Determination of the potential of Pistia stratiotes L. in removing nickel from the environment by utilizing its rhizofiltration capacity

Abstract: The aim of this study is to explain the biological response and rhizofiltration capacity of Pistia stratiotes, which is an aquatic macrophyte, in alleviating heavy metal stress. In our study, Pistia species were exposed to Nickel (Ni) at different concentrations over seven days. The potential of the aquatic macrophytes in accumulating heavy metals in the water and in removing them from the environment was evaluated by determining the bio-concentration factors (BCF). Selected biological parameters in the leaves of Pistia stratiotes, including metal accumulation, photosynthetic pigment amount, lipid peroxidation activity, and growth rates were measured at the end of the seven-day period. The highest amount of Ni accumulation in P. stratiotes occurred at a concentration of 20 mg l-1. The amount of chlorophyll a (chl a) in P. stratiotes reached a value of 0.087 mg g-1 at the Ni concentration of 20 mg l-1. The relative growth rate (RGR) of P. stratiotes showed a negative correlation with the increases in the concentration levels of the metal. Malondialdehyde (MDA) levels increased to 8.214 nmol/g at the concentration of 20 mg l-1, depending on Ni concentration and time. In our study, the use of P. stratiotes has been determined to be an appropriate plant as an effective Ni accumulator to be utilized with the purpose of rhizofiltration.

Estimation of herbicide bioconcentration in sugarcane (Saccharum officinarum L.) / Modelagem de bioconcentração de herbicidas em cana (Saccharum officinarum L.)

Sugarcane is an important crop for sugar and biofuel production in Brazil. Growers depend greatly on herbicides to produce it. This experiment used herbicide physical-chemical and sugarcane plant physiological properties to simulate herbicide uptake and estimate the bioconcentration factor (BCF). The (BCF) was calculated for the steady state chemical equilibrium between the plant herbicide concentration and soil solution. Plant-water partition coefficient (sugarcane bagasse-water partition coefficient), herbicide dilution rate, metabolism and dissipation in the soil-plant system, as well as total plant biomass factors were used. In addition, we added Tebuthiuron at rate of 5.0kg a.i. ha-1 to physically test the model. In conclusion, the model showed the following ranking of herbicide uptake: sulfentrazone > picloram >tebuthiuron > hexazinone > metribuzin > simazine > ametryn > diuron > clomazone > acetochlor. Furthermore, the highest BCF herbicides showed higher Groundwater Ubiquity Score (GUS) index indicating high leaching potential. We did not find tebuthiuron in plants after three months of herbicide application.

A cana de açúcar é uma cultura importante para produção de açúcar e biocombustíveis no Brasil e exige elevada utilização de herbicidas. Utilizamos modelo matemático para ajudar na compreensão da absorção de herbicida dessa cultura. Propriedades físico-químicas dos herbicidas e propriedades fisiológicas das plantas de cana foram usados para estimar a absorção e também o fator de bioconcentração, bioconcentration factor (BCF), calculado para o equilíbrio químico entre a concentração do herbicida na planta e na solução do solo. O coeficiente de partição planta/água, a taxa de diluição de herbicida, o metabolismo e a dissipação no sistema solo-planta e biomassa total das plantas foram adicionados ao modelo. O herbicida tebuthiuron aplicado ao solo na dose de 5,0kg ha-1 i.a. foi utilizado para testar o modelo. A absorção dos herbicidas mostrada pelo modelo indicou em ordem o seguinte: sulfentrazone> picloram> tebuthiuron> hexazinone> metribuzin> simazina> ametryn> diuron> clomazone> acetochlor. Esses herbicidas com alto índice (BCF) também apresentaram alto índice de potencial de lixiviação para água subterrânea "Groundwater Ubiquity Score" (GUS). Tebuthiuron não foi encontrado nas plantas após três meses de aplicação.

Proteínas totales y factor de bioconcentración por exposición a metales en la Gambusia punctata (Poeciliidae) / Total proteins and bioconcentration factor by metal exposure in Gambusia punctata (Poeciliidae)

El objetivo del presente trabajo fue evaluar niveles de proteínas totales y el factor de bioconcentración por exposición a metales en la Gambusia punctata. La especie fue muestreada en el ecosistema Filé y luego trasladada hacia condiciones de laboratorio, donde fueron diseñados 3 tratamientos a 2 réplicas con 25 ejemplares. Se determinó la concentración letal media (CL-50) como parámetro de toxicidad durante 48 horas de bioensayo. Los metales analizados fueron plomo y cadmio, cuantificados por espectroscopia de plasma inductivamente acoplados con vista axial. Transcurrido el experimento, la CL-50 correspondió a 0,1, ensayándose las concentraciones 0,06 y 5,78 mg/L, además del control negativo. Posteriormente se cuantificó el nivel de proteínas totales y los metales en agua, tejido y su relación mediante el factor de bioconcentración. El menor valor de proteínas fue ante la exposición al cadmio, con 43,9 por ciento de inhibición (p< 0,05) en comparación con el control; en el caso del plomo se determinó 2,5 por ciento de estimulación. Las mayores concentraciones en agua y tejido correspondieron a este último, no así para el factor de bioconcentración. Se concluyó que los resultados mostraron sensibilidad en la respuesta del contenido de proteínas totales y alta capacidad bioacumulativa para ambos metales.

The aim of this study was to evaluate levels of total proteins and the bioconcentration factor by metal exposure in Gambusia punctata. The species was sampled in the ecosystem Filé and then transferred to the laboratory, where 3 treatments in 2 replications with 25 copies were designed. Mean lethal concentration (CL-50) was determined as a toxicity parameter for 48 hours of bioassay. The analyzed metals were lead and cadmium, quantified by plasma spectroscopy inductively coupled with axial view. After the experiment, the CL-50 corresponded to 0.1 and concentrations of 0.06 and 5.78 mg/L and the negative control were tested. Then the level of total proteins and metals in water, tissue and its relationship by means of the bioconcentration factor were quantified. The lower value of proteins was by exposure to cadmium with 43.9 percent of inhibition (p <0.05) compared with the control; for lead 2.5 percent of stimulation was determined. The highest concentrations in water and tissue corresponded to the latter, but not for the bioconcentration factor. It was concluded that the results showed sensitivity in the response of total protein content and a high bioaccumulative capacity for both metals.

Accumulation of chromium and interaction with other elements in Chlorella vulgaris (Cloroficeae) and Daphnia magna (Crustacea, Cladocera).

Assays with Chlorella vulgaris Beijerinck Novakova, 1890 and Daphnia magna Straus, 1820 were performed to determine Cr and other elements concentration in tissues of both species by instrumental neutron activation analysis (INAA), after being exposed to 150, 280 and 350 .g l-1Cr (VI). Interaction among Cu, Zn, Fe and Cr were also registered. In the control of C. vulgaris, the amount of Cr was < 4μg g-1; in the treatments with Cr (VI) the values were 47, 82 and 100 folds greater than the control for the lowest, intermediate and highest concentrations tested respectively. In the control of D. magna, the amount of Cr was <3 μg g-1; in the treatments with Cr (VI) the values were 14, 13 and 27 folds higher than the control for the lower, intermediate and higher Cr (VI) concentrations respectively, and from 3 to 9 times less than for C. vulgaris These results show that C. vulgaris is very efficient accumulator of Cr (VI) from polluted waters, and in consequence, it is proposed to be used in phytoremediation procedures.

The Influence of Surfactants on Food Safety / 环境与健康杂志

Surfactants are employed widely in household and industryial products wordwide.Everyday millions pounds surfactants and their products are dispersed into soil, water, food and human body that posing a threat to human health. The paper expatiated on the topic that the threats of surfactants on food safety with arguments as: acute toxicity, genetic toxicity, estrogenic effects, bioconcentrate and so on. At last, the article emphasized it is essential to have comprehensive study on the surfactants toxicity and influence on food safety.