Wood pellet fly ash and bottom ash as an effective liming agent and nutrient source for rye grass (Lolium perenne L.) and oats (Avena sativa)

Fly ash (FA) and bottom ash (BA) from a softwood pellet boiler were characterized and evaluated as soil amendments. In a greenhouse study, two plant species (rye grass, Lolium perenne L. and oats, Avena sativa) were grown in three different treatments (1% FA, 1% BA, non-amended control) of a silty loam soil. Total concentrations of plant nutrients Ca, K, Mg, P and Zn in both ashes were elevated compared to conventional wood ash. Concentrations of Cd, Cr, Pb, Se and Zn were found to be elevated in the FA relative to BA and the non-amended soil. At 28 d, oat above-ground biomass was found to be significantly greater in soil amended with FA. Potassium and Mo plant tissue concentrations were significantly increased by addition of either ash, and FA significantly increased Zn tissue concentrations. Cadmium and Hg tissue concentrations were elevated in some cases. As soil amendments, either pellet ash is an effective liming agent and nutrient source, but high concentrations of Cd and Zn in FA may preclude its use as an agricultural soil amendment in some jurisdictions. Lower ash application rates than those used in this study (i.e. <1%) may still provide sufficient nutrients and effective neutralization of soil acidity.     

The effect of ozone on pollen development in Lolium perenne L

Perennial ryegrass plants (Lolium perenne L.) were exposed in "Closed-Top Chambers" to different ozone concentrations and to charcoal filtered ambient air to study the effect of ozone on the development of pollen. Ozone at ambient (65 nl l(-1), 8h) and elevated (110 nl l(-1), 4h) concentrations affected the maturing of pollen by inhibiting starch accumulation in pollen throughout the anther. Affected pollen persisted in the vacuolated state while normal pollen in the same anther were filled with amyloplasts. The percentage of underdeveloped pollen-determined in transversal sections-was significantly higher in exposed plants than in plants grown in filtered air. Results indicate that ozone stress was responsible for the disrupted development of pollen in L. perenne.     

Arbuscular mycorrhiza enhanced arsenic resistance of both white clover (Trifolium repens Linn.) and ryegrass (Lolium perenne L.) plants in an arsenic-contaminated soil

In a compartmented cultivation system, white clover (Trifolium repens Linn.) and ryegrass (Lolium perenne L.), with their roots freely intermingled, or separated by 37 microm nylon mesh or plastic board, were grown together in an arsenic (As) contaminated soil. The influence of AM inoculation on plant growth, As uptake, phosphorus (P) nutrition, and plant competitions were investigated. Results showed that both plant species highly depended on mycorrhizas for surviving the As contamination. Mycorrhizal inoculation substantially improved plant P nutrition, and in contrast markedly decreased root to shoot As translocation and shoot As concentrations. It also showed that mycorrhizas affected the competition between the two co-existing plant species, preferentially benefiting the clover plants in term of nutrient acquisition and biomass production. Based on the present study, the role of AM fungi in plant adaptation to As contamination, and their potential use for ecological restoration of As contaminated soils are discussed.     

Relationship between ammonia stomatal compensation point and nitrogen metabolism in arable crops: current status of knowledge and potential modelling approaches

The ammonia stomatal compensation point of plants is determined by leaf temperature, ammonium concentration ([NH4+]apo) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal compensation point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83-110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal compensation point is to adequately model [NH4+]apo. This [NH4+]apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal compensation point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH4+]apo.     

Interaction of bioaccumulation of heavy metal chromium with water relation, mineral nutrition and photosynthesis in developed leaves of Lolium perenne L

Contamination by chromium (Cr) is widespread in agricultural soils and industrial sites. This heavy metal represents a risk to human health. In order to gain fundamental insights into the nature of the adaptation to Cr excess, the characterisation of physiological indices, including responses of photosynthetic gas exchange and chlorophyll a fluorescence along with changes in mineral nutrient contents and water status were studied in ray grass (Lolium perenne L.). Increased concentrations of Cr(VI) (0-500 microM Cr) in the Co?c and Lessaint nutrient solution were applied. The growth of Lolium perenne is decreased by chromium and the leaves have lost their pigments. Chromium accumulation was greater in roots than in leaves and reached 2450 and 210 microg g(-1) DW, respectively with 500 microM Cr(VI) in nutrient medium. The physiological parameters were severely reduced by this heavy metal. Cr induced toxicity arising from 100 microM Cr(VI) and resulted in a modification of mineral content in roots and leaves, especially for Ca, Mg and Fe. The chromium stress decreased CO2 assimilation rates mainly due to stomatal closure, which reduced water loss by transpiration without decreasing the cellular available CO2. The fluorescence parameters associated with photosystem II (PSII) activity and the photochemical activity are modified by chromium. Non-radiative energy dissipation mechanisms were triggered during stress since non-photochemical quenching was increased and efficiency of excitation capture by open centers was reduced.     

The effect of ryegrass (Lolium perenne) on decrease of PAH content in long term contaminated soil

The biodegradation of polycyclic aromatic hydrocarbons in microecosystems containing long-term contaminated soil was investigated. Soil was contaminated by different chemicals, including PAHs since World War II. Aging of the soil was expected to act as a principal factor limiting biodegradation. Half of the microecosystems contained ryegrass (Lolium perenne) and long-term selected natural soil microflora originally present in contaminated soil. The others contained contaminated soil with natural microflora only. Half of the microecosystems in each parallel experiment was fertilised with N-P-K fertiliser. Cultivation was carried out at 12 and 18 months in a greenhouse with a natural photoperiod and the ability to degrade 15 chosen PAH was investigated. For analysis, the soil from each pot was divided into three horizontal layers for mutual comparison among layers and each layer was further divided into four equal samples. Soil extracts were analysed using HPLC. After a one-year-cultivation period the content of the monitored PAHs declined to 50%. Mostly, there were no significant differences between the microecosystems. Best degraded were fluoranthene and pyrene, which were the major contaminants present in original soil. Also, other compounds were successfully degraded, even benzo[a]pyrene and benzo[ghi]perylene. Dibenz[a,h]anthracene and indeno[1,2,3-cd]pyrene were the only PAHs, examined that showed no significant degradation. Although some differences between the soil layers were detected, no conclusive trends could be found. However, significantly lower concentrations of PAHs were determined mostly in the bottom layer of the analysed profiles. In vegetated microecosystems the decline of PAHs concentrations was more remarkable after 18 months cultivation.     

Bathymetric variation of epiphytic assemblages on Posidonia oceanica (L.) Delile leaves in relation to anthropogenic disturbance in the southeastern Mediterranean

A survey of the epiphytic leaves of Posidonia oceanica was conducted along a depth transect at both the control station Attaya in the Kerkennah Islands and the disturbed Mahres station on the Sfax coast (Tunisia). Samples were collected by scuba divers at depths of 5, 10, 15, and 20 m in July 2008. We evaluated whether the pattern of spatial variability of the macroepiphyte assemblages of leaves of Posidonia oceanica differed in relation to anthropogenic interference. The results indicate that the decrease in shoot density and leaf length according to depth was low at Mahres. The biomass of epiphytic leaves and the percentage cover of epiphytic assemblages decreased with depth for both stations and heavily at Mahres, this decline being related to anthropogenic disturbance. This study shows that the highest values of epifauna and epiflora were detected at the disturbed station Mahres. Macroalgae assemblages decreased with depth at both stations and were dominated by Rhodophyta, whereas the percentage cover of the epifauna leaf that decreases according to depth was dominated by Hydrozoa and Bryozoa. Changes in epiphyte assemblages, epiphytic biomass, percentage cover, and species richness in proportion to Heterokontophyta, Rhodophyta, Cyanobacteria, Hydrozoa, Porifera, and Tunicata between the two stations constitute promising tools for detecting environmental disturbance.     

Ammonia fluxes and derived canopy compensation points over non-fertilized agricultural grassland in The Netherlands using the new gradient ammonia—high accuracy—monitor (GRAHAM)

During a measurement period from June till November 2004, ammonia fluxes above non-fertilized managed grassland in The Netherlands were measured with a Gradient Ammonia—High Accuracy—Monitor (GRAHAM). Compared with earlier ammonia measurement systems, the GRAHAM has higher accuracy and a quality control system.Flux measurements are presented for two different periods, i.e. a warm, dry summer period (from 18 July till 15 August) and a wet, cool autumn period (23 September till 23 October). From these measurements canopy compensation points were derived. The canopy compensation point is defined as the effective surface concentration of ammonia. In the summer period (negative) deposition fluxes are observed in the evening, night and early morning due to leaf surface wetness, while in the afternoon emission fluxes are observed due to high canopy compensation points. The mean NH₃-flux in this period was 4 ng m⁻² s⁻¹, which corresponds to a net emission of 0.10 kg N ha⁻¹ over the 28 day sampling period. The NH₃-flux in the autumn period mainly shows (negative) deposition fluxes due to small canopy compensation points caused by low temperatures and a generally wet surface. The mean NH₃-flux in this period is −24 ng m⁻² s⁻¹, which corresponds to a net deposition of 0.65 kg N ha⁻¹ over the 31 day sampling period.Frequency distributions of the NH₃-concentration and flux show that despite higher average ambient NH₃-concentrations (13.3 μg m⁻³ in the summer period vs. 6.4 μg m⁻³ in the autumn period) there are more emission events in the summer period than in the autumn period (about 50% of the time in summer vs. 20% in autumn). This is caused by the high canopy compensation points in summer due to high temperatures and a dry surface. In autumn, deposition dominates due to a generally wet surface that induces low canopy compensation points.For our non-fertilized agricultural grassland site, the derived canopy compensation points (at temperatures between 7 and 29 °C) varied from 0.5 to 29.7 μg m⁻³ and were on an average 7.0 μg m⁻³, which is quite high for non-fertilized conditions and probably caused by high nitrogen inputs in the past or high dry deposition amounts from local sources. The average value for the ratio between NH₄⁺ and H⁺ concentration in the canopy, Γ_c, that was derived from our data was 2200.     

Date palm (Phoenix dactylifera L.) leaves as biomonitors of atmospheric metal pollution in arid and semi-arid environments

The leaves of date palms were evaluated as a possible biomonitor of heavy metal contamination in Ma’an city, Jordan. Concentrations of (Fe), (Pb), (Zn), (Cu), (Ni), and (Cr) were determined in washed and unwashed leaves and soil samples collected from different sites with different degrees of metal contamination (urban, suburban, industrial, highway and rural sites); separate leaves were taken from outside the city to be used as a control sample. Samples collected from industrial sites were found to have high concentrations of all metals except those of Cu, Ni and Pb, which were found at high levels in the highway site samples which is associated with the road traffic. The difference between unwashed and washed samples showed that metal pollutants exist as contaminants, particularly Pb, Zn and Ni, which varied in concentration, depending on the source of the metal.     

Acquired changes in stomatal characteristics in response to ozone during plant growth and leaf development of bush beans (Phaseolus vulgaris L.) indicate phenotypic plasticity

Bush bean (Phaseolus vulgaris L.) lines 'S156' (O3-sensitive)/'R123' (O3-tolerant) and cultivars 'BBL 290' (O3-sensitive)/'BBL 274' (O3-tolerant) were used to study the effects of O3 on stomatal conductance (gs), density, and aperture size on leaf and pod surfaces with the objective of establishing links between the degree of plant sensitivity to O3 and plasticity of stomatal properties in response to O3. Studies in open-top chambers (OTCs) and in continuously stirred tank reactors (CSTRs) established a clear relationship between plant developmental stages, degrees of O3 sensitivity and gs: while 'S156' had higher gs rates than 'R123' earlier in development, similar differences between 'BBL 290' and 'BBL 274' were observed at later stages. Gs rates on the abaxial leaf surfaces of 'S156' and 'BBL 290', accompanied by low leaf temperatures, were significantly higher than their O3-tolerant counterparts. Exposure to O3 in CSTRs had greater and more consistent impacts on both stomatal densities and aperture sizes of O3-sensitive cultivars. Stomatal densities were highest on the abaxial leaf surfaces of 'S156' and 'BBL 290' at higher O3 concentrations (60 ppb), but the largest aperture sizes were recorded on the adaxial leaf surfaces at moderate O3 concentrations (30 ppb). Exposure to O3 eliminated aperture size differences on the adaxial leaf surfaces between sensitive and tolerant cultivars. Regardless of sensitivity to O3 and treatment regimes, the smallest aperture sizes and highest stomatal densities were found on the abaxial leaf surface. Our studies showed that O3 has the potential to affect stomatal plasticity and confirmed the presence of different control mechanisms for stomatal development on each leaf surface. This appeared to be more evident in O3-sensitive cultivars.     

Factors determining the uptake of persistent pollutants in an eel population (Anguila anguilla L.)

The distribution of persistent pollutants in an eel population from a eutrophic lake of southern Scandinavia was examined. The origin of PCBs, DDT, DDE and lindane found in the fish was most likely the atmosphere. The most important factors for uptake of the chlorinated hydrocarbons was age (exposure time), growth rate and fat content. The life cycle of the eel is unique with a stage in freshwater when energy reserves (fat stored in muscular tissue) and lipophilic pollutants are accumulated. This stage is followed by a long migration to the spawning areas in the Sargasso Sea when pollutants are released from the fat deposits. These two stages followed by a once-in-a-lifetime spawning behaviour, makes the eel especially vulnerable to persistent pollutants. The effects of persistent pollutants combined with the eel's unusual life cycle may explain the decline in the eel population in northern Europe in recent decades.     

Seasonal variations in the concentrations of cadmium, copper, lead and zinc in leaves of the horse chesnut (Aesculus hippocastanum L.)

The concentrations of cadmium, copper, lead and zinc have been measured in the leaves of a deciduous tree the horse chestnut (Aesculus hippocastanum L.) over the period of their lifetime (7 months). The average concentrations for the total sample based on ash weight are: (microg g(-1)) cadmium, 0.197; copper, 129; lead, 294; and zinc, 299. The temporal trends in the concentrations of the metals can be related to their dominant source. Copper and zinc concentrations are highest in the new leaves and decrease with time, suggesting the main source of the elements are uptake from the soil. The decrease occurs partly because of dilution by leaf material as it increases over the growing period. In the case of zinc, however, aerial deposits appear to be also a significant source. Lead concentrations, on the other hand, show an increase with time, which can be related to increasing deposits from aerosol lead arising from the combustion of petrol lead. The increase is enough to offset the dilution effect. For cadmium there is no significant trend, but the tendency is a decrease with time. It is not possible, however, to distinguish between soil uptake and aerial deposit as both are small compared with increase in leaf material.     

The effects of low-dose biochar amendments on arsenic accumulation in rice (Oryza sativa L.)

Environmental Science and Pollution Research - The accumulation of arsenic (As) in rice is one of the food security-related concerns in As-contaminated areas all over the world. Biochar, a...     

Effect of nitrogenous air pollutants on changes in protein spectra with the onset of winter in the leaves and shoots of the bilberry (Vaccinium myrtillus L.)

Electrophoretic profiles of 0.1 m Tris-HCl (pH 9.0)-soluble proteins in the leaves and stems of the bilberry (Vaccinium myrtillus L.) were investigated in the latter part of the growing season (July-October), in a highly-polluted industrial area with serious forest damage (main emissions NO(2), SO(2), NH(3), urea and fertilizer dust) in Oulu, northern Finland, and in an unpolluted control forest with the same climatic and edaphic conditions. About ten protein components in the leaves and seven in the stems increased in concentration in SDS-PAGE towards the autumn, while one to four other components decreased in concentration. The pollutants in the industrial area caused a considerable decrease in the concentrations of soluble proteins, particularly in the leaves in August and September. A decrease was obtained in six components in the leaves and three components in the stems, while increases were observed in one component in the leaves (10 kDa) and four components in the stems (10, 43, 50 and 65 kDa). One reason for the lowered cold-resistance in the bilberry caused by air pollutants could thus be the lowered concentrations of certain soluble cytoplasmic proteins that protect the plant against winter conditions.     

Use of Co speciation and soil properties to explain variation in Co toxicity to root growth of barley (Hordeum vulgare L.) in different soils

The influence of soil properties on the bioavailability and toxicity of Co to barley (Hordeum vulgare L.) root elongation was investigated. Ten soils varying widely in soil properties were amended with seven doses of CoCl₂. Soil properties greatly influenced the expression of Co toxicity. The effective concentration of added Co causing 50% inhibition (EC₅₀) ranged from 45 to 863 mg kg⁻¹, representing almost 20-fold variation among soils. Furthermore, we investigated Co toxicity in relation to Co concentrations and free Co²⁺ activity in soil solution. The EC₅₀ values showed variation among soils of 17- and 29-fold, based on the Co concentration in soil solution and free Co²⁺ activity, respectively. Single regressions were carried out between Co toxicity threshold values and selected soil properties. Models obtained showed that soil effective cation exchange capacity (eCEC) and exchangeable calcium were the most consistent single predictors of the EC₅₀ values based on soil added Co.     

The significance of water ionic strength on aluminium toxicity in brown trout (Salmo trutta L.)

The toxicity of aluminium to fish is related to interactions between aluminium and the gill surface. We investigated the possible effect of water ionic strength on this interaction. The mortality of brown trout (Salmo trutta L.) exposed to three different degrees of Al polymerisation was compared in water with increased ionic strength (mean 7.31 x 10(-4) M) after additions of the base cations Ca2+, Mg2+, Na+ or K+, and in water with no such addition (mean ionic strength 5.58 x 10(-4) M). Only a very slight ameliorating effect of increased ionic strength was observed, while the degree of Al polymerisation was of major importance in fish mortality. In addition, it was observed that smaller fish survived the Al exposures for a longer time than larger fish. We hypothesise that this is because larger fish are more susceptible to hypoxia than smaller fish.     

The growth and Cu and Zn uptake of pakchois (Brassica chinesis L.) in an acidic soil as affected by chicken or pig manure

In a pot experiment, pig manure (PM) and chicken manure (CM) were applied to an acidic soil at application rates of 2%, 4% and 8% (W/W) to evaluate their effects on the growth, Cu and Zn uptake and transfer of five cultivars of pakchoi (Brassica chinesis L.). The results showed that alkaline manures significantly increased the biomass of pakchois, and also pH and electrical conductivity of the soil. Both 0.01 M CaCl₂ and 1.0 M NH₄NO₃ salt solutions predict the Zn transfer from soil to pakchois well, but not for Cu. For the cultivar Siyueman, the transfer factors of Cu (or Zn) in the PM treatments were higher than that in the CM treatments. In our experiment the Cu and Zn concentrations in pakchois did not exceed the Chinese Food Hygiene Standard, but more attention should be paid to heavy metals risk on pakchois at lower soil pH and salt impairment by manures application.     

The growth and Cu and Zn uptake of pakchois (Brassica chinesis L.) in an acidic soil as affected by chicken or pig manure

In a pot experiment, pig manure (PM) and chicken manure (CM) were applied to an acidic soil at application rates of 2%, 4% and 8% (W/W) to evaluate their effects on the growth, Cu and Zn uptake and transfer of five cultivars of pakchoi (Brassica chinesis L.). The results showed that alkaline manures significantly increased the biomass of pakchois, and also pH and electrical conductivity of the soil. Both 0.01 M CaCl2 and 1.0 M NH4NO3 salt solutions predict the Zn transfer from soil to pakchois well, but not for Cu. For the cultivar Siyueman, the transfer factors of Cu (or Zn) in the PM treatments were higher than that in the CM treatments. In our experiment the Cu and Zn concentrations in pakchois did not exceed the Chinese Food Hygiene Standard, but more attention should be paid to heavy metals risk on pakchois at lower soil pH and salt impairment by manures application.     

The importance of atmospheric deposition, charge and atomic mass to the dynamics of minor and rare elements in developing, ageing, and wilted leaves of beech (Fagus sylvatica L.)

The amounts of sixty elements in developing, maturing, senescent and wilting leaves, and in the wintering dead leaves attached to the branches, are reported for a beech (Fagus sylvatica) forest on mor Podzol in south Sweden, a site with no local sources of pollution or geological anomalies. The amounts (contents per leaf) of K (potassium), Rb (rubidium), Cs (caesium), Cu (copper) and P (phosphorus) were highest in young leaves, decreasing throughout the growing season and usually in the subsequent winter. The entirely opposite pattern with a continuous, mostly even increase of the amounts was measured with Be (beryllium), Ba (barium), Hg (mercury), Al (aluminium), Tl (thallium), Pb (lead), Bi (bismuth), V (vanadium), W (tungsten), As (arsenic), Sb (antimony), and Se (selenium). Amounts of rare-earth elements and some transition metals, such as Co (cobalt), Ti (titanium), and the actinides Th (thorium) and U (uranium) were more stable during the growing season, after an initial increase in early summer, but increased greatly in the winter. This winter increase in dead attached leaves has to be accounted for by uptake from long-distance transported constituents in dry and wet deposition. It was similar to deposition rate estimates using moss carpets from the same locality. A passive uptake was positively related to ionic charge and atomic mass. However, the amounts of several, mainly non-essential elements, such as Ni (nickel), Sc (scandium), Zr (zirconium), Cr (chromium), Ag (silver), and Cd (cadmium) were not much lower in the young or maturing leaves than in the wintered dead leaves of this deciduous (hardwood) forest and a proportion apparently originated from internal translocation in the trees. Seasonal fluxes or cycling of many of the scarce or rare elements reported here have never been studied before in forest ecosystems.