Early stage litter decomposition across biomes

(2018) Early stage litter decomposition across biomes. . : -.
Enllaç
Doi: 10.1016/j.scitotenv.2018.01.012

Resum:

Joining empirical and modelling approaches to estimate dry deposition of nitrogen in Mediterranean forests

García-Gómez H., Izquieta-Rojano S., Aguillaume L., González-Fernández I., Valiño F., Elustondo D., Santamaría J.M., Àvila A., Bytnerowicz A., Bermejo V., Alonso R. (2018) Joining empirical and modelling approaches to estimate dry deposition of nitrogen in Mediterranean forests. Environmental Pollution. 243: 427-436.
Enllaç
Doi: 10.1016/j.envpol.2018.09.015

Resum:

In Mediterranean areas, dry deposition is a major component of the total atmospheric N input to natural habitats, particularly to forest ecosystems. An innovative approach, combining the empirical inferential method (EIM) for surface deposition of NO3 − and NH4 + with stomatal uptake of NH3, HNO3 and NO2 derived from the DO3SE (Deposition of Ozone and Stomatal Exchange) model, was used to estimate total dry deposition of inorganic N air pollutants in four holm oak forests under Mediterranean conditions in Spain. The estimated total deposition varied among the sites and matched the geographical patterns previously found in model estimates: higher deposition was determined at the northern site (28.9 kg N ha−1 year−1) and at the northeastern sites (17.8 and 12.5 kg N ha−1 year−1) than at the central-Spain site (9.4 kg N ha−1 year−1). On average, the estimated dry deposition of atmospheric N represented 77% ± 2% of the total deposition of N, of which surface deposition of gaseous and particulate atmospheric N averaged 10.0 ± 2.9 kg N ha−1 year−1 for the four sites (58% of the total deposition), and stomatal deposition of N gases averaged 3.3 ± 0.8 kg N ha−1 year−1 (19% of the total deposition). Deposition of atmospheric inorganic N was dominated by the surface deposition of oxidized N in all the forests (means of 54% and 42% of the dry and total deposition, respectively). The relative contribution of NO2 to dry deposition averaged from 19% in the peri-urban forests to 11% in the most natural site. During the monitoring period, the empirical critical loads provisionally proposed for ecosystem protection (10–20 kg N ha−1 year−1) was exceeded in three of the four studied forests. Dry deposition of atmospheric N in four forests of Quercus ilex represented 77% of the total deposition of N and it was dominated by the surface deposition of oxidized N. © 2018 Elsevier Ltd

Llegeix més

Atmospheric deposition of particulate matter between Algeria and France: Contribution of long and short-term sources

Lequy E., Avila A., Boudiaf Nait Kaci M., Turpault M.-P. (2018) Atmospheric deposition of particulate matter between Algeria and France: Contribution of long and short-term sources. Atmospheric Environment. 191: 181-193.
Enllaç
Doi: 10.1016/j.atmosenv.2018.08.013

Resum:

Large worldwide sources of dust, such as the Saharan desert, play a key role in the amounts and composition of atmospheric particulate deposition (APD), but their relative contribution compared to other sources remain unclear. Our study aimed to apportion Saharan, regional, and anthropogenic sources of APD in three sampling along a long transect affected by Saharan outbreaks. We quantified total APD, and analyzed its mineralogical and chemical composition between 2011 and 2012.. Strong markers of Saharan dust, such as large amounts of APD and of a low Al2O3:CaO ratio allowed identifying clear periods influenced by Saharan outbreaks. Nitrogen and phosphorus reflected soil affected by agricultural practices, while Cd, Pb, Sb and Sn tracked traffic and industrial sources – as confirmed by enrichment factors. Then, we designed a conceptual model including sensitivity analyses to estimate the contribution of unanalyzed (10–11%, likely chlorites or sulfates), organic (34–41%), anthropogenic (11–22%), mineral-regional (5–25%) and mineral-Saharan (10–38%) matter over our entire study period. Our study shows the rapidly decreasing contribution of Saharan outbreaks – and the decreasing flux of Ca and Mg, from 40 to 0.4 kg.ha−1 over the study period between Algeria and France. Yet, Saharan outbreaks were still noticeable in APD at a site 1500 km away. Our study also shows the large relative contribution of organic and anthropogenic sources to APD in the three sampling sites, and their possible influence on nutrient budgets. © 2018 Elsevier Ltd

Llegeix més