Morpho-physiological and molecular responses of Lepidium sativum L. seeds induced by bismuth exposure.

Bismuth (Bi) is considered a "green metal" as its toxicity has been reported to be lower than other metals, particularly lead. Even though the low presence in the environment, an increase of Bi concentrations in soil and wastewater is predictable due to its enhanced uses for many industrial and medical applications. Therefore, given the little literature on the matter, particularly in plants, information on the effects of Bi on living organisms is needed. In this study, seeds of garden cress (Lepidium sativum L.), a model plant for ecotoxicological assays (OECD), were exposed to increasing Bi concentrations (0 to 485 mg L-1 Bi(NO3)3·5H2O in deionised water) in petri plates. After 72 h, the percent germination index (GI%) revealed no effects at the lowest Bi concentrations, while a slight toxicity occurred at 242 and 485 mg L-1 Bi nitrate. A significant reduction of the root length was observed in Bi-treated seedlings, especially at the highest Bi concentrations. Consistently, the Alkaline Comet Assay revealed a genotoxic effect induced by Bi exposure in garden cress seedlings. A Bi concentration-dependent metal accumulation in plantlets was also observed, with a Bi concentration higher than 1200 mg kg-1 found in plantlets at the highest Bi concentration assayed. The toxicity effects observed in the study were discussed, as contribution to the expansion of knowledge on Bi ecotoxicity and genotoxicity in plants.

Ecotoxicological and genotoxic effects of dimethyl phthalate (DMP) on Lemna minor L. and Spirodela polyrhiza (L.) Schleid. plants under a short-term laboratory assay.

The environmental occurrence of phthalates (PAE) is of great concern for the ecosystem and human health. Despite of their recognized toxicity on biota, a lack of knowledge is still present about the effects of PAE on plants. In this scenario, the effects of dimethyl phthalate (DMP) on duckweed plants (Lemna minor L. and Spirodela polyrhiza (L.) Schleid.), two model plant species for ecotoxicological and trophic studies, were investigated. Under a 7-day lab assay, morphological (biometric indicators), physiological (pigment content and photosynthetic performance) and molecular (DNA damage) parameters were studied. No effects were observed at growth and physiological level in both plants at 3 and 30 mg/L DMP. On the contrary, at 600 mg/L DMP, a concentration used for plant acute toxicity studies, a remarkable growth inhibition and pigment content and photosynthetic parameters reduction compared to control were observed in both plants species, particularly in Spirodela. Alkaline Comet assay in 24 h-treated plants revealed a genotoxic damage induced by DMP, particularly relevant in Spirodela. These results described for the first time the adverse effects exerted by DMP on aquatic plants, contributing to highlight the environmental risk associated to the presence of this compound in the aquatic ecosystem.

PRE-ANTHROPIC AND PRESENT OUTDOOR GAMMA EQUIVALENT DOSE RATE OF THE HISTORIC CENTER OF ROME (ITALY).

The outdoor gamma background of the historic center of Rome was studied by in situ measurements and average values of the outcropping geological formations. The survey resulted in two maps of dose equivalent rate, related to pre-anthropic and present conditions. Presently, the average of the dose equivalent rate from outdoor gamma-ray field is equal to 0.31 µSv h-1, corresponding to an outdoor annual effective dose equivalent of 0.548 mSv a-1 and to an outdoor excess lifetime cancer risk [International Commission on Radiological Protection (ICRP). Recommendations of the ICRP, 21, 1/3, Publication 60, 1990] of 2.56 × 10-3. The originary radioactivity was enhanced by anthropic action up to a level of health risk comparable to that one deriving by fine particulate matter. The assessment of the evolution and dispersion of the outdoor gamma background offers a new perspective to study the urban architectural evolution. Such a mapping allows us to individuate mitigation actions and neighborhoods in which the monitoring of illicit trafficking of radioactive material can be efficiently tested.

Evaluation of morpho-physiological traits and contaminant accumulation ability in Lemna minor L. treated with increasing perfluorooctanoic acid (PFOA) concentrations under laboratory conditions.

There is increasing concern about the effects of releasing emerging contaminants (i.e. endocrine-disrupting chemicals, pharmaceuticals, personal-care products and flame retardants) into the environment. Particular attention is being paid to perfluoroalkyl substances (PFAS) because of their persistence and bioaccumulation, especially in the aquatic environment. In this paper, we present results of a study aimed at evaluating the effects of different perfluorooctanoic acid (PFOA) concentrations (2, 20 and 200 µg/L) on morpho-physiological traits in Lemna minor L. plants. The accumulation of PFOA in the plant's tissues was also monitored. L. minor was selected as a model plant for ecotoxicological studies, and we performed a seven-day assay for this investigation. The results highlight the lack of inhibitory effects on biometric parameters such as mean frond area, total frond number, multiplication rate, doubling time of frond number and average specific growth rate, for each of tested PFOA concentrations. Also, at photosynthetic level, physiological measurements showed that chlorophyll content and electron transport rate (ETR) were not affected by the exposure to PFOA. Remarkably, the chlorophyll fluorescence images, used for the first time in a study on PFOA, evidenced no impairment to the photosynthetic efficiency, measured by the maximum quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), the quantum efficiency of PSII photochemistry (ΦPSII) and the non-photochemical quenching (NPQ) over the leaf surface of PFOA-treated plants, in comparison to control. Quantification of PFOA in the growth medium at the end of the seven-day test revealed no statistically different concentrations in plates with or without L. minor plants. We detected increasing PFOA accumulation in plant tissues, in accordance with the PFOA concentrations in the medium. Therefore, the L. minor plants were capable of taking up and accumulating PFOA. The ecological impact of the environmentally relevant PFOA concentrations tested in this work on biological organisms of the aquatic environment is discussed.

(212)Pb as tracer for PM deposition on urban vegetation.

(212)Pb concentration in outdoor air is closely correlated with fine suspended particulate matter in the atmosphere. Thanks to this association, this isotope can be used to trace the sinking processes of particulate matter due to the vegetation, also providing accurate estimations of the deposition velocity on foliar surfaces. This approach is particularly effective in areas with high thoron fluxes and, consequently, high (212)Pb fluxes from soil. The contribution of vegetation to the improvement of air quality (AQImp) in the municipality area (MA) of Rome (Latium, Italy), almost entirely located on Th-enriched volcanic soils, was estimated by studying (212)Pb deposition velocity on the grasses (0.9-2.5mm·s(-1)) and on the most common tree classes, namely conifers (1.5-15mm·s(-1)), evergreen (1-4mm·s(-1)) and deciduous (0.2-1.5mm·s(-1)). (212)Pb activity in outdoor air was determined by gamma spectrometry after air pumping with accumulation on cellulose filters and after collection on artificial electrostatically charged surfaces (ECS). The high (212)Pb activity values obtained from this analysis (0.90±0.6Bqm(-3) and 0.58±0.15Bqm(-3), respectively near and far from the soil) are consistent both with the average regional thoron flux from volcanic soils (2.9·10(4)Bqm(-2)·h(-1)) and with the thoron flux measured in the volcanic soils of the study area. Thoron and (212)Pb fluxes were also measured both in laboratory and in the field under different soil moisture conditions. The total AQImp for the period from September 2014 to September 2015, calculated after the classification of the MA of Rome into six classes of vegetation, provided a value of 0.20 corresponding to 2.3 Tons per day of removed PM10. The role of grasslands in the PM10 removal, the contribution of the vegetation to the improvement of AQImp and the possibility of improving the sinking efficiency of green areas by increasing conifer trees coverage were also highlighted.