carbon content and the volume of the digestion solution, In all situations, pressure profile curves were built up, Samples were analyzed by flow injection cold vapor atomic absorption spectrometry, Two programs were checked by using standard reference material (IAEA-350) for fish muscular tissue and laboratory intercomparison (Laboratory of Biofisica, UFRJ/RJ) for sediment samples, The fish fat content had no influence on the yield of the solubilization process, but the percentage of carbon in the sediments influenced the behavior of the sample digestion, In both cases, recoveries higher than 90% were calculated, The account the routine analysis, according to an automated mercury determination.

The chemical composition of the phycocolloids from two Senegalese red algae Anatheca montagnei and Meristotheca senegalensis (Soleriaceae) has been compared with the hybrid iota-kappa carrageenan from commercial Euchema spinosum. A partially desulfated major iota carrageenan was identified. The milk strengths of gels from the Senegalese species were similar to those from Euchema spinosum suggesting potential economical applications.