Effect of simulated acid rain on the survival, mortality, behaviour and morphology of African mud catfish Clarias gariepinus (Burchell, 1822) / Efeito da chuva ácida simulada sobre a sobrevivência, mortalidade, comportamento e morfologia do peixe-gato de lama africana Clarias gariepinus (Burchell, 1822)

This study simulated acidic habitat for different life stages of Clarias gariepinus to know the effect on survival, mortality, morphology and behaviour. The fish were exposed to pHs 3, 4, 5, 6 and 8.01 (control) for 35 days. 100% mortality was recorded for all the life stages in pH 3, and 80, 62 and 36% of mortality of fingerlings, juveniles and adults respectively were recorded in pH 4. In pH 5, 30, 26 and 12% mortalities of fingerlings, juveniles and adults respectively were recorded and at pH 6 mortalities of fingerlings, juveniles and adults were 12, 10 and 4% respectively. Control pH mortalities were 10, 6 and 2% for fingerlings, juveniles and adults respectively. Mortality was due to lack of oxygen uptake, stress and circulatory collapse. All these elicited the behavioural responses and morphological abnormalities like erratic swimming, gasping, dark body colouration and lethargy. The study showed that different life stages of C. gariepinus tolerate different acidic pH waters, with high mortalities of the fingerlings, juveniles and adults in pHs 3, pH 4 is sub-lethal to fingerlings, juveniles and adult, pH 5 sub-lethal to fingerlings and sub-optimal for juveniles, and pH 6 optimal for all life stages.(AU)

Este estudo simulou um habitat ácido para diferentes estágios de vida de Clarias gariepinus para conhecer o efeito na sobrevivência, mortalidade, morfologia e comportamento. Os peixes foram expostos aos pH 3, 4, 5, 6 e 8.01 (controle) por 35 dias. A mortalidade de 100% foi registrada em todos os estágios da vida em pH 3, e 80, 62 e 36% da mortalidade de alevinos, juvenis e adultos, respectivamente, foram registradas em pH 4. Em pH 5, 30, 26 e 12% de mortalidade de alevinos, juvenis e adultos, respectivamente, foram registrados e, a pH 6, a mortalidades de aletanas, juvenis e adultos foram 12, 10 e 4%, respectivamente. A mortalidade por pH de controle foi de 10, 6 e 2% para alevinos, juvenis e adultos, respectivamente. A mortalidade deveu-se à falta de absorção de oxigênio, estresse e colapso circulatório. Tudo isso provocou respostas comportamentais e anormalidades morfológicas como natação errática, ofegante, coloração do corpo escuro e letargia. O estudo evidenciou que diferentes estágios de vida de C. gariepinus toleram diferentes águas ácidas do pH, com alta mortalidade de alevinos, juvenis e adultos em pH 3, pH 4 é sub-letal para alevinos, juvenis e adultos, pH 5 sub-letal para alevinos e sub-ótima para juvenis, e pH 6 ideal para todos os estádios da vida.(AU)

Effect of simulated acid rain on the survival, mortality, behaviour and morphology of African mud catfish Clarias gariepinus (Burchell, 1822) / Efeito da chuva ácida simulada sobre a sobrevivência, mortalidade, comportamento e morfologia do peixe-gato de lama africana Clarias gariepinus (Burchell, 1822)

This study simulated acidic habitat for different life stages of Clarias gariepinus to know the effect on survival, mortality, morphology and behaviour. The fish were exposed to pHs 3, 4, 5, 6 and 8.01 (control) for 35 days. 100% mortality was recorded for all the life stages in pH 3, and 80, 62 and 36% of mortality of fingerlings, juveniles and adults respectively were recorded in pH 4. In pH 5, 30, 26 and 12% mortalities of fingerlings, juveniles and adults respectively were recorded and at pH 6 mortalities of fingerlings, juveniles and adults were 12, 10 and 4% respectively. Control pH mortalities were 10, 6 and 2% for fingerlings, juveniles and adults respectively. Mortality was due to lack of oxygen uptake, stress and circulatory collapse. All these elicited the behavioural responses and morphological abnormalities like erratic swimming, gasping, dark body colouration and lethargy. The study showed that different life stages of C. gariepinus tolerate different acidic pH waters, with high mortalities of the fingerlings, juveniles and adults in pHs 3, pH 4 is sub-lethal to fingerlings, juveniles and adult, pH 5 sub-lethal to fingerlings and sub-optimal for juveniles, and pH 6 optimal for all life stages.

Este estudo simulou um habitat ácido para diferentes estágios de vida de Clarias gariepinus para conhecer o efeito na sobrevivência, mortalidade, morfologia e comportamento. Os peixes foram expostos aos pH 3, 4, 5, 6 e 8.01 (controle) por 35 dias. A mortalidade de 100% foi registrada em todos os estágios da vida em pH 3, e 80, 62 e 36% da mortalidade de alevinos, juvenis e adultos, respectivamente, foram registradas em pH 4. Em pH 5, 30, 26 e 12% de mortalidade de alevinos, juvenis e adultos, respectivamente, foram registrados e, a pH 6, a mortalidades de aletanas, juvenis e adultos foram 12, 10 e 4%, respectivamente. A mortalidade por pH de controle foi de 10, 6 e 2% para alevinos, juvenis e adultos, respectivamente. A mortalidade deveu-se à falta de absorção de oxigênio, estresse e colapso circulatório. Tudo isso provocou respostas comportamentais e anormalidades morfológicas como natação errática, ofegante, coloração do corpo escuro e letargia. O estudo evidenciou que diferentes estágios de vida de C. gariepinus toleram diferentes águas ácidas do pH, com alta mortalidade de alevinos, juvenis e adultos em pH 3, pH 4 é sub-letal para alevinos, juvenis e adultos, pH 5 sub-letal para alevinos e sub-ótima para juvenis, e pH 6 ideal para todos os estádios da vida.

Effects of simulated deposition of acid mist and iron ore particulate matter on photosynthesis and the generation of oxidative stress in Schinus terebinthifolius Radii and Sophora tomentosa L.

Particulate matter is a natural occurrence in the environment, but some industries, such as the iron ore sector, can raise the total amount of particles in the atmosphere. This industry is primarily a source of iron and sulfur dioxide particulates. The effects of the pollutants from the iron ore industries on representatives of restinga vegetation in a Brazilian coastal ecosystem were investigated using physiological and biochemical measures. Two species, Schinus terebinthifolius and Sophora tomentosa, were exposed to simulated deposition of acid mist and iron ore particulate matter in acrylic chambers in a greenhouse. Parameters such as gas exchange, fluorescence emission, chlorophyll content, total iron content, antioxidant enzyme activity and malondialdehyde content were assessed in order to evaluate the responses of the two species. Neither treatment was capable of inducing oxidative stress in S. terebinthifolius. Nevertheless, the deposition of iron ore particulates on this species increased chlorophyll content, the maximum quantum efficiency of photosystem II and the electron transport rate, while iron content was unaltered. On the other hand, S. tomentosa showed a greater sensitivity to the treatments. Plants of S. tomentosa that were exposed to acid mist had a decrease in photosynthesis, while the deposition of iron particulate matter led to an increase in iron content and membrane permeability of the leaves. The activities of antioxidant enzymes, such as catalases and superoxide dismutase, were enhanced by both treatments. The results suggested that the two restinga species use different strategies to overcome the stressful conditions created by the deposition of particulate matter, either solid or wet. It seems that while S. terebinthifolius avoided stress, S. tomentosa used antioxidant enzyme systems to partially neutralize oxidative stress. The findings also point to the potential use of S. tomentosa as a biomarker species under field conditions.

Effect of acid rain on building material of the El Tajín archaeological zone in Veracruz, Mexico.

Three limestone slabs (approx. 20 cm2 each) were extracted from the El Tajin archaeological zone in Veracruz, Mexico. X-ray diffraction analysis revealed three components: calcite (81.2%), quartz (17.9%) and feldspar (0.9%). Calcite content by x-ray diffraction analysis was slightly higher than that determined by chemical reaction between the limestone sample and nitric acid. The latter analysis, carried out in triplicate, yielded a calcite content of 77.1%. Mean water absorption, density and porosity of the limestone samples were also determined. Dissolution of limestone samples was investigated using an experimental rainfall simulation chamber, in which the stone samples were irrigated with artificial rain matching the pH and the ionic composition with 40 rainfall samples collected at El Tajin from August 18, 2002, to April 9, 2003. According to calcium and bicarbonate net concentrations found in the effluent of the chamber, a chemical mechanism by which limestone at El Tajin is dissolved by acid rain is proposed. A model used to investigate the air transport pathways corresponding to precipitation events at El Tajin shows that air parcels come mainly from the Gulf of Mexico, although no directional preference is evident for acidic vs. non-acidic events.

Responses of an Amazonian teleost, the tambaqui (Colossoma macropomum), to low pH in extremely soft water.

Our goal was to compare the internal physiological responses to acid challenge in an acidophilic tropical teleost endemic to dilute low-pH waters with those in nonacidophilic temperate species such as salmonids, which have been the subjects of most previous investigations. The Amazonian tambaqui (Colossoma macropomum), which migrates between circumneutral water and dilute acidic "blackwater" of the Rio Negro, was exposed to a graded low-pH and recovery regime in representative soft water (Na+ = 15, Cl- = 16, Ca2+ = 20 mumol L-1). Fish were fitted with arterial catheters for repetitive blood sampling. Water pH was altered from 6.5 (control) to 5.0, 4.0, 3.0, and back to 6.5 (recovery) on successive days. Some deaths occurred at pH 3.0. Throughout the regime, there were no disturbances of blood gases (O2 and CO2 tensions and contents) or lactate levels, and only very minor changes in acid-base status of plasma and red cells. However, erythrocytic guanylate and adenylate levels increased at pH's less than or equal to 5.0. Down to pH 4.0, plasma glucose, cortisol, and total ammonia levels remained constant, but all increased at pH 3.0, denoting a stress response. Plasma Na+ and Cl- levels declined and plasma protein concentration increased at pH 3.0, indicative of ionoregulatory and fluid volume disturbance, and neither recovered upon return to pH 6.5. Cortisol and ammonia elevations also persisted. Transepithelial potential changed progressively from highly negative values (inside) at pH 6.5 to highly positive values at pH 3.0; these alterations were fully reversible. Experimental elevations in water calcium levels drove the transepithelial potential positive at circumneutral pH, attenuated or prevented changes in transepithelial potential at low pH, and reduced Na+ and Cl- loss rates to the water during acute low-pH challenges. In general, tambaqui exhibited responses to low pH that were qualitatively similar but quantitatively more resistant than those previously documented in salmonids.