Accumulation of heavy metals and antioxidant responses in Vicia faba plants grown on monometallic contaminated soil

The purpose of this study was to explore the effects of soil contamination by selected metals (cadmium, copper, nickel, lead or zinc) on the antioxidant response of Vicia faba plants. The levels of the antioxidants: glutathione, proline, non-protein thiols, as well as guaiacol peroxidase and catalase activities were measured in the upperparts of plants. Additionally, the potential bioavailability of metals in the soil and their concentrations in V. faba plants were compared. Treatment with metal caused the problem of an elevation in its bioavailability in soil and its concentration in leaves and stems. The most serious problems seemed to be metal elevations in soil, especially Zn and Ni as well as in the aerial parts of V. faba plants. The antioxidant responses appeared to be metal specific. The elevation of guaiacol peroxidase activity in leaves and stems as well as the proline in leaves was the only more general reaction to metal exposure. Upon analysis of the effects of soil metal contamination on V. faba plants, we recommend the use of some measurements such as guaiacol peroxidase activity and proline level as useful tools in biological monitoring.     

NOX Levels in the Caracas Valley

An analysis of air quality data from 1970-1975 in the Los Angeles (LA) Basin has been made with emphasis on factors relevant to high hourly NO₂ concentrations, (NO₂). Detailed analysis of CO and SO₂ air quality and the (NO _x )/(CO) and (CO)/(SO₂) ratios reveals that high (NO₂) result mainly from vehicular sources; contributions from stationary sources to these high (NO₂) of greater than 10% occur rarely. Meteorological conditions (very low early-morning inversion base height and low wind speed) favoring the formation of high (NO₂) restrict the impact of elevated point NO _x sources on the ground level (NO₂) during the early to mid-morning hours. The overnight leftover NO _x during high NO₂ days is shown to originate largely from local sources near the monitoring sites. A regression analysis using NO₂, NO _x and HC data from downtown LA shows that a 50% reduction in (NO _x ) reduces high (NO₂) by 40-45%; a 50% reduction in (HC) reduces high (NO₂) by 5-10%. The present analysis supports assumptions used in an earlier generalized rollback model that related NO _x emissions to high 1-h average (NO₂) observed at downtown LA.     

Determination and analysis of distribution coefficients of 137Cs in soils from Biscay (Spain)

The distribution coefficient of (137)Cs has been determined in 58 soils from 12 sampling points from Biscay by treating 10 g with 25 ml of an aqueous solution with an activity of 1765 Bq in the radionuclide, by shaking during 64 h and measuring the residual activity with a suitable detector. Soils were characterised by sampling depth, particle size analysis and the usual chemical parameters. Soils were thereafter treated to fix the chemical forms of (137)Cs speciation by successive extractions in order to determine fractions due to exchangeable, associated with carbonates, iron oxide and organic matter fractions, obtaining by difference the amount taken by the rest of the soil constituents. For this research, 16 soils from four points were selected from the previous samples. The greatest mean percentages of (137)Cs sorption were with the rest (69.93), exchangeable (13.17) and organic matter (12.54%) fractions. This paper includes also the calculation of partial distribution coefficients for chemical species as well as relations of distribution coefficients both among them and with soil parameters.     

Use of solvent extraction for the removal of heavy metals from liquid wastes

Solvent extraction is recommended as a suitable method for the removal of heavy metals from the waste waters of the chemical and electronic industries. Common extractants are organic compounds with molecular mass 200–450, almost insoluble in water (5–50 ppm), that selectively extract metals from aqueous solutions. On the basis of data from the literature, the extraction conditions are reviewed for the metals that cause problems in waste waters. The extraction conditions are understood to mean the type of extractant, anion present in the aqueous phase, and pH. As far as the data permit, the metals are ordered according to their extractability by given extractants. Special attention is paid to the main source of contamination of waste waters by heavy metals, namely electroplating plants. Two examples of the design of mixer-settler batteries are presented, which demonstrate continuous removal of heavy metals from the waste waters of electroplating plants to levels below the permissible limits. The first example illustrates removal of cadmium using triisooctylamine in a mixer-settler battery with the pertraction flow-arrangement; the second, removal of zinc and lead from rinse waters using the organophosphoric acid DEHPA (bis (2-ethylhexyl) phosphoric acid) in a battery with counter-current flow and reflux. The extraction equilibrium data were obtained in laboratory experiments using chloride solutions in concentrations close to those in the rinse waters of electroplating plants (erná and Volaufová, 1991).     

A field study of the influence of land management and soil properties on runoff and soil loss in central Spain

Since the 1950s afforestation of degraded land has been the principal means of combatting erosion in a seasonally arid area of central Spain. In the 1970s tree planting of steep hillsides and gully sides was preceded by bench terracing. Experimental sites have been established to monitor runoff and soil losses under mature Pinus forest, 12-year-old Pinus forest, and Cistus matorral. The experiment is being conducted at three scales: large gully or small watershed (c. 3.5 ha), runoff erosion plot (10–21.5 m²), and rainfall simulation plot (1 m²). Monitoring began in October 1992. Discharge was recorded continuously, while sediment loss and soil moisture content were measured on a storm basis. The paper presents summary data on runoff and soil erosion for the three scales and comments on relationships between land management, site characteristics, and these losses. We stress the crucial role of vegetation and its interrelationship with soil properties such as structure and aggregate stability. Matorral was effective in combatting water and soil loss, but we question the practice of afforesting seasonally arid, steeply sided areas that have highly erodible soils.     

Monitoring dioxins and furans in the vicinity of an old municipal waste incinerator after pronounced reductions of the atmospheric emissions

In order to get an overall picture of the environmental impact of an old municipal solid waste incinerator (MSWI) from S. Adrià del Besòs (Barcelona, Catalonia, Spain), a monitoring program addressed at determining the levels of a number of pollutants in the vicinity of the facility was initiated in 1998. In March 1999, an adaptation was carried out due to EU legislation on pollutant emissions from the stack. As a result, emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were notably reduced, and a significant (30%) decrease was found in the levels of PCDD/F in herbage samples collected in the vicinity of the MSWI. In March 2001, herbage samples were collected at the same sampling points and the PCDD/F levels measured again. The current PCDD/F concentrations range from 0.23 to 1.43 ng I-TEQ kg(-1) (dry matter), with median and mean values of 0.58 and 0.66 ng I-TEQ kg(-1) (dry matter), respectively, while in the 2000 survey the PCDD/F concentrations ranged from 0.22 to 1.20 ng I-TEQ kg(-1) (dry matter), with median and mean values of 0.57 and 0.61 ng I-TEQ kg(-1) (dry matter), respectively. Although the current PCDD/F concentrations in herbage samples are comparable to those found in recent surveys carried out in various places of Catalonia, an exhaustive evaluation of the data, including principal component analysis, indicates that other emission sources of PCDD/Fs also have a notable environmental impact on the area under direct influence of the MSWI.     

Geostatistical analysis of densities of Liocarcinus depurator (Brachyura: Portunidae) on the western Mediterranean from 1994 to 2003

Bottom trawl estimates of densities of the portunid crab Liocarcinus depurator along the Mediterranean coast of Spain from 1994 to 2003, covering a depth range of 50–800 m, were analysed using non-linear geostatistical techniques. The variation of the spatial distribution was modelled through variogram analysis using depth as a covariate. Patch size ranged from 20 to 75 km. Crab density showed a general decrease from 1994 to 2003. L. depurator high-density areas were characterised as either occasional or permanent (always present every year). High-density patches appeared to be associated with either upwelling or strong river influence, i.e. the Western Alborán Sea and the Ebro Delta. The application of non-linear geostatistical techniques proved useful in identifying permanent high-density population patches, thereby highlighting regions of special interest for the ecology of the species.     

Structure and diversity of small mammal communities in agriculture landscape

Small mammal communities were snaptrapped for six years in agricultural landscapes to establish their relationship to various crop habitats in southern Moravia, Czech Republic. The presence of 14 small mammals was documented; 77% of the community found in crops consisted of three rodents, namely Microtus arvalis, Apodemus microps and A. sylvaticus, whereas in woody habitats, 89% of the community was represented by Clethrionomys glareolus, Apodemus flavicollis and A. sylvaticus. In permanent habitats (windbreaks, small woods and fallow land), the community was more abundant and diversified. Among the crop fields, the lowest abundance was found in cereal fields whereas the lowest diversity was observed in alfalfa. Soil-cultivating practices affected abundances especially in sugar beat and maize. Seasonal variation in numbers was lowest in forest and fallow land. Species richness decreased from spring and summer to autumn and winter in annual crops (cereal, maize, sugar beet and other crops), increased in alfalfa and fallow land, and remained relatively stable in windbreaks and forests. Based on similarity indices, two groups of small mammal communities were identified: one for field crops and another for permanent habitats. The fallow land assemblages in spring and summer were more similar to field crop species assemblages and in autumn and winter to permanent habitats one. Trophic requirements of small mammals and the food supply available in the various habitats are discussed.     

Quantitative analysis of foraging behaviour in a field population of the South American sun-star Heliaster helianthus

Foraging behaviour in the South American sunstar Heliaster helianthus (Lamarck) was investigated quantitatively on a subtropical rocky shore in central Peru. H. helianthus feeds mainly on two mussel species, Semimytilus algosus (Gould) and Perumytilus purpuratus (Lamarck). A sequence of foraging behaviour was described and observations were made of the timing of attacks on mussel beds by sun-stars. Although H. helianthus is capable of foraging out of water, an unusual trait for asteroids, the timing of such foraging appears to be well adjusted to avoid the risk of prolonged heat and desiccation. Foraging activity began 4 h 52 min before high tide and 3 h 19 min after high tide, with a mode between 2 h 30 min and 2 h before high tide. Fifty-two percent of all foraging activity began between 3 h 30 min and 2 h before high tide, while only 12.4% began after high tide. This suggests that H. helianthus mainly relies upon changes in the rate of tidal increase as a cue to begin foraging. Foraging activity ceased between 3 h 40 min before and 4 h 29 min after high tide, with 48% ending between 2 and 0.5 h before high tide. The duration of foraging ranged from 19 to 190 min, with values between 30 and 80 min accounting for 67.4% of all observations. The median duration was 62 min. No significant correlation was detected between the time when foraging activity commenced and its duration. The intensity of foraging activity varied on consecutive days, with a general pattern of decreasing intensity after a day of relatively high activity. Foraging location in relation to a mussel bed was analysed on a marked, 8 m stretch of rocky shore. The numbers of foraging H. helianthus observed on different sections of the shore were related neither to the width of the mussel zone nor to the vertical position of the lower edge of the mussel zone, indicating that sun-stars do not rely upon these factors to assess prey availability and that ideal free distribution with regard to prey abundance does not occur on the spatial scale examined.