Nanoparticle formation by ozonolysis of inducible plant volatiles

International audienceWe present the first laboratory experiments of aerosol formation from oxidation of volatile organic species emitted by living plants, a process which for half a century has been known to take place in the atmosphere. We have treated white cabbage plants with methyl jasmonate in order to induce the production of monoterpenes and certain less-volatile sesqui- and homoterpenes. Ozone was introduced into the growth chamber in which the plants were placed, and the subsequent aerosol formation and growth of aerosols were monitored by measuring the particle size distributions continuously during the experiments. Our observations show similar particle formation rates as in the atmosphere but much higher growth rates. The results indicate that the concentrations of nonvolatile oxidation products of plant released precursors needed to induce the nucleation are roughly an order-of-magnitude higher than their concentrations during atmospheric nucleation events. Our results therefore suggest that if oxidized organics are involved in atmospheric nucleation events, their role is to participate in the growth of pre-existing molecular clusters rather than to form such clusters through homogeneous or ion-induced nucleation

Visits to national parks and hiking areas: a panel data analysis of their socio-demographic, economic and site quality determinants

This study examines the impacts of socio-demographic, economic and park quality determinants on visits to nature areas. The authors apply panel data estimation techniques to Finnish data on 46 national parks and hiking areas between 2000 and 2008. The main results show that ‘visits to nature areas’, as a variable, reacts positively to the population size and quality features but negatively to gasoline prices and income level. Of the age classes, the population share of ‘young retirees’ – people aged between 65 and 74 – increased the number of visits to nature areas significantly, whereas the share of ‘baby boomers’ – people aged between 55 and 64 – was insignificant in explaining the number of visits. As the baby boomers are reaching retirement age, and assuming that their generation behaves like the young retirees in this study, the demand for national parks and hiking areas may increase substantially in the coming years. This will increase the pressure to expand current parks and establish new ones. </jats:p

Host location behavior of Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) in ambient and moderately elevated ozone in field conditions

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