Impact on soil quality of a 10-year-old short-rotation coppice poplar stand compared with intensive agricultural and uncultivated systems in a Mediterranean area

Bioenergy crops play an ecologically and economically fundamental role as an alternative to agri-food productions and as renewable energy sources. Little attention has been focused on soil quality following conversion of agricultural lands to biomass crops. Here, we assessed the impact of a 10-year-old short-rotation coppice (SRC) poplar stand on the main soil chemical parameters, microbial biomass carbon, soil respiration, and arbuscular mycorrhizal fungi (AMF), compared with intensive agricultural and uncultivated systems. Three different harvest frequencies of poplar SRC (annual T1, biannual T2 and triennial T3 cutting cycles) were evaluated. Multivariate analysis showed that poplar SRC improved soil quality compared with intensive agricultural and uncultivated systems. T1 and T2 positively affected AMF inoculum potential and root colonisation of a co-occurring plant species, while T3 improved the majority of soil chemical and biochemical parameters. Moreover, three different AMF morphospecies belonging to the genera Glomus and Scutellospora were found in poplar SRC, while morphospecies belonging exclusively to genera Glomus were recorded in intensive agricultural and uncultivated systems. Such aspects have agro-ecological implications, since the positive changes of soil nutrient availability and carbon content together with a high abundance and diversity of soil biota show clear soil sustainability of poplar SRC.     

Circannual variations of lizard circadian activity rhythms in constant darkness

The daily pattern of locomotor activity of Podarcis sicula in the field changes from unimodal in spring to bimodal in summer, becoming unimodal again in autumn. Short-term experiments in which P. sicula collected in different months were tested under constant conditions immediately after capture showed that the activity pattern typical of each season is retained in the lizard circadian locomotor rhythm. In constant conditions, the bimodal pattern is associated with a short free-running period (τ) of the circadian locomotor rhythm and a long circadian activity (α), while the unimodal pattern is associated with a long τ and short α. To test whether seasonal changes in circadian locomotor rhythms are driven by a circannual clock, we recorded locomotor activity of lizards over 12–15 months in constant temperature and darkness. The present results demonstrate, for the first time in a vertebrate, the existence of circannual changes in constant darkness of both τ and α. In most lizards, the longest τ along its circannual cycle is associated with a short α, and the shortest τ in the same cycle with a long α, so that the pattern of mutual association between τ and α is the same as in short-term experiments. Most lizards, however, stayed unimodal all the time. This shows that changes in activity pattern from unimodal to bimodal (and vice versa) are induced by seasonal changes in environmental factors, instead of being incorporated into a circannual rhythm. Circannual changes in τ and α of locomotor rhythms may adaptively predispose the circadian system of P. sicula to a change in activity pattern as soon as seasonal changes in the environment demand it. Received: 22 January 1999 / Received in revised form: 14 April 1999 / Accepted: 19 April 1999     

Seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk from a high altitude pasture in the Italian Alps

The seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk was studied in a high altitude pasture in the Alps (1900 m a.s.l.). PCB contamination in vegetation shows a concentration peak in June, which is mainly interpreted as the consequence of a temporary PCB enrichment of the air layer above the ground due to net emission fluxes from the soil. A three compartment dynamic model was developed to test this hypothesis. The North/South enrichment factor in the vegetation was 1.5-1.6 for penta- and hexa-substituted congeners and 1.7 for hepta- and octa-PCBs, according to the effect of temperature on compounds having higher K_oa values. Milk concentrations followed the vegetation seasonal trend. The congener abundance in milk is in agreement with the biotransformation susceptibility, absorption efficiency and residence time of the different congeners in dairy cows.     

Effect of clomazone herbicide on biochemical and histological aspects of silver catfish (Rhamdia quelen) and recovery pattern

The effects of the herbicide, clomazone, on acetylcholinesterase (AChE), catalase and TBARS formation in teleost fish (Rhamdia quelen) were studied. The fish were exposed to 0.5 or 1.0 mg L⁻¹ of clomazone for 12, 24, 48, 96 and 192 h. After 192 h of exposure period, fish were transferred to clean water and kept in the same for 192 h to study the recovery response. Same parameters as that of exposure period were assayed after 96 and 192 h of recovery period. Specific AChE activity was reduced in the brain and muscle after treatments, reaching a maximum inhibition of 47% in the brain and 45% in the muscle after 12 h of exposure. Fish exposed to clomazone increased TBARS production in the liver for all exposure periods. The brain presented elevated TBARS levels after 12, 24 and 48 h, but after 96 and 192 h, these levels decreased. The decrease of TBARS levels persisted in brain tissue after 96 h of recovery and returned to the control value after 192 h in clean water. Catalase activity was reduced for all periods of exposure. Histological analysis showed vacuolation in the liver after herbicide exposure. Some of the alterations observed were completely restored after recovery period.     

Clay charge reversal effects on aqueous polymer sorption on lateritic soils

The effects of charge reversal about the measured point of zero charge (pH(0) approximately 5.2) of untreated and treated Sete Lagoas lateritic soil of Brazil on aqueous polymer sorption was investigated. The polymers are anionic sodium carboxymethyl cellulose (CMCA), nonionic polyethylene oxide (PEO), and cationic polyacrylamide (PAM). They were prepared at aqueous concentrations and pH ranges of 0.1-2.0 g l(-1) and 2-9, respectively. Soil treatment involved the removal of iron oxides by treatment with dithionate-bicarbonate-citrate. Batch sorption test results show that the presence of iron oxides in lateritic soil tends to suppress sorption of CMCA (especially at pH=pH(0)) and PEO (for the whole pH range) but has uncertain effects on cationic PAM sorption. CMCA sorption on the untreated soil improves on either side of pH(0), in direct proportionality to solution concentration, except at pH<4.0, where disassociation of the polymer molecules may decrease sorption energy. Increase in the sorption of non-cationic polymers (CMCA and PEO) at pH>pH(0) is attributable to dispersion of clay, cation bridging and polymer molecular reconfiguration. For cationic PAM, electrostatic bonding to negatively charged soil particle surfaces accounts for the sorption increase. For treated soil samples, polymer sorption pattern is similar to those expected for the montmorillonitic clayey soils of temperate zones. These results indicate that the pH(0) of lateritic soils, within the regime that exists in the field, should be considered in assessing the potential effectiveness of polymer dust suppressants for tropical lateritic soils.     

Isolation and characterization of melanopsin and pinopsin expression within photoreceptive sites of reptiles

Non-mammalian vertebrates have multiple extraocular photoreceptors, mainly localised in the pineal complex and the brain, to mediate irradiance detection. In this study, we report the full-length cDNA cloning of ruin lizard melanopsin and pinopsin. The high level of identity with opsins in both the transmembrane regions, where the chromophore binding site is located, and the intracellular loops, where the G-proteins interact, suggests that both melanopsin and pinopsin should be able to generate a stable photopigment, capable of triggering a transduction cascade mediated by G-proteins. Phylogenetic analysis showed that both opsins are located on the expected branches of the corresponding sequences of ortholog proteins. Subsequently, using RT-PCR and RPA analysis, we verified the expression of ruin lizard melanopsin and pinopsin in directly photosensitive organs, such as the lateral eye, brain, pineal gland and parietal eye. Melanopsin expression was detected in the lateral eye and all major regions of the brain. However, different from the situation in Xenopus and chicken, melanopsin is not expressed in the ruin lizard pineal. Pinopsin mRNA expression was only detected in the pineal complex. As a result of their phylogenetic position and ecology, reptiles provide the circadian field with some of the most interesting models for understanding the evolution of the vertebrate circadian timing system and its response to light. This characterization of melanopsin and pinopsin expression in the ruin lizard will be important for future studies aimed at understanding the molecular basis of circadian light detection in reptiles.     

Utilization of kaolin processing waste for the production of porous ceramic bodies

The kaolin processing industry generates large amounts of waste in producing countries such as Brazil. The aim of this study was to characterize kaolin processing waste and evaluate its suitability as an alternative ceramic raw material for the production of porous technical ceramic bodies. The waste material was physically and chemically characterized and its thermal behaviour is described. Several formulations were prepared and sintered at different temperatures. The sintered samples were characterized to determine their porosity, water absorption, firing shrinkage and mechanical strength. Fired samples were microstructurally analysed by X-ray diffraction and scanning electron microscopy. The results indicated that the waste consisted of quartz, kaolinite, and mica, and that ceramic formulations containing up to 66% of waste can be used for the production of ceramics with porosities higher than 40% and strength of about 70 MPa.     

Bioaccumulation of chlorinated pesticides and PCBs in the tropical freshwater fish Hoplias malabaricus: histopathological, physiological, and immunological findings

For assessing the impact of chlorinated compounds, such as organochlorine pesticides, polychlorinated biphenyls, chlorotriazines (atrazine, simazine), and chlorinated phenylureas (diuron), on the Ponta Grossa lake South of Brazil, ten freshwater trahira fish (Hoplias malabaricus) were collected in October 2005. The contamination status was evaluated by the energy budget and various histopathological markers. The results showed detectable amounts of persistent organic pollutants (POPs) in the liver and muscle; the bioaccumulation was higher in the liver than in the muscle. The presence of some banned pesticides, such as hexachlorobenzene and dichlorodiphenyltrichloroethane, in the liver suggests an acute exposure to these compounds. Some physiological disturbances and morphological damages found in the liver of H. malabaricus were associated with chlorinated-compound bioaccumulation. The most important alterations in the liver were lesions such as fibrosis, large necrosis area, leukocyte infiltration, and the absence of melanomacrophages (MM). Individuals containing higher concentrations of pesticides, such as aldrin, alachlor, and dichloroaniline (a metabolite of diuron), showed the nonoccurrence of MM in the liver. These data suggest an immunosuppression in the individuals from Ponta Grossa Lake after exposure to POPs. According to the present data, the POPs found in the studied site are bioavailable, induce severe damages in target organs such as the liver, and can disturb the immune system of the trahira. This is the first study of POPs in the Paraná state, and one among the few studies in the south of Brazil. The present data suggest and motivate further chemical and biomonitoring studies in freshwater ecosystems in the south of Brazil.