Can Winter Road De-Icing Affect Mortality of Organisms in Aquatic Ecosystems? An Experimental Approach

Road maintenance in winter using de-icing agents, which is widely used in Eastern Europe, is the cause of water salinization in neighbouring environments, which might lead to biodiversity loss in aquatic ecosystems. In this study, we investigated NaCl toxicity to test young organisms: Daphnia magna and Poecilla reticulata (standard tests organisms). The salinity of NaCl was measured by electrolytic conductivity (EC). It was statistically demonstrated that the test solutions should be prepared using natural water. For D. magna the NOEC was 7.17 mS/cm and the LC50 9.76 mS/cm. Poecilla reticulata showed resistance to salinity up to a conductivity of 25.2 mS/cm, and no lethal effects were recorded for any individual in the test population. The study showed that winter salinities recorded in inland waters (without emergencies such as sudden influx of pollutants due to industrial accidents) are unlikely to affect fish but may be hazardous to small plankton. However, the high dare of D. magna may result in a reduction of planktivorous fish.

Improving salinity tolerance in Salvia officinalis L. by foliar application of salicylic acid

Background Higher absorption and translocation of sodium (Na) and chlorine (Cl) ions in plant tissue can lead to serious physiological and biochemical changes. However, salicylic acid (SA) is a natural signaling molecule responsible for the induction of environmental stress tolerance in plants. Spraying SA could provide protection against several types of stress such as salinity. This study aimed to show the influence of SA spraying (0.5 and 1 mM) on the damaging effects of NaCl toxicity (150 mM) in Salvia officinalis L. plants. Results The results showed that salinity strongly inhibited the growth of aerial and root parts and this inhibition was accompanied by a significant decrease in the production of chlorophyll pigments (by 63%). There was also a significant accumulation of Na, mainly in the roots. This accumulation of Na+ ions was accompanied by a decrease of calcium (Ca), potassium (K) and phosphorus (P) concentrations. However, SA mainly at 0.5 mM, greatly improved plant growth, essential oils and chlorophyll pigments synthesis. Besides, SA led to a decrease in Na content and an improvement in Ca, K and P content in the leaves and roots. Salt stress decreased the essential oil yield from 1.2% (control) to 0.4% (NaCl). Furthermore, gas chromatography–mass spectrometry analysis of essential oils exhibited that the 1,8-cineol, α-thujone, and camphor were identified as the main components of essential oils under all treatments. However, we noted in stressed plant treated or not with SA the appearance of the new majority compound thujanone. Salt stress decreased the major compounds content. SA spray under stress condition increased the content of major compounds compared to stressed plants untreated with SA. The histological study in scanning electron microscopy showed the peltate glands density decreased strongly under NaCl toxicity. However, SA application on stressed plants increased peltate glands density. On the other hand, the glands of stressed plants often show certain anomalies in the morphology: the first anomaly observed was the presence of glandular structures characterized by deformations in the form of small protuberances located on the head of the gland. The second, a less common abnormality is the morphological change in certain glands that change from a spherical to an ovoid shape. On another hand, all these anomalies were not detected in stressed plants sprayed with SA. Therefore, the absence of these anomalies under the effect of SA showed the repairing effect of this growth regulator. Conclusion The findings of the present work suggest that spraying of SA may be useful for improving the plant growth in NaCl-contaminated areas.