Arkadiusz Przybysz

Accumulation of particulate matter and trace elements on vegetation as affected by pollution level, rainfall and the passage of time

Particulate matter is harmful to human health. To reduce its concentration in air, plants could be used as biological filters, accumulating particulate matter on their foliage. In a study carried out at three sites with differing pollution levels and exposure to precipitation, the capacity of evergreen species (Taxus baccata L., Hedera helix L. and Pinus sylvestris L.) to accumulate particulate matter and trace elements from ambient air in urban areas was investigated. The effects of rainfall and the passage of time on particulate matter deposition on foliage were also determined. The results showed that foliage accumulated an increasing quantity of particulate matter in successive months, but the actual amount of particulate matter and trace elements accumulated differed considerably between sites and plant species. The greatest accumulation of air pollutants occurred on the foliage of plants protected from the rain at a site exposed to traffic related pollution and the smallest accumulation at a rural site. Among the species analysed, the deposited mass of particulate matter and trace elements was the greatest on P. sylvestris. In all species, precipitation removed a considerable proportion of particles accumulated on foliage. Most of the removed particulate matter was large size fraction, but little belong to the smallest size fraction. These results showed that both, the dynamics of deposition and leaf washing by rain during the season need to be considered when evaluating the total effect of vegetation in pollutant remediation.

The Role of Plant–Microbe Interactions and Their Exploitation for Phytoremediation of Air Pollutants

Since air pollution has been linked to a plethora of human health problems, strategies to improve air quality are indispensable. Despite the complexity in composition of air pollution, phytoremediation was shown to be effective in cleaning air. Plants are known to scavenge significant amounts of air pollutants on their aboveground plant parts. Leaf fall and runoff lead to transfer of (part of) the adsorbed pollutants to the soil and rhizosphere below. After uptake in the roots and leaves, plants can metabolize, sequestrate and/or excrete air pollutants. In addition, plant-associated microorganisms play an important role by degrading, detoxifying or sequestrating the pollutants and by promoting plant growth. In this review, an overview of the available knowledge about the role and potential of plant–microbe interactions to improve indoor and outdoor air quality is provided. Most importantly, common air pollutants (particulate matter, volatile organic compounds and inorganic air pollutants) and their toxicity are described. For each of these pollutant types, a concise overview of the specific contributions of the plant and its microbiome is presented. To conclude, the state of the art and its related future challenges are presented.

The effects of Mg enrichment of vegetable sprouts on Mg concentration, yield and ROS generation

BACKGROUND Two-thirds of the worlds population do not consume the recommended amount of Mg, hence the demand for the production of Mg-enriched plants. Sprouts represent promising targets for enrichment. This study evaluated the effects of enriching broccoli, radish, alfalfa and mung bean sprouts with Mg (50-300 mg L(-1) ) on (i) the concentration of Mg and other ions, (ii) biomass accumulation, (iii) levels of reactive oxygen species (ROS), and (iv) the activity/content of enzymatic and non-enzymatic components of antioxidative systems. RESULTS Enrichment of sprouts with Mg led to a significant increase in Mg concentration, especially in alfalfa (increase of 23-152 %), without depletion of other ions. A higher Mg concentration had a minor effect on biomass accumulation, but increased, often significantly, ROS generation and affected enzymatic and non-enzymatic antioxidative systems. The level of O2 (•-) increased most in broccoli, by 59-158%, while OH(•) increased most in radish, by 200-350%. CONCLUSIONS Enrichment of sprouts with Mg is possible, but attention must be paid to elevated ROS levels in food. Mung bean sprouts are best suited to enrichment as they make a considerable contribution to the daily supplementation of Mg, at still low levels of ROS in enriched plants.

Platinum uptake, distribution and toxicity in Arabidopsis thaliana L. plants

Platinum (Pt) occurs at very low levels in parent rock and soils in unpolluted areas, however concentrations of this element in urban areas is steadily increasing. At the levels recorded in urban environments, Pt is not yet phytotoxic, but it already poses a threat to human health, particularly when present in airborne particulate matter. In this study an attempt was made to evaluate Pt(II) uptake, distribution and toxicity in Arabidopsis thaliana L. plants. Arabidopsis thaliana plants were hydroponically grown with increasing Pt(II) concentrations in the range of 0.025-100µM. Pt(II) was taken up by the roots and translocated to the rosette. At lower Pt(II) concentrations (≤ 2.5μM) hormesis was recorded, plant growth was stimulated, the efficiency of the photosynthetic apparatus improved and biomass accumulation increased. Higher Pt(II) concentrations were phytotoxic, causing growth inhibition, impairment of the photosynthetic apparatus, membrane injuries and a reduction in biomass accumulation. Exposure of A. thaliana to Pt(II) also resulted in an increased content of phytochelatins throughout the plant and glutathione in the rosette. Uptake and translocation of Pt(II) to harvestable organs of A. thaliana suggests that species of higher biomass accumulation from the Brassicaceae family can probably be used for the phytoextraction of Pt-polluted sites.

Stress acclimation and particulate matter accumulation in Pinus sylvestris saplings affected by moderate combinations of urban stressors

To predict how the function of urban vegetation and the provision of ecosystem services respond to combinations of natural and anthropogenic drivers, a better understanding of multiple stress interactions is required. This study tested combined effects of moderate levels of drought, soil salinity and exposure to diesel exhaust on parameters of physiology, metabolism, morphology and growth of Pinus sylvestris L. saplings. We found that plant responses were primarily dominated by single stressors and a few two-way interactions. Stressor combinations did not have considerable additional negative effects on plant performance compared to single stressors. Hence, synergistic and antagonistic interactions were rare and additive effects frequent. Drought cycles caused most negative effects, from chlorophyll a fluorescence and epicuticular wax content to growth responses, while soil salinity caused fewer negative effects but contributed to reduction in fine root growth and fluorescence parameters at low air contamination. Interestingly, the air contamination alone had only marginal effects on plant morphology and growth, but contributed an antagonistic effect, dampening the negative effect of drought and salinity on the maximum quantum efficiency of PSII photochemistry (Fv/Fm) and fine root biomass. Although, these effects were moderate, it appears that exhaust exposure had a cross-acclimation effect on plant responses to drought and salinity. We also found that salinity had a negative effect on the accumulation of particulate matter on shoots, illustrating that the plant stress situation can affect the provisioning of certain ecosystem services like pollution attenuation. These findings have implications for the understanding of the complex natural and anthropogenic stress situation of urban, and how to maintain the ecological functions and delivery of ecosystem services.

Effect of nitrophenolates on pod damage caused by the brassica pod midge on the photosynthetic apparatus and yield of winter oilseed rape

Abstract Oil seed rape (Brassica napus L.) is one of the most commonly grown crops in Central Europe, and the brassica pod midge (Dasineura brassicae Winn.) is one of the most important pests there. Insecticides against this pest applied during flowering may harm bees and other beneficial insects. The use of biostimulants such as nitrophenolates, which are not harmful to beneficial insects, can be an environmentally friendly way to control this pest. Nitrophenolates activate lignin synthesis in rape pods so the brassica pod midge is not able to penetrate pods. Nitrophenolates also regulate the efficiency of the photosynthetic apparatus, thus increasing yield. For these reasons nitrophenolates were tested in field conditions in Central Europe in 2005, 2007 and 2008. Nitrophenolates were applied on 10-m2 plots, and their effect was compared to that of conventional insecticides. The number of damaged pods and yield parameters were assessed; the lignin content as well as photosynthetic rate was measured. Expression of genes related to lignin biosynthesis was examined in Arabidopsis thaliana L. The application of nitrophenolates decreased pod damage caused by the brassica pod midge. Expression levels of four genes related to lignin biosynthesis were increased after the application of nitrophenolates. The yield was higher in nitrophenolate-treated plots, which was attributed to an increase in the intensity of photosynthesis, higher chlorophyll content and improved chlorophyll a fluorescence parameters. The results showed that nitrophenolates have potential as a protective agent, but a further study is required. The application of nitrophenolates holds promise for reducing chemical input into the environment.

Impact of particulate matter accumulation on the photosynthetic apparatus of roadside woody plants growing in the urban conditions

Particulate matter (PM) is one of the most harmful inhaled pollutants. When pollutants are emitted into the atmosphere, the only possible method for cleaning the air is through phytoremediation, where plants act as biological filters for pollutants. However, PM also has negative impacts on plants, although knowledge concerning the effects of PM on vegetation remains limited. In this work, an attempt was therefore made to define the amount of PM and waxes on foliage, and to evaluate the efficiency of the photosynthetic apparatus in seven plant species (three trees, three shrubs and one climber) grown in two locations (centre and suburbs of Warsaw) that differed in their level of PM pollution in the air. More PM and waxes accumulated on the foliage of plants grown in the highly polluted location. These plants also exhibited a lowered efficiency of their photosynthetic apparatus, manifested by a lower photosynthesis rate that corresponded with an increased stomatal resistance. Plants grown in the more polluted environment also showed decreased values of Fv/Fm parameter and no statistically significant trend to increase total chlorophyll content. Among the tested species, Betula pendula Roth accumulated the greatest amount of PM and Physocarpus opulifolius L. showed no weakening of its parameters of photosynthesis in a more contaminated environment.