Over 10⁹ Kg of PCB have been produced world-wide in the last 5 decades and about one-third of this is estimated to be in mobile environmental reservoirs. Entropic dispersion is decreasing geographic distinctions in residue levels, but hazards still persist in spite of dramatic decreases in production and release.

Laser frequency modulation (FM) spectroscopy is a method of optical heterodyne spectroscopy capable of sensitive and rapid detection of absorption or dispersion features /1/. With this technique, quantum (shot noise) limited sensitivity can be readily achieved /2/, rendering FM spectroscopy a very useful tool e.g. for trace gas detection. A particularly attractive version of FM spectroscopy is high-frequency modulation spectroscopy with semiconductor lasers /3,4/: This scheme is implemented by modulating the injection current of the laser diode at radio frequencies, combining the simple and convenient tuning and modulation methods available for diode lasers with the high sensitivity and fast time response of optical heterodyne techniques. Recently, these features have been demonstrated /5/ with a GaAlAs laser diode emitting in the near infra-red.

The epiphytic lichen Parmelia caperata collected in San Rossore park was analyzed for trace elements. Metal deposition in the park was found to be low throughout the year. A slight increase in Cu, Co, and Ni occurred at the east-southeastern edge of the park adjacent to Pisa. Lichens ware not affected by the sea-spray which has destroyed the coastal vegetation. The contrast with the results of previous pine needle biomonitoring is discussed.

One hundred and thirty-four episodes of stone colic occurring in one center in 1984 were studied. Urinary stone formation was frequent in the hot season. Actual daily climatic factors which provoked the stone to cause colic were examined. Falling barometric pressure was followed by a high incidence of colic, and rising pressure was followed by a low incidence. Falling air temperature in the cold season and rising temperature in the hot season were associated with high incidence of colic.

Assessing the significance of toxicological tests and observations for risks to both humans and other organisms is impossible without defining the exposures to the hazardous agent (chemical or otherwise). The risk assessor must use a collection of techniques to express the exposures of target organisms in terms that are compatible with the measurements of exposure reported in the literature on toxicological tests.

The chemistry of the snowpack and snowmelt was investigated at the Turkey Lakes Watershed during the spring melt period in 1985. Ions in the snowmelt were 2 to 10 times more concentrated than those in the pre-melt snowpack and approximately 50% of the H⁺, SO₄ and NO₃ were lost from the snowpack with the first 30% of the melt. Rainfall flowed directly through the snow cover even during the early stages of the melt. Four rain events, which accounted for only 18% of the flowthrough collected, were responsible for about 50% of the H⁺ and SO₄ and 37% of the NO₃ ions exported from the snowpack. Sulphate to nitrate equivalent ratios in the pre-melt snowpack were generally about 0.6 but an enrichment of SO₄ relative to NO₃ in atmospheric deposition during the spring (SO₄:NO₃ > 1) resulted in snowmelt with an increasing SO₄ content relative to NO₃.

The regeneratable forms of pollutant metals in lake sediments were estimated using different chemical extractants and the effects of lake acidification on the mobilization of such metal fractions studied in laboratory microcosm. The release of each metal was found to increase exponentially below a threshold pH value, which was about 4.0 for Cu, Ni, Zn, Cd and Fe. The data suggest that a large percentage of pollutant metals are mobile as determined by chemical extraction techniques and long-term release experiments.

A pollution-related study has been carried out for the Swiss city of Bienne that is located in complex terrain at the foot of the Jura mountains. The study consists of an analysis of pollutant transport and dispersion from various emittors located in the city, using a coupled system of mesoscale and micro-scale atmospheric numerical models. Simulations of atmospheric flow with the mesoscale model over a 20 × 20 km domain (horizontal resolution: 500 m; vertical resolution: 250 m) are used to initialize a micro-scale model centered over the city. The domain of this latter model is 4 × 4 km (horizontal resolution: 100 m; vertical resolution: 10 m). Plume trajectories are computed in the micro-scale model, and are a function of the regional-scale flow field previously calculated by the mesoscale model. Results show that the flow — and hence the plume trajectories embedded within this motion field — an sensitive not only to channeling effects by the local valley systems, but also to local or regional meteorological effects resulting from cloud activity, urban heat island, and the direction of the synoptic scale flow with respect to the orientation of the Jura mointains.