Eros Bacci

BIOCONCENTRATION OF ORGANIC CHEMICAL VAPOURS IN PLANT LEAVES : THE AZALEA MODEL

Abstract Experimental data on the accumulation and release kinetics of azalea leaves exposed to constant vapour levels of alachlor, dieldrin and 3,4,3′,4′-tetrachlorobiphenyl are reported. Calculated leaf/air bioconcentration factors for these and other 11 organic chemical vapours are used to improve a correlation with the 1- octanol water and air/water equilibrium partition coefficients.

Chlorinated hydrocarbons in plant foliage: an indication of the tropospheric contamination level

Abstract Levels of some chlorinated hydrocarbons in foliage from the Italian peninsula and other countries of the world are reported. The use of plant leaves in monitoring and for the prediction of potential environmental distribution of persistent hydrophobic pollutants is discussed.

Chlorinated dioxins: volatilization from soils and bioconcentration in plant leaves.

Polychlorinated dibenzodioxins (PCDDs) are a group of xenobiotics of extreme environmental interest, by virtue of their high toxic potential, coupled with high bioaffinity and resistance to degradation. One in particular (2,3,7,8tetrachloro dibenzo-p-dioxin, 2,3,7,8-TCDD), is probably the most poisonous substance ever introduced into the environment. PCDDs are not intentionally produced, but mainly arise from combustion processes and certain industrial activities; all the sources of these substances are not yet completely known (Hutzinger and Fiedler 1989). However, loads to the environment are certainly significant as PCDD residues may be found in many different environmental matrices (Jones and Bennet 1989).

Polychlorinated biphenyls in plant foliage: Translocation or volatilization from contaminated soils?

Physical properties such as water solubility, vapor pressure, and Henrys law constant suggest that polychlorinated biphenyls (PCBs) can easily reach the troposphere as vapor. The potential of plant foliar tissues to take up PCBs as vapor has probably been underrated in some of the previous works. Nevertheless recently it was reported that the level of PCBs found in the foliage is mainly due to vapor transport from the soil, rather than to translocation through the plant. This research has been planned to assess the influence of translocation on the concentration of PCBs in the foliage of different plant species.

MED POL survey of organotins in the Mediterranean

A pilot survey of tributyltin (TBT) and its derivatives in Mediterranean areas was undertaken in 1988 within the framework of the MED POL activities. The areas studied were the French Mediterranean coast, the Northern Tyrrhenian coast, the Southern coast of Turkey and the Alexandria (Egypt) coastal area. 113 water samples were analysed from the first three areas and 35 sediment samples from the fourth. Samples were collected at sites selected according to differing environmental conditions and potential inputs of TBT. Two shellfish-culture areas in the South of France located near marinas were included. The data reported represent the first coordinated survey of butyltin levels in seawater and sediments from Mediterranean areas. The concentrations generally exceed the no-observed effect level (NOEL) of 20 ng l−1 and are comparable to those previously reported for similar situations outside the Mediterranean area.

The use of terrestrial plant biomass as a parameter in the fugacity model

Abstract A new compartment, the terrestrial plant biomass, is proposed for inclusion in the fugacity model. Two possibilities of calculation have been developed and exemplified: the first considers the plant as a whole, the second takes into account foliage, trunk and roots separately.

Heavy metals in organisms from the Northern Tyrrhenian sea

The concentrations of zinc, manganese, copper, cadmium, lead and mercury have been determined in soft tissues of four marine organisms (Mytilus galloprovincialis Lmk., Nephrops norvegicus L., Mullus barbatus L., Engraulis encrasicolus L.) collected seasonally from the winter of 1976 to the spring of 1980 in various areas of the Tyrrhenian Sea (western Mediterranean). In all four species levels of all metals, except mercury in all areas are alike while mercury levels vary and, furthermore, are higher than in specimens from other areas of the Mediterranean and also from other seas. The possible natural origin of the mercury from cinnabar (HgS) ore as well as the suitability of the four species as bioindicators is discussed.

Geothermal power plants at Mt. Amiata (Tuscany–Italy): mercury and hydrogen sulphide deposition revealed by vegetation

At Mt. Amiata (Italy) geothermal energy is used, since 1969, to generate electricity in five plants with a nominal capacity of 88 MW. Anomalous levels of mercury characterise geothermal fluids of Mt. Amiata, an area renowned for its vast cinnabar deposits and for the mercury production carried out in the past. Mercury emission rates range from 300 to 400 g/h, or 3-4 g/h per MW electrical installed capacity. These emissions are coupled with a release of 7-8 kg/(h MW) of hydrogen sulphide (H2S). Mercury is discharged as Hg0 gaseous species and reaches the atmosphere with the non-condensable gas fraction. In this fraction, CO, is the major component (94-98%), H2S is around 1% and mercury concentration is as high as 1-10 mg/Nm3. Leaves of a spontaneous grass (Avena sterilis), at the end of the vegetative cycle, were used as mercury bioconcentrators to map deposition near geothermal power plants and to calculate the corresponding average levels of Hg0 in the air. Direct measurements of mercury and hydrogen sulphide vapours in the air reached by power plant emissions showed a ratio of about 1-2000. This ratio was applied to calculate average levels of hydrogen sulphide starting from mercury deposition mapping: typical concentrations of mercury and hydrogen sulphide were of the order of 10-20 ng/m3 and 20-40 microg/m3, respectively.

Complementary accumulation of selenium and mercury in fish muscle

The concentrations of total selenium and total mercury in the muscle of striped mullet from four stations in the Northern Tyrrhenian Sea and one in the Black Sea were analyzed. If the sum of the concentrations of mercury and selenium (expressed as nmoles/g) is plotted against the age of the specimens, a single function describes all of the results. The explanation suggested by the authors is that Se-Hg receptors exist and increase with the age of the animal. These receptors may be occupied by mercury in proportion to its concentration in the environment.

Models, field studies, laboratory experiments: An integrated approach to evaluate the environmental fate of atrazine (s-triazine herbicide)

Abstract A 3-step procedure was applied to the study of the environmental distribution and fate of atrazine. This comprised: (1) physical-mathematical models, following the fugacity approach; (2) field studies of the disappearance of atrazine from treated soil and a contaminated lake; (3) laboratory experiments to evaluate the main routes of disappearance of atrazine from fortified soils and waters. Models were used to evaluate the main trends in the environmental distribution of atrazine and to point out potential reservoirs and sinks. On the basis of these evaluations, field experiments were planned. Laboratory experiments were carried out to analyse the information from the field, by individual study of the main transport and transformation mechanisms. Through water runoff and leaching, atrazine tends to move from treated soils to water compartments. Volatilization from soils and water seems negligible. In water, the bioaccumulation potential of this chemical is poor (BCF c. 10, for fish muscle). The degradation in soil follows pseudo-I-order kinetics, t 1 2 around 50 days; similar kinetics have been found for atrazine degradation in natural lake waters, but with a slower rate ( t 1 2 = 168 days ).