Losses Of Cu Research Articles

Copper plasmonics with excitons

We investigate the propagation of surface plasmons (SPPs) in a thin layer of copper surrounded by copper oxide Cu$_2$O. It is shown that particularly strong excitons in Cu$_2$O can have considerable impact on plasmon propagation, providing many opportunities for plasmon-exciton and plasmon-plasmon interactions. It is demonstrated that by the use of sufficiently thin metal layer, one can excite the so-called long range plasmons (LRSPPs) which can overcome the inherently high ohmic losses of Cu as compared to usual plasmonic metals such as silver. Analytical results are confirmed by numerical calculations.

Effects of varying sources of Cu, Zn, and Mn on mineral status and preferential intake of salt-based supplements by beef cows and calves and rainfall-induced metal loss.

Three studies were completed to evaluate the effects of Cu, Zn, and Mn source on preferential intake, trace mineral status, and rainfall-induced metal loss of salt-based mineral supplements. Mineral supplements were formulated to contain 2,500, 5,500, and 4,000 mg/kg of Cu, Zn, and Mn, respectively. Supplements differed only by source of Cu, Zn, and Mn, which were hydroxychloride, organic, or sulfate sources. In Exp. 1, the three formulations were offered simultaneously for 18 wk to preweaned beef calves (four pastures; 17 calves per pasture) within separate containers inside covered cow-exclusion areas. Consumption averaged 21 ± 2.4 g/calf daily (sum of all three sources), with a greater (P < 0.001) percentage of the total intake coming from the hydroxychloride vs. organic or sulfate sources of Cu, Zn, and Mn. In Exp. 2, the same sulfate and hydroxychloride formulations were randomly assigned to pastures (n = 4 pastures per treatment) containing 18 to 20 cow–calf pairs/pasture. Treatments were offered for 20 wk within covered areas designed to assess cow and calf intake separately. At weaning, liver biopsies were collected from four cow–calf pairs/pasture (n = 16 cows and calves per treatment). Source of Cu, Zn, and Mn had no effect on voluntary mineral intake among calves (P = 0.44) and cows (P = 0.14). Calves consuming mineral containing hydroxychloride sources of Cu, Zn, and Mn tended (P = 0.06) to have greater average daily gain over the 20-wk period compared with calves consuming sulfate sources of the same elements (1.09 vs. 1.06 kg/d; SEM = 0.013). Mineral status of cows and calves was not affected (P ≥ 0.17) by source of Cu, Zn, and Mn. In Exp. 3, each of the mineral formulations from Exp. 1 was exposed to a 10.2-cm precipitation event delivered in three equal 3.4-cm applications within a week. To accomplish this, 750 g of mineral was placed into Buchner funnels (177 cm2) on 20- to 25-µm pore filter paper. Deionized water (pH adjusted to 5.6) was poured over the mineral. Total leaching losses of Cu, Zn, and Mn were less (P < 0.001) for formulations containing hydroxychloride vs. organic and sulfate sources. These results imply that, when offered a choice, calves preferentially consume mineral supplements formulated with hydroxychloride vs. sulfate or organic sources of Cu, Zn, and Mn. In addition, hydroxychloride sources of Cu, Zn, and Mn are less susceptible to rainfall-induced leaching losses compared with sulfate and organic sources.

Probabilistic assessment of the daily intake of microelements and toxic elements via the consumption of rice with different degrees of polishing.

The polishing process plays a key role in determining the beneficial quality of rice. However, the effects of polishing on human exposure to essential and toxic elements are not well reported. This study evaluated the effects of polishing on the levels of essential and toxic elements in rice grains and evaluated the status of their daily intake using probabilistic assessment. The levels of essential elements decreased as the degree of polishing increased. The highest reduction percentages of essential elements [24% of copper (Cu), 26% of nickel (Ni), and 52% of manganese (Mn)] were found after the first polishing step. The highest zinc (Zn) reduction (15%) was found after the fourth polishing step. For toxic elements, polishing significantly reduced the arsenic (As) concentration (15-31%) from that of the whole grains, of which 26% was removed after the first step. Polishing removed both essential and toxic elements from rice grains. The highest losses of Cu, Mn, Ni, and As were found after the first polishing step since these elements generally localize in the aleurone layers of rice grains. The last polishing step caused a significant Zn reduction from the grain. Polishing had no significant effect on the cadmium (Cd) concentration in grains. The consumption of all types of rice could not supply sufficient amounts of all microelements except Mn to maintain optimum health. Both As and Cd intake levels were lower than the benchmarks of toxic health effects. Thus, the potential health impacts of both of these elements in rice can be neglected. © 2020 Society of Chemical Industry.

Impact of (nano)formulations on the distribution and wash-off of copper pesticides and fertilisers applied on citrus leaves

Environmental contextThere are great concerns around current wide usage of copper-based agrochemicals. We compare the fate of nano- and conventional forms of copper, in particular their resistance to wash-off by rain (rainfastness), following their application to citrus leaves. Results showing large differences between the formulations in the amount and forms of copper washed from the leaves provide essential information to optimise agrochemical efficacy while minimising the environmental impact. AbstractThis study compares the rainfastness of nine forms of Cu, including nano and conventional Cu-based fungicide formulations, as well as their salt or bulk equivalents. Rainfastness is the ability to resist wash-off; it is a key property for improving pesticide formulations and for assessing the potential transfer of pesticides to the soil. A new protocol was developed to characterise losses of Cu from treated leaves. It consisted of dipping the leaves in rainwater and then in an acid/ethanol mixture followed by size fractionation. The proportion of Cu lost by wash-off from citrus leaves ranged from &amp;lt;2% (Tribasic, nCuO or Cu(OH)2) up to 93% (CuSO4) of the initial amount of Cu applied. Intermediate Cu losses were observed for formulations with silica (nano)particles (9–14% of applied Cu), Kocide (22%), ChampDP (31%), and a formulation with graphene oxide (47%). Smaller particles generally resulted in less wash-off, possibly due to stronger attachment to the leaf surface, but other factors such as the particle shape and solubility also played an essential role. The retention of nCuO to the leaves was particularly high, and the exact mechanisms involved (e.g. foliar uptake) deserve further work. Most of the Cu was washed off in its ionic form (&amp;gt;74%). Two Cu formulations (one commercial formulation and the formulation with graphene oxide) also showed wash off in significant proportions of Cu (~17%) in the nano-sized fraction. This study provides essential information on the amounts and forms of Cu that may reach the soil after the application of Cu-based agrochemicals. The great diversity in behaviour across the range of formulations considered highlights the need for more systematic research to fully exploit the potential improvements of current agrochemicals through (nano)formulation technologies.

Trace element repletion following severe burn injury: A dose-finding cohort study

Major burn patients are characterized by large exudative losses of Cu, Se and Zn. Trace element (TE) repletion has been shown to improve clinical outcome. Having increased the TE doses over time, the study aimed at analysing if our repletion protocol corrected TE plasma concentrations and if the necessity for continuous renal replacement therapy (CRRT) might increase the TE needs. Retrospective analysis of prospectively collected data in burn patients requiring intensive care (ICU) between 1999 and 2015. Admission on day 1, full treatment, burned surface area (TBSA) ≥20% and ≥1 TE plasma determination during the stay. Four groups were constituted according to protocol changes. Period 1 (P1): 1999-2000, P2: 2001-2005, P3: 2006-2010, P4: 2011-2015. Changes consisted in increasing TE repletion doses and duration. Demographic data, daily TE intakes and weekly plasma concentrations were retrieved for the first 21 ICU-days. Data as median (IQR). 139 patients completed the criteria, aged 37 (28) years, burned on 35 (25) % TBSA. As a result of prescription, Cu, Se and Zn intakes increased significantly between P1 and P4, resulting in normalization of plasma Cu (16μmol/l) since P3 and Zn (13.5μmol/l) since P2. Median plasma Se were above reference range (1400nmol/l) during P3 and P4. CRRT patients required higher doses of Cu for maintenance within normal ranges. This dose finding study shows that the latest repletion protocol is safe and normalizes Cu and Zn concentrations. Se doses result in supra-normal Se concentrations, suggesting prescription reduction. CRRT patients are at high risk of Cu depletion and require specific monitoring.

Reaction of native copper in contact with pyrite and bentonite in anaerobic water at elevated temperature

ABSTRACTCopper pellets were reacted with different solutions, reference minerals, and well-characterised bentonites to investigate the effect of different bentonites on the stability of native copper in repository concepts for high-level radioactive waste. The reaction of Cu in contact with bentonite used as barrier material to store high-level radioactive waste was significantly affected by the presence of sulphides (e.g. pyrite) leading to a specific corrosion. Bentonites free of pyrite are not actively involved in a reaction with Cu. Nevertheless, slightly different Cu mass losses were found for different bentonites. For different bentonites, different coatings were found on the Cu surface. The characteristics of these coatings are probably responsible for different Cu mass losses of Cu in contact with different bentonites. As an example, particularly dense coatings led to a decrease in Cu mass loss. No relation of the Fe-corrosivity of different bentonites with Cu mass loss was found, which proves that the Fe-corrosion mechanism differs from the Cu-corrosion at the metal/bentonite interface. The experiments also demonstrated the importance of the presence even of traces of oxygen.

Continuous flow 70 °C archaeal bioreactor for iron oxidation and jarosite precipitation

This study is the first demonstration of a continuous culture bio-catalysed iron oxidation and jarosite precipitation reactor using thermophilic archaea, for use in hydrometallurgical process flow sheets to oxidize and partially remove iron from solution while minimizing valuable base metal (i.e. Ni and Cu) losses. A two-stage continuous stirred tank reactor (CSTR) system comprised of two CSTRs, each with its own settler, was operated to achieve biological iron oxidation and precipitation at 70°C. The two-stage reactor configuration was used to allow the growth of microorganisms that prefer different redox regimes. The bioreactors were inoculated with a mixed culture of extreme thermophilic iron oxidisers from genera Acidianus, Metallosphaera and Sulfolobus. The influent (pH1.5) contained (gL−1): 15 Fe2+, 1.5 Cu, 1.5 Ni (all as sulfates), nutrients and trace elements. The system demonstrated efficient iron oxidation and precipitation of the oxidised iron in the form of well settling jarosite with only minor losses of Cu and Ni via co-precipitation. At a total hydraulic retention time (HRT) of 13–14h in the two reactors, the overall iron oxidation rate was up to 1.0gL−1h−1 and conversion extent of >95%. During this time, the pH values were 1.3–1.6 and 1.3–1.6, and redox potentials (Ag/AgCl reference) were 440–530mV and 510–610mV, in the first and second reactor, respectively. The extent of Fe and sulfate removal, was relatively high, 52 and 25% respectively, while valuable Cu and Ni losses were low, i.e. 0.46% and 0.03%, respectively. The precipitates were exclusively jarosite, with potassium jarosite being the dominant form (38–51%), followed by hydronium (30–35%), ammonium (13–18%) and sodium jarosites (6–9%). The precipitates had good settling properties facilitating effective solid–liquid separation. Bioreactor performance was, however, found to be sensitive to instantaneous exposure to high concentrations of typical contaminants in hydrometallurgical processing streams, when added simultaneously. The addition of (gL−1) 2.0 Al, 0.05 As, 0.05F, 0.2 Co, 5.0 Mg and 0.4 Mn to the influent solution decreased iron oxidation and jarosite content in precipitates.

Hydrothermal conversion of graphite to carbon nanotubes (CNTs) induced by bubble collapse

Cu–Fe–CNTs and Ni–Fe–CNTs coatings were deposited on gray cast iron by a hydrothermal approach. It was demonstrated that, the flaky graphite of gray cast iron was exfoliated to graphene nanosheets under hydrothermal reactions, and graphene nanosheets were scrolled to CNTs. After high temperature treatments, the volume losses of Cu–Fe–CNTs and Ni–Fe–CNTs coatings were 52.6 % and 40.0 % of gray cast iron substrate at 60min wear tests, respectively, obviously increasing the wear properties of gray cast iron. During hydrothermal reactions, water jets and shock waves were produced by bubble collapse. Induced by the water jets and shock waves, exfoliation of flaky graphite was performed, producing exfoliated graphene nanosheets. Attacked by the radially distributed water jets and shock waves, graphene nanosheets were curved, shaped to semicircle morphology and eventually scrolled to tubular CNTs.

Arc Erosion Behavior of Cu–0.23Be–0.84Co Alloy after Heat Treatment: An Experimental Study

The arc erosion behavior of Cu–0.23Be–0.84Co alloy after heat treatment was investigated experimentally by a JF04C electric contact test system. The arc duration, arc energy, contact resistance and contact pressure of Cu–0.23Be–0.84Co alloy after solution treatment and aging treatment were analyzed. The arc erosion morphologies were contrastively observed by a three-dimensional measuring system and scanning electron microscopy. For the Cu–0.23Be–0.84Co alloy in solution state and aging state, the maximum values of arc duration are 90 and 110 ms, and the arc energies are 15,000 and 18,000 mJ, respectively. The maximum value of the contact resistance of Cu–0.23Be–0.84Co alloy in different states is about 33 mΩ. The contact pressure of Cu–0.23Be–0.84Co alloy in solution state generally changes between 50 and 60 cN during whole make-and-break contacts, while in aging state, it has a larger fluctuation range. Moreover, the quality of moving contact (anode) decreases, while static contact (cathode) increases. The materials transfer from anode to cathode during make-and-break contacts. The total mass losses of Cu–0.23Be–0.84Co alloy in solution state and aging state are 3 and 1.2 mg, respectively. In addition, a number of discrete corrosion pits, molten droplet, porosity and cavity distribute on the surface of moving contact and static contact. The arc erosion model of Cu–0.23Be–0.84Co alloy in make-and-break contact was built. The arc erosion resistance of Cu–0.23Be–0.84Co alloy after heat treatment is closely related to the microstructure and the properties of contact materials. This experimental study is important to evaluate the anode or cathode electrocorrosion fatigue life.

Biohydrometallurgical iron oxidation and precipitation: Part II — Jarosite precipitate characterisation and acid recovery by conversion to hematite

This study reports the characterisation of precipitates formed in a two-stage continuous stirred tank bioreactor (CSTR) system operated for continuous iron oxidation and removal from high strength iron liquor. The system was operated at ambient temperature without biomass carrier or neutralising agent addition. The elemental composition of the precipitates, for each of the influent pH solutions (pH1.1–2.2), contained varying amounts (%w/w) of Fe (29.2–34.0%), S (11.8–13.2%), K (0.92–5.67%), N (0.10–0.77%), Na (0.055–0.74%), Cu (0.044–0.15%) and Ni (0.002–0.016%). Importantly, the process resulted in efficient precipitation of ferric iron and sulphate with only minor co-precipitation losses of Cu and Ni, making it suitable for use in base metal process flow sheets. The precipitates were predominantly (75–99%) jarosite, with potassium jarosite formation occurring preferentially over that of hydronium, ammonium and sodium jarosite. The jarosite precipitate showed good filterability and settling characteristics which are important for larger scale industrial processes. The jarosite precipitates could be readily converted to hematite and acid by autoclaving at 225°C. The physical and chemical characterisation of jarosite, determined in this study, is relevant in the design and deployment of iron oxidation, precipitation and residue treatment processes in hydrometallurgical flow sheets.

Modeling the influence of raindrop size on the wash-off losses of copper-based fungicides sprayed on potato (Solanum tuberosum L.) leaves

Modeling the pesticide wash-off by raindrops is important for predicting pesticide losses and the subsequent transport of pesticides to soil and in soil run-off. Three foliar-applied copper-based fungicide formulations, specifically the Bordeaux mixture (BM), copper oxychloride (CO), and a mixture of copper oxychloride and propylene glycol (CO-PG), were tested on potato (Solanum tuberosum L.) leaves using a laboratory raindrop simulator. The losses in the wash-off were quantified as both copper in-solution loss and copper as particles detached by the raindrops. The efficiency of the raindrop impact on the wash-off was modeled using a stochastic model based on the pesticide release by raindrops. In addition, the influence of the raindrop size, drop falling height, and fungicide dose was analyzed using a full factorial experimental design. The average losses per dose after 14 mm of dripped water for a crop with a leaf area index equal to 1 were 0.08 kg Cu ha−1 (BM), 0.3 kg Cu ha−1 (CO) and 0.47 kg Cu ha−1 (CO-PG). The stochastic model was able to simulate the time course of the wash-off losses and to estimate the losses of both Cu in solution and as particles by the raindrop impacts. For the Cu-oxychloride fungicides, the majority of the Cu was lost as particles that detached from the potato leaves. The percentage of Cu lost increased with the decreasing raindrop size in the three fungicides for the same amount of dripped water. This result suggested that the impact energy is not a limiting factor in the particle detachment rate of high doses. The dosage of the fungicide was the most influential factor in the losses of Cu for the three formulations studied. The results allowed us to quantify the factors that should be considered when estimating the losses by the wash-off of copper-based fungicides and the inputs of copper to the soil by raindrop wash-off.

Trace metal leaching in a spodosol irrigated with tomato packinghouse wastewater

Tomato packinghouse wastewater is often applied to land in Florida, but the sandy soils, low levels of organic matter, shallow groundwater and abundant rainfall present favourable conditions for leaching of wastewater-borne trace metals. We investigated the leaching of copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) from a sandy siliceous, hyperthermic Oxyaquic Alorthods packed in two distinct soil horizons (Ap and A/E) in 12 polyvinyl chloride soil columns (30 cm internal diameter × 50 cm length). Thirty leaching events were conducted by daily applying tomato packinghouse wastewater at low (0.84 cm/day), medium (1.68 cm/day) and high (2.51 cm/day) rates for 30-days period. Control treatment received de-ionized water at the same application rate as the medium treatment (1.68 cm/day). Application of wastewater at three rates did not affect the mean concentrations of Cu in leachate (0.19–0.2 mg/L) because of retention of Cu in the soil profile. However, leachate Zn concentrations were twice as much (0.3–0.32 mg/L) following wastewater application than for the control (0.13 mg/L) treatment. Leaching losses of Cu and Zn were smaller with the medium wastewater treatment (similar to control treatment) than for the high wastewater treatment. Concentrations of Cu and Zn at the 50 cm soil depth were much less than the drinking water standards, suggesting a minimum risk of groundwater contamination under fields to which wastewater was applied. Our results imply that tomato packinghouse wastewater can be safely land-applied at 1.68 cm/day to Florida’s Spodosols under vegetable production without concerns of significant trace metal leaching.

Effects of Chelating Compounds on Mobilization and Phytoextraction of Copper and Lead in Contaminated Soils

Six chelating compounds: ethylenediamine-tetraacetic acid (EDTA), ethylenediamine-N, N'-disuccinic acid (EDDS), tartaric acid, citric acid, glycine and histidine, were tested as potential agents to mobilize copper (Cu) and lead (Pb) from two soils polluted with the emissions from copper smelters. Copper was mobilized with the following efficiency: EDTA > citric and tartaric acids > histidine > EDDS and glycine, while Pb extractability followed the order: EDTA > EDDS >> tartaric and citric acid >> glycine and histidine. With respect to these results, EDTA and EDDS were chosen for a pot experiment on chelate-induced phytoextraction of Cu and Pb by maize (Zea mays). Chelates were applied at the rates of 0.2, 0.5, and 1.0 mmol kg−1, and this experiment was carried out at two different watering regimes. Both EDTA and EDDS caused significant increase of Cu uptake from soils, but its concentrations in biomass were far below those required for efficient soil remediation. Lead uptake was only slightly affected by chelate application. Losses of Cu from soil by leaching were much higher than those caused by plant uptake.

Investigation of a Flotation Process with De-Sliming and Attrition to Upgrade and Recover Cu and Mo from a Cu-Mo Flotation Tailing

In some (Cu-Mo) mines around the world, Mo recovery is low due to poor liberation, fine dissemination in gangue minerals, and losses of Cu and Mo to tailing streams. Studies to recover these materials as a new resource will increasingly become an attractive option. In the current study, a flotation tailing sample obtained from a mine recovering only 40% Mo was re-floated to upgrade Cu and Mo. The sample containing 0.07% Cu and 0.01% Mo, was used in the study and the goal was to improve the grades to over 2.0% Cu and 0.5% Mo, to obtain an additional feed for the flotation process. Sodium aluminium silicate (NaAlSi3O8) and quartz (SiO2) were observed as the dominant mineral phases. The original samples were milled and screened to pass 105 μm screen to be used in the subsequent tests. To evaluate the efficiency of the process, both single and multi-stage flotation steps including de-sliming for the removal of fines and attrition for surface activation, together with other parameters (pH, PAX concentration, time) were performed. Based on the experimental results, a four-stage flotation process allowed the improvement of Cu and Mo grades to 1.63% and 0.24% respectively. A single-stage flotation process with de-sliming and attrition stages before flotation with PAX and MIBC concentrations of 40 g/t improved Cu and Mo grades to 2.07% and 0.64%, with a recovery of 48.60% and 65.97% respectively.

Leaching potential of heavy metals (Cd, Ni, Pb, Cu and Zn) from acidic sandy soil amended with dolomite phosphate rock (DPR) fertilizers

There is an increasing concern on heavy metal leaching from the soils amended with sewage sludge. A column study was conducted to examine the extent of leaching of five important heavy metals (Cd, Ni, Pb, Cu and Zn) from an acidic sandy soil amended with different dolomite phosphate rock (DPR) fertilizers (an application rate of 1% fertilizers) developed from DPR and N-Viro (consisting of biosolids and fly ash) at 0%, 10%, 20%, 30%, 40%, 50% and 100% DPR. Ten leaching events were carried out with each event done at an interval of 7 days and with total leaching volume of 1183 mm, which is equivalent to the mean annual rainfall of this region during the period of 2001–2003. Leachate was collected after each leaching event and analyzed for heavy metals. The maximum leachate concentrations of Cd, Ni, Pb, Cu and Zn were all below drinking water quality guidance limits set by Florida Department of Environmental Protection and World Health Organization, suggesting that the application of DPR fertilizers may not pose a threat to water quality by leaching. Most of leachate concentrations of Cd, Ni and Pb were below their detection limits and there were no significant differences between the control and the treatments with different DPR fertilizers. By contrast, there were higher leachate concentrations of Cu and Zn (ranging from 0.7 to 37.1 μg Cu/l and 5.1 to 205.6 μg Zn/l for all treatments) due to their higher contents in both the soil and different DPR fertilizers compared with Cd, Ni and Pb. The leachate concentrations of Cu and Zn for each treatment decreased with increasing leaching events. The differences in leachate concentrations of Cu and Zn between the control and the treatments with different DPR fertilizers containing N-Viro were significant, especially in the first several leaching events and, moreover, they increased with increasing proportion of N-Viro in the DPR fertilizers. There were similar trends in total losses of Cu and Zn after ten leaching events. Greater differences in both leachate concentrations and total losses of Zn between the control and the treatments containing N-Viro were noted. Total losses of Zn for the treatments containing N-Viro were 3.0–5.1 times higher than those for the control compared with 1.4–2.2 times higher for total losses of Cu, suggesting that greater proportions of Zn losses came from the DPR fertilizers due to the greater mobility of Zn in the DPR fertilizers compared with Cu.

Influence of leaching medium and drying time between successive leaching periods on the emission of chromium, copper, and boron from treated wood

Laboratory studies were conducted to determine leaching of Cu, Cr, and B from pine sapwood treated with Cr-Cu-B (CCB) preservative in different leaching media (ultrapure water [UPW], rainwater [RW], and soil water [SW]). Losses of metals from CCB-treated wood, expressed in percentage of initial content, were always highest for B (11.2-63.5%) and lowest for Cr (0.02-0.36%) in any of the leaching media assayed. Losses of B and Cr from treated wood were not affected by the leaching medium; however, losses of Cu were 1.5 to 2.5 times higher in SW than in UPW and RW. The influence of drying time between successive leaching periods on release of metals also was determined. Treated wood was submitted to wetting-drying cycles of 24 h/d, 18 h/d, and 6 h/d in contact with the leaching medium over a total contact time of 276 h. For an equivalent contact period of CCB-treated wood with either UPW or RW, leaching of B was from 1.1 to 1.9 times higher for continual wetting than under intermittent wetting conditions. Leaching of Cu was not affected by the wetting-drying periods when wood was in contact with RW, but it was 1.2 to 1.5 times higher for continual wetting with UPW. In general, leaching of Cr was not affected by the wetting-drying cycles when in contact with UPW or RW. However, when CCB-treated wood was in contact with SW under discontinuous wetting of 6 h/d, Cu and Cr emissions were approximately 1.2 and 2.5 times higher, respectively, than with continuous wetting. This study shows that the type of leaching medium and the drying time between successive wetting periods must be considered when evaluating metal losses from CCB-treated wood during service life.

Surface runoff losses of copper and zinc in sandy soils.

Increased anthropogenic inputs of Cu and Zn in soils have caused considerable concern relative to their effect on water contamination. Copper and Zn contents in surface soil directly influence the movement of Cu and Zn. However, minimal information is available on runoff losses of Cu and Zn in agricultural soils, and soil-extractable Cu and Zn in relation to runoff water quality. Field experiments were conducted in 2001 to study dissolved Cu and Zn losses in runoff in Florida sandy soils under commercial citrus and vegetable production and the relationship between soil-extractable Cu and Zn forms and dissolved Cu and Zn concentrations in runoff water. Five extraction methods were compared for extracting soil available Cu and Zn. Concentrations of dissolved Cu and Zn in runoff were measured and runoff discharge was monitored. Mean dissolved Cu in field runoff water was significantly correlated with the extractable Cu obtained only by 0.01 mol L(-1) CaCl2, Mehlich 1, or DTPA-TEA methods. Dissolved Zn in runoff water was only significantly correlated with extractable Zn by 0.01 mol L(-1) CaCl2. The highest correlations to dissolved Cu in runoff were obtained when soil-available Cu was extracted by 0.01 mol L(-1) CaCl2. The results indicate that 0.01 mol L(-1) CaCl2-extractable Cu and Zn are the best soil indexes for predicting readily released Cu and Zn in the sandy soils. Both runoff discharge and 0.01 mol L(-1) CaCl2-extractable Cu and Zn levels had significant influences on Cu and Zn loads in surface runoff.

Surface Runoff Losses of Copper and Zinc in Sandy Soils

Increased anthropogenic inputs of Cu and Zn in soils have caused considerable concern relative to their effect on water contamination. Copper and Zn contents in surface soil directly influence the movement of Cu and Zn. However, minimal information is available on runoff losses of Cu and Zn in agricultural soils, and soil-extractable Cu and Zn in relation to runoff water quality. Field experiments were conducted in 2001 to study dissolved Cu and Zn losses in runoff in Florida sandy soils under commercial citrus and vegetable production and the relationship between soil-extractable Cu and Zn forms and dissolved Cu and Zn concentrations in runoff water. Five extraction methods were compared for extracting soil available Cu and Zn. Concentrations of dissolved Cu and Zn in runoff were measured and runoff discharge was monitored. Mean dissolved Cu in field runoff water was significantly correlated with the extractable Cu obtained only by 0.01 mol L−1 CaCl2, Mehlich 1, or DTPA–TEA methods. Dissolved Zn in runoff water was only significantly correlated with extractable Zn by 0.01 mol L−1 CaCl2 The highest correlations to dissolved Cu in runoff were obtained when soil-available Cu was extracted by 0.01 mol L−1 CaCl2 The results indicate that 0.01 mol L−1 CaCl2–extractable Cu and Zn are the best soil indexes for predicting readily released Cu and Zn in the sandy soils. Both runoff discharge and 0.01 mol L−1 CaCl2–extractable Cu and Zn levels had significant influences on Cu and Zn loads in surface runoff.

Total metal concentrations in serum of dialysis patients and fractionation of Cu, Rb, Al, Fe and Zn in spent continuous ambulatory peritoneal dialysis fluids

Total metal concentrations were determined in the serum of 12 continuous ambulatory peritoneal dialysis (CAPD) patients and in fresh and spent CAPD fluids by electrothermal and flame atomic absorption spectrometry (ETAAS, FAAS). Concentrations of Cu in serum of CAPD patients ranged from 720 to 1780 ng cm −3, Rb from 128 to 346 ng cm −3, Al from 10 to 72 ng cm −3, Fe from 800 to 2300 ng cm −3 and Zn from 659 to 1310 ng cm −3. The accuracy of the analytical procedure was checked by the analysis of the reference material Seronom™, Trace Elements in Serum. Good agreement between the certified and determined values was obtained for Al, Cu, Fe and Zn. The data on the total metal concentrations in CAPD fluids indicated that during CAPD fluid exchange the losses of Cu from 5.0 to 35 ng cm −3, of Rb from 50 to 110 ng cm −3 and of Al from 3.0 to 14.0 ng cm −3 occurred through the peritoneal membrane. Although fresh CAPD fluids contained traces of Fe (3.0–5.0 ng cm −3), the transfer of this element took place through the peritoneal membrane into spent CAPD fluid (13.0–38.0 ng cm −3). Zn concentrations were in general lower in spent (20.0–80 ng cm −3) than in fresh CAPD fluids (∼100 ng cm −3). To follow the mechanisms of the transfer of trace elements through the peritoneal membrane of CAPD patients, fractionation of metals was carried out in spent CAPD fluids by size exclusion chromatography with UV and AAS detection, applying Superdex HR 10/30 column. The chromatographic run was followed at 278 nm and separated metal species also determined ‘off line’ in 1 cm 3 fractions by ETAAS or FAAS. From the UV chromatograms and AAS analysis of trace elements in the separated fractions it was demonstrated that Cu, Al, Fe and Zn were bound to proteins and only partially to low molecular weight (LMW) species, while Rb was associated exclusively with LMW species. For characterisation of the high molecular weight (HMW) binding proteins, fractions containing trace elements were subjected to SDS-PAGE electrophoresis. Al and Fe were presumably bound to transferrin, but due to its low concentration in spent CAPD fluids, it was not possible to confirm its presence in the separated fractions. About 10% of Al and 15% of Fe corresponded to LMW species. A fraction of HMW proteins of Cu in spent CAPD fluids was most probably bound to albumin and Zn to albumin and globulins. About 50% of Cu and Zn existed in LMW proteins, while Zn was also found partially in ionic form.

Propagation losses of copper-ion-exchanged channel optical waveguides

We have measured the propagation losses of Cu—Na-ion-exchanged channel glass waveguides using both scattering and interferometric methods. In the first method, the waveguide was coated with a fluorescence film to enhance the scattered optical field along the channel waveguide which was then captured by a charge-coupled device camera. A straight line is adjusted to the intensity profile by the least-squares method, and the slope yields the attenuation coefficient. In the interferometric method, the temperature of the waveguides was changed and the intensity output was, measured. From contrast changes of waveguide's intensity output, the attenuation coefficient is calculated. Also, an analysis of the optical absorption of copper waveguides in the 200–1900 nm range to detect the copper oxidation state is presented.