Historical alteration in the nitrogen concentration and N natural abundance of mosses in Germany: Indication for regionally varying changes in atmospheric nitrogen deposition within the last 140 years

Historical alterations of nitrogen deposition in the western part of Germany were investigated by comparing nitrogen concentrations and ¹⁵N natural abundance of historical and recent samples of the two pleurocarpous mosses Pleurozium schreberi and Scleropodium purum. Pooling of the data revealed only slight tissue N increases over the past 140 years which were significant nevertheless. At closer examination on the single site level historical increases of N concentrations were found particularly for some sites in regions where agricultural activities were considerably intensified during the second half of the 20th century. The comparison of δ¹⁵N values showed a strong depletion of ¹⁵N natural abundance in areas currently heavily influenced by livestock management. This indicates an increased impact of NH_y compounds. However, the almost unchanged δ¹⁵N values in some low mountain range areas with only moderate intensification of agriculture point to a more or less constant ratio of NH_y/NO_x input over time. Significant correlations of both tissue N concentrations and ¹⁵N natural abundance between the two species justify the assumption that they use the same nitrogen source, probably atmospheric deposition.     

Diffusion of US army chemical weapons disposal technologies: public perception of technology attributes

This study was conducted to identify factors that influence individuals' acceptance of environmental management technologies for cleaning up hazardous materials. The study sample consisted of approximately 2600 residents living within emergency response zones surrounding eight US Army's Chemical Weapons Stockpile sites. The findings suggest that residents perceive clear differences between the desirable characteristics of the two technologies: incineration and neutralization. In a relative comparison, the majority of positive technological attributes were associated with incineration. Positive perceptions toward incineration were associated with individuals who trust the Army, who perceive that the media have made them more trusting of weapons disposal activities, who are ready to participate, and who are male. Unlike incineration, there was insufficient evidence that individual factors influence variations in perceptions toward neutralization. No community factor was related to perceptions toward either incineration or neutralization.     

Cadmium sorption by sodium and thiourea-modified zeolite-rich tuffs

In the present investigation, two zeolite-rich tuffs from Guaymas and El Cajon(State of Sonora), which were conditioned with a sodium chloride solution and subsequently modified with a thiourea solution, were chosen to evaluate the removal of Cd from aqueous systems. The zeolitic materials were characterized by scanning electron microscopy and X-ray diffraction. The surface area was also determined. The experiments were performed in a batch system, and the influences of p H, contact time between phases, and the concentration of Cd in the solution on the adsorption by sodium or thiourea-modified zeolite-rich tuff were investigated. It was found that the efficiency of Cd ion removal from aqueous solutions is influenced by the p H of the aqueous systems. The Cd adsorption kinetic data were well fitted to a pseudo-second-order model in all cases. The Langmuir and Langmuir–Freundlich isotherms adequately described the Cd sorption behavior by the zeolite from El Cajon pretreated with Na Cl and the zeolite from Guaymas modified with thiourea, respectively.