Germinação de Phaseolus aureus contaminados com diferentes fontes de cromo (VI) / Germination of Phaseolus aureus contaminated with different sources of chromium (VI)

O excesso de Cr nas plantas pode provocar inibição no crescimento das plantas, clorose nas folhas, desequilíbrio nutricional e alteração na germinação das sementes, sendo também altamente tóxico para humanos. Objetivou-se avaliar a germinação de sementes de feijão submetidas a diferentes fontes de Cr, em câmara germinadora durante 9 dias. As fontes de Cr utilizadas: cromato de potássio e dicromato de potássio, em 128 subamostras em soluções de concentrações crescentes de Cr (0, 5,10, 20, 45, 90, 200 e 400 mg L-1). Realizou contagem de sementes normais, anormais e mortas. Conclui-se que sementes de feijão submetidas ao dicromato de potássio germinam 47,5% em média, sem efeitos prejudiciais ao seu desenvolvimento, com apenas 0,87% de sementes anormais e 1,6% em média de sementes mortas, ambas com tolerância de até 400 mg L-1.

Influence of accumulation of heaps of steel slag on the environment: determination of heavy metals content in the soils

The presence of high level of heavy metals involves a human healthy risk that could induce chronic diseases. This work reports on the metal contamination due to heaps of steel-slag accumulated during more than 40 years in allotments and industrial areas in the southern part of Madrid (Spain). Several slag and soil samples were collected in an area of 10 km² and characterized by different conventional (XRD and XRF) and no so common methods (ESEM, thermoluminescence and EDS-WDS). The analysis reveal the presence of: (i) important amounts of Fe (43 percent), Mg (26 percent), Cr (1.1 percent), Mn (4.6 percent), S (6.5 percent) in the form of Fe-rich slag phases (wustite, magnetite...), Si and Ca-rich phases (larnite, ghelenite...), Cr (chromite), Mn (bustamite) and graphite, (ii) traces of some other contaminants such as Cr (7700 ppm), Zn (3500 ppm), Ba (3000 ppm), Pb (700 ppm) or Cu (500 ppm) on pathway soil samples that come from the steel slag, and (iii) Co (13 ppm), Pb (78 ppm) and V (54 ppm) in farmland soil samples. Although the existing heavy metals content is not appropriate for the current use, the extremely high metal contamination of the surrounding areas is more worrying. The properties of the soil farmlands (pH circa 7, 13 percent of clay, mainly illite, and 1-4 percent of organic matter content) show suitable conditions for the retention of cationic metals, but further studies on the movilization of these elements have to be performed to determine the possibility of severe human health risks. This sort of study can provide useful information for the politicians regarding the appropriate use of the territory to prevent possible health hazard for the population.

A presença de altos niveis de metais pesados envolve riscos à saúde humana e pode induzir doenças crônicas. Este trabalho relata a contaminação metálica causada por pilhas de escória siderúrgica acumulada durante mais de 40 anos em áreas industriais na parte sul de Madrid (Espanha). Amostras de escória e solo foram coletadas em uma área de 10 km² e caracteri-zada por diferentes métodos, convencionais (XRD, XRF) ou não (ESEM, termoluminescência e EDS-WDS). A análise revela a presença de: i) quantidades importantes de Fe (43 por cento), Mg (26 por cento), Cr (1,1 por cento), Mn (4,6 por cento), S (6,5 por cento) formando várias fases ricas em Fe (wüstita, magnetita), Si e Ca (larnita, guelenita), Cr (cromita), Mn (bustamita) e grafite; (ii) tiajos de outros contaminantes, como Cr (7700 ppm), Zn (3500 ppm), Ba (3000 ppm), Pb (700 ppm) e Cu (500 ppm), no solo dos caminhos para as pilhas de resíduos e (iii) Co (13 ppm), Pb (78 ppm) e V (54 ppm) em amostras de solo agrícola. Embora os teores de metais pesados não sejam apropriados para uso corrente, a elevada contaminação de areas adjacentes é mais preocupante. Os solos adjacentes (pH ca. 7, 13 por cento de argila - principalmente ilita) e 1-4 por cento de matéria orgânica mostram condições adequadas para a retenção de cátions, mas outros estudos deverão ser realizados para determinar a possibilidade de riscos à saúde humana. Este tipo de trabalho pode fornecer informaçãoo útil para gestores públicos, com relação ao uso do território e prevenção de riscos à saúde da população.

Growth and accumulation of cadmium in Amaranthus [Amaranthus tricolor L.] as influenced by various levels of cadmium in soil

A pot experiment with six levels of cadmium [0, 1, 3, 5. 7 and 9 mg kg[-1] soil] conducted to investigate the effects of cadmium on the growth of Amaranthus [Amaranthus tricolor L.] a popular leafy vegetable crop in Bangladesh, and Cd accumulation in it. Plants were harvested at 30 and 45 days after sowing [DAS]. Plant height and biomass production of shoot and root were significantly affected by Cd treatments and there was a depression of yield due to increased Cd application. Cadmium accumulation in Amaranthus and the shoot: root ratio of Cd increased with increasing Cd concentrations in soil. The increase of soil contamination level led to a decrease of bioaccumulation coefficient in shoot and root at both the stages. The capacity for Cd accumulation in edible parts of Amaranthus with the absence of any visual symptoms indicates a potential danger for human consumption

The association of lead-contaminated house dust and blood lead levels of children living on a former landfill in Puerto Rico

Exposure to lead in children living on a former landfill in Vega Baja-Puerto Rico, a United States Environmental Protection Agency (USEPA) designated Superfund Site, is a major health concern. Direct contact with lead-contaminated soil is considered a major exposure source. However, there is a lack of information regarding the contribution of lead-contaminated house dust to children's blood lead concentrations. This study evaluated the relationship between lead contaminated-house dust and children's blood lead levels. Blood from 42 children, aged 6 years old or less, and dust from 29 houses were analyzed for lead, and face-to-face interviews were performed to gather information on potential risk factors for high blood lead levels. Blood lead levels ranged from 0.97 to 7.79 micrograms/dL. Lead values for floors fluctuated from 0.12 to 98.30 micrograms/ft2, with 17 per cent of houses surpassing the USEPA standard of 40 micrograms/ft2. Multiple regression analysis showed that lead in window sills, toy chewing and soil eating habits were significant predictors of blood lead levels. Further investigations aimed at assessing the long-term effects of constant exposure to environmental lead in these children are warranted.

Influence of selected insecticides on phosphatase activity in groundnut (Arachis hypogeae L.) soils.

Selected insecticides, Chloropyrifos, Dichlorovos, Methyl parathion, Phorate and Methomyl, at concentrations ranging from 0 to 10 kg ha(-1) were tested for their non-target effects towards activity of phosphatases in two soils. In soil samples receiving 2.5 kg ha(-1) of the insecticides Dichlorovos, Phorate and Methomyl and also in soil samples receiving 5.0 kg ha(-1) of the insecticides, Chloropyrifos and Methyl parathion, the activity of phosphatase was significantly more at 20 days period of incubation and decreased progressively with increasing period of incubation.

Determination of chlorimuron and metsulfuron residues in two soils of Argentina using a rapid seed-bioassay.

The presence of chlorimuron ethyl and metsulfuron methyl in two soils was determined by a modified petri dish bioassay. Pregerminated seeds of maize and sunflower were placed in petri dishes containing 85 to 100 g of treated soil. Radicle root lengths were measured after 24 h. Chlorimuron had no effect on maize on the Balcarce soil, however 0.007 microg g(-1) decreased sunflower root length. Chlorimuron decreased maize and sunflower root length regardless application dose on the San Cayetano soil. Metsulfuron decreased maize root length at 0.04 microg g(-1) and sunflower at 0.021 microg g(-1) on the Balcarce soil. On the San Cayetano soil metsulfuron at 0.001 microg g(-1) decreased maize and sunflower root length. The phytotoxicity of chlorimuron and metsulfuron changed according to soil type and dose. Maize and sunflower were 1.3-1.5 and 1.3-1.8 times respectively more sensitive to chlorimuron on the San Cayetano soil than on the Balcarce soil. In the case of metsulfuron, maize was similarly sensitive on both soils but sunflower was 1.7-2.0 times more sensitive on the San Cayetano soil than on the Balcarce soil. Phytotoxicity increased as organic matter (OM) content decreased and/or when the soil pH and concentration increased.

Cell fusion and chromatin degeneration in an inbred line of maize

A large number of maize genotypes are currently being evaluated to determine the effect of environmental stress caused by the aluminum found in cerrado soils on meiotic behavior. In the present study we report the occurrence of cell fusion followed or not by chromatin degeneration in meiocytes of some plants of an inbred line of maize grown on acid and corrected soil in the Brazilian central plateau. The results suggest the absence of any soil effect on the irregularities observed since the number of affected plants was higher among those grown on corrected soil. The possible causes of these irregularities and their influence on male sterility are discussed.