Is there a downside to plant ecological services in the city? Influences of particulate matter on the two-spotted spider mite (Tetranychus urticae) foraging on the small-leaved lime in urban conditions

The aim of this research was to examine how particulate matter (PM) pollution affects the life history of the two-spotted spider mite (TSSM), Tetranychus urticae (Trombidiformes: Tetranychidae), in modelled urban conditions. For this purpose, experimental populations of TSSM were cultured on the foliage of small-leaved lime (Tilia cordata) contaminated with PM at intensities corresponding to differing city zones such as a park, a busy road and an industrial area. The control samples in the study were washed, unpolluted leaves. The spider mite was selected as a model organism due to its cosmopolitan distribution, broad host spectrum, resistance to a variety of pesticides and food-intake mode involving cell-content sucking, while T. cordata is widely planted in cities and has demonstrated a considerable capability for PM capture. Data on the longevity and mortality of particular instars and on female fecundity at different pollution levels were collected and statistically evaluated. Concentrations of PM typical for roads and industrial city zones significantly reduced total female fecundity (avg. 53.9 and 55.9 eggs/female, respectively, vs 79.2 in control), which entailed a slower population increase, while the survival rate of particular developmental instars (P = 0.52) and fertility curves (P = 0.19) remained unchanged. The presence of PM caused physiological effects in the mites, despite the lack of direct consumption of the pollutant by adult and juvenile instars. Considering the incomparable resilience of TSSM to unfavourable environmental factors, it is predicted that the detrimental influence of PM on other representatives of urban arthropods may be even more severe. The results suggest that there is a need for further investigations into the ecological ramifications of air purification provided by urban green spaces.

Where trees cannot grow - Particulate matter accumulation by urban meadows

It has already been proven that trees and shrubs, can efficiently remove particulate matter (PM) from air. However, almost nothing is known about PM accumulation by herbaceous plants (grasses and forbs) found in urban meadows. Meadows, unlike trees and shrubs, can be located close to roads, one of the main sources of PM in cites. The aim of this study was to investigate the tolerance to urban condition and PM accumulation in the immediate roads vicinity of selected plants species in urban meadows. PM accumulation of annual and perennial meadows was compared with that of lawns. Results were interpreted in the context of species composition, biomass production, soil conditions and ambient PM concentrations. Of the species grown in annual meadows, the highest PM accumulation was found in Achillea millefolium L., Chenopodium album L. and Echium vulgare L., while Centaurea scabiosa L., Echium vulgare L. and Convolvulus arvensis L. accumulated the largest amounts of PM in perennial meadows. PM deposition on plants was positively correlated with a feathery leaf shape. For species in the annual meadows, a positive correlation was also found between PM accumulation and the wax content on plants. The presence of hairs on leaves, leaf size and plant growth pattern had no effect on PM deposition on plants. PM accumulation in one square metre of urban meadow was on average greater than that of lawn, regardless of meadow species' composition, age and location. The greatest accumulation of PM was found in a perennial meadow with low biodiversity but the greatest biomass. It would appear that the biomass produced by meadows and canopy structure has a crucial impact on the amount of PM accumulated by meadow plants. The results obtained indicate that meadows could be an important element of nature-based solutions for mitigating air pollution in urbanised areas.

Particulate Matter deposition on Quercus ilex leaves in an industrial city of central Italy

A number of studies have focused on urban trees to understand their mitigation capacity of air pollution. In this study particulate matter (PM) deposition on Quercus ilex leaves was quantitatively analyzed in four districts of the City of Terni (Italy) for three periods of the year. Fine (between 0.2 and 2.5 μm) and Large (between 2.5 and 10 μm) PM fractions were analyzed. Mean PM deposition value on Quercus ilex leaves was 20.6 μg cm(-2). Variations in PM deposition correlated with distance to main roads and downwind position relatively to industrial area. Epicuticular waxes were measured and related to accumulated PM. For Fine PM deposited in waxes we observed a higher value (40% of total Fine PM) than Large PM (4% of total Large PM). Results from this study allow to increase our understanding about air pollution interactions with urban vegetation and could be hopefully taken into account when guidelines for local urban green management are realized.

Plant species differences in particulate matter accumulation on leaf surfaces

Particulate matter (PM) accumulation on leaves of 22 trees and 25 shrubs was examined in test fields in Norway and Poland. Leaf PM in different particle size fractions (PM(10), PM(2.5), PM(0.2)) differed among the species, by 10- to 15-folds at both test sites. Pinus mugo and Pinus sylvestris, Taxus media and Taxus baccata, Stephanandra incisa and Betula pendula were efficient species in capturing PM. Less efficient species were Acer platanoides, Prunus avium and Tilia cordata. Differences among species within the same genus were also observed. Important traits for PM accumulation were leaf properties such as hair and wax cover. The ranking presented in terms of capturing PM can be used to select species for air pollution removal in urban areas. Efficient plant species and planting designs that can shield vulnerable areas in urban settings from polluting traffic etc. can be used to decrease human exposure to anthropogenic pollutants.

Radiation exposure in stent-grafting of abdominal aortic aneurysms

In recent years, endovascular stent-grafting of abdominal aortic aneurysms has become more and more common. The radiation dose associated with these procedures is not well documented however. The aim of the present study was to estimate the radiation exposure and to simulate the effects of a switch from C-arm radiographic equipment to a dedicated angiographic suite. Dose-area product (DAP) was recorded for 24 aortic stent-grafting procedures. Based on these data, entrance surface dose (ESD) and effective dose were calculated. A simulation of doses at various settings was also performed using a humanoid Alderson phantom. The image quality was evaluated with a CDRAD contrast-detail phantom. The mean DAP was 72.3 Gy cm(2) at 28 min fluoroscopy time with a mean ESD of 0.39 Gy and a mean effective dose of 10.5 mSv. If the procedures had been performed in an angiographic suite, all dose values would be much higher with a mean ESD of 2.9 Gy with 16 patients exceeding 2 Gy, which is considered to be a threshold for possible skin injury. The image quality for fluoroscopy was superior for the C-arm whilst the angiographic unit gave better acquisition images. Using a C-arm unit resulted in doses similar to percutaneous coronary intervention (PCI). If the same patients had been treated using dedicated angiographic equipment, the risk of skin injury would be much higher. It is thus important to be aware of the dose output of the equipment that is used.