Three-dimensional modelling of mercury cycling in the Gulf of Trieste.

The Gulf of Trieste (Northern Adriatic) is subject to mercury pollution from a former mercury mine in Idrija, located along a river which transports mercury-contaminated sediments into the Gulf. Concentrations in suspended and bottom sediments are up to two orders of magnitude higher than in the central and southern Adriatic. Extensive research has been carried out on measurements and modelling of the transport and fate of mercury in the Gulf. Two- and three-dimensional models have been developed to include the influence of the significant advective transport due to currents. Wind, thermohaline forcing, and the Soca river momentum are the most important forcing factors. A two-dimensional model simulated the transport of non-methylated and methylated mercury in dissolved, particulate and plankton fractions. Mercury processes included the input of atmospheric mercury, sedimentation, reduction, methylation and demethylation. The model simulations gave basically what were proper trends of the phenomena; quantitatively the measured and computed results are mainly within a factor of three. To simulate the non-uniform distribution of parameters over the depth, an existing three-dimensional (3D) hydrodynamic and transport-dispersion (TD) model, PCFLOW3D, was adapted and applied. As it was found that most mercury transport is related to suspended sediment particles, a new 3D sediment transport module was also developed and included in the model. Three cases are presented: one describing the simulation of TD of dissolved total mercury; another the simulation of the TD of particulate mercury in the Gulf during a river flood; and the third simulating sediment transport in the Gulf during a period of strong ENE wind. Comparison with measurements was only partly possible, but mainly the computed and measured results were within a factor of two and proper trends of the phenomena were obtained by the simulations. The combination of modelling and measurements has resulted in some interesting conclusions about the phenomenon of the transport and fate of mercury in a coastal sea.

Mercury in contaminated coastal environments; a case study: the Gulf of Trieste.

Some general facts, uncertainties and gaps in current knowledge of Hg cycling in coastal and oceanic environments are given. As a case study the Gulf of Trieste is chosen. The Gulf is subject to substantial Hg pollution, originating from the Soca river, that drains the cinnabar deposits of the world's second largest Hg mining area, Idrija, Slovenia. The Gulf belongs to one of the most polluted areas in the Mediterranean. Apart from Hg problems, the Gulf is also a subject to industrial and sewage pollution. Due to deteriorating water quality in the Gulf there is a great concern that Hg can be remobilized from sediments to the water column as well as enhance methylation rates which may consequently increase already elevated Hg levels in aquatic organisms. The paper presents data from a recent study which aims to assess the extent of contamination of the Gulf of Trieste after the closure of the Hg mine. Mercury and methylmercury were measured in various environmental compartments (estuarine and marine waters, sediments, and organisms) during the period 1995-1997. Data obtained show that even 10 years after closure of the Hg mine, Hg concentrations in river sediments and water are still very high and did not show the expected decrease of Hg in the Gulf of Trieste. A provisional annual mercury mass balance was established for the Gulf of Trieste showing that the major source of inorganic mercury is still the River Soca (Isonzo) while the major source of methylmercury is the bottom sediment of the Gulf.

Histochemical characteristics of bulbospongiosus and ischiocavernosus muscles in man.

The histochemical profiles of the bulbospongiosus (BS) and ischiocavernosus (IC) muscles were investigated on autopsy samples obtained from 13 men aged 18 to 33. Adenosine triphosphatase (ATPase) reactions were used for differentiation of muscle fibres into type 1 (slow twitch, tonic), and type 2 (fast twitch, phasic) and subtypes 2A, 2B, 2C. The activity of oxidative and glycolytic enzymes was also assayed. Because the percentage and diameters of both fibre types varied considerably in different areas of the same muscle, two methods of counting were applied and at least two fields of each sample were evaluated. The mean percentage of type 1 fibres in BS muscles was 34.8% and 23.2%, that in IC muscles 49.7% and 39.7%. The mean diameter of type 1 fibres was 31.0 microns (BS) and 26.2 microns (IC), that of type 2 fibres ranged from 30.0 microns (BS) to 36.6 microns (IC). The comparison of BS and IC muscles with other nonskeletal voluntary muscles revealed that BS and IC muscles are similar to the striated sphincters, particularly with regard to the numerical distribution of fibre types and fibre diameters.

Histochemistry of abductor hallucis muscle in children with idiopathic clubfoot and in controls.

The histochemical composition of the abductor hallucis (AH) muscle was investigated in 39 children with idiopathic clubfoot (CF), aged 0-11 years, and in 42 controls. In the youngest group of patients (0-2 years) the percentage of type 1 (slow twitch, tonic) fibers was significantly higher than in controls. In older groups, there was no difference between patients and controls. The relative predominance of type 1 fibers could be due to immobilization, passive shortening or stretching, or primary overactivity of this muscle in CF promoted by an unknown neural factor. None of these interpretations could be proven.

Muscle fibre types in the human vastus lateralis muscles: do symmetrical sites differ in their composition?

Muscle samples obtained from distinct symmetrical sites of left and right vastus lateralis muscles from 10 young healthy males were analysed. A computer-aided system was applied for the determination of muscle fibre types I, IIA, IIB and IIC and for their quantitative analysis. No statistically significant differences were established regarding percentage and surface area of all the four fibre types studied. In 2 cases of IIA and in one case of IIB fibre type significantly different diameters were measured between the left and right muscle. Regarding percentage and surface area no differences were proved between superficial and deep layers of the muscles observed. Fibre diameter but differed significantly in many muscles, there was no rule about whether it was larger in superficial or in deep muscle layers. One biopsy sample can not represent the whole muscle, especially as far as the relative number and surface area of the type IIA and IIB fibres are concerned. A slight asymmetry in fibre diameters of biopsy samples from both legs does not indicate any pathological change and can still be taken for normal.

The fibre type composition of thoracic and lumbar paravertebral muscles in man.

Samples of longissimus and multifidi muscles at the thoracic and lumbar levels of the spine were examined histochemically on autopsy specimens from 21 adult male subjects (aged 22 to 46 years) and on biopsies from 17 adult patients during surgery for disorders of the lumbar intervertebral disc. In the superficial and deep thoracic muscles, 74% of fibres were of the Type I variety. In the lumbar region, Type I fibres amounted to 57% in the superficial, and to 63% in the deep muscles. The diameter of Type I fibres was significantly greater than that of Type II fibres.

The nonspecificity of the lead method for the histochemical demonstration of adenosine triphosphatases in human skeletal muscle fibres.

The lead method for the histochemical demonstration of presumptive mitochondrial adenosinetriphosphatase was applied to biopsy and autopsy samples of the human vastus lateralis muscle. The effect of p-chloromercuribenzoate and of Triton X-100 was tested microdensitometrically and the activity of 'mitochondrial' ATPase was compared to the activity of enzymes of the oxidative metabolism succinic dehydrogenase and NAD-tetrazolium reductase. It is concluded that the ATPase activity displayed is not mainly mitochondrial. In autopsy material, it seems to be predominantly myofibrillar.

Selective type II fibre muscular atrophy in patients with osteoarthritis of the hip.

The size and the distribution of type I and tye II fibres was determined in the gluteus maximus (21 cases), gluteus medius (56 cases) and tensor faciae latae (27 cases) muscles of patients with osteoarthritis of the hip. The patients were of both sexes, aged between 37 and 64 years (younger group) and between 65 and 78 years (older group). Autopsy material of the two comparable age groups and of a group of "normal" adults (aged 22-44 years) served as controls. It was shown statistically that the diameter of both types of fibres and the relative number of type II fibres diminished with progressing age. In patients with osteoarthritis the degree of the selective atrophy of type II fibres was significantly higher than in the control groups. The atrophy is interpreted as a consequence of diminished muscular activity. No neurogenic lesions were detected either in the muscles of the patients or in those of the control groups.

Histochemical type I fibres in the soleus of the rat.

Based on oxidative enzyme activity levels, fibres exhibiting moderate and high levels may be identified in the soleus of the rat. Fibres showing moderate activity are classified as Type I fibres, while those showing high activity may belong to Type I or Type II. According to the level of ATPase activity in fixed sections, we can distinguish three types of fibres in the soleus of the rat (IA, IB and II) and, by application of acid pre-incubation, also sub-classes of Type II (IIA and IIC). Type IB fibres possess high oxidative and glycolytic enzyme activities, moderate ATPase activity after fixation, and behave in the same way as Type I fibres after alkaline and acid pre-incubation. For the histochemical classificationof fibre types, we should consider not only reactions to ATPase, and after acid pre-incubation, but also reactions to the enzymes of oxidative and glycolytic metabolism.

Vascularization of the ureter after experimental ureterolysis in rabbits.

The left ureter was isolated and its nutritive arteries interrupted in 43 rabbits. The blood flow in the isolated and in the control ureters was estimated intravitally by measuring the temperature in the wall of the ureters, and postmortally by counting the capillaries injected with India ink. The vascularization of the isolated ureter was lowered at 3 days after surgery and returned to normal values at 14 days.

H incision--method of choice for radical neck dissection.

To prevent skin necrosis, fistula formation and rupture of the carotid arteries after RND, vascularization of the skin of the neck has been considered. The neck vessels (in cadavers) were injected with coloured media and specimens of the skin were cleared (Spalteholz method). The arteries supplying the skin of the neck followed in general an obviously longitudinal course: one group of cutaneous arteries descending from the branches of the external carotid; another group ascending from the branches of the subclavian artery. The upper and lower groups of arteries joined approximately in the middle of the neck. The density of cutaneous arteries in the neck was much poorer than in the facial skin. On the basis of these anatomic data, an incision for RND has been proposed in the form of an H or three-quarter H, in which the transverse line of the incision follows the least vascularized skin region of the neck, without interrupting the great skin vessels. Incisions in the form of a Z or a double Y, OR McFee's incision, do not fulfil this requirement. The authors also report the results of wound healing after RND in 184 patients who were operated in the period fron 1968 to 1975 at the E. N. T. clinic of Ljubljana, where the H incision or one of its modifications was used.