Biomass carbon ratio of polymer composites included biomass or petroleum origin resources

The biomass carbon ratios of various polymer composites were studied. The biomass carbon ratios of polymer composites were estimated by the ratios of ¹⁴C to ¹²C measured by accelerator mass spectrometry (AMS) based on ASTM D 6866-08. The pretreatment conditions of the polymer composite of each constituent for the AMS measurement are described. The repeatability and accuracy of the biomass carbon ratio evaluation by AMS for the polymer composites with an inorganic filler, which are biomass-based plastics with mineral calcium carbonate and petroleum-based plastics with biobased calcium carbonate, such as shell powder or an organic filler, are discussed. The standard deviation of the polymer composite was less than 1%, and it was sufficiently lower compared with the limit of the AMS measurement (0.12%). Also, the biomass carbon ratio of each constituent of the polymer composite including the inorganic filler was significant based on the AMS measurement by changing the pretreatment conditions.     

Novel evaluation method of biodegradabilities for oil-based polycaprolactone by naturally occurring radiocarbon-14 concentration using accelerator mass spectrometry based on ISO 14855-2 in controlled compost

The biodegradabilities of poly(?-caprolactone) (PCL) powders (av. size = 180.7 μm) in controlled compost at 58 °C have been studied using the microbial oxidative degradation analyzer (MODA) based on ISO 14855-2 entitled “Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 2: Gravimetric measurement of carbon dioxide evolved in a laboratory-scale test”. The biodegradability of the PCL powders was 101.4% in a 56-day test period by the ISO method. The biodegradabilities of PCL powders have been studied using percent modern carbon (pMC) measured by accelerated mass spectrometry (AMS). Trapped CO₂ was analyzed by AMS to determine the pMC (sample) using ¹⁴C radiocarbon concentration. By using the theory that the pMC (sample) was the sum of pMC (compost) (104.88%) and pMC (PCL) (0%) as the respective ratios in the determined period, CO₂ (respiration) was calculated only from one reaction vessel. The biodegradability of PCL powders was 79.9% in a 56-day test period by the AMS method. It was found that respiration activities in the sample vessel including PCL, compost and sea sand were the same as that in the blank vessel including compost and sea sand without PCL during the active biodegradation period (0-33 day) at 58 °C. It was confirmed that respiration activities in the sample vessel were slightly higher than that in the blank vessel after active biodegradation due to the propagation of microorganisms using energy and metabolites by PCL biodegradation during those periods.     

Source apportionment of atmospheric carbonaceous particulate matter based on the radiocarbon

A method was established to quantitatively estimate sources of atmospheric carbonaceous matter, using a combination of radiocarbon technology, linear regression of organic carbon (OC) -K⁺ and elemental carbon (EC) tracer method. Fractional contributions of fossil fuels, biomass burning, biogenic secondary organic carbon (BSOC) and soil dust to the atmospheric size-resolved carbonaceous matters in Shanghai suburb were estimated using this new method. The fossil carbon contributed most of the OC in particles smaller than 0.49 μm, and its fraction decreased with the increase of particle size. Biomass burning contributed 17–28 % to the OC. The BSOC contributed comparable proportions to the OC in particles smaller than 3.0 μm with the biomass burning, but larger in the particles lager than 3.0 μm. The soil dust contributed least fraction to the OC of each size with a proportion of 2–13 %. The biomass burning and fossil sources shared comparable fraction of the EC in all size range.     

New approaches to the separation of evaporation and atomization-excitation in atomic spectrometry

This review is aimed at compiling the references of those communications which deal with the construction principles and applications of combined spectroscopic sources. A “combined source” is considered here as having an on-line coupling of two high temperature units; the one producing gaseous species, vapour species and/or aerosol particles from the sample, and the other serving for the spectroscopic observation (absorption, emission, fluorescence) of the substance generated. Combined sources are classified into two groups according to whether vapour or aerosol is transported predominantly between the interfaced units for the less volatile constituents of samples.     

Method comparison study on soot-selective techniques

In a long-term field study at two locations with different air pollution levels several soot-selective measurement techniques were compared with a thermochemical method which measures non-extractable carbon (NEC) detecting the evolved CO₂ by means of coulometric titration. The attenuation measurement technique (aethalometer) and the aerosol photoemission method showed good correlations to NEC for concentrations ranging from 1.6g/m³ to 40.8g/m³. The specific mass absorption coefficient of black carbon with respect to NEC varied between 8.4m²/g and 13.7m²/g with respect to the measurement sites, but the value was found to remain constant at each site independent of seasonal or meteorological variations. The ratio of photoelectric signal to NEC varied between 16 fA·(g/m³)^–1 and 33 fA·(g/m³)^–1 depending on the age of the aerosol. The diurnal variations of that ratio showed strong similarities to the traffic patterns. Additionally a slight temperature dependence of this ratio was found for the aged aerosol with a proportionality factor of – 0.35 fA·(K·g/m³)^–1. With the reflectance measurement technique (smoke shade method) reliable NEC determination was not possible for NEC concentrations 5 g/m³.     

Applicability of anthracite filtration‒micro electrolysis‒sand filtration for the treatment of surface waters containing high turbidity

The effect of combined filtration efficiency on the performance of anthracite filtration?micro electrolysis?sand filtration (AMS) was investigated. Impact of different operating parameters, such as iron?carbon ratio of micro electrolytic units, filtration velocity of AMS, were studied. It was found that when iron?carbon ratio was 6: 4, the AMS’s average turbidity removal rate was 96.75% at the filtration velocity of 3 m h^?1. The results showed that when the filtration rate was 3?9 m h^?1 and iron?carbon ratio was 6: 4, the turbidity removal efficiency was over 94%, and the turbidity of the effluent was less than 1 NTU in effective filtration cycle. The effective filtration cycle can last for more than 5 h or longer. Meanwhile, the removal rate of UV₂₅₄ was above 33%, and the concentration of iron ions in the effluent is less than 0.15 mg L^?1. Turbidity and iron indicators have reached the national drinking water standards. It was also found the mechanism of iron?carbon micro electrolytic enhanced filtration by infrared spectroscopy and scanning electron microscopy. And It was also speculated the reasons for the reaction passivation.     

Bioprospecting of Microalgae Isolated from the Adriatic Sea: Characterization of Biomass,Pigment, Lipid and Fatty Acid Composition,and Antioxidant and Antimicrobial Activity

Marine microalgae and cyanobacteria are sources of diverse bioactive compounds with potential biotechnological applications in food, feed, nutraceutical, pharmaceutical, cosmetic and biofuel industries. In this study, five microalgae, Nitzschia sp. S5, Nanofrustulum shiloi D1, Picochlorum sp. D3, Tetraselmis sp. Z3 and Tetraselmis sp. C6, and the cyanobacterium Euhalothece sp. C1 were isolated from the Adriatic Sea and characterized regarding their growth kinetics, biomass composition and specific products content (fatty acids, pigments, antioxidants, neutral and polar lipids). The strain Picochlorum sp. D3, showing the highest specific growth rate (0.009 h⁻¹), had biomass productivity of 33.98 ± 0.02 mg L⁻¹ day⁻¹. Proteins were the most abundant macromolecule in the biomass (32.83–57.94%, g g⁻¹). Nanofrustulum shiloi D1 contained significant amounts of neutral lipids (68.36%), while the biomass of Picochlorum sp. D3, Tetraselmis sp. Z3, Tetraselmis sp. C6 and Euhalothece sp. C1 was rich in glycolipids and phospholipids (75%). The lipids of all studied microalgae predominantly contained unsaturated fatty acids. Carotenoids were the most abundant pigments with the highest content of lutein and neoxanthin in representatives of Chlorophyta and fucoxanthin in strains belonging to the Bacillariophyta. All microalgal extracts showed antioxidant activity and antimicrobial activity against Gram-negative E. coli and S. typhimurium and Gram-positive S. aureus.     

Detection capabilities: some historical footnotes

Part I Summary of relevant topics from 1923 to present—including: Currie (Anal Chem 40:586–593, 1968) detection concepts & capabilities; International detection & uncertainty standards; Failure of classical ¹⁴C dating and birth of new scientific disciplines; Exploratory nuclear data analysis of ⁸⁵Kr monitors found coincident with the collapse of the Iron Curtain (1989); Faulty statistics proved responsible for mistaken assertions that Currie’s L _C yields excessive false positives; Low-level counting and AMS for atmospheric ³⁷Ar and µmolar fossil/biomass carbon in the environment; Erroneous assumption that our low-level background is a Poisson Process, linked to ~8 % spurious anticoincidence events. Part II Exact treatment of bivariate Poisson data—solved in 1930s by Przyborowski and Wilenski, Krakow University, for detecting extreme trace amounts of a malicious contaminant (dodder) in high purity seed standards. We adapted their treatment to detection capabilities in ultra-low-level nuclear counting. The timing of their work had great historical significance, marking the start of World War II, with the invasion of Poland (1939).     

Thallium and cadmium in recent snow and firn layers in the Canadian Arctic by atomic fluorescence and absorption spectrometries

Compared to the Antarctic and Greenland, the Canadian Arctic has seen extremely few trace metal studies on snow and ice. Surface, subsurface and depth samples of snow and firns were collected from the Agassiz Ice Cap, Ellesmere Island, Canada using clean room practices. Results for Tl (directly determined by LEAFS) and Cd (determined by GFAAS) are reported. To our knowledge, the thallium depth profile presented here is the first one so far reported for both polar systems, Greenland or other places. Tl concentrations peak in the winter-spring periods, when the Arctic atmosphere is loaded with foreign pollutants and suspended particulates which sometime severely reduce the visibility, creating a phenomenon commonly known as the Arctic haze. These results are in general accordance with the historical Arctic air pollution and acidity/conductivity data on ice cores. Surface concentrations of Tl range from 0.3 to 0.9 pg/g, which is a few times higher than those found in Antarctica. Cadmium shows seasonal characteristics similar to Tl although there is not a definite correlation between the two. However, there could be two predominant origins of metals which were deposited in the snow: Eurasian origin in January–April corresponding to high level metals (main deposition), and a less definite origin in May–December corresponding to low level metals.     

Some case studies of skewed (and other ab-normal) data distributions arising in low-level environmental research

Three general classes of skewed data distributions have been encountered in research on background radiation, chemical and radiochemical blanks, and low levels of ⁸⁵Kr and ¹⁴C in the atmosphere and the cryosphere. The first class of skewed data can be considered to be theoretically, or fundamentally skewed. It is typified by the exponential distribution of inter-arrival times for nuclear counting events for a Poisson process. As part of a study of the nature of low-level (anti-coincidence) Geiger– Müller counter background radiation, tests were performed on the Poisson distribution of counts, the uniform distribution of arrival times, and the exponential distribution of inter-arrival times. The real laboratory system, of course, failed the (inter-arrival time) test – for very interesting reasons, linked to the physics of the measurement process. The second, computationally skewed, class relates to skewness induced by non-linear transformations. It is illustrated by non-linear concentration estimates from inverse calibration, and bivariate blank corrections for low-level ¹⁴C–¹²C aerosol data that led to highly asymmetric uncertainty intervals for the biomass carbon contribution to urban “soot”. The third, environmentally skewed, data class relates to a universal problem for the detection of excursions above blank or baseline levels: namely, the widespread occurrence of ab-normal distributions of environmental and laboratory blanks. This is illustrated by the search for fundamental factors that lurk behind skewed frequency distributions of sulfur laboratory blanks and ⁸⁵Kr environmental baselines, and the application of robust statistical procedures for reliable detection decisions in the face of skewed isotopic carbon procedural blanks with few degrees of freedom.     

SPME-GC-MSD for Determination of Nine Phenyl Compounds in Snow Water in Beijing China

Solid phase microextraction (SPME) then capillary gas chromatography with mass spectrometric detection have been used for determination of nine phenyl compounds in snow water in Beijing City. Headspace extraction with a fiber coated with 100 µm PDMS was used to extract the compounds. Extraction and desorption times were optimized at 8 and 2 min, respectively. Relative standard deviation (RSD) of the analytical method was found to be less than 5%. The linear range was wide and limits of detection were less than 5 ng mL⁻¹ for the nine target analytes. Several phenyl compounds at ng mL⁻¹ levels were detected in snow samples in Beijing, indicating the corresponding air pollution.     

Concept and validation of a novel approach for producing large batches of reference material of ambient aerosols on filters

A novel method for preparing reference material of aerosol particulate matter (PM) on filters was developed by using the concept of very high volume, multiport sampling, and this was subsequently applied to produce more than 300 well-characterised units. The dedicated sampler built for this purpose features a 0.94-m-diameter, vacuum-tight main chamber with a total of 349 monitor ports, each holding a 37-mm-diameter, cellulose acetate–nitrate ester (CA) membrane filter with a nominal pore size of 0.8 m. At a pressure difference of about 130 hPa across the filter cassettes, the total initial air flow rate was 350 m³ h^–1 (1.0 m³ h^–1 per filter). Investigations into the variability of filter parameters showed that the flow resistance of CA filters is mostly determined by and proportional to their blank mass, with a mean uncertainty of about 5%. Total suspended particulate matter (TSP) was sampled for a total of 50 h using 349 selected filters with a relatively narrow spread in blank mass. The mean TSP mass per filter thus produced was 3.35 mg. Corrected for small differences in blank mass of the filters, the normalised aerosol masses per filter of 96% of the samples exhibited normal distributions with standard deviations of only 2.1 and 3.4%, depending on details of the normalisation procedure. Within the limits of the technique, a variation of aerosol mass with radial distance from the centre of the sampler is not clearly evident. The results provide evidence that the multiport approach allows large batches of particulate matter on filters to be produced in a reliable manner.     

Highly Porous Carbons Synthesized from Tannic Acid via a Combined Mechanochemical Salt-Templating and Mild Activation Strategy

Highly porous activated carbons were synthesized via the mechanochemical salt-templating method using both sustainable precursors and sustainable chemical activators. Tannic acid is a polyphenolic compound derived from biomass, which, together with urea, can serve as a low-cost, environmentally friendly precursor for the preparation of efficient N-doped carbons. The use of various organic and inorganic salts as activating agents afforded carbons with diverse structural and physicochemical characteristics, e.g., their specific surface areas ranged from 1190 m²·g⁻¹ to 3060 m²·g⁻¹. Coupling the salt-templating method and chemical activation with potassium oxalate appeared to be an efficient strategy for the synthesis of a highly porous carbon with a specific surface area of 3060 m²·g⁻¹, a large total pore volume of 3.07 cm³·g⁻¹ and high H₂ and CO₂ adsorption capacities of 13.2 mmol·g⁻¹ at −196 °C and 4.7 mmol·g⁻¹ at 0 °C, respectively. The most microporous carbon from the series exhibited a CO₂ uptake capacity as high as 6.4 mmol·g⁻¹ at 1 bar and 0 °C. Moreover, these samples showed exceptionally high thermal stability. Such activated carbons obtained from readily available sustainable precursors and activators are attractive for several applications in adsorption and catalysis.     

Use of scanning reference electrode technique for characterizing pitting and general corrosion of carbon steel in neutral media

The scanning reference electrode technique (SRET) was used to characterize the corrosion behavior of carbon steel in the NaNO₂-containing chloride solution and tap water. In 10⁻³ MNaNO₂+10⁻³ MNaCl+10⁻³ MNa₂SO₄ solution, the passivated carbon steel surface suffered the pitting. In this case, the size of anodic and cathodic areas on the corroding surface varied with the exposed time, but anodic and cathodic sites did not change. On the contrary, the carbon steel was corroded generally in the tap water. The localized anodes and cathodes on the corroding surface were not fixed but movable with the exposed time during the whole corrosion process, and the “movable anodes” can be in situ monitored and momentarily identified by SRET measurements.     

The Use of High Surface Area Mesoporous-Activated Carbon from Longan Seed Biomass for Increasing Capacity and Kinetics of Methylene Blue Adsorption from Aqueous Solution

Microporous- and mesoporous-activated carbons were produced from longan seed biomass through physical activation with CO₂ under the same activation conditions of time and temperature. The specially prepared mesoporous carbon showed the maximum porous properties with the specific surface area of 1773 m²/g and mesopore volume of 0.474 cm³/g which accounts for 44.1% of the total pore volume. These activated carbons were utilized as porous adsorbents for the removal of methylene blue (MB) from an aqueous solution and their effectiveness was evaluated for both the adsorption kinetics and capacity. The adsorption kinetic data of MB were analyzed by the pseudo-first-order model, the pseudo-second-order model, and the pore-diffusion model equations. It was found that the adsorption kinetic behavior for all carbons tested was best described by the pseudo-second-order model. The effective pore diffusivity (D_e) derived from the pore-diffusion model had the values of 4.657 × 10⁻⁷–6.014 × 10⁻⁷ cm²/s and 4.668 × 10⁻⁷–19.920 × 10⁻⁷ cm²/s for the microporous- and mesoporous-activated carbons, respectively. Three well-known adsorption models, namely the Langmuir, Freundlich and Redlich–Peterson equations were tested with the experimental MB adsorption isotherms, and the results showed that the Redlich–Peterson model provided the overall best fitting of the isotherm data. In addition, the maximum capacity for MB adsorption of 1000 mg/g was achieved with the mesoporous carbon having the largest surface area and pore volume. The initial pH of MB solution had virtually no effect on the adsorption capacity and removal efficiency of the methylene blue dye. Increasing temperature over the range from 35 to 55 °C increased the adsorption of methylene blue, presumably caused by the increase in the diffusion rate of methylene blue to the adsorption sites that could promote the interaction frequency between the adsorbent surface and the adsorbate molecules. Overall, the high surface area mesoporous carbon was superior to the microporous carbon in view of the adsorption kinetics and capacity, when both carbons were used for the removal of MB from an aqueous solution.     

Acid-Catalyzed Liquefaction of Biomasses from Poplar Clones for Short Rotation Coppice Cultivations

Liquefaction of biomass delivers a liquid bio-oil with relevant chemical and energetic applications. In this study we coupled it with short rotation coppice (SRC) intensively managed poplar cultivations aimed at biomass production while safeguarding environmental principles of soil quality and biodiversity. We carried out acid-catalyzed liquefaction, at 160 °C and atmospheric pressure, with eight poplar clones from SRC cultivations. The bio-oil yields were high, ranging between 70.7 and 81.5%. Average gains of bio-oil, by comparison of raw biomasses, in elementary carbon and hydrogen and high heating, were 25.6, 67, and 74%, respectively. Loss of oxygen and O/C ratios averaged 38 and 51%, respectively. Amounts of elementary carbon, oxygen, and hydrogen in bio-oil were 65, 26, and 8.7%, and HHV averaged 30.5 MJkg⁻¹. Correlation analysis showed the interrelation between elementary carbon with HHV in bio-oil or with oxygen loss. Overall, from 55 correlations, 21 significant and high correlations among a set of 11 variables were found. Among the most relevant ones, the percentage of elementary carbon presented five significant correlations with the percentage of O (−0.980), percentage of C gain (0.902), percentage of O loss (0.973), HHV gain (0.917), and O/C loss (0.943). The amount of carbon is directly correlated with the amount of oxygen, conversely, the decrease in oxygen content increases the elementary carbon and hydrogen concentration, which leads to an improvement in HHV. HHV gain showed a strong positive dependence on the percentage of C (0.917) and percentage of C gain (0.943), while the elementary oxygen (−0.885) and its percentage of O loss (0.978) adversely affect the HHV gain. Consequently, the O/C loss (0.970) increases the HHV positively. van Krevelen’s analysis indicated that bio-oils are chemically compatible with liquid fossil fuels. FTIR-ATR evidenced the presence of derivatives of depolymerization of lignin and cellulose in raw biomasses in bio-oil. TGA/DTG confirmed the bio-oil burning aptitude by the high average 53% mass loss of volatiles associated with lowered peaking decomposition temperatures by 100 °C than raw biomasses. Overall, this research shows the potential of bio-oil from liquefaction of SRC biomasses for the contribution of renewable energy and chemical deliverables, and thereby, to a greener global economy.     

Evaluation of Medicinal Plant Decomposition Efficiency Using Microwave Ovens and Mini-Vials for Cd Determination by TS-FF-AAS

Sample preparation is an important step in the analytical process because it can introduce different error sources. Its efficiency is checked based on the quality and reliability of the data obtained, and the time spent on this task. This work evaluates medicinal plant decomposition parameters using polypropylene mini-vials heated by microwave radiation, applying the single vessel concept. As an example, sample mass amount (5 mg), mixture of oxidant agents (200 µL conc. HNO₃+150 µL 30% v/v H₂O₂), microwave time and power were evaluated by heating 24 mini-vials in both closed-vessel (CV) and focused (F) microwave ovens. In order to achieve the best-optimised condition for sample preparation, cadmium and residual carbon determinations were carried out for all experiments. The residual carbon (between 0.30 and 0.45%) was determined by CHN elemental analysis and the cadmium concentration (up to 0.80 µg g⁻¹) by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) in three different medicinal plants. The accuracy of the proposed methods was assessed using certified reference materials (rye grass, BCR 281 and bovine liver, NIST 1577b) as well as conventional microwave assisted decomposition. The new method used a minimum sample amount (5 mg) and reagent volume (ca. 400 µL) and only 4 and 10 min of microwave sample decomposition for CV and F ovens, respectively. In addition, the capacity of both microwave ovens was increased up to 4 times while contamination risks were inherently reduced with the single vessel concept.     

Determination of Cd,Pb, and Cu in the Atmospheric Aerosol of Central East Antarctica at Dome C (Concordia Station)

Trace heavy metals Cd, Pb, and Cu were determined (by square wave anodic stripping voltammetry) in aerosol samples collected at Dome C (the Italo-French Station Concordia), a remote site of the Central East Antarctic plateau, for which no data are available until now. During the Austral Summer 2005–2006, three PM10 high-volume impactors were installed in two locations nearby of Concordia station: the first one very close and downwind of the station (about 50 m north), the other two (very close to each other) in a ‘distant’ site, upwind of the station and close to the astrophysics tent (not used in that expedition) at ~800 m south of Station Concordia. For each sample, the availability of the mass of the aerosol collected (obtained by differential weighing carried out on site), in addition to the volume of the filtered air, allowed us to express results both in terms of metal mass fractions in the aerosol and in the usual way of metal atmospheric concentrations. Metal contents increased in the order Cd < Pb < Cu with the following ranges of values: Cd 1.0–8.4 µg g⁻¹ (0.09–3.1 pg m⁻³), Pb 96–470 µg g⁻¹ (12–62 pg m⁻³), and Cu 0.17–20 mg g⁻¹ (0.027–2.4 ng m⁻³). From the metal temporal profiles obtained we estimated the following background values for the area of Dome C, expressed both in mass fractions and in atmospheric concentrations: Cd 1.2 ± 0.2 µg g⁻¹ (0.24 ± 0.13 pg m⁻³), Pb (here fixed as upper limit) 113 ± 13 µg g⁻¹ (21 ± 8 pg m⁻³), and Cu 0.91 ± 0.48 mg g⁻¹ (0.12 ± 0.07 ng m⁻³). The highest values were observed in the first part of the season, and particularly for the site close to the station, possibly related to sample contamination linked to intense activity at the Concordia station connected with the beginning of the expedition, including aircraft arrivals/departures. Increments of up to 10 times (and even 20 times for Cu) were recorded with respect to the background values. The metal excesses of the contaminated over background samples were found approximately, except for Cu, in the same proportion of the metal contents of the special Antarctic blend (SAB) diesel fuel, which is used almost exclusively at Concordia Station. The effect of the wind direction was also observed. Thus in the intermediate period of the campaign, when the wind direction reversed for several days with respect to the prevailing one, Cd and Pb metal contents decreased at the sampling point installed close to the station, now upwind of Concordia station, and increased at the ‘clean’ site astrophysics tent, turned downwind at the main station. No simple and easily interpretable effect of the wind direction was observed for Cu, which suggests that some other extemporaneous and not clearly identified factor may have intervened in this case. These results suggest that the human impact at Dome C influences mainly the zone very close to the station, but also the area in the neighborhood, including the supposed clean site of the astrophysics tent (about 800 m far from the station), when the wind direction reverses with respect to the prevailing one, leaving the site downwind of the station Concordia. Since no other data are reported for the Dome C area, our results are compared with literature data referred to the South Pole Station (the only other plateau site for which data are available) and several other coastal Antarctic sites, observing that our results (excluding Cu) are the lowest ever observed for Antarctic aerosol.     

Mercury, zinc, manganese, and iron accumulation in leachate pond sediments from a refuse tip in Southeastern Brazil

This work evaluates Hg, Zn, Fe and Mn transfer from the leachate of a refuse tip based on their accumulation in a sediment core of 17 cm collected in a leachate pond of a small refuse tip ageing approximately 10 years. Sediment samples were digested with an acid mixture (50% acqua regia solution), heated at 70 °C during 1 h, in a thermal-kinetic reactor “cold finger”. The extract was analysed to obtain Hg content by cold vapour absorption atomic spectrometry (CVAAS). Fe, Mn and Zn contents were obtained by flame atomic absorption spectrometry (FAAS) after total decomposition of the samples. Concentration ranges along the core varied from 0.16 to 0.58 μg g^− 1; 7.3 to 145 μg g^− 1; 11.7 to 116 μg g^− 1 and 0.21% to 1.82% for Hg, Zn, Mn and Fe, respectively. All metals showed enrichment in the upper layers (above 6 cm) which probably correspond to the year 1996. Results indicated that Hg transfer is one order of magnitude higher than Zn and suggest that metals accumulation in sediments probably reduce their migration to groundwater.