Heavy Metals Bioindication Potential of the Common Weeds Senecio vulgaris L., Polygonum aviculare L. and Poa annua L.

In recent years, heavy metals (HMs) levels in soil and vegetation have increased considerably due to traffic pollution. These pollutants can be taken up from the soil through the root system. The ability of plants to accumulate HMs into their tissues can therefore be used to monitor soil pollution. The aim of this study was to test the ruderal species Senecio vulgaris L., Polygonum aviculare L., and Poa annua L., as possible candidates for biomonitoring Cu, Zn, Cd, Cr, Ni and Pb in multiple environments. The soils analyzed in this work came from three different environments (urban, woodland, and ultramafic), and therefore deeply differed for their metal content, texture, pH, and organic matter (OM) content. All urban soils were characterized by high OM content and presence of anthropogenic metals like Pb, Zn, Cd, and Cu. Woodland soils were sandy and characterized by low metal content and low OM content, and ultramafic soils had high Ni and Cr content. This soil variability affected the bioindication properties of the three studied species, leading to the exclusion of most metals (Zn, Cu, Cr, Cd, and Pb) and one species (P. aviculare) due to the lack of linear relations between metal in soil and metal in plants. Senecio vulgaris and Poa annua, conversely, appeared to be good indicators of Ni in all the soils tested. A high linear correlation between total Ni in soil and Ni concentration in P. annua shoots (R2 = 0.78) was found and similar results were achieved for S. vulgaris (R2 = 0.88).

Compound-specific δ15N values express differences in amino acid metabolism in plants of varying lignin content.

Amino acid δ15N values of foliage of various plant taxa, grown at the experimental farm stations of North Wyke, UK and Bad Lauchstädt, Germany were determined by GC-C-IRMS. The difference between δ15N values of glutamate (Glx) and phenylalanine (Phe) were found to differ significantly between woody and herbaceous plants, with mean Δ15NGlx-Phe (i.e. δ15NPhe - δ15NGlx) values of -9.3 ±â€¯1.6‰ and -5.8 ±â€¯2.1‰, respectively. These differences in values are hypothesised to be due to the involvement of Phe in the phenylpropanoid pathway, by which lignin and other phenolic secondary metabolites are produced, leading to isotopic fractionation and enrichment of the remaining Phe pool available for protein biosynthesis. This results in the more negative Δ15NGlx-Phe values observed in woody plants relative to herbaceous plants, as the former are assumed to produce more lignin. To test this assumption, plant leaf tissue lignin concentrations were estimated by solid state 13C cross-polarisation, magic-angle-spinning (CPMAS) NMR spectroscopy for a subset of plants, which showed that tree foliage has a higher concentration of lignin (12.6 wt%) than herbaceous foliage (6.3 wt%). The correlation of lignin concentration with Δ15NGlx-Phe values demonstrates that the difference in these values with plant type is indeed due to differential production of lignin. The ability to estimate the lignin content of plants from amino acid δ15N values will, to give one example, allow refinement of estimates of herbivore diet in present and past ecosystems, enabling more accurate environmental niche modelling.

Role of Plant Volatiles in Host Plant Recognition by Listronotus maculicollis (Coleoptera: Curculionidae).

The annual bluegrass weevil (ABW), Listronotus maculicollis Kirby, is an economically important pest of short cut turfgrass. Annual bluegrass, Poa annua L., is the most preferred and suitable host for ABW oviposition, larval survival and development. We investigated the involvement of grass volatiles in ABW host plant preference under laboratory and field conditions. First, ovipositional and feeding preferences of ABW adults were studied in a sensory deprivation experiment. Clear evidence of involvement of olfaction in host recognition by ABW was demonstrated. Poa annua was preferred for oviposition over three bentgrasses, Agrostis spp., but weevils with blocked antennae did not exhibit significant preferences. ABW behavioral responses to volatiles emitted by Agrostis spp. and P. annua were examined in Y-tube olfactometer assays. Poa annua was attractive to ABW females and preferred to Agrostis spp. cultivars in Y-tube assays. Headspace volatiles emitted by P. annua and four cultivars of Agrostis stolonifera L. and two each of A. capillaris L. and A. canina L. were extracted, identified and compared. No P. annua specific volatiles were found, but Agrostis spp. tended to have larger quantities of terpenoids than P. annua. (Z)-3-hexenyl acetate, phenyl ethyl alcohol and their combination were the most attractive compounds to ABW females in laboratory Y-tube assays. The combination of these compounds as a trap bait in field experiments attracted adults during the spring migration, but was ineffective once the adults were on the short-mown turfgrass. Hence, their usefulness for monitoring weevil populations needs further investigation.

Level of contamination with mycobiota and contents of mycotoxins from the group of trichothecenes in grain of wheat , oats, barley, rye and triticale harvested in Poland in 2006- 2008.

INTRODUCTION AND OBJECTIVE: The risk of cereal exposure to microbial contamination is high and possible at any time, starting from the period of plant vegetation, through harvest, up to the processing, storage and transport of the final product. Contents of mycotoxins in grain are inseparably connected with the presence of fungal biomass, the presence of which may indicate the occurrence of a fungus, and indirectly also products of its metabolism. MATERIALS AND METHOD: Analyses were conducted on 378 grain samples of wheat, triticale, barley, rye and oats collected from grain silos located at grain purchase stations and at mills in Poland in 2006, 2007 and 2008. The concentrations of ERG and mycotoxins from the group of trichothecenes, as well as CFU numbers were analysed. RESULTS: The tested cereals were characterised by similarly low concentrations of both the investigated fungal metabolites and the level of microscopic fungi. However, conducted statistical analyses showed significant variation between tested treatments. Oat and rye grain contained the highest amounts of ERG, total toxins and CFU. In turn, the lowest values of investigated parameters were found in grain of wheat and triticale. CONCLUSIONS: Chemometric analyses, based on the results of chemical and microbiological tests, showed slight differences between contents of analysed metabolites between the years of the study, and do not confirm the observations on the significance of the effect of weather conditions on the development of mycobiota and production of mycotoxins; however, it does pertain to treatments showing no significant infestation. Highly significant correlations between contents of trichothecenes and ERG concentration (higher than in the case of the correlation of the total toxin concentrations/log cfu/g), indicate that the level of this metabolite is inseparably connected with mycotoxin contents in grain.

Development of natural treatment system consisting of black soil and Kentucky bluegrass for the post-treatment of anaerobically digested strong wastewater.

To develop a sound post-treatment process for anaerobically-digested strong wastewater, a novel natural treatment system comprising two units is put forward. The first unit, a trickling filter, provides for further reduction of biochemical oxygen demand and adjustable nitrification. The subsequent soil-plant unit aims at removing and recovering the nutrients nitrogen (N), phosphorus (P) and potassium (K). As a lab-scale feasibility study, a soil column test was conducted, in which black soil and valuable Kentucky bluegrass were integrated to treat artificial nutrient-enriched wastewater. After a long-term operation, the nitrification function was well established in the top layers, despite the need for an improved denitrification process prior to discharge. P and K were retained by the soil through distinct mechanisms. Since they either partially or totally remained in plant-available forms in the soil, indirect nutrient reuse could be achieved. As for Kentucky bluegrass, it displayed better growth status when receiving wastewater, with direct recovery of 8%, 6% and 14% of input N, P and K, respectively. Furthermore, the indispensable role of Kentucky bluegrass for better treatment performance was proved, as it enhanced the cell-specific nitrification potential of the soil nitrifying microorganisms inhabiting the rhizosphere. After further upgrade, the proposed system is expected to become a new solution for strong wastewater pollution.

Active matrix-based collection of airborne analytes: an analyte recording chip providing exposure history and finger print.

In the field of sensors that target the detection of airborne analytes, Corona/lens-based-collection provides a new path to achieve a high sensitivity. An active-matrix-based analyte collection approach referred to as "airborne analyte memory chip/recorder" is demonstrated, which takes and stores airborne analytes in a matrix to provide an exposure history for off-site analysis.

Predicting As, Cd, Cu, Pb and Zn levels in grasses (Agrostis sp. and Poa sp.) and stinging nettle (Urtica dioica) applying soil-plant transfer models.

The aim of this study was to derive regression-based soil-plant models to predict and compare metal(loid) (i.e. As, Cd, Cu, Pb and Zn) concentrations in plants (grass Agrostis sp./Poa sp. and nettle Urtica dioica L.) among sites with a wide range of metal pollution and a wide variation in soil properties. Regression models were based on the pseudo total (aqua-regia) and exchangeable (0.01 M CaCl2) soil metal concentrations. Plant metal concentrations were best explained by the pseudo total soil metal concentrations in combination with soil properties. The most important soil property that influenced U. dioica metal concentrations was the clay content, while for grass organic matter (OM) and pH affected the As (OM) and Cu and Zn (pH). In this study multiple linear regression models proved functional in predicting metal accumulation in plants on a regional scale. With the proposed models based on the pseudo total metal concentration, the percentage of variation explained for the metals As, Cd, Cu, Pb and Zn were 0.56%, 0.47%, 0.59%, 0.61%, 0.30% in nettle and 0.46%, 0.38%, 0.27%, 0.50%, 0.28% in grass.

Clothianidin and Imidacloprid Residues in Poa annua (Poales: Poaceae) and Their Effects on Listronotus maculicollis (Coleoptera: Curculionidae).

Competitive enzyme-linked immunosorbent assay was used to quantify the amounts of the neonicotinoids clothianidin and imidacloprid in Poa annua L. clippings from treated golf course fairways. Average clothianidin residues 7 d after application ranged from 674 to 1,550 ng/g tissue in 2012 and 455-2,220 ng/g tissue in 2013. Average clothianidin residues the day of application ranged from 17,100-38,800 ng/g tissue in 2014. Average imidacloprid residues 7 d after treatment ranged from 1,950-3,030 ng/g tissue in 2012 and 7,780-9,230 ng/g tissue in 2013. Average imidacloprid residues the day of application ranged from 31,500-40,400 ng/g tissue in 2014. Neonicotinoid or bifenthrin-neonicotinoid combination products applied in field plots in 2012 did not significantly reduce the numbers of larvae relative to the untreated control. However, in 2013, statistically significant reductions in the numbers of larvae recovered from treated field plots were associated with the presence of bifenthrin alone or when used in combination with neonicotinoid active ingredients. Listronotus maculicollis (Kirby) adults caged on neonicotinoid-, bifenthrin-, and bifenthrin-neonicotinoid-treated P. annua turf plugs fed on P. annua leaves, but mortality was only highly significantly different between treated and untreated foliage when weevils were placed on treated foliage the day after treatment and allowed to feed for 7 d. The modest degree of population suppression with bifenthrin in these experiments may not be adequate to justify the continued use of these products due to the increased risk of insecticide resistance and disruption of biological control.

Chemical characterization of chars developed from thermochemical treatment of Kentucky bluegrass seed screenings.

Seed mill screenings would be a considerable biofeedstock source for bioenergy and char production. Char produced from the gasification of residues resulting from cleaning of grass seed and small grains could be recycled to a cropping system as a soil amendment if chemical characterization determined that the gasification process had not produced or concentrated deleterious chemical or physical factors that might harm the environment, crop growth or yield. Previous reports have shown that char derived from the pyrolysis of a variety of biomass feedstocks has potential to enhance soil quality by pH adjustment, mineral amendment, and improved soil porosity. The objective of this research was to characterize char produced from Kentucky bluegrass seed mill screenings (KBss) by a small-scale gasification unit, operated at temperatures between 600 and 650°C, with respect to polycyclic aromatic hydrocarbons, selected heavy metals, as well as other physical and chemical characteristics, and determine its suitability for agricultural application as a soil amendment. We utilized KBss as a model for seed and grain-cleaning residues with the understanding that chemical and physical characteristics of char produced by gasification or other cleaning residues may differ based on soil and environmental conditions under which the crops were produced. Our results support the hypothesis that KBss char could be applied in a cropping system without toxic environmental consequences and serve multiple purposes, such as; recycling critical plant macro- and micro-nutrients back to existing cropland, enhancing soil carbon sequestration, managing soil pH, and improving water holding capacity. Crop field trails need to be implemented to further test these hypotheses.

Rapid assessment of mineral concentration in meadow grasses by near infrared reflectance spectroscopy.

A near infrared reflectance spectroscopy (NIRS) method for rapid determination of nitrogen, phosphorous and potassium in diverse meadow grasses was developed with a view towards utilizing this material for biogas production and organic fertilizer. NIRS spectra between 12,000 cm(-1) and 4,000 cm(-1) were used. When validated on samples from different years to those used for the calibration set, the NIRS prediction of nitrogen was considered moderately useful with R(2) = 0.77, ratio of standard error of prediction to reference data range (RER) of 9.32 and ratio of standard error of prediction to standard deviation of reference data (RPD) of 2.33. Prediction of potassium was less accurate, with R(2) = 0.77, RER of 6.56 and RPD of 1.45, whilst prediction of phosphorous was not considered accurate enough to be of any practical use. This work is of interest from the point of view of both the removal of excess nutrients from formerly intensively farmed areas and also for assessing the plant biomass suitability for conversion into carbon neutral energy through biogas production.

Uptake of heavy metals by native species growing in a mining area in Sardinia, Italy: discovering native flora for phytoremediation.

This study assessed the distribution and availability of plant uptake of Zn, Pb, and Cd present in an abandoned mine at Ingurtosu, Sardinia (Italy). Geological matrix samples (sediments, tailings, and soil from a nearby pasture site) and samples of the predominant plant species growing on sediments and tailings were collected. Mean values of total Zn, Pb and Cd were respectively (mg kg(-1)) 7400, 1800, and 56 in tailings, 31000, 2900, and 100 in sediments, and 400, 200, and 8 in the pasture soil. The metal concentration values were high even in the mobile fractions evaluated by simplified sequential extraction (Zn 7485-103, Pb 1015-101, Cd 47-4 mg kg(-1)). Predominant native species were identified and analyzed for heavy metal content in various tissues. Among the plant species investigated Inula viscosa, Euphorbia dendroides, and Poa annua showed the highest metal concentration in aboveground biomass (mean average of Zn: 1680, 1020, 1400; Pb: 420, 240, 80; Cd: 28, 7, 19 mg kg(-1), respectively). The above mentioned species and A. donax could be good candidates for a phytoextraction procedure. Cistus salvifolius and Helichrysum italicus generally showed behavior more suitable for a phytostabilizer.

Interactive effects of plant-available soil silicon and herbivory on competition between two grass species.

BACKGROUND AND AIMS: The herbivore defence system of true grasses (Poaceae) is predominantly based on silicon that is taken up from the soil and deposited in the leaves in the form of abrasive phytoliths. Silicon uptake mechanisms can be both passive and active, with the latter suggesting that there is an energetic cost to silicon uptake. This study assessed the effects of plant-available soil silicon and herbivory on the competitive interactions between the grasses Poa annua, a species that has previously been reported to accumulate only small amounts of silicon, and Lolium perenne, a high silicon accumulator. METHODS: Plants were grown in mono- and mixed cultures under greenhouse conditions. Plant-available soil silicon levels were manipulated by adding silicon to the soil in the form of sodium silicate. Subsets of mixed culture pots were exposed to above-ground herbivory by desert locusts (Schistocerca gregaria). KEY RESULTS: In the absence of herbivory, silicon addition increased biomass of P. annua but decreased biomass of L. perenne. Silicon addition increased foliar silicon concentrations of both grass species >4-fold. Under low soil-silicon availability the herbivores removed more leaf biomass from L. perenne than from P. annua, whereas under high silicon availability the reverse was true. Consequently, herbivory shifted the competitive balance between the two grass species, with the outcome depending on the availability of soil silicon. CONCLUSIONS: It is concluded that a complex interplay between herbivore abundance, growth-defence trade-offs and the availability of soil silicon in the grasses' local environment affects the outcome of inter-specific competition, and so has the potential to impact on plant community structure.

Volatile constituents of Festuca nigrescens, Phleum alpinum and Poa alpina from N. W. Italian Alpine pastures.

The composition of the volatile fractions of three important grasses from sub-alpine N.W. Italian pastures, namely Festuca nigrescens Lam. non Gaudin (chewing fescue), Phleum alpinum L. (alpine timothy) and Poa alpina L. (alpine bluegrass) was investigated. The fresh aerial parts were collected at the flowering stage during the summer season. The volatile oils obtained from green tissues by steam distillation in a Clevenger-type apparatus, were analyzed by GC/FID and GC/MS. The oil yield was 0.04 +/- 0.01% weight/fresh weight bases for each of the investigated species. Several classes of compounds were found in the volatile fractions, including aldehydes, alcohols, acids, hydrocarbons, esters, ketones, terpenes, and phenolics. Qualitative and quantitative differences were observed.

Forage as a primary source of mycotoxins in animal diets.

The issue of moulds and, thus, contamination with mycotoxins is very topical, particularly in connexion with forages from grass stands used at the end of the growing season. Deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUM) and aflatoxins (AFL) are among the most common mycotoxins. The aim of the paper was to determine concentrations of mycotoxins in selected grasses (Lolium perenne, Festulolium pabulare, Festulolium braunii) and their mixtures with Festuca rubra an/or Poa pratensis during the growing season as a marker of grass safety, which was assessed according to content of the aforementioned mycotoxins. During the growing season grass forage was contaminated with mycotoxins, most of all by DON and ZEA. The contents of AFL and FUM were zero or below the limit of quantification. Moreover, the level of the occurrence of mould was quantified as ergosterol content, which was higher at the specific date of cut. All results were statistically processed and significant changes were discussed.

Climate sensitivity of gaseous elemental mercury dry deposition to plants: impacts of temperature, light intensity, and plant species.

Foliar accumulations of gaseous elemental mercury (GEM) were measured in three plant species between nominal temperatures of 10 and 30 °C and nominal irradiances of 0, 80, and 170 W m(-2) (300 nm-700 nm) in a 19 m(3) controlled environment chamber. The plants exposed were as follows: White Ash (Fraxinus americana; WA); White Spruce (Picea glauca; WS); and Kentucky Bluegrass (Poa partensis; KYBG). Foliar enrichments in the mercury stable isotope ((198)Hg) were used to measure mercury accumulation. Exposures lasted for 1 day after which the leaves were digested in hot acid and the extracted mercury was analyzed with ICPMS. Resistances to accumulative uptake by leaves were observed to be dependent on both light and temperature, reaching minima at optimal growing conditions (20 °C; 170 W m(-2) irradiance between 300-700 nm). Resistances typically increased at lower (10 °C) and higher (30 °C) temperatures and decreased with higher intensities of irradiance. Published models were modified and used to interpret the trends in stomatal and leaf interior resistances to GEM observed in WA. The model captured the experimental trends well and revealed that stomatal and internal resistances were both important across much of the temperature range. At high temperatures, however, stomatal resistance dominated due to increased water vapor pressure deficits. The resistances measured in this study were used to model foliar accumulations of GEM at a northern US deciduous forest using atmospheric mercury and climate measurements made over the 2003 growing season. The results were compared to modeled accumulations for GEM, RGM, and PHg using published deposition velocities. Predictions of foliar GEM accumulation were observed to be a factor of 5-10 lower when the temperature and irradiance dependent resistances determined in this study were used in place of previously published data. GEM uptake by leaves over the growing season was shown to be an important deposition pathway (2.3-3.7 µg m(-2) of one-sided leaf area; OSLA) when compared to total mercury wet deposition (1.2 µg m(-2) OSLA) and estimates of reactive mercury dry deposition (0.1-6 µg m(-2) OSLA). Resistance-Temperature-Irradiance relationships are provided for use in models.

Changing leaf litter feedbacks on plant production across contrasting sub-arctic peatland species and growth forms.

Plant species and growth forms differ widely in litter chemistry, which affects decay and may have important consequences for plant growth via e.g. the release of nutrients and growth-inhibitory compounds. We investigated the overall short-term (9.5 months) and medium-term (21.5 months) feedback effects of leaf litter quality and quantity on plant production, and tested whether growth forms can be used to generalise differences among litter species. Leaf litter effects of 21 sub-arctic vascular peatland species on Poa alpina test plants changed clearly with time. Across all growth forms, litter initially reduced plant biomass compared with untreated plants, particularly litters with a high decomposition rate or low initial lignin/P ratio. In the second year, however, litter effects were neutral or positive, and related to initial litter N concentration (positive), C/N, polyphenol/N and polyphenol/P ratios (all negative), but not to decomposability. Differences in effect size among several litter species were large, while differences in response to increasing litter quantities were not significant or of similar magnitude to differences in response to three contrasting litter species. Growth forms did not differ in initial litter effects, but second-year plant production showed a trend (P<0.10) for differences in response to litters of different growth forms: evergreen shrubs

Soil amendments reduce trace element solubility in a contaminated soil and allow regrowth of natural vegetation.

We tested the effects of three amendments (a biosolid compost, a sugar beet lime, and a combination of leonardite plus sugar beet lime) on trace element stabilisation and spontaneous revegetation of a trace element contaminated soil. Soil properties were analysed before and after amendment application. Spontaneous vegetation growing on the experimental plot was studied by three surveys in terms of number of taxa colonising, percentage vegetation cover and plant biomass. Macronutrients and trace element concentrations of the five most frequent species were analysed. The results showed a positive effect of the amendments both on soil chemical properties and vegetation. All amendments increased soil pH and TOC content and reduced CaCl(2)-soluble-trace element concentrations. Colonisation by wild plants was enhanced in all amended treatments. The nutritional status of the five species studied was improved in some cases, while a general reduction in trace element concentrations of the aboveground parts was observed in all treated plots. The results obtained show that natural assisted remediation has potential for success on a field scale reducing trace element entry in the food chain.

Long-term effects of clipping and nitrogen management in turfgrass on soil organic carbon and nitrogen dynamics: the CENTURY model simulation.

Experiments to document the long-term effects of clipping management on N requirements, soil organic carbon (SOC), and soil organic nitrogen (SON) are difficult and costly and therefore few. The CENTURY ecosystem model offers an opportunity to study long-term effects of turfgrass clipping management on biomass production, N requirements, SOC and SON, and N leaching through computer simulation. In this study, the model was verified by comparing CENTURY-predicted Kentucky bluegrass (Poa pratensis L.) clipping yields with field-measured clipping yields. Long-term simulations were run for Kentucky bluegrass grown under home lawn conditions on a clay loam soil in Colorado. The model predicted that compared with clipping-removed management, returning clippings for 10 to 50 yr would increase soil C sequestration by 11 to 25% and nitrogen sequestration by 12 to 28% under a high (150 kg N ha(-1) yr(-1) nitrogen (N) fertilization regime, and increase soil carbon sequestration by 11 to 59% and N sequestration by 14 to 78% under a low (75 kg N ha(-1) yr(-1)) N fertilization regime. The CENTURY model was further used as a management supporting system to generate optimal N fertilization rates as a function of turfgrass age. Returning grass clippings to the turf-soil ecosystem can reduce N requirements by 25% from 1 to 10 yr after turf establishment, by 33% 11 to 25 yr after establishment, by 50% 25 to 50 yr after establishment, and by 60% thereafter. The CENTURY model shows potential for use as a decision-supporting tool for maintaining turf quality and minimizing negative environmental impacts.