Characterization of mercury species in soils by HPLC-ICP-MS and measurement of fraction removed by diffusive gradient in thin films

The properties and behaviour of Hg depend on both the oxidation state and the chemical form: the bioavailability, toxicity, persistence and accumulation of mercury in the food web are strongly influenced by chemical speciation. The present work aims to determine the chemical forms of mercury present in soil and to evaluate the fraction of mercury in soil solution available to plants. In order to do this, we analyzed eight samples of contaminated soils with Hg concentrations ranging from 1.31 to 21.7 mg kg⁻¹, collected from different depths (0–10 and 40–50 cm) close to an abandoned industrial site in Val Basento (southern Italy). Two innovative analytical techniques were used: HPLC–ICP-MS and diffusive gradient in thin films (DGT). The analytical procedure was validated using ERM 580-certified sediment and spiked samples in the case of HPLC–ICP-MS, and by a performance test in the case of DGT. In all samples, the only species found in soil and soil solution was MeHg⁺ and Hg²⁺. In soil, the MeHg⁺/Hg_tot ratio ranged from 0.05% to 0.82%; total mercury in soil solution was less than 0.01% of total mercury in soil. The percentage of MeHg⁺ in soil solution varied considerably (from 0% to 50%), with a maximum concentration of 0.02 mg L⁻¹. The root available concentration evaluated by DGT is comparable to the total mercury content of the soil solution measured by HPLC–ICP-MS. The DGT results suggest that all mercury in solution is available for uptake in DGT, and that mercury is supplied from soil to solution. However, for all samples the soluble and root available (DGT-labile) fractions of mercury are generally very low with respect to the total mercury concentration. This study confirmed that both HPLC–ICP-MS and DGT techniques are suitable tools for the estimation of Hg root availability and in assessing the risk from contaminated soils.     

Recent developments in the theory of orographic cyclogenesis: Impact of orographic modifications on statistical properties

Summary Recent developments in the normal mode theory of lee cyclogenesis are presented. The topographic modifications of the most unstable eigenmode are computed in the most general case of primitive equations and isolated topography. The basic state about which linearization is performed is a midlatitude jet with maximum speed at tropopause level. The orographic modification consists in a pressure dipole scaling on the Rossby deformation radius already found in previous theoretical and numerical studies. The modifications of the statistical properties introduced by topography on the nonlinear feedback between zonal wind and transient waves are determined using a simple quasi-geostrophic two-layer model. Systematic differences are found to be consistent with the predictions of linear theories. A brief discussion on the limits of the linear theory is also included Paper presented at the IV Congresso del Gruppo Nazionale per la Fisica dell'Atmosfera e dell'Oceano, June 22–24, 1987, Rome.     

Urban crematoria emissions as they stand with current practice

In order to assess the pollutant load attributable to crematoria, a study was undertaken on the emissions from cremators sited in urban areas. This paper reports some preliminary results from the testing program on an urban cremator emission as it stands with current cremation practices in Italy. Results concern the concentration of the following parameters at the stack: total particulate matter, metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Sn, Tl, V, Zn), organic micropollutants such as dioxins (PCDD_s), dibenzofurans (PCDF_s), polycyclic aromatic hydrocarbons (PAH_s) and polychlorinated biphenyls (PCB_s).     

Evidence for two back-to-back high-p T jets inK + p interactions at 70 GeV/c

Nucleon structure functions obtained from neutrino and anti-neutrino scattering on iron nuclei at high energies (E _v =30 to 250 GeV) are presented. These results are compared with the results of other lepton-nucleon scattering experiments. The structure functions are used to test the validity of the Gross-Llewellyn-smith sum rule, which measures the number of valence quarks in the nucleons, and to obtain leading and second order QCD fits.     

Inclusive pion production in 360 GeV/cpp interactions

In a study of proton-proton interactions at \(\sqrt s = 26GeV\) , inclusive distributions of single pions and systems of pions of various charge combinations are presented, as well as the production ratio obtained in association with various trigger particles. The results are compared to current phenomenological models in an attempt to understand multiparticle productions in hadron collisions.     

A study ofK + p elastic scattering and reactionK + p→K + pπ+π− at 70 GeV/c

Results are presented onK ⁺ p elastic scattering and on the reactionK ⁺ p→K ⁺ pπ⁺π^? at 70 GeV/c. For the elastic channel, we measured the total ((2.29±0.04)mb) and differentialdσ/dt cross sections. The reactionK ⁺ p→K ⁺ pπ⁺π^? has a total cross section of (470±23) μb and is shown to be dominated by diffractive dissociation processes. The contributions of the quasi-two-body channels $$K^ + p \to K*^0 (890)\Delta ^{ + + } (1,236)$$ and $$K^ + p \to K*^0 (1,430)\Delta ^{ + + } (1,236)$$ and of the Double-Pomeron Exchange (DPE) processes are estimated.     

InclusiveK *'s and∑ *'s production in 360 GeV/cpp interactions using the European hybrid spectrometer

We have studied the inclusive production of strange meson and baryon resonances in 360 GeV/cpp interactions. Cross sections forK ^*+(892) andK ^*?(892) are estimated to be 4.42±0.62 mb and 2.54±0.47 mb respectively and those for∑ ⁺(1385) and∑ ^?(1385) are 0.67±0.11 mb and 0.26±0.07 mb respectively. Longitudinal and transverse momentum distributions forK ^*(892) and Σ(1385) are presented, as well as for their decay productsK ⁰ and Λ. An estimation is given on theK ^*(1430) and∑ ^*(1915) productions.