Dietary tissue cadmium accumulation in an amazonian teleost (Tambaqui, Colossoma macropomum Cuvier, 1818)

Understanding the effects of metal contamination in the Amazon basin is important because of the potential impact on this region of high biodiversity. In addition, the significance of fish as the primary source of protein for the local human population (living either alongside the Amazon River or in the city of Manaus) highlights the need for information on the metal transfer through the food chain. Bioaccumulation of metals in fish can occur at significant rates through the dietary route, without necessarily resulting in death of the organism. The goal of this work was to expose an economic relevant species from the Amazon basin (tambaqui, Colossoma macropomum) to dietary cadmium (Cd) at concentrations of 0, 50, 100, 200, and 400 µg.g-1 dry food. Fish were sampled on days 15, 30, and 45 of the feeding trials. Tissues were collected for analysis of Cd concentration using graphite furnace atomic absorption spectrophotometry. Cd accumulation in the tissues occurred in the following order: kidney > liver > gills > muscle. Relative to other freshwater fish (e.g., rainbow trout, tilapia), tambaqui accumulated remarkably high levels of Cd in their tissues. Although Cd is known to affect Ca2+ homeostasis, no mortality or growth impairment occurred during feeding trials.

O entendimento dos efeitos da contaminação por metais na Bacia Amazônica é importante devido ao potencial impacto sobre esta região de elevada biodiversidade. Além disso, a relevância dos peixes como fonte primária de proteína para a população humana local (tanto nas comunidades ribeirinhas ao longo do rio Amazonas, quanto na cidade de Manaus), ressalta a necessidade de informação sobre a transferência de metais através da cadeia alimentar. Bioacumulação de metais em peixes pode ocorrer em taxas significativas através da dieta, sem necessariamente resultar na morte do indivíduo. O objetivo deste estudo foi expor cronicamente uma espécie de importância comercial nativa da Amazônia (tambaqui, Colossoma macropomum) a dietas enriquecidas com cádmio (Cd) em concentrações de 0, 50, 100, 200, and 400 µg.g-1 alimento seco. Os peixes foram amostrados nos dias 15, 30 e 45 do tratamento experimental. Os tecidos foram coletados para análise quanto a concentração de Cd por meio de espectrofotometria de absorção atômica acoplado a forno de grafite. O acúmulo de Cd nos tecidos ocorreu na seguinte ordem: rim > fígado > brânquias > músculo. Comparando-se com outras espécies de peixes de água doce (por exemplo, truta arco-íris, tilápia), o tambaqui acumulou níveis de Cd extremamente mais elevados em seus tecidos. Apesar do Cd ser conhecido por afetar a homeostase do Ca2+, não houve mortalidade ou retardo no crescimento durante os testes dietários.

Influence of joint application of heavy metals on level of each metal accumulated in the periwinkle Tympanotonus fuscatus (Gastropoda: Potamididae)

Most laboratory assessments of toxicity and bioaccumulation of heavy metals have been concentrated on the accumulation of these metal ions when exposed singly to the test organisms. However, under the natural environmental settings, the metals are never present in isolation and may interact with each other, therefore justifying the need to study the influence of joint application of metals on accumulated levels in exposed animals. In this study, exposure of the periwinkle Tympanotonus fuscatus to sublethal concentrations (equivalent to 0.1 and 0.01 of 96 h LC50) of heavy metals revealed that they were bioaccumulative varying amounts, depending on the type of metal, exposure period and concentration in the test media. While Zn and Pb ion accumulation increased steadily with exposure time, the amounts of Cu accumulated fluctuated regularly over the 30-day experimental period. The levels of Zn, Cu and Cd bioaccumulated over the 30-day experimental period were reduced by over 2-6 folds (with bioaccumulation ratio values ranging from 0.15 to 0.81) when compared to concentrations of the respective metals accumulated during single bioaccumulation studies. However, Pb concentrations accumulated during the joint action studies increased nearly 2-fold (bioaccumulation ratio range 1.36 to 2.0-fold).

La mayoría de los análisis de laboratorio sobre toxicidad y bioacumulación de metales pesados se han concentrado en la acumulación individual de los iones metálicos en los organismos de prueba expuestos a ellos. Sin embargo, bajo condiciones naturales del ambiente, los metales nunca se presentan en forma aislada y deben interactuar unos con otros, justificando así la necesidad de estudiar el efecto de la aplicación conjunta de metales en animales de prueba. En este estudio la exposición de Tympanotonus fuscatus a concentraciones subletales (0.1-0.01 de 96 h LC50) de metales pesados reveló que la bioacumulación varía según el tipo de metal, el período de exposición y la concentración en el medio de prueba. Mientras los iones de Zn y Pb incrementaron gradualmente su acumulación al pasar el tiempo, las cantidades de Cu fluctuaron regularmente durante los 30 días del experimento. Los niveles de Zn, Cu y Cd bioacumulados durante los 30 días del experimento son de dos a seis veces menores (con un rango de bioacumulación de 0.15-0.81) que los que se obtienen por la exposición a los metales en forma individual. Por el contrario, la acumulación de Pb aumentó al doble (rango de bioacumulación 1.36-2.0).

Growth and cadmium uptake in barley under cadmium stress.

Effect of various additions of cadmium (5 to 3125 microg g(-1) air dried soil) was studied on growth and Cd uptake in barley grown in pots containing two soil types- a loamy sand and a sandy loam, during different stages of growth. While lower doses (5 to 25 microg g(-1)) led to an increase, the higher doses resulted in a substantial decrease in barley growth. The plant Cd content increased with an increase in soil applied Cd. A decrease in translocation ratio prevailed at higher soil applied Cd, indicating the existence of an exclusion mechanism.

Plant availability of cadmium in presence of organic acids: an interactive aspect.

The present communication reports the effect of various carboxylic and amino acids on the uptake and translocation of root-absorbed Cd by maize (Zea mays). Statistically significant increases in Cd accumulation in various plant tissues with increasing supplementation of organic acids suggested the existence of Cd-organic acid interaction in soil-rhizosphere environment of the plant. The potentiality of phytochelators (organic acids) to form plant available organically bound Cd is discussed.

Cobre, cadmio y plomo en el pez Cyprinodon dearborni, sedimentos y agua en dos lagunas de Venezuela / Cooper, cadmium and lead in the Cyprinodon dearborni fish, in the sediments and in the water in two Venezuela's lagoons

The concentration of copper, cadmium and lead in superficial sediment, water and the fish Cyprinodon dearborni was determined in two coastal lagoons of Sucre State, Venezuela. Chacopata lagoon is hyper saline while Los Patos lagoon is hypo saline and receives significant wastewater from Cumaná city. Water, sediment and fish samples were collected in February 1998. In the laboratory, samples underwent acid digestion and were analyzed by atomic absorption spectophotometry. The mean values of the metals in C. dearborni from the Chacopata lagoon were: 159.26 +/- 210.68 microg/g for Cu, 44.71 +/- 45.58 microg/g for Cd, and 9.31 +/- 23.34 microg/g for Pb, while for Los Patos lagoon the mean values were: 64.88 +/- 16.30, 19.48 +/- 5.81 and 22.85 +/- 20.00, respectively. In the water column, the metal concentration ranges were: 2.3-11.6, 3.9-5.4 and 21-32 mg/l for copper, cadmium and lead, respectively. These results suggest that metal levels in sediment, water column and organisms in both lagoons do not differ, except for lead, even though only Los Patos receives waste water.

Response of Java citronella (Cymbopogon winterianus Jowitt) to toxic heavy metal cadmium.

Cadmium at 200 mg kg-1 soil and above concentrations was fatal as growth was inhibited ultimately leading to death of Java citronella (Cymbopogon winterianus Jowitt.). The surviving plants at 50 and 100 mg kg-1 treatments also exhibited pronounced retardation of growth and biomass yield. There was considerable reduction in the level of essential oil in herbage and oil quality deteriorated. Cadmium accumulation profile showed that highest accumulation was in root, followed by stem, leaf sheath and leaf. Very high accumulation in root for higher doses appeared to be the reason for fatality.

Effect of trisodium pentetat on the distribution of cadmium in some body organs & on hepatic metallothionein in rats.

The pre- and post-treatment with calcium trisodium diethylene-triaminepentaacetic acid (CaNa3DTPA) was investigated for their efficacy to mobilize cadmium (Cd) from various tissues and hepatic metallothionein (MT) in Cd-exposed rats. Pretreatment with CaNa3 DTPA significantly reduced the hepatic and renal Cd absorption while, post Cd treatment with CaNa3 DTPA was effective in reducing renal and brain Cd. Pretreatment with CaNa3DTPA significantly increased the Cd induced hepatic metallothionein (MT) level, MT-bound Cd, Zn and Cu contents while, post treatment with CaNa3DTPA reduced the hepatic MT, MT-bound Cd compared to Cd alone treated rats.

Uptake of cadmium by isolated human red blood cells.

Uptake of Cd by human RBC in vitro was studied. The uptake was found to be biphasic with a rapid initial phase followed by a slower second phase which was still increasing at the time of the last experiment (60 min). Both the phases were found to be independent of metabolically derived energy and unaffected by zinc in the incubation medium.