Low Concentrations Of Most Elements Research Articles

Below‐ and above‐ground effects of deadwood and termites in plantation forests

AbstractDeadwood is an important legacy structure in managed forests, providing continuity in shelter and resource availability for many organisms and acting as a vehicle by which nutrients can be passed from one stand to the next following a harvest. Despite existing at the interface between below‐ and above‐ground systems, however, much remains unknown about the role woody debris plays in linking these zones. Moreover, it remains untested whether the accelerative effects of wood‐feeding insects on wood decomposition influence tree growth or nutritional status in forests. In this study, we added different quantities of pine logs to the bases of saplings in two‐year‐old loblolly pine (Pinus taedaL.) plantations in Mississippi,USA. We included a treatment in which subterranean termites (Blattodea: Rhinotermitidae:Reticulitermes) were excluded from logs to determine how these insects affect the release of nutrients from wood and, in turn, tree growth. After 51 months of decomposition, we quantified below‐ground effects by measuring microbial biomass, plant‐available forms of N, and ectomycorrhizal diversity associated with fine tree roots. Meanwhile, above‐ground measurements focused on the elemental concentrations in decomposing wood either protected or unprotected from termites and tree metrics related to growth and nutrient status. We found additions of wood to significantly increase nitrate and potential net nitrification relative to reference treatments but detected no significant effects on tree growth, needle nitrogen concentrations, or ectomycorrhizal diversity. Soil nitrate and potential net nitrification were higher under protected vs. unprotected logs, and plant‐available forms of N were mostly more abundant short distances away from both protected and unprotected logs than directly under them. The wood of logs protected from termites had significantly lower concentrations of most elements compared to that of unprotected logs, largely due to the large amounts of soil imported into unprotected logs by termites. Termite exclusion had no measurable effect on tree growth, nutritional status, or ectomycorrhizal diversity, however. Our findings indicate that deadwood and termites both contribute to the spatial heterogeneity of soil properties but may have limited short‐term local effects on tree growth. Longer‐term studies and studies on less fertile sites are needed.

Mineralogy and leaching characteristics of beneficiated coal products from Santa Catarina, Brazil

Abstract Petrographic, mineralogical and geochemical studies have been carried out on beneficiated coal products from mines and preparation plants in the Santa Catarina Basin, southern Brazil, to investigate the range of characteristics exhibited by the materials and the potential impact of their stockpiling and storage on the environment. The coals contain varying proportions of vitrinite and inertinite macerals, and have vitrinite reflectance values ranging from 0.44 to 1.38%. With the exception of one material blended with peat from an external source, they have relatively high percentages of ash (30–58%) and mineral matter (36–66%). The mineral matter consists mainly of clay minerals (kaolinite, illite and illite/smectite), together with 15–25% quartz, up to 10% feldspar, up to 5% calcite and/or dolomite and up to 5% pyrite, and around 1% anatase and/or rutile. Bassanite is also present in low-temperature ash derived from the coals, mainly derived from interaction of Ca and S associated with the organic matter. Jarosite is formed by pyrite oxidation in coals that have been exposed in stockpiles for extended periods. Most of the trace elements in most of the coals have higher concentrations than average values for world coals generally, probably due to the relatively high mineral matter content. A lower-ash product representing a blend of coal and peat has similar to lower concentrations of most elements, but higher concentrations of B, Ba, Be, Cd, Ge and Mn, which may be associated with the peat component. Interaction of relatively fresh coals with water in laboratory tests produces leachates with near-neutral to mildly acid pH values, but leaching of oxidized, jarosite-bearing coal produces a strongly acid leachate, with higher concentrations of Cd, Co, Cu, Ni and Zn. Leachates derived from coals in which the pyrite has been oxidized during storage would thus be expected to have a more adverse environmental impact than leachates derived from coals in which such oxidation has not had an opportunity to develop.

Determination of trace elements in olive oil by ICP-AES and ETA-AAS: A pilot study on the geographical characterization

The determination of trace elements in edible oils is important because of both the metabolic role of metals and possibilities for adulteration detection and oil characterization. The most commonly used techniques for the determination of metals in oil samples are inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectrometry (AAS). For this study, a microwave assisted decomposition of the olive oil in closed vessels using a mixture of nitric acid and hydrogen peroxide was applied as sample preparation. The low achievable LODs enable the determination by ICP-AES of even very low concentrations of most elements of interest. The proposed ICP-AES method permits the determination of Ca, Fe, Mg, Na, and Zn in olive oils. Elements present in small amounts (Al, Co, Cu, K, Mn, Ni) were measured by ETA-AAS in the same sample digest. The concentrations of Al, Co, Cu, K, Mn, and Ni were in the range from 0.15 to 1.5 μg/g and differ according to the geographical origin of the oils. For the amounts of Fe, Mg, Na, and Zn in the samples, no significant differences according to the geographical origin of the oils could be observed, the mean concentrations being 15.31, 3.26, 33.10, and 3.39 μg/g, respectively. The Ca content varies in the range of 1.3 to 9.0 μg/g. The dependency of the trace elemental content of olive oils on their geographical origin can be used for their local characterization.

Geochemistry of the infiltrating water in the vadose zone of a remediated tailings impoundment, Kristineberg mine,northern Sweden.

At the remediated tailings Impoundment 1 at Kristineberg, Northern Sweden, installations of tension lysimeters were performed in the protective cover (10, 50, and 100 cm), in the oxidised tailings (150 cm), in the unoxidised secondarily enriched tailings (200 cm) and in the unoxidised tailings (260 cm). The lysimeters in the till protective cover contained relatively low concentrations of most elements. After infiltration through the sealing layer, consisting of 0.3 m compacted clayey till, pH decreased and conductivity, together with the concentrations of several major and trace elements, increased significantly. In the lysimeters installed in the tailings at depths of 150 and 200 cm average pH decreased to 3.4 at 150 cm and 3.2 at 200 and average conductivity increased to 2.9 mS/cm. Elements such as Al, Cd, Co, Fe, Mn, Mo, Ni,Pb, S, Si and Zn had the highest concentrations in the lysimeter at 200 cm depth. Examples of concentration averages for this lysimeter are Cd 600 μg/L, Fe 1500 mg/L, Mn 11 mg/L, Ni 1.06 μg/L, S 1800 mg/L, and Zn 190 mg/L. Between the depths of 200 and 260 cm the concentration of most elements decreased. The increase between the lysimeters at the depths of 150 and 200 cm can be explained by remobilization of secondarily retained oxidation products as well as from the continued oxidation. The decrease between the second and the third lysimeters is interpreted as co-precipitation with different Fe oxyhydroxides as well as adsorption onto secondarily formed minerals and primary mineral surfaces. Calculations of saturation indices indicate that several different hydroxides might precipitate at this level. This retainment takes place mainly due to the increase in pH. The pH increases from 3.2 up to 4–4.4 in this depth interval. Between the deepest lysimeter and the groundwater table, the element concentrations probably decrease even further. pH increases to 5–6.5 in the groundwater. Most of the pre-remediation oxidation products that are secondarily retained above or below the oxidation front and are released by the small amount of infiltrating water together with the present oxidation products are retained again during continued transport downwards. If the depth to the groundwater table is large enough, most of the metals released by the infiltrating water and the diffusing O 2 do not reach the groundwater.

The controls on the major- and trace-element evolution of shales, siltstones and sandstones of Ordovician to tertiary age in the Wet Mountains region, Colorado, U.S.A.

A vertical section of shales, siltstones and sandstones from Ordovician to Eocene age in a limited geographic area east of the Wet Mountains and Sangre de Cristo Mountains in Colorado have been analyzed for major elements and a variety of trace-element concentrations, including the REE. In addition, the petrography of the sandstones has been determined. The quartz-rich arenites contain considerably lower concentrations of most elements relative to coexisting shales or siltstones at the same outcrop. The arkosic sandstones contain similar to lower concentrations of most elements compared to coexisting shales or siltstones in the same area. Accordingly, the average concentrations of Al 2O 3, Fe 2O 3, MgO, TiO 2, LOI, Rb, Th, Co, Sc, Cr, Cs, Nb, Y and REE are significantly lower in all sandstones relative to all shales and siltstones. The exceptions are SiO 2, Na 2O and Ba concentrations, and the Eu/Eu ★, La Sc and Th Sc ratios as they are higher in the sandstones than the shales and siltstones. There is no significant difference in the MnO, CaO, K 2O and Sr concentrations or the sol La Co , Th Co , La Ni , Cr Th and ( La Lu cn ratios of the average sandstones relative to the shales and siltstones. Many of these differences may be related to the higher quartz and feldspar and lower clay mineral amounts in the sandstones than in the shales and siltstones. For example, average La Sc , Th Sc , Eu Eu ★ and ( La Lu cn ratios of th arkosic sandstones tend to be higher than the coexisting shales and siltstones due to enrichment of the arkoses in feldspar relative to the other minerals (e.g., Eu Eu ★ = 0.82 ± 0.19 in average arkoses in the Trinidad, Vermejo, Raton, Poison Canyon and Cuchara Formations; Eu Eu ★ = 0.63 ± 0.19 in average shales and siltstones in the same formations). In addition, the elemental concentrations and ratios are more variable for most elements in the sandstones than the shales and siltstones. This suggests that the shales are rapidly homogenized near the source. The elemental fractionation in the arkosic sandstones due to enrichment of feldspar relative to other minerals suggests that they are poorer indicators of provenance that the associated shales, whereas, the more homogeneous elemental distributions in the shales and siltstones suggest that they may be better indicators of provenance than the sandstones. Nevertheless, the elemental ratios that are most similar in the sandstones and in the shales and siltstones are consistent with their derivation from similar average intermediate to silicic source rocks.

Studies of elemental distributions within discrete coal macerals: Use of secondary ion mass spectrometry and X-ray photoelectron spectroscopy

Secondary ion mass spectrometry has been used to measure qualitatively the distributions of many trace and minor elements within some well-characterized coal macerals: vitrinite, fusinite and exinite. Complementary information was obtained by using X-ray photoelectron spectroscopy. Within the vitrinite specimens studied, a widely-dispersed largely inorganic aluminosilicate phase was identified, which contained a number of other trace elements. By contrast, within the organic-rich phase of this macerai, titanium was detected in a very even distribution; this suggests that some titanium may be bonded in an organic complex. The fusinite was shown to contain elevated concentrations of calcium, magnesium and fluorine, dispersed over a large portion of the maceral. The high fluorine content could be identified as an organo-fluoro compound using XPS. Exinite was found to contain lower concentrations of most elements, compared to other macerals. The organic composition of this maceral was significantly different from that of surrounding macerals; this could be seen from the enhanced emission of the C 2H 2-secondary ion and images of this ion thus clearly outlined the position of such macerals.