The Potted-Plant Microcosm Substantially Reduces Indoor Air VOC Pollution: II. Laboratory Study

Indoor air-borne loads of volatile organic compounds (VOCs) are usually significantly higher than those outdoors, and chronic exposures can cause health problems. Our previous laboratory studies have shown that the potted-plant microcosm, induced by an initial dose, can eliminate high air-borne VOC concentrations, the primary removal agents being potting-mix microorganisms, selected and maintained in the plant/root-zone microcosm. Our office field-study, reported in the preceding paper, showed that, when total VOC (TVOC) loads in reference offices (0 plants) rose above about 100 ppb, levels were generally reduced by up to 75% (to < 100 ppb) in offices with any one of three planting regimes. The results indicate the induction of the VOC removal mechanism at TVOC levels above a threshold of about 100 ppb. The aims of this laboratory dose-response study were to explore and analyse this response. Over from 5 to 9 days, doses of 0.2, 1.0, 10 and 100 ppm toluene and m-xylene were applied and replenished, singly and as mixtures, to potted-plants of the same two species used in the office study. The results confirmed the induction of the VOC removal response at the lowest test dosage, i.e in the middle of the TVOC range found in the offices, and showed that, with subsequent dosage increments, further stepwise induction occurred, with rate increases of several orders of magnitude. At each dosage, with induction, VOC concentrations could be reduced to below GC detection limits (< 20 ppb) within 24 h. A synergistic interaction was found with the binary mixtures, toluene accelerating m-xylene removal, at least at lower dosages. The results of these two studies together demonstrate that the potted-plant microcosm can provide an effective, self-regulating, sustainable bioremediation or phytoremediation system for VOC pollution in indoor air.     

Evaluation of genetic resources in the genus <Emphasis Type="Italic">Asparagus</Emphasis> for resistance to <Emphasis Type="Italic">Asparagus virus 1</Emphasis> (AV-1)

Forty-four Asparagus officinalis cultivars, gene bank accessions and breeding lines as well as thirty-four accessions of wild relatives of Asparagus were evaluated for resistance to Asparagus virus 1. Three different test strategies were developed for the assessment of individual plants: (1) natural infection under field conditions, or two vector-mediated infection assays using the green peach aphid Myzus persicae (2) in an insect-proof gauze cage or (3) in a climate chamber. The AV-1 infections were verified by DAS-ELISA and RT-PCR approaches. All tested 660 individual plants of A. officinalis germplasm were susceptible to AV-1 infection. In contrast, in 276 plants of 29 Asparagus wild accessions no virus infection could be detected. These resistant accessions comprised of nineteen diploid, tetraploid and hexaploid species of both the Eurasian clade and the African clade of the asparagus germplasm. Data of the AV-1 resistance evaluation are discussed in relation to the genetic distance of the resistance carrier and potential application in breeding.     

The Potted-Plant Microcosm Substantially Reduces Indoor Air VOC Pollution: I. Office Field-Study

Volatile organic compounds (VOCs) are major contaminants of indoor air, with concentrations often several times higher than outdoors. They are recognized as causative agents of “building-related illness” or “sick-building syndrome”. Our previous laboratory test-chamber studies have shown that the potted-plant/root-zone microorganism microcosm can eliminate high concentrations of air-borne VOCs within 24 hours, once the removal response has been induced by an initial dose. However, the effectiveness of the potted-plant microcosm in ‘real-world’ indoor spaces has never previously been tested experimentally. This paper reports the results of a field-study on the effects of potted-plant presence on total VOC (TVOC) levels, measured in 60 offices (12 per treatment), over two 5–9 week periods, using three planting regimes, with two ‘international indoor-plant’ species. Fourteen VOCs were identified in the office air. When TVOC loads in reference offices rose above 100 ppb, large reductions, of from 50 to 75% (to <100 ppb), were found in planted offices, under all planting regimes The results indicate that air-borne TVOC levels above a threshold of about 100 ppb stimulate the graded induction of an efficient metabolic VOC-removal mechanism in the microcosm. Follow-up laboratory dose-response experiments, reported in the following paper, confirm the graded induction response, over a wide range of VOC concentrations. The findings together demonstrate that potted-plants can provide an efficient, self-regulating, low-cost, sustainable, bioremediation system for indoor air pollution, which can effectively complement engineering measures to reduce indoor air pollution, and hence improve human wellbeing and productivity.     

Phytostabilization Ability of <Emphasis Type="Italic">Baccharis linearis</Emphasis> and Its Relation to Properties of a Tailings-Derived Technosol

Spontaneous colonization of mine tailing dams by plants is a potential tool for phytostabilization of such reservoirs. However, the physical and chemical properties of each mine tailings deposit determine the success of natural plant establishment. The plant Baccharis linearis is the main native nanophanerophyte species (evergreen sclerophyllous shrub) that naturally colonizes abandoned copper tailings dams in arid to semiarid north-central Chile. This study compare growth of B. linearis against the physical and chemical properties of a Technosol derived from copper mine tailings. Five sites inside the deposit were selected based on B. linearis vegetation density (VD), at two soil sampling depths under the canopy of adult individuals. Physical and chemical properties of tailings samples and nutrient concentrations in tailings and plants were each determined. Some morphological features of the plants (roots and aerial parts) were also quantified. There were significant differences in soil available water capacity (AW) and relative density (Rd) at different VD. Sites with low AW and high Rd had lower nutrient concentrations and higher Zn content in tailings, decreased infection by arbuscular mycorrhizal fungi, and increased fine root abundance and root hair length in individual plants. In contrast, higher AW, which was positively correlated with fine particles and organic matter content, had a positive effect on vegetation coverage, increased N and P contents in tailings, and increased N contents in leaf tissues, even when available N and P levels in tailings were low. Multiple constraints, such as low AW, N, P, and B contents and high Zn concentrations in the tailings restricted vegetation coverage, but no phenotypic differences were observed between individuals. Thus, in order to promote dense coverage by B. linearis, water retention in these tailings must be improved by increasing colloidal particles (organic and/or inorganic) contents, which have a positive effect on colonization by this species.     

Evidence that fresh weight measurement is imprecise for reporting the effect of plant growth-promoting (rhizo)bacteria on growth promotion of crop plants

Eight greenhouse experiments were performed to compare the effect of seven plant growth-promoting (rhizo)bacteria (PGPR/PGPB) on fresh and dry weights of four crop plants. This has been done to validate if fresh weight measurements of plant variables can serve as reliable values when reporting the effect of these bacteria on plant growth. These experiments show that the growth promotion effects by the tested PGPR/PGPB, including Bacillus amyloliquefaciens GB03, Bacillus subtilis IN-937B, Bacillus altitudinis INR7, and Pseudomonas mandelii 89B-27 in corn and cucumber and Azospirillum brasilense Cd, A. brasilense Sp 245, and Azospirillum lipoferum Br 17 in pepper and tomato, varied significantly between fresh and dry weights of shoot, root, and/or whole plant in the repeated greenhouse experiments. These results support our hypothesis that using fresh weight determination for assessing plant growth promotion by beneficial bacteria is inherently faulty. Therefore, it is recommended that dry weight determination rather than fresh weight determination is used for plant growth promotion tests.     

<Emphasis Type="Italic">Marsilea quadrifolia:</Emphasis> a New Bioagent for Treating Wastewater

We report for the first time the capability of four-leaf clover (Marsilea quadrifolia), a wetland plant which grows rooted in soil, in efficiently treating sewage. The use of M. quadrifolia was made possible because of the special attributes of the SHEFROL^® (SHEet Flow ROot Level) bioreactor in which it was employed. This bioreactor enables the use of free-floating aquatic plants as well as terrestrial and rooted-in-soil wetland plants by hydroponics. The plants are staked in narrow channels to enable them to support each other while sewage is made to flow rapidly as a sheet of wastewater at a level that covers only the plant roots (hence the name). It was seen that M. quadrifolia was able to treat sewage of strength varying in the chemical oxygen demand (COD) range of 600–1800 mg/L to the extent of >?80% at a hydraulic retention time (HRT) of just 4.5 h. There was a near total removal of biological oxygen demand and suspended solids while total Kjeldahl nitrogen, soluble phosphorous, and heavy metal zinc were also substantially removed. The macrophyte was equally effective when used indoors under artificial lighting, as well as when used outdoors.     

Response of <Emphasis Type="Italic">Piptatherum miliaceum</Emphasis> to co-culture with a legume species for the phytostabilisation of trace elements contaminated soils

Purpose

The presence of high concentrations of trace elements (TEs) in mine soils like those in the Sierra Minera of La Unión-Cartagena (SE Spain) limits the development of a vegetation cover on such sites, and pollution dispersion by water and wind erosion represents a serious risk for the surrounding ecosystems. The aim of this study was to evaluate different phytostabilisation procedures based on the co-culture of a legume (Bituminaria bituminosa) and a high-biomass (Piptatherum miliaceum) species for this type of soils.

Materials and methods

A pot experiment was carried out where B. bituminosa was tested as a soil pre-treatment strategy. Five different procedures were followed to study the growth stimulation or competition of both species in a contaminated soil from the Sierra Minera: (i) sowing of P. miliaceum without B. bituminosa (control treatment), (ii) sowing of P. miliaceum for co-cultivation of both species, (iii) sowing of P. miliaceum and co-cultivation of both species in soil with compost, (iv) harvesting and elimination of the aerial part of the plants before sowing of P. miliaceum and (v) harvesting and incorporation to the soil of the aerial part of B. bituminosa before sowing of P. miliaceum.

Results and discussion

The results showed that the co-culture of both species favoured the growth of P. miliaceum, whilst incorporating the aerial part of the legume to the soil increased nitrogen concentration in P. miliaceum but reduced its growth. The use of compost improved both the growth and N uptake of P. miliaceum and did not inhibit nodulation in B. bituminosa. TE extractability in the soils and accumulation in the plants were rather low and very little affected by the addition of the amendments or by co-culture of species.

Conclusions

Nitrogen availability plays an important role in P. miliaceum growth in TE-contaminated mine soils. The addition of compost together with legume cultivation is proposed as an effective combination for the cultivation of P. miliaceum in these soils, as both plant growth and soil conditions were improved following this procedure.

     

Induction of toluene degradation and growth promotion in corn and wheat by horizontal gene transfer within endophytic bacteria

Some experiments involving important crop plants, corn and wheat, were carried out to characterize the agronomic and environmental application of Burkholderia cepacia strain FX2 able to degrade toluene and containing plasmids with the gene encoding for catechol 2, 3-dioxygenase (C23O), a key enzyme in the degradation pathway of monocyclic aromatic compounds. The inoculation of corn and wheat with FX2 led to the promotion of plant growth and reduction in evapotranspiration of toluene into the air. Endophytic bacteria able to grow on toluene as the only source of carbon and containing a C23O gene were found in the plants inoculated with FX2 but not in their non-inoculated controls. Compared to control plants, a greater number of toluene-degrading, phosphate-solubilizing and siderophore-producing endophytes were found in inoculated plants. Furthermore, a direct correlation occurred between plant biomass responses and the magnitude of C23O-containing endophytes. Phylogenetic tree comparison, plasmid analysis and filter mating assays showed that the C23O gene was transferred horizontally from FX2 to the natural endophytic bacteria of corn and wheat. Horizontal gene transfer among endophytic bacteria might contribute to pollutant degradation, growth promotion and potential for disease suppression in corn and wheat.     

Catalase and Phosphatase Activities During Hydrocarbon Removal from Oil-Contaminated Soil Amended with Agro-Industrial By-products and Macronutrients

Microbiological activities are essential in the bioremediation of polluted soils. The enzymatic activities of microorganisms are usually used as a biological indicator of soil health. The aim of this work was to observe the catalase, acid phosphatase (AcP), and alkaline phosphatase (AlP) activities in soil that was amended with agro-industrial by-products and macronutrients during the process of total petroleum hydrocarbon (TPH) removal. To this end, microcosm tests were performed with soil and agro-industrial by-products ratios of 100:2:2, for soil:sugarcane bagasse pith:filter cake mud (SSF); 100:2, for both soil:sugarcane bagasse pith (SS); and for soil filter cake mud (SF). The macronutrients—carbon, nitrogen, and phosphorus—in the experimental treatments were adjusted to 100:10:1 with a solution of NH₄NO₃ and K₂HPO₄. The best TPH removal (51.4%) was obtained with SSF at 15 days. In addition, a significant correlation was observed between TPH removal and AlP as well as AcP (r = 0.74, p < 0.0001; r = 0.70, p < 0.0107, respectively). Fungi growth was also correlated with both AlP (r = 0.97, p < 0.0001) and AcP (r = 0.95, p < 0.0001) activities. Besides, bacterial and fungi growth showed a correlation with TPH (r = 0.86, p < 0.001; r = 0.77, p < 0.0034, respectively). It could be said that the agro-industrial by-products and macronutrients contributed to pollutant removal from the oil-polluted soil at relatively short amount of time. In addition, the enzymatic activities were increased after the treatment; in this study, the high sensitivity enzyme was AlP, and it could be used as an indirect indicator of oil pollutant removal.     

Characterization of wild Beta populations in and adjacent to sugar beet fields in the Imperial Valley,California

Populations of wild Beta L. species exist as weeds in commercial sugar beet (Beta vulgaris L. subspecies vulgaris) fields in the Imperial Valley, California. Significant losses to sugar yield and quality result if these wild plants are not removed. In cases of extreme infestation, fields are abandoned without harvest. No selective chemicals are available to differentiate conventional sugar beet from wild relatives and hand removal is labor intensive and expensive. Planting sugar beet varieties with tolerance to glyphosate is a potential solution for infested fields, but risk of gene flow to adjacent wild relatives must be determined. Previous research identified these populations as either Beta vulgaris L. subspecies maritima (L.) Arcang. or Beta macrocarpa Guss. This distinction is critical because B. v. subsp. maritima will readily cross hybridize with cultivated sugar beet while B. macrocarpa rarely will. In April 2011, we collected herbarium samples, mature seed, and leaf tissue from wild Beta populations in 25 infested sugar beet fields throughout the Imperial Valley. Bolting cultivated beets were identified at two locations. Taxonomy of whole plant herbarium samples was unclear due to wild beet stem elongation when under competition with sugar beet plants for canopy light. Morphology of plants from collected seed grown in non-competitive conditions assigned taxonomy of these populations to B. macrocarpa. We used molecular tools to determine the genetic structure of wild Beta populations throughout the Imperial Valley. Extracted DNA was genotyped with 22 simple sequence repeat molecular markers and evaluated for population structure. The bolting beet samples were clearly separated from the majority of B. macrocarpa samples, except for two. The remaining wild populations were further divided into two subgroups suggesting exchange of genetic information or a common ancestor.     

The role of inoculum identity in drought stress mitigation by arbuscular mycorrhizal fungi in soybean

It is well known that arbuscular mycorrhizal fungi (AMF) effects on plant growth largely depend on fungus identity. The objective of this study was to test whether three individual AMF isolates and their mixture mitigate drought stress (DS) differentially in soybean (Glycine max) genotype, predicting that under DS, the mixture of the AMF isolates would provide greater benefits to soybean plants than individual ones. In a greenhouse experiment, a drought-susceptible soybean genotype was inoculated with Septoglomus constrictum, Glomus sp., and Glomus aggregatum, known to be among the most abundant in agricultural and natural soils from central Argentina, and their mixture (Mx). Whereas under well-watered (WW) conditions, individual isolates and Mx treatment were similarly infective; under DS conditions, the Mx treatment showed lower rates of root colonization. Between WW and DS conditions, biomass was decreased in all treatments, although this effect was more marked in non-AM plants. Moreover, AMF strains improved water content and P and N concentrations. Under DS, the Mx treatment was unable to exceed the highest contents that were recorded by AMF isolates. However, under WW conditions, the Mx treatment showed a higher N content than individual isolates. Under both watering conditions, AM plants reduced oxidative damage evaluated as malondiadehyde and chlorophyll content and keep constant osmotic metabolites such as soluble sugars and proline content, without significant differences between AMF isolates and the Mx treatment. These results show that AMF play an important role in mitigating drought impacts on soybean, but that mixtures of AMF isolates did not perform as well as the best single strain inoculum, excluding complementarity effects and suggesting selection effect of AMF on DS alleviation in soybean.     

Effect of aerotechnogenic emissions on the content of heavy metals in herbaceous plants of the Lower Don region

The effect of soil properties and distance from the source of technogenic emission on the input of Pb, Zn, Cd, Cu, Mn, Cr, and Ni into daisy family plants (Asteraceae) has been studied. It has been found that the high level of anthropogenic load related to the atmospheric emissions from the Novocherkassk power plant (NPP) favors the accumulation of heavy metals (HMs) in herbaceous plants. Contamination with Pb, Cd, Cr, and Ni is revealed in plants growing near the NPP. The main factors affecting the distribution of HMs in the above- and underground organs of plants include individual physiological features of plant species controlling the barrier functions of different plant organs. Ambrosia artemisiifolia L., Artemisia austriaca Pall. ex. Wild. Jack., and Tanacetum vulgare L. are accumulators of HMs. The resistance of herbaceous plants to pollution has been determined from the acropetal coefficient and actual biogeochemical mobility of HMs. Ambrosia artemisiifolia L. is most resistant to contamination with Mn; Achillea nobilis L. is most resistant to Pb, Ni, and Cd; Cichorium intybus L. is most resistant to Zn and Cu.     

Potential of Pyrene Removal from Urban Environments by the Activities of Bacteria and Biosurfactant on Ornamental Plant Leaves

Pyrene is a dominant PAH in urban environments. It can combine with airborne particulates and accumulate on plant leaves. To investigate pyrene’s biodegradation potential, this study initially monitored the abundance of airborne and phyllosphere bacteria. The number of airborne pyrene-degrading bacteria ranged from 22 to 152 CFU m^?3 air, and more bacteria were found in the proximity of the ornamental plant swath than along the roadside. Pyrene-degrading bacteria averaged 5 × 10⁴ CFU g^?1 on the leaves of all tested plant species and accounted for approximately 7% of the total population. Four pyrene-degrading bacteria were isolated from I. coccinea to use as model phyllosphere bacteria. To increase the bioavailability of pyrene, a lipopeptide biosurfactant was applied. Kocuria sp. IC3 showed the highest pyrene degradation in the medium containing biosurfactant. The removal of deposited pyrene at 30 μg g^?1 leaf was monitored in a glass chamber containing I. coccinea twigs. After 14 days, leaves containing both Kocuria sp. IC3 and 0.1× CMC biosurfactant showed 100% pyrene removal with the most abundant bacteria. The system with biosurfactant alone also enhanced the activities of phyllosphere bacteria with 94% pyrene removal. Consequently, the bioremediation of deposited pyrene could be achieved by spraying biosurfactant on ornamental shrubs.     

Do the impacts of alien invasive plants differ from expansive native ones? An experimental study on arbuscular mycorrhizal fungi communities

No studies have compared so far the effects of alien invasive and expansive native (widespread, mono-dominant) plants on arbuscular mycorrhizal fungi (AMF). Four global or European most successful invaders (Impatiens glandulifera, Reynoutria japonica, Rudbeckia laciniata, Solidago gigantea) and two expansive plants native to Europe (Artemisia vulgaris, Phalaris arundinacea) were grown in pots to elucidate the magnitude and direction of changes in AMF abundance, species richness, and species composition in soils from under multispecies native vegetation. In a second stage, the effects of these changes on a native plant, Plantago lanceolata, were assessed. Plant species identity had larger impact on AMF abundance, species richness, and species composition as well as on P. lanceolata than origin of the species (alien vs. native). This could be due to the character of AMF relationships with the plants, i.e., their mycorrhizal status and dependency on AMF. However, the alterations induced by the plant species in soil chemical properties rather than in AMF community were the major drivers of differences in shoot mass and photosynthetic performance of P. lanceolata. We determined that the plants produced species-specific effects on soil properties that, in turn, resulted in species-specific soil feedbacks on the native plant. These effects were not consistent within groups of invaders or natives.     

The Relationship Study of Biomass,Situation, and Artificial Control: the Degradation of NP Using Estuary-Derived Fungi

Cultural situation generally played a crucial role on biodegradation mechanism establishment of pollutant. Extensive studies had focused on the optimization of cultivation environment based on in situ conditions. However, there were still few reports on the effects of artificial control on microbial growth and degradation. In this work, the relationship of biomass, situation, and artificial control was explored through the biodegradation of nonylphenols as standard containments by four trains named A. niger, A. terreus SHPP01, A. terreus NIH2624, and T. aff. harzianum from the estuary sediment of Jiaozhou Bay. Various culture conditions covering mineral salt medium, glucose synergistic medium, and carbon rich complex medium had been used to quest the relationship. As a conclusion, different strains usually showed different mechanisms within the same media. The correlation ship between biomass and degradation and removal rate was positive, and the natural medium was usually the best choice for microbial study in situ simulation. Hence, our study provided a valuable reference for the realization of more efficient and rapid biodegradation of pollutants.     

Assessment of <Emphasis Type="Italic">Koelreuteria paniculata</Emphasis> Seedling for Phytroremediation of Pyrene-Contaminated Soils

Phytoremediation is a cost-effective and environmentally friendly technology using plants for the cleanup of both inorganic and organic contaminated sites. In this study, a pot culture experiment has been conducted for 180 days in a greenhouse to examine the capability of Koelreuteria paniculata on pyrene (Pyr) dissipation in contaminated soil. Three treatments were employed and they were: (1) polluted soil with K. paniculata fine roots addition (T1), (2) polluted soil with planted seedlings (T2), and (3) polluted soil (C). Results showed Pyr concentration in soils was reduced by 21.4, 36.2, and 86.4% by natural losses, fine roots addition, and planted K. paniculata treatments, respectively, meaning plants substantially enhanced the dissipation of Pyr from soil. Cultivated K. paniculata seedlings significantly increased soil total nitrogen (TN), total organic carbon, dissolved organic carbon (DOC), and microbial biomass carbon, but not total phosphorus, when compared to the control. The removal efficiency of Pyr was lower in the adding of fine roots treatment than in the planted K. paniculata treatment. The principal component analysis indicated the promotional dissipation of Pyr in soil by planted K. paniculata was likely attributed to increased microbial quantity and activity, DOC, and TN content in the rhizosphere. Our results suggest that K. paniculata is a suitable plant species used in phytoremediation for Pyr-contaminated soils and the efficiency on the dissipation of Pyr is considerably enhanced using living plants than adding dead organic matters. The study provided a reference for the application of K. paniculata in the remediation of Pyr-contaminated soil.     

Optimization of <Emphasis Type="Italic">o</Emphasis>-Chlorophenol Biodegradation by Combined Mycelial Pellets Using Response Surface Methodology

In the present study, the immobilizing fermentation characteristics and o-chlorophenol biodegradation of Rhodopseudomonas palustris using mycelial pellets as a biomass carrier were investigated. To improve the o-chlorophenol degradation efficiency of the combined mycelial pellets, eight cultivation variables including glucose concentration, yeast extract concentration, spore inoculum size, pH, and agitation speed were optimized with an integrated strategy involving a combination of statistical designs. First, Plackett-Burman experiments identified glucose, yeast extract, and spore inoculum size as three statistically significant factors important for o-chlorophenol removal. Then, the steepest ascent method was used to access the optimal region of these significant factors. Finally, response surface methodology by Box-Behnken optimization was used to examine the mutual interactions among these three variables to determine their optimal levels. The ideal culture conditions for maximum o-chlorophenol removal according to a second-order polynomial model were as follows: 15.60 g/L glucose, 3.09 g/L yeast extract, and 9% (v/v) spore inoculum size, resulting in an expected o-chlorophenol removal rate of 92.60% with an o-chlorophenol initial concentration of 50 mg/L and 96-h culture time. The correlation coefficient (R ² = 0.9933) indicated excellent agreement between the experimental and predicted values, whereas a fair association was observed between the predicted model values and those obtained from subsequent experimentation at the optimized conditions.     

Actinomycetes in the rhizosphere of semidesert soils of Mongolia

The population density of actinomycetes in the desert-steppe soil, rhizosphere, and the above-ground parts of plants varies from tens to hundreds of thousands of colony-forming units (CFU) per gram of substrate. The actinomycetal complexes of the brown desert-steppe soil without plant roots are more diverse in their taxonomic composition than the actinomycetal complexes in the rhizosphere and the aboveground parts of plants. Additionally to representatives of the Streptomyces and Micromonospora genera, actinomycetes from the Nocardia, Saccharopolyspora, Thermomonospora, and Actinomadura genera were identified in the soil. The population density of actinomycetes in the rhizosphere and in the soil reached hundreds of thousand CFU/g; it considerably exceeded the population density of actinomycetes in the aboveground parts of plants. The maximum population density of actinomycetes was determined in the rhizosphere of Asparagus gobicus, Salsola pestifera, and Cleistogenes songorica.     

Accumulation of polycyclic aromatic hydrocarbons in soils and plants of the tundra zone under the impact of coal-mining industry

Thirteen polycyclic aromatic hydrocarbon (PAH) compounds were identified in organic horizons of tundra surface-gleyed soils ( Histic Stagnosols (Gelistagnic) and plants. The total content of PAHs in contaminated soils exceeded the background values by three times. Concentrations of low-molecular weight hydrocarbons in soils at different distances from the coalmines were relatively stable. Concentrations of highmolecular weight hydrocarbons had a distinct maximum at a distance of about 0.5 km from the source of emission. The increased values of correlation coefficients were found between PAH concentrations in organic soil horizons, plants, and coal of the Vorkutinskaya mine. Mostly low-molecular weight structures predominated in the organic soil horizons and in the studied plant species. The maximum capacity for the biological accumulation of PAHs was displayed by Pleurozium schreberi and the minimum capacity was displayed by Vaccinium myrtillus. Mosses and lichens actively absorbed polyarenes from the surface; most of the PAHs were transported into the plants. This phenomenon was not observed for Vaccinium myrtillus Concentrations of PAHs on the surface and in plant tissues decreased with an increase in the distance from the mine. Distribution of polyarenes in plant organs was nonuniform. Insignificant excess of concentration of polyarenes was found in dead part of Pleurozium schreberi in comparison with its living part. The accumulation of polyarenes in the leaves of Vaccinium myrtillus was higher than that in its stems and roots.     

Comparative Analysis of Bacteriophages and Bacteria Removal in Soils and Pyrophyllite-Amended Soils: Column Experiments

The objective of the present study was to investigate the transport and removal of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, bacteriophage MS2, and bacteriophage Phix174 in the soils and pyrophyllite-amended soils. Laboratory columns experiments were performed under saturated flow conditions. Our results showed that bacteriophages passed through the soils more easily than bacteria under the given experimental conditions (pulse injection?=?15 min, flow rate?=?0.5 mL/min, column length?=?20 cm, inner diameter?=?2.5 cm, pH?=?7.6, electrical conductivity (EC)?=?150.1 μS/cm); the log removals of bacteria were in the range of 0.44 to 1.72, whereas the log removals of bacteriophages were between 0.01 and 0.13. Our results also demonstrated that the transport of bacteria and bacteriophages in the soil columns could be reduced considerably in the presence of pyrophyllite. Under the same column experimental conditions above, the log removals for MS2 and Phix174 in 50% soil?+?50% pyrophyllite were 2.64 and 3.05, respectively, whereas the log removals in 100% pyrophyllite were 5.70 for MS2 and 5.10 for Phix174; those values were far greater than the log removals in 100% soil (MS2?=?0.063, Phix174?=?0.128). Additional column experiments (step injection, flow rate?=?0.3 mL/min, column length?=?30 cm, inner diameter?=?2.5 cm, solution pH?=?8.4, EC?=?39.8 mS/cm) showed that the log removals for B. subtilis (1.72) and Phix174 (1.48) in the pyrophyllite were greater than those in the soil (B. subtilis?=?1.41; Phix174?=?0.39). This study demonstrated that the pyrophyllite amendment method could be used for protecting groundwater from microbial contamination by animal carcass burial soils.