peer reviewed

International audience

International audience

peer reviewed | The effects of enhanced (NH4)(2)SO4 (NS) deposition on Norway spruce (Picea abies [L.] Karst) fine root biomass, vitality and chemistry were investigated using root-free in-growth cores reproducing native organic and mineral soil horizons. The cores were covered and watered every 2 weeks with native throughfall or throughfall supplemented with NS to increase deposition by 75 kg ha(-1) a(-1) NH4+-N (86 kg ha(-1) a(-1) SO42--S). The in-growth cores were sampled after 19 months and assessed for root biomass, necromass, length, tip number, tip vitality and fine root chemistry. Root biomass and fine root aluminium (Al) concentration were negatively correlated, but NS deposition had no effect on root growth or root tip vitality. NS deposition caused increased fine root nitrogen (N) concentrations in the organic horizon and increased Calcium (Ca) concentrations in the mineral horizon. Fine root biomass was higher in the organic horizon, where fine root Al and potassium (K) concentrations were lower and Ca concentrations higher than in the mineral horizon. Results highlighted the importance of soil stratification on fine root growth and chemical composition.

This paper presents some preliminary results on the implementation of a biodegradability batch test to fraction different types of wastewater samples to assess the variability of the WWTP influent composition.

Studies were conducted to assess factors that may influence the rate and extent of biodegradation of polyaromatic hydrocarbons (PAHs) in waters of Guayanilla Bay (latitude, 18°N; longitude, 66.45°W) Puerto Rico. Phenanthrene was used as a model PAHs compound. Both the rate and extent of phenanthrene degradation by natural microbial flora present in seawater samples from Guayanilla Bay were quite slow. Addition of KNO3 as a source of inorganic nitrogen (N) resulted in a 10-fold increase in the rate of phenanthrene degradation within a 125 h period, whereas, addition of K2HPO4 as a source of inorganic nutrient phosphorus (P) had no effect. Phenanthrene degradation was strongly inhibited when seawater pH was adjusted to 10.0. Phenanthrene in seawater samples degraded rapidly when first pretreated with hydrogen peroxide (H2O2) and then inoculated with a known indigenous phenanthrene degrading bacterium, Alteromonas sp. Pretreatment of phenanthrene with Triton-x-100 had little or no effect on its degradation by the same bacteria, whereas, degradation in samples preheated at 60°C was somewhat inhibited.