Weak Acid Extraction Research Articles

Geochemical estimation of the potential danger of waste rocks from the Veduginskoe deposit

Using a series of analytical and experimental methods, a predictive estimate was obtained for the possible environmental impact of the waste rocks of the Veduginskoe gold deposit. All samples of the country rocks were analyzed for major and 13 trace elements. This allowed us to demonstrate that the accumulation of elements in the water phase (water and weak acid extracts) is not always correlated with their contents in the solid material but controlled by their chemical speciation in the water-rock system. The dynamics of 20-week leaching of a series of contrasting rock samples supported the plausibility of criteria selected for their differentiation: the filtrates of one group remained neutral to weakly alkaline up to the end of experiments, whereas an “acid mine drainage” was produced in the other group. Acid sulfate solution with high contents of Fe, Al, and heavy metals can also accumulate Be, As, and Hg. However, the slightly alkaline solutions that have not received proper attention during environmental protection operations may transport elements with specified maximum permissible concentrations (MPC): anion-forming Sb, As, and Mo; amphoteric Be; and supertoxic Hg.

Quantification of Intracellular Phosphorylated Carbohydrates in HT29 Human Colon Adenocarcinoma Cell Line Using Liquid Chromatography−Electrospray Ionization Tandem Mass Spectrometry

The quantitative understanding of the role of sugar phosphates in regulating tumor energetic metabolism at the proteomic and genomic level is a prerequisite for an efficient rational design in combined drug chemotherapy. Therefore, it is necessary to determine accurately the concentration of the main sugar phosphate pools at the lower concentrations present in the often-limited volume of tumor cell samples. Taking as an example the human adenocarcinoma cell line HT29, we here report a fast and reliable quantitative method based on the use of liquid nitrogen, a weak acid extraction, and liquid chromatography-electrospray ionization tandem mass spectrometry to quantify simultaneously the intracellular concentration of sugar phosphate pools. The method was set up using standard addition curves. Thus, it is possible to identify and quantify hexose phosphate, pentose phosphate, and triose phosphate pools up to 0.02-0.10 ng x microL(-1), depending on the analyte. The method developed was here used for the quantitative study of changes in phosphorylated carbohydrates of central carbon metabolism when high or low glucose concentration conditions are induced in vitro in the HT29 human colon adenocarcinoma cell line.

Controls on dense non-aqueous-phase liquid transport in Permo-Triassic sandstones, UK

Abstract The Permo-Triassic sandstones are geographically and lithologically diverse, and exhibit large variations in porosity (ф), pore-throat size, gas permeability ( k ) and mineral phases. These parameters influence considerably the flow and transport of contaminants. The aquifer is susceptible to contamination by a range of pollutants from both contemporary and historic sources as it outcrops in a number of large industrial towns. One such class of pollutants are chlorinated hydrocarbons, which have been used extensively for years in dry-cleaning and metal degreasing. The physical, chemical and biological properties of these dense non-aqueous-phase liquids (DNAPLs) make them a particular cause of groundwater contamination. Standard physical property measurements, along with a weak nitric acid extraction to determine dominant minerals, were carried out on consolidated sandstones. A laboratory method was developed to produce pressure-saturation curves for a DNAPL-water-sandstone system. Entry pressures were found to be lower than predicted from theoretical considerations, which could be explained in part by the relative amounts of calcite and dolomite present in the pore space. Calculations on relative permeability show that at roughly 60% DNAPL saturation no water flow occurs. Understanding the controls on DNAPL transport can greatly assist the need for appropriate remedial action.

Transport and sediment–water partitioning of trace metals in acid mine drainage: an example from the abandoned Kwangyang Au–Ag mine area, South Korea

Transport and sediment–water partitioning of trace metals (Cr, Co, Fe, Pb, Cu, Ni, Zn, Cd) in acid mine drainage were studied in two creeks in the Kwangyang Au–Ag mine area, southern part of Korea. Chemical analysis of stream waters and the weak acid (0.1 N HCl) extraction, strong acid (HF–HNO3–HClO4) extraction, and sequential extraction of stream sediments were performed. Heavy metal pollution of sediments was higher in Chonam-ri creek than in Sagok-ri creek, because there is a larger source of base metal sulfides in the ores and waste dump upstream of Chonam-ri creek. The sediment–water distribution coefficients (Kd) for metals in both creeks were dependent on the water pH and decreased in the order Pb ≈ Al > Cu > Mn > Zn > Co > Ni ≈ Cd. Kd values for Al, Cu and Zn were very sensitive to changes in pH. The results of sequential extraction indicated that among non-residual fractions, Fe–Mn oxides are most important for retaining trace metals in the sediments. Therefore, the precipitation of Fe(–Mn) oxides due to pH increase in downstream sites plays an important role in regulating the concentrations of dissolved trace metals in both creeks. For Al, Co, Cu, Mn, Pb and Zn, the metal concentrations determined by 0.1 N HCl extraction (Korean Standard Method for Soil Pollution) were almost identical to the cumulative concentrations determined for the first three weakly-bound fractions (exchangeable + bound to carbonates + bound to Fe–Mn oxides) in the sequential extraction procedure. This suggests that 0.1 N HCl extraction can be effectively used to assess the environmentally available and/or bioavailable forms of trace metals in natural stream sediments.

Evidence for enhanced bioavailability of trace elements in the marine ecosystem of Deception Island, a volcano in Antarctica

This study assessed whether trace elements present at Deception Island, an active submarine volcano in the Antarctic Peninsula, show enhanced biological availability to the local marine community. Using a weak acid extraction method to dissolve organic material and leach associated but not constitutive trace elements of sediments, fifteen elements were measured from seafloor sediment, seawater particulates, and tissues of benthic (bivalves, brittlestars, sea urchins) and pelagic (demersal and pelagic fishes, krill) organisms collected in the flooded caldera. The highest element concentrations were associated with seafloor sediment, the lowest with seawater particulates and organism tissues. In the case of Ag and Se, concentrations were highest in organism tissue, indicating contamination through the food chain and biomagnification of those elements. The elements Al, Fe, Mn, Sr, Ti, and to a lesser extent Zn, were the most concentrated of the trace elements for all sample types. This indicates that the whole ecosystem of Deception Island is contaminated with trace elements from local geothermal activity, which is also reflected in the pattern of element contamination in organisms. Accordingly, element concentrations were higher in organisms collected at Deception Island compared to those from the neighboring non-active volcanic King George Island, suggesting that volcanic activity enhances bioavailability of trace elements to marine organisms. Trace element concentrations were highest in digestive tissue of organisms, suggesting that elements at Deception Island are incorporated into the marine food web mainly through a dietary route.

Changes in the volume and salinity of Lake Khubsugul (Mongolia) in response to global climate changes in the upper Pleistocene and the Holocene

Two gravity cores (1.1 and 2.2 m long) of deep-water bottom sediments from Lake Khubsugul (Mongolia) were studied. The Holocene, biogenic silica and organic matter-rich part of the first core was subjected to AMS radiocarbon dating which placed the date of dramatic increase of pelagic diatoms (40 cm below sediment surface) at a calendar age of 11.5 cal ky BP. ICP-MS analysis of weak nitric acid extracts revealed that the upper Pleistocene, compared to the Holocene samples, were enriched in Ca, C inorg, Sr, Mg and depleted of U, W, Sb, V and some other elements. Transition to the Holocene resulted in an increase of total diatoms from 0 to 10 8 g −1, of BiSi from 1% to 20%, of organic matter from <1% to >6%. The Bølling–Allerød–Younger Dryas–Holocene abrupt climate oscillations manifested themselves in oscillations of geochemical proxies. A remarkable oscillation also occurred at 22 cm (ca. 5.5 ky BP). The Pleistocene section of the second, longer core was enriched in carbonate CO 2 (up to 10%) and water-extractable SO 4 2− (up to 300 times greater than that in Holocene pore waters). All this evidence is in an accord with the earlier finding of drowned paleo-deltas at ca. 170 m below the modern lake surface of the lake [Dokl. Akad. Nauk 382 (2002) 261] and suggests that, due to low (ca. 110 mm) regional precipitation at the end of the Pleistocene, Lake Khubsugul was only 100 m deep, and that its volume was ca. 10 times less than today.

HEAVY METAL IN SEDIMENTS AND BIOACCUMULATION IN THE BIVALVE Corbula gibba IN A DRILLING DISCHARGE AREA

The longterm bioavailability of heavy metals in sediments of a Northern Adriatic Sea shelf area affected by drilling mud and cutting discharges was discussed. Levels of Mn, Cu, Cr, Zn and Pb in different geochemical phases of the sediment and in soft tissues of the bivalve Corbula gibba were recorded and the relationships between biological and geochemical metal investigated. Total metal content, acetic acid extractable-, exchangeable-, carbonate-, easily reducible-, moderately reducible-, oxidable- and residual-fractions were determined on sediment samples. Corbula gibba was collected from wet sediments at the same times and sites, and the soft-tissue metal contents were determined. Correlations show that the fractions with greatest bioavailability are the exchangeable and carbonate for Cr and the exchangeable, carbonate, easily and moderately reducible fractions for Zn. Data also show a possible bioavailability of Pb only from the residual fraction, consisting of very resistant matter of more recent anthropogenic origin. Near the platform, total Mn content in sediments and in C. gibba tissues show a strong correlation suggesting that this organism is sensitive to variations of the Mn-oxi-hydroxides superficial film. No relationships were found between biological and sediment-bound Cu, however the discharged muds did not cause Cu enrichment. The metal fraction determined by weak acetic acid extraction at no point seems related to metal levels in Corbula gibba.

Reductive dehalogenation of halomethanes in iron- and sulfate-reducing sediments. 1. Reactivity pattern analysis.

The incorporation of reductive transformations into environmental fate models requires the characterization of natural reductants in sediments and aquifer materials. For this purpose, reactivity patterns (range and relative order of reactivity) for a series of 14 halogenated methanes were measured in iron- and sulfate-reducing sediments and two representative model systems: adsorbed Fe(II)/goethite [Fe(II)ads/alpha-FeOOH] and iron sulfide (FeS). Both Fe(II)ads and FeS are naturally occurring reductants. The strong similarity in reactivity patterns between the iron- and sulfate-reducing sediments suggests that the two share a common reductant despite their different chemical compositions (i.e., the sulfate-reducing sediment contained FeS). An orthogonal regression analysis of the halomethane transformation rate data in the sediment and model systems supports the assumption that a common mechanism for halomethane transformation exists between the sediments and the Fe(II)ads/alpha-FeOOH system and further corroborates the conclusion that Fe(II) adsorbed to Fe(III)-containing minerals is the dominant reductant in both sediment systems. Weak (0.5 N) and strong (6.0 N) acid extraction of the sediments indicated that solid-phase Fe(II) was 67% higher in the sulfate-reducing sediment than in the iron-reducing sediment, which is consistent with the observations that the halomethanes were transformed a factor of 3 times faster in the sulfate-reducing sediment and that Fe(II) was the dominant reductant.

Towards a better understanding of tetrachloroethene entry pressure in the matrix of Permo-Triassic sandstones

The pressure required for a chlorinated solvent to enter a geological medium can be calculated given knowledge of the characteristic pore size of the medium and the interfacial tension (IFT) and contact angle of the solvent–water–rock system. Using a centrifuge-based method, capillary pressure–saturation curves have been determined for 30 water-saturated samples of Permo-Triassic sandstones for the solvent tetrachloroethene (PCE). These curves have been successfully fitted using the van Genuchten function to determine PCE entry pressure for each of the sandstone samples. A plot of PCE entry pressures against average pore diameter shows a linear relationship in log–log space; however, observed values for PCE entry pressure are significantly lower than would be expected theoretically for a sandstone–PCE–water system. This may be explained either by a decrease in the IFT or an increase in the contact angle. The IFT may decrease during contact with sandstones due to hysteresis effects during imbibition and drainage of fluids, but this is unlikely to be sufficient to account for the low entry pressures observed. Therefore, it is inferred that the low observed PCE entry pressures are due to higher than expected PCE contact angles, and that the average pore-throat surface of the sandstones is more solvent wetting than would be expected. A weak acid extraction indicates the presence of calcite and dolomite in the sandstone cores, and a correlation is observed between carbonate content per unit porosity and a reduction in PCE entry pressure. It is suggested that these mineral phases are responsible for observed wettability changes and a conceptual model is proposed. One consequence of the lower observed entry pressures is that solvents are likely to penetrate deeper into the matrix of water-saturated sandstones than previously expected.

Aging of Iron (Hydr)oxides by Heat Treatment and Effects on Heavy Metal Binding

Amorphous iron (hydr)oxides are used to remove heavy metals from wastewater and in the treatment of air pollution control residues generated in waste incineration. In this study, iron oxides containing heavy metals (e.g., Pb, Hg, Cr, and Cd) were treated at 50, 600, and 900 °C to simulate their transformations caused by heat treatment prior to disposal or aging at a proper disposal site. The transformations were investigated by XRD, SEM, XANES, EXAFS, surface area measurements, pH static leaching tests, and extractions with oxalate and weak hydrochloric acid. It was found that at 600 and 900 °C the iron oxides were transformed to hematite, which had a greater thermodynamic stability but less surface area than the initial products. Heat treatment also caused some volatilization of heavy metals (most notably, Hg). Leaching with water at pH 9 (L/S 10, 24 h) and weak acid extraction showed that heat treatment caused a part of the metals bound in the oxides to be released, thus increasing metals leachability by 1−2 orders of magnitude depending on the metal. Pb and Cd were released in particularly significant concentrations, suggesting less incorporation into the iron oxides after heat-induced transformation. For Pb, this transformation of the chemical state of the bound metal was clearly supported by the X-ray absorption fine structure (XAFS) studies. A fraction of the bound Cr remained stable even after treatment at the highest temperature used in the study. It was concluded that the heat treatment of iron oxides may be advantageous to improve the thermodynamic stability of the product but that thermal treatment at both 600 and 900 °C significantly reduced the binding capacity for heavy metals.

The Effects of Behaviour on Ceramic Composition: Implications for the Definition of Production Locations

Using petrographic, weak-acid extraction inductively coupled plasma spectrometry, and experimental analyses, this study illustrates that the Classic period (ad 200–800) potters of prehispanic Ejutla (Oaxaca, Mexico) made a diverse array of ceramic products. Ancient Ejutla potters modified the handling and firing of local clay to make fine and coarse wares as well as reduced and oxidized vessels. Our analyses indicate that these different production strategies had distinct effects on compositional signatures. Yet, by employing a multidimensional analytical tack, we are able to associate an assortment of ceramic varieties with the Ejutla producers and their local clay.

Mussels as bioindicators of trace metal pollution in the Danube Delta of Romania

Specimens of mussels species Anodonta anatina, Unio pictorum, U. tumidus and surfical sediment samples were collected in the summers of 1994 and 1995 from twelve lakes in the Danube Delta, Romania. Whole mussel tissues were analyzed for metals (Ag, As, Cd, Co, Cu, Cr, Ni, Pb, Se and Zn), and sediment samples were subjected to weak acid extraction and to a sequential extraction procedure, and analyzed for Cr, Cu, Ni and Zn. Total mean Cu and Ag concentrations were statistically greater in Unio species than in Anodonta species, but other metal levels did not significantly differ between mussel species. There was a ten fold variation for Cd and Pb and five fold variation for Zn, Ag and Co concentrations in mussels among lakes. Mean concentrations of As, Cu, Se and Zn in mussel tissues varied two fold among lakes. Zn, Co and Cd concentrations in mussels were significantly negatively correlated with distance gradients from the origin of the Delta and with distance from main channels of the Danube. Other metal concentrations in mussels did not correlate with either distance gradient. Trace metal levels in mussel tissues were correlated with those in weak acid and in sequential extractions of sediment. Zn concentrations in the carbonate fraction was the best predictor of Zn concentrations in mussels. Cu and Ni levels in the organic matter and sulfide fraction were the best estimators of Cu and Ni concentrations in mussels.

Intraregional Connections in the Development and Distribution of Salado Polychromes in Central Arizona

Salado polychrome is associated with Classic period (A.D. 1270-1450) sites across much of the American Southwest, but its distributions are variable. Although multiple production centers are recognized for these decorated vessels, their roles in intraregional social networks are still open to interpretation. Recent compositional studies using petrography and weak-acid extraction ICP-MS compare locally produced wares to the characterization of Salado polychromes. Data from several adjacent study areas are used to assess the development and distributions of Pinto, Gila, and Tonto Polychromes. These decorated vessels are evidence of a highly differentiated intraregional network of exchange and communication which spanned the platform mound communities of central Arizona.

An Evaluation of the Archaeological Relevance of Weak-Acid Extraction ICP: White Mountain Redware as a Case Study

A weak-acid extraction technique for inductively coupled plasma spectroscopy (ICP) was recently advocated as an inexpensive, highly precise method of chemical characterization of archaeological ceramics. We critically evaluate this approach on the basis of a large sample of Southwestern ceramics which were analysed both by weak-acid extraction ICP and neutron activation analysis. The comparison of the two data sets shows significant compositional discrepancies that lead to widely divergent archaeological interpretations.

Severn Sound Sediment Chemistry and Bioassessment, 1988–1990

Abstract Fine-grained sediment in the embayments of Severn Sound contains metals that exceed the Ontario Ministry of the Environment's lowest effect level, the level at which some disturbance of the sediment dwelling community can be expected. Sediment in Penetang Bay has concentrations of Cr that are above the provincial Severe Effect Level, the level at which a compound is expected to be detrimental to the majority of benthic species. Nevertheless, chronic sediment bioassays resulted in little measurable sublethal toxicity. Based on evidence from weak acid extraction of metals from sediment, the lack of toxicity may be due to the limited bioavailability of metals. The potential for metals to enter the food web was suggested by metal bioaccumulation observed for test species. Chromium and Ni concentrations in mayflies were significantly correlated with total Cr and Ni in sediment, and Zn and Cu tissue concentrations were not correlated with total metals in sediment. In general, the bioaccumulation of Cd, Cr, Cu, Ni and Pb by test species was more strongly correlated with extractable metals and with metals in the &amp;lt;63 µm size fraction than with total metals in bulk sediment, demonstrating that the total sediment pool of metals was not biologically available. Remedial actions for sediment in Severn Sound should focus on source control and natural sediment recovery, given the lack of sublethal chronic toxicity. Confirmation that active sources are not present and an ability to predict the natural recovery period for marginally contaminated regions would assist in fully restoring the sound.

A weak acid extraction method as a tool for the metal pollution assessment in surface sediments

A simple technique has been evaluated for the initial assessment of heavy metal pollution in coastal sediments, in order to overcome many difficulties involved in routine monitoring of such analytes. The leaching of sediment samples with a cold dilute HC1, which affects only the non-residual part of the metals, gives the “anthropogenic fingerprints” on the bottom deposits and provides more data on the extent of heavy metal pollution relatively to the total sediment analysis. The proposed technique has been applied in most Hellenic coastal regions, both polluted and unpolluted. Comparisons between the various regions with the use of an “enrichment factor” have been made, which establish the gross degree to which a sediment population has been subjected to heavy metal pollution from the overlying waters.

Dietary nicotine: A source of urinary cotinine

Foods, principally from plants in the family Solanaceae, and a number of teas were examined for the presence of nicotine. Dietary nicotine would give rise to cotinine in urine and compromise estimates of exposure to tobacco smoke that depend on urinary cotinine. All foods were homogenized, extracted and analysed for nicotine and cotinine by gas chromatography with nitrogen-sensitive detection (GC) and/or GC/MS (mass spectrometry). Weak acid and aqueous extracts of the teas were analysed in a similar manner. Nicotine was not detected (< 1 ng/ml of extractm) in egg plant or green pepper. The average values for nicotine in tomato and potato were 7.3 ng/g wet weight and 15 ng/g wet weight, respectively. Black teas, including regular and decaffeinated brands, had nicotine contents ranging from non-detectable to > 100 ng/g wet weight. Instant teas yielded the highest nicotine contents observed (up to 285 ng/g wet weight). The possible sources of nicotine in these foods are discussed. A range of potential values for urinary cotinine concentrations (0.6 to 6.2 ng/ml) was calculated based upon estimated average and maximal consumptions of these foods and beverages. Because of the potential for exposure to nicotine by way of these routes, the use of urinary cotinine as a biomarker of exposure to environmental tobacco smoke may be compromised.

GROWTH AND NUTRIENT UPTAKE PATTERNS OF AN EPISODIC AND CONTINUOUS GROWING WOODY PLANT

Current recommendations for sufficiency of nutrients in soil-less media for container grown nursery crops have been based on weak acid extraction and pour through sampling of media. Since the concentration of nutrients found in pour through samples are similar to those available in the media solution, sufficiency levels as determined by hydroponics studies have also been considered to be applicable to plants grown in a solid medium such as pine bark. Many variables, however, may affect nutrient availability in a solid medium which are not the same as those in a well-stirred hydroponics system. Objectives of this experiment were to compare growth and nutrient uptake patterns of Euonymous kiautschovica `Manhattan' and Prunus persica `Jefferson' grown in a pine bark/sand medium or a hydroponics system. Quantitative growth characteristics, depletion rates of nutrients in solution, concentration of ions in pour through samples, and tissue levels of N, P, K, Ca, and Mg will be reported.

Laboratory methods for estimating available nitrogen in manures and sludges

A soil incubation experiment was conducted to determine nitrate N(NO 3−N) accumulation rates and available N ( AAN t) values for stored liquid manures from dairy cattle and swine, various poultry manures and a municipal sewage sludge applied to Norfolk and Cecil soils. Potentially available N ( PAN t) in the manures and sludge was also estimated by chemical tests which included an acid permanganate extraction, weak acid extraction, strong acid extraction and pepsin digestion. The resulting PAN t values were compared to the AAN t values from the soil incubation study. The rates in which NO 3-N accumulated in soils treated with waste were described using first-order kinetics. The rate constants were highest for soils treated with poultry manure which contained high initial concentrations of ammonia N (NH 3-N) and rapidly mineralizable ORG-N. The lowest rate constants were for soils treated with municipal sludge which contained low concentrations of NH 3-N. Incubation tests showed significant reductions in inorganic N (IN-N) in the first 2 weeks, which suggested immobilization and/or possibly denitrification or NH 3-N volatilization. After 26 weeks' incubation, AAN t varied with waste type and soil type, being from 40% to 67% of total Kjeldahl N (TKN) applied to a Norfolk sandy soil and from 17% to 38% for a Cecil sandy loam.

The influence of palaeosalinity, grain size distribution and clay minerals on the content of B, Li and Rb in Quaternary sediments from Eastern Jutland, Denmark

ABSTRACTBulk sample analysis of Late‐ and Postglacial sediments from the Randers fjord area, Eastern Jutland, seem to indicate a relationship between palaeosalinity and B, Li and Rb contents determined on weak acid extracts of the sediment. Investigations of different size fractions, grain size distribution, and of clay minerals show, however, that variations in palaeosalinity as determined by palaeontological methods in this case have no direct influence on the chemistry.The variation of Li and Rb is related to variation in grain size, while the B variation seems to be related to the content of montmorillonite in the clay fraction.