Using Lichen Chemistry to Assess Airborne Tungsten and Cobalt in Fallon, Nevada

This paper describes the use of lichen chemistry to assess airborne tungsten and cobalt in Fallon, Nevada, where a cluster of childhood leukemia has been on going since 1997. Lichens and their rock substrates were collected from Rattlesnake Hill within Fallon as well as from four different rock outcrops located north, east, south, and west of Fallon and at least 20 km away from the town center. In the lichens themselves, W and Co are significantly higher within Fallon than in the combined control site outside of Fallon. In the rock substrates of the lichens, no differences exist in W and Co. The W and Co differences in lichens cannot be attributed to substrate geochemistry. Fallon is distinctive in west central Nevada for high airborne W and Co, and given its cluster of childhood leukemia, it stands to reason that additional biomedical research is in order to test directly the leukogenicity of combined airborne W and Co.     

Estimated Variability of National Atmospheric Deposition Program/Mercury Deposition Network Measurements Using Collocated Samplers

The National Atmospheric Deposition Program/Mercury Deposition Network (MDN) provides long-term, quality-assured records of mercury in wet deposition in the USA and Canada. Interpretation of spatial and temporal trends in the MDN data requires quantification of the variability of the MDN measurements. Variability is quantified for MDN data from collocated samplers at MDN sites in two states, one in Illinois and one in Washington. Median absolute differences in the collocated sampler data for total mercury concentration are approximately 11% of the median mercury concentration for all valid 1999–2004 MDN data. Median absolute differences are between 3.0% and 14% of the median MDN value for collector catch (sample volume) and between 6.0% and 15% of the median MDN value for mercury wet deposition. The overall measurement errors are sufficiently low to resolve between NADP/MDN measurements by ±2 ng·l⁻¹ and ±2 μg·m⁻²·year⁻¹, which are the contour intervals used to display the data on NADP isopleths maps for concentration and deposition, respectively.     

A near real-time system for continuously monitoring airborne subtilisin-type enzymes in the industrial atmosphere

We describe the development and validation of a portable system comprising an air sampler coupled to an automated flow injection analysis device. The system is able to monitor airborne concentrations of subtilisin-type enzymes in the workplace atmosphere on a continuous basis. Sampling is in two stages: using a sampling head that is designed to mimic human respiration at approx. 1 m s(-1) at a sampling rate of 600 l min(-1). In the second stage, the captured particles are deposited by impaction from the air stream onto the inner surface of a cyclone that is continuously washed with a jet of buffer solution. Deposited particles are then washed into a reservoir from which samples are taken every 5-6 min and injected automatically into a continuous flow injection analysis system. Proteolytic enzyme in the sample passes through a bioreactor maintained at about 40 degrees C. This contains a cellulose solid phase matrix on which is covalently immobilised Texas Red-labelled gelatin as substrate. The passing enzyme partially digests the substrate releasing fluorophore that is detected down stream in a flow cell coupled to a fluorimeter. The system is calibrated using enzyme standards and the intensity of the resulting peaks from the ex-air samples is converted to airborne concentrations using a mathematical model programmed into a PC. The system has a limit of detection of 4.8 ng m(-3) and a dynamic range of 5-60 ng m(-3). The within assay precision (RSD) is 6.3-9.6% over this range. The within batch precision is 20.3% at 20 ng m(-3) and the corresponding between batch value is 19.5%. The system has been run for periods up to 8 h in the laboratory and for up to 4 h at a factory site and the values obtained compared with time-averaged values obtained from a conventional Galley sampler and in-house analysis when reasonable agreement of the results was observed. The stability of the system over 21 days of continuous use with standards injected periodically was studied. Linearity was observed for all the standard plots throughout. At the end of 21 days, after a total exposure equivalent to 2395 ng ml(-1) of Savinase, the signal due to the 5.0 ng ml(-1) standard was still easily detectable.     

Photodegradation of organophosphorus insecticides - investigations of products and their toxicity using gas chromatography-mass spectrometry and AChE-thermal lens spectrometric bioassay

Four organophosphorus compounds: azinphos-methyl, chlorpyrifos, malathion and malaoxon in aqueous solution were degraded by using a 125 W xenon parabolic lamp. Gas chromatography-mass spectrometry (GC-MS) was used to monitor the disappearance of starting compounds and formation of degradation products as a function of time. AChE-thermal lens spectrometric bioassay was employed to assess the toxicity of photoproducts. The photodegradation kinetics can be described by a first-order degradation curve C=C0e(-kt), resulting in the following half lives: 2.5min for azinphos-methyl, 11.6 min for malathion, 13.3 min for chlorpyrifos and 45.5 min for malaoxon, under given experimental conditions. During the photoprocess several intermediates were identified by GC-MS suggesting the pathway of OP degradation. The oxidation of chlorpyrifos results in the formation of chlorpyrifos-oxon as the main identified photoproduct. In case of malathion and azinphos-methyl the corresponding oxon analogues were not detected. The formation of diethyl (dimethoxy-phosphoryl) succinate in traces was observed during photodegradation of malaoxon and malathion. Several other photoproducts including trimethyl phosphate esters, which are known to be AChE inhibitors and 1,2,3-benzotriazin-4(3H)-one as a member of triazine compounds were identified in photodegraded samples of malathion, malaoxon, and azinphos-methyl. Based on this, two main degradation pathways can be proposed, both result of the (P-S-C) bond cleavage taking place at the side of leaving group. The enhanced inhibition of AChE observed with the TLS bioassay during the initial 30 min of photodegradation in case of all four OPs, confirmed the formation of toxic intermediates. With the continuation of irradiation, the AChE inhibition decreased, indicating that the formed toxic compounds were further degraded to AChE non-inhibiting products. The presented results demonstrate the importance of toxicity monitoring during the degradation of OPs in processes of waste water remediation, before releasing it into the environment.     

Removal of added nitrate in the single, binary, and ternary systems of cotton burr compost, zerovalent iron, and sediment: Implications for groundwater nitrate remediation using permeable reactive barriers

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe(0)) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and autotrophic denitrification in the Fe(0) system. Questions arise as whether the more expensive Fe(0) is more effective than the less expensive carbonaceous solid materials for groundwater nitrate remediation, and whether there is any synergistic effect of mixing the two different types of materials. We carried out batch tests to study the nature and rates of removal of added nitrate in the suspensions of single, binary, and ternary systems of cotton burr compost, Peerless Fe(0), and a sediment low in organic carbon. Cotton burr compost acted as both organic carbon source and supporting material for the growth of indigenous denitrifiers. Batch tests showed that cotton burr compost alone removed added nitrate at a greater rate than did Peerless Fe(0) alone on an equal mass basis with a pseudo-first-order rate constant k=0.0830+/-0.0031 h(-1) for cotton burr compost and a k=0.00223+/-0.00022 h(-1) for Peerless Fe(0); cotton burr compost also removed added nitrate at a faster rate than did cotton burr compost mixed with Peerless Fe(0) and/or the sediment. Furthermore, there was no substantial accumulation of ammonium ions in the cotton burr compost system, in contrast to the systems containing Peerless Fe(0) in which ammonium ions persisted as major products of nitrate reduction. It is concluded that cotton burr compost alone may be used as an excellent denitrification medium in a PRB for groundwater nitrate removal. Further study is needed to evaluate performance of its field applications.     

Sorption of organic contaminants by biopolymers: role of polarity, structure and domain spatial arrangement

Sorption behavior of hydrophobic organic contaminants (HOCs) (i.e., pyrene, phenanthrene and naphthalene) by native and chemically modified biopolymers (lignin, chitin and cellulose) was examined. Lignins (native and treated) showed nonlinear sorption for all compounds studied, emphasizing their glassy character. Chitins and celluloses had linear isotherms for phenanthrene and naphthalene, illustrating the dominance of partitioning, while pyrene yielded nonlinear isotherms. Sorption capacity (K(oc)) of HOCs was negatively correlated with the polarity [(O+N)/C] of the biopolymers. Aromatic and alkyl+aromatic C percentages, rather than alkyl C content, demonstrated a better correlation with K(oc) values, indicating the importance of aromatic structures for HOC affinity. Hydrophobicity (K(ow))-normalized K(oc) values decreased sharply with increasing percentage of O-alkyl C versus total aliphatic C (O-alkyl C/total aliphatic C) or with polar C/(alkyl+aromatic C) ratio of the biopolymers until their values reached 80% and 4, respectively, illustrating the effect of surrounding polar groups on reducing affinity for HOCs. Overall, the results of this study highlight the role of spatial arrangement of domains within biopolymers in sorption of HOCs, and point to sorbent properties, such as functionality, polarity and structure, jointly regulating the sorption of HOCs in biopolymers.     

Advanced oxidation processes for the treatment of olive-oil mills wastewater

In this work, the treatment of an actual industrial waste with three advanced oxidation processes (AOP) has been studied: conductive-diamond electrooxidation (CDEO), ozonation and Fenton oxidation. The wastewater comes from olive-oil mills (OMW) and contains a COD of nearly 3000 mg dm(-3). CDEO allowed achieving the complete mineralization of the waste with high current efficiencies. Likewise, both ozonation and Fenton oxidation were able to treat the wastes, but they obtained very different results in terms of efficiency and mineralization. The accumulation of oxidation-refractory compounds as final products excludes the use of ozonation and Fenton oxidation as a sole treatment technology. This confirms that besides the hydroxyl-radical mediated oxidation, CDEO combines other important oxidation processes such as the direct electro-oxidation on the diamond surface and the oxidation mediated by other electrochemically formed compounds generated on this electrode.     

Lichen and moss bags as monitoring devices in urban areas. Part II: trace element content in living and dead biomonitors and comparison with synthetic materials

Lobes of the lichen Pseudevernia furfuracea (L.) Zopf and shoots of the moss Hypnum cupressiforme Hedw. were subjected to different treatments (water washing, oven drying, HNO3 washing, NH4-oxalate extraction) to assess the influence of vitality on accumulation efficiency, during a 6-week exposure in bags in two Italian cities, Trieste and Naples. No trend emerged between treatments, in terms of accumulation ability, for major and trace elements. Only water-washed lichens showed an increased C and N content after exposure in both cities. Element concentrations generally reached higher values in mosses than in lichens, especially for Al, Fe, and Zn (both cities), and for Cu, Mg and Na (Naples). Surface development strongly influenced accumulation capacity of the biomonitors. Quartzose and cation exchange filters revealed, on a weight basis, a poor performance. In urban environments, surface interception of atmospheric particulate seems to play a major role in accumulation, irrespective of organism vitality.     

Dynamic responses of photosystem II in the Namib Desert shrub, Zygophyllum prismatocarpum, during and after foliar deposition of limestone dust

The effects of limestone dust deposition on vegetation in desert ecosystems have not yet been reported. We investigated these effects in a succulent shrub from the Namib Desert at a limestone quarry near Skorpion Zinc mine (Namibia). Effects of limestone dust were determined in Zygophyllum prismatocarpum (dollar bush) plants with heavy, moderate and no visible foliar dust cover by means of chlorophyll a fluorescence measurements. Limestone dust deposition decreased overall plant performance through loss of chlorophyll content, inhibition of CO(2) assimilation, uncoupling of the oxygen-evolving complex and decreased electron transport. Importantly, dynamic recovery occurred after termination of limestone extraction at the quarry. Recovery was accelerated by rainfall, mainly because of dust removal from leaves and stimulation of new growth. These results indicate that limestone dust has severe effects on photosynthesis in desert shrubs, but that recovery is possible and that, in arid environments, this process is modulated by rainfall.     

Pentachlorophenol association with fulvic acids from recycled wastes

The apparent water solubility of pentachlorophenol was measured at pH=6 and at 25 degrees C in pure water, aqueous solutions of three salts (NaCl, KNO(3) and CaCl(2) at 0.010, 0.10 and 1.0M) and in aqueous solutions of three fulvic acids samples extracted from a natural soil (sFA), composted sewage sludge (csFA) and composted livestock's material (lsFA). A solubility enhancement method was developed for the measurement of partition coefficients (K(oc), L/kg organic carbon). Pentachlorophenol associates strongly with the fulvic acid samples and the calculated K(oc) were the following (averages and standard deviations): (sFA) (211+/-22) x 10(2), (csFA) (253+/-26) x 10(2), (lsFA) (235+/-10) x 10(2). For comparison purposes the K(oc) for pyrene were also calculated for the three FA samples and were the following: (sFA) (119+/-10) x 10(2), (csFA) (239+/-21) x 10(2), (lsFA) (92+/-10) x 10(2). The analysis of variance (one-way ANOVA) of the effect of the type of FA sample on the solubilization of pentachlorophenol and pyrene shows that this factor causes significant differences on the aqueous solubilization of these two organic substances.