Environmental Chemistry Letters (v.11, #1)
Sequestration of heavy metals from soil with Fe–Mn concretions and nodules
by Dionisios Gasparatos (pp. 1-9).
In recent years, heavy metal contamination has become a major environmental issue in many parts of the world. Fe and Mn oxides, oxyhydroxides and hydroxides have long been recognized as scavengers playing an important role in controlling the location, mobility and bioavailability of metal contaminants in soils. Fe–Mn concretions and nodules are discrete bodies made of soil or sediment materials cemented together under the influence of Fe and Mn oxides. Here metals sorption by Fe–Mn concretions and nodules are surveyed and critical reviewed. Valuable available literature data demonstrate that the formation of Fe–Mn concretions and nodules is the most efficient and durable process for metal contaminants sequestration in the soils. The papers discussed in this review show that the application of Fe–Mn concretions and nodules, as geochemical scavengers for remediating metal contaminated soils, is strongly recommended.
Keywords: Soil; Contamination; Fe–Mn oxides; Heavy metals; Remediation
Microbial functional genes reveal selection of microbial community by PAHs in polluted soils
by Zhenyi Zhang; Xuan Zhao; Yuting Liang; Guanghe Li; Jizhong Zhou (pp. 11-17).
This report shows an increase of PAH-related microbial functional genes with PAH concentration in soils. Adaptation of microbial communities to organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) is a crucial issue. However, there is little knowledge on mechanisms ruling microbial community selection. Here, we studied microbial functional genes in soils contaminated by PAHs. We used GeoChip, an advanced functional gene array for gene analysis. Soil PAH concentrations were measured and microbial functional genes were categorized. PAH-related microbial functional genes, bph, nah, nidA, phd, dfb, and qor, were quantitatively expressed. Total microbial functional genes and PAH-related microbial functional genes were compared with PAH concentration by cluster analysis and curve-fitting analysis. We found that the average abundance of PAH-related microbial functional genes increased from 0.13 to 0.33, whereas that of total microbial functional genes decreased from 0.22 to 0.10 when PAHs concentration increased from 1.01 to 164.28 mg kg−1. It was also found that the classification of microbial community structure characteristics based on PAH-related microbial functional genes was closely similar to the classification based on PAHs concentration. Findings reveal that PAH stress promotes the dominance of PAH-related microbial communities.
Keywords: Polycyclic aromatic hydrocarbons; Microbial functional genes; Environmental stress; Microarray; GeoChip; Microbial community selection
Lichens reveal air PAH fractionation in the Himalaya
by Vertika Shukla; D. K. Upreti; D. K. Patel; M. Yunus (pp. 19-23).
This paper shows that gas/particulate phase partitioning of polycyclic aromatic hydrocarbons (PAHs) can be monitored using lichens. Anthropogenic sources are responsible for the release of PAHs, which are bioaccumulated in plants at various spatial scales based on their physicochemical properties. Atmospheric PAHs are distributed both in the gaseous and particulate states. Here, a lichen species, Dermatocarpon vellereum Zschacke, has been collected at different altitudes in and around the Rudraprayag valley, located in Central Himalayan region of India, in order to study the spatial distribution of PAHs in the valley. Results show that PAH concentration ranged from 0.136 to 4.96 μg g−1. Findings reveal that the bioaccumulation of 2- and 3-ringed PAHs was higher in high-altitude samples, whereas bioaccumulation of fluoranthene, a 4-ringed PAH, showed higher concentration in samples from localities away from town centre. 5- and 6-ring PAHs were then confined to the lower altitude at the base of the valley, thus justifying their particulate-bound nature. This is the first report showing the utility of lichen to biomonitor PAHs in the Himalayan ecosystem.
Keywords: Altitudinal gradient; Dispersal of PAHs; Gas- and particle-bound PAHs; Lichen
t-BuOK catalyzed bio-oil production from woody biomass under sub-critical water conditions
by Kubilay Tekin; Selhan Karagöz (pp. 25-31).
The substitution of fossil fuels and fossil-based products with biofuels and biomass-based products is indispensable for a sustainable society and a green environment. The liquefaction of biomass to produce biofuels under sub- and/or super-critical water conditions is one of the most promising methods that might allow this substitution. Here, for the first time, we report the results of the liquefaction of woody biomass under sub-critical water conditions at 250, 300, and 350 °C using potassium tert-butoxide (t-BuOK) as a catalyst. To compare and evaluate the catalytic performance of t-BuOK, the experiments were also performed under identical conditions using KOH as the catalyst. The product distributions obtained using either KOH or t-BuOK as the catalyst were very similar. The total oil yields increased and the solid residue yields decreased when either KOH or t-BuOK were used at reaction temperatures of 300 and 350 °C. The total bio-oil yields obtained at 300 °C with t-BuOK and KOH were 41.9 weight (%) and 43.0 weight (%), respectively, whereas the total bio-oil yield from the thermal run at 300 °C was approximately 24.0 weight (%). Although the O/C ratio of the raw material is 0.70, the O/C ratios of the light and heavy bio-oils obtained from the KOH catalytic run are 0.38 and 0.25, respectively. In addition, the O/C ratios for the light and heavy oils obtained from the t-BuOK catalyst are 0.41 and 0.26, respectively. We estimate that the heating values of the light and heavy bio-oils obtained by either catalytic run (t-BuOK or KOH) are approximately 24 MJ kg−1 and 29 MJ kg−1, respectively
Keywords: Biomass; Sub-critical water; Light bio-oil; Heavy bio-oil; t-BuOK; Liquefaction
Oyster shell reduces PAHs and particulate matter from incense burning
by Chi-Ru Yang; Tzu-Hsing Ko; Yuan-Chung Lin; Suen-Zone Lee; Yih-Feng Chang; Hsin-Ta Hsueh (pp. 33-40).
This is the first report showing reduction of particle matter and PAHs from incense burning by addition of oyster shell. Worshiping ancestors and gods by burning incense sticks and joss paper is a very important tradition in many Asian regions. More than 45 % of families in Taiwan burn incense twice a day. Unlike joss paper burning, most of the incense burning occurs indoors, thus creating a risk for human health. Previous reports have indeed evidenced toxicity of incense, notably due to particulate matter and polycyclic aromatic hydrocarbons (PAHs). However, there are few methods to reduce particle matter and PAHs from incense burning. We hypothesize that oyster shell may be used to reduce incense fumes toxicity. Indeed a large amount of unused oyster shell is discarded due to increasing seafood consumption. Here, two types of incense were made in the laboratory, and then 5–30 % of oyster shells were added to the incense to study the reduction of particle matter and PAHs. Results show that reduction of particle matter and PAH emission increased with oyster shell addition. The reduction of emission factors is −35 % for mean particle matter, −21 % for particle-phase PAHs, and −37 % for benzo[a]pyrene equivalent concentration (BaPeq), using 30 % oyster shell additive. The addition of 10 % oyster shell reduces the burning time by 8.3 min, increases the burning rate by 3.4 mg/min, and reduces particle matter by 6.4 mg/g incense, particle-phase PAHs by 0.67 μg/g incense, and BaPeq by 0.23 μg/g incense. The reductions of particle matter, particle-phase PAHs, and BaPeq correspond to about 640 metric tons, 67, and 23 kg, respectively, per year. Our findings will help to produce safer and cleaner incense.
Keywords: Incense sticks; Oyster shell; Particle matter; PAHs; Benzo[a]pyrene equivalent concentration
First determination of Cu adsorption on soil humin
by Jinjing Zhang; Shuai Wang; Qinghe Wang; Nan Wang; Cuilan Li; Lichun Wang (pp. 41-46).
Humic substances are heterogeneous mixtures of organic compounds occurring in huge amounts mainly in waters, soils, sediments and organic wastes. They are formed during the decay of living organisms. They play a very important role in many environmental processes including carbon sequestration, water cleaning and retention, soil erosion, fertility and pollutant retention. However, due to their complex nature, humic substances are still poorly characterized and much less known than living matter. Humin is the most insoluble and, in turn, the least understood fraction of humic substances. To our knowledge, no information is currently available on the adsorption and desorption behaviors of metal ions on soil humin. Here, we report the adsorption and desorption properties of Cu(II) on humin and humic acids isolated from a forest soil in northeast China using the batch equilibration method. Solid-state 13C cross-polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy was used to characterize and compare the chemical structures of humin and humic acid. The batch experiments’ results show that humin has a lower adsorption capacity and higher adsorption reversibility for Cu(II) than humic acid. The adsorption isotherms well fitted both the Langmuir and Freundlich equations. Humin, therefore, plays an important role in controlling the fate, transport and bioavailability of Cu(II) in the environment. The 13C CPMAS NMR spectra showed that compared with humic acid, humin was higher in alkyl C, carbohydrate C and phenolic C and was lower in methoxyl C, aryl C and carbonyl C. These findings mean that humin was less alkylated, more aliphatic and more hydrophobic.
Keywords: Humin; Humic acid; Cu(II); Adsorption; Desorption; 13C NMR
Efficient arsenic depollution in water using modified maize powder
by Shalini Srivastava; Kumar Rohit Raj; Abhishek Kardam (pp. 47-53).
This article reports the synthesis of an efficient, low-cost material from maize powder to depollute arsenic-contaminated water. Arsenic is toxic for humans and other organisms even at low concentrations. The most well-known and severe case of arsenic poisoning through drinking water has been found in India and Bangladesh. Numerous inorganic materials have been tested for the removal of arsenic from water bodies over the last two decades. However, all such materials have several disadvantages such as unpredictable arsenic ion removal, high cost and the generation of toxic sludge that is often more difficult to manage. Alternatively, organic material from agricultural waste may be modified to enrich functional groups responsible for As sorption and, in turn, used to depollute contaminated waters. Here, Zea mays cob powder has been modified to remove arsenic species from water. Two modified materials were produced: an aminated maize powder and a thiolated maize powder. Amination was done using epichlorohydrin and dimethylamine. Thiolation was done using thioglycolic acids. Amination increased As (III) sorption from 70 to 75.8 % and As (V) sorption from 85 to 94.42 %, compared with unmodified maize powder. Thiolation increased As (III) sorption from 70 to 81.7 % and As (V) sorption from 85 to 90 %. Amination increased usability cycles from 3 to 5. Thiolation increased usability cycles from 3 to 6. The novel modified maize biosorbent has enough potential for the development of a low-cost technological pre-treatment step, prior to high-tech chemical treatments.
Keywords: Modifications; Sorption efficiency; Zea mays cob powder (maize powder); Arsenic; Reusability of biomaterial
Pb in medicinal plants from Jordan
by Ahmed Alomary; Eshraq El Jamal; Idrees Al-Momani; Abdulrahman Attiyat; Safwan Obeidat (pp. 55-63).
This is the first report on Pb in medicinal herbs from Jordan. Medicinal herbs may present a health risk due to the presence of toxic metals. Seventy-nine dry medicinal plant samples were collected from herbalist shops in Jordan. The plants were digested with acids and analyzed for total Pb concentration using atomic absorption spectrometry. Mean Pb concentration was 15.9 μg/g on a dry weight basis. Our results show that Pb concentrations in Jordan medicinal plants are higher than published data in other countries. The highest level of 33.4 μg Pb/g was determined in Inula viscosa, and the lowest level of 3.0 μg Pb/g was found in Nigella sativa. Calculated daily intakes of Pb of most analyzed herbs were high; most of them are higher than recommended values by the world health organization (WHO). Fortunately, the herbs that contain the highest Pb levels are the less commonly used medicinal herbs in Jordan. The mean Pb levels in the most commonly, commonly and less commonly used herbs in Jordan are 13.9, 13.1 and 16.9 μg Pb/g, respectively. The average dietary intake of Pb through a mixture of these medicinal herbs consumption, assuming 5.0 g herbs is consumed daily, is 79.5 μg Pb/day, which is higher than the maximum daily limit allowed by WHO. We conclude that most of the medicinal plants consumed in Jordan contain significant amount of Pb, and therefore, people of Jordan should not consume large amounts of these herbs.
Keywords: Lead; Acid digestion; Medicinal plants; Jordan; AAS
Improved soil carbonate determination by FT-IR and X-ray analysis
by Viktor J. Bruckman; Karin Wriessnig (pp. 65-70).
In forest soils on calcareous parent material, carbonate is a key component that influences both chemical and physical soil properties and thus fertility and productivity. At low organic carbon contents, it is difficult to distinguish between organic and inorganic carbon, e.g. carbonates, in soils. The common gas-volumetric method to determine carbonate has a number of disadvantages. We hypothesize that a combination of two spectroscopic methods, which account for different forms of carbonate, can be used to model soil carbonate in our region. Fourier transform mid-infrared spectroscopy was combined with X-ray diffraction to develop a model based on partial least squares regression. Results of the gas-volumetric Scheibler method were corrected for the calcite/dolomite ratio. The best model performance was achieved when we combined the two analytical methods using four principal components. The root mean squared error of prediction decreased from 13.07 to 11.57, while full cross-validation explained 94.5 % of the variance of the carbonate content. This is the first time that a combination of the proposed methods has been used to predict carbonate in forest soils, offering a simple method to precisely estimate soil carbonate contents while increasing accuracy in comparison with spectroscopic approaches proposed earlier. This approach has the potential to complement or substitute gas-volumetric methods, specifically in study areas with low soil heterogeneity and similar parent material or in long-term monitoring by consecutive sampling.
Keywords: Forest soil; Carbonate; Fourier transform mid-infrared spectroscopy; X-ray diffraction; Partial least squares regression; Scheibler method
Real-time monitoring of nanoparticle retention in porous media
by Jeff Rottman; Reyes Sierra-Alvarez; Farhang Shadman (pp. 71-76).
Nanoparticles are not specifically targeted in conventional treatment schemes; consequently, typical wastewater treatment systems are ineffective for nanoparticles removal. With rapidly increasing concern over their health effects, improved understanding of nanoparticle transport and retention in porous media filters is critical because of its application in new wastewater treatment methods and for assessment of the fate of the discharged nanoparticles in soil. In this study, a unique and robust integrated method is developed and validated. Experimentally, this approach uses an on-line, real-time, and in situ method for measuring nanoparticle retention dynamics, eliminating the laborious and less accurate sampling and off-line analysis. The data analysis part is a process simulator which provides both kinetic properties of the retention process as well as the overall capacity and loading. This technique is validated by application to the transport and retention of TiO2 nanoparticles in two vastly different porous filtration media—activated carbon and sand. TiO2 retained concentrations ranged from 0.24 to 0.37 mg g−1 for activated carbon and 0.01–0.014 mg g−1 for sand. The integrated method presented here is useful for both comparison of the filtration effectiveness of various porous materials as well as for process optimization and scale-up for industrial applications.
Keywords: Activated carbon; Dispersant; Model; Nanomaterials; Sand; TiO2
13C isotope evidence for photochemical production of atmospheric formaldehyde, acetaldehyde, and acetone pollutants in Guangzhou
by Songjun Guo; Mei Chen (pp. 77-82).
Ambient formaldehyde, acetaldehyde, and acetone are harmful air pollutants with potential carcinogenic effects on human health. They are considered as important photochemical products from photo-oxidation of atmospheric hydrocarbons. However, little is known on the effet of photodegradation of air pollutants on δ13C values. Here, we report the first 13C isotope evidence for the photochemical production of ambient formaldehyde, acetaldehyde, and acetone. Air samples were collected each day during early morning, noon, early afternoon, and late afternoon on 17–19 September 2008 in Guangzhou by drawing air through 2,4-dinitrophenylhydrazine-coated cartridges. The samples were analyzed using high-performance liquid chromatography for concentration analysis and then using gas chromatography-combustion-isotope ratio mass spectrometry for δ13C analysis. Our results show that ambient formaldehyde, acetaldehyde, and acetone were enriched by 1–5 ‰ in 13C in the early afternoon relative to other sampling durations, and they also exhibited the highest concentrations in the early afternoon. Measured δ13C values of formaldehyde, acetaldehyde, and acetone were in the range from −37.15 to −29.01 ‰. The observed enrichment in 13C implied important photochemical production together with the highest concentrations in the early afternoon. Especially, measured δ13C range from −37.15 to −29.01 ‰ was in accordance with forecasted δ13C range from −43 to −28 ‰ based on the mass balance in 13C between the carbonyls and its major hydrocarbon precursors, providing important 13C isotope evidence for the photochemical production of ambient formaldehyde, acetaldehyde, and acetone.
Keywords: Formaldehyde; Acetaldehyde; Acetone; 13C isotope evidence; Photochemical production
Enantioselective HPLC analysis and biodegradation of atenolol, metoprolol and fluoxetine
by Ana Rita Ribeiro; Carlos Magalhães Afonso; Paula M. L. Castro; Maria Elizabeth Tiritan (pp. 83-90).
The accurate quantification of enantiomers is crucial for assessing the biodegradation of chiral pharmaceuticals in the environment. Methods to quantify enantiomers in environmental matrices are scarce. Here, we used an enantioselective method, high-performance liquid chromatography with fluorescence detection (HPLC-FD), to analyze two beta-blockers, metoprolol and atenolol, and the antidepressant fluoxetine in an activated sludge consortium from a wastewater treatment plant. The vancomycin-based chiral stationary phase was used under polar ionic mode to achieve the enantioseparation of target chiral pharmaceuticals in a single chromatographic run. The method was successfully validated over a concentration range of 20–800 ng/mL for each enantiomer of both beta-blockers and of 50–800 ng/mL for fluoxetine enantiomers. The limits of detection were between 5 and 20 ng/mL and the limits of quantification were between 20 and 50 ng/mL, for all enantiomers. The intra- and inter-batch precision was lower than 5.66 and 8.37 %, respectively. Accuracy values were between 103.03 and 117.92 %, and recovery rates were in the range of 88.48–116.62 %. Furthermore, the enantioselective biodegradation of atenolol, metoprolol and fluoxetine was followed during 15 days. The (S)-enantiomeric form of metoprolol was degraded at higher extents, whereas the degradation of atenolol and fluoxetine did not show enantioselectivity under the applied conditions.
Keywords: Pharmaceuticals; Chiral ecotoxicity; Enantioselective biodegradation; HPLC-FD; Polar ionic mode; Chirobiotic V
Fast and efficient synthesis of N-substituted β-aminobutyric acids by grinding at room temperature
by Subrahmanya Ishwar Bhat; Darshak R. Trivedi (pp. 91-97).
Green chemistry is gaining increasing interest due to the growing awareness of the chemical community for sustainable development. Green chemistry solutions include synthesis without solvent and catalyst because many solvents and catalysts are toxic and expensive. Herein, we report the solvent and catalyst free method for the synthesis of N-substituted derivatives of β-aminobutyric acid by direct aza-Michael addition of amines to crotonic acid. The protocol involves simple mixing or grinding the reactants at room temperature. The β-amino acid derivatives were obtained in 82–100 % yield with a short reaction time without any tedious workup procedures. Our findings thus reveal a promising alternative to previously used procedures.
Keywords: β-Aminobutyric acid; Aza-Michael addition; Solvent- and catalyst-free grinding; Green protocol; Atom economical reaction; Crotonic acid
First evidence of large-scale PAH trends in French soils
by Estelle J. Villanneau; Nicolas P. A. Saby; Thomas G. Orton; Claudy C. Jolivet; Line Boulonne; Giovanni Caria; Enrique Barriuso; Antonio Bispo; Olivier Briand; Dominique Arrouays (pp. 99-104).
Polycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants. Soils are a reservoir of PAHs because some soil constituents favour PAH accumulation. Therefore, soil is a key indicator of the degree of contamination. So far, studies mapping soil PAH levels over large territories are very rare. Here, we report the first nation-wide maps of soil PAHs in France. Results were obtained within the French National Soil Monitoring Network, which is the first European network monitoring systematically soil PAHs. We used advanced geostatistics to map PAH distribution over the whole French territory. Our results show clear trends of PAH levels at the nation scale. For instance, the highest PAH levels are found in Northern and Eastern France. This high contamination is explained by the intense industrial activity of these regions during the last century. High levels of PAH are also found near some coastlines. This observation could be explained by long-range atmospheric transportation. In addition, we found that light PAHs are rarely found in French topsoils.
Keywords: PAH; Geostatistics; Topsoil; France; Mapping