Heavy metal contamination in "chemicalized' green revolution banana fields in southern India

Determination of Macro- and Microelements in the Inflorescences of Banana Tree Using ICP OES: Evaluation of the Daily Recommendations of Intake for Humans

The inflorescence of Musa paradisiaca, known as “banana heart” is a structure that includes flowers and bracts of banana, commonly used as food source worldwide. The aims of this study were (1) to determine the mineral components of Musa paradisiaca and (2) to compare the obtained results with previously reported data of Recommendation Dietary Allowances (RDAs) and edible plant permissible limits set by FAO/WHO. The samples were digested using microwave-assisted equipment, while elemental contents were determined by inductively coupled plasma optical emission spectroscopy (ICP OES). Metal (Mg, Ca, Cr, Ni, Cu, Fe, and Zn) and nonmetal (S and P) contents were detected. According to RDA, the inflorescences could be excellent sources of Mg, P, Cr, Cu, Zn, and Fe for females, males, and pregnant women, all age 31–50 y, as well as children (4–8 y). Bracts are good source of Zn for male and pregnant women and good source of Fe for children. All the samples contained considerable amounts of Mg, Ca, P, Ni, Cu, Zn, and Fe, which were quite low to induce deleterious effects (UL). FAO/WHO limits for edible plants have not yet been established for S, P, Mg, and Ca, but Ni and Zn are below of those limit values. However, Cr and Cu concentrations are higher than the values established for edible plants and may pose a threat to human health. Farmers should be encouraged by government agencies, not only for sustainability of production but also to ensure the storage and trade of banana tree inflorescence.

Excess Copper-Induced Changes in Antioxidative Enzyme Activity, Mineral Nutrient Uptake and Translocation in Sugarcane Seedlings

Sugarcane is a potential species for use in heavy metal remediation. To analyze the effect of excess copper on sugarcane, the biomass, mineral nutrient content and activities of antioxidative enzymes were measured under copper stress. The results revealed that the biomass of roots and shoots significantly decreased with increasing copper concentration in solution. Most copper accumulated in the roots, and the translocation factor of copper decreased with an increase in copper stress. The MDA content in sugarcane roots notably increased under copper stress. The POD activity in sugarcane roots increased, and CAT activity decreased under copper stress. The Zn, Fe and Mn contents in shoots increased significantly under 200 μmol L^-1 Cu²⁺ treatments. The Zn and Mg contents in roots notably decreased under copper stress, while the Zn and Mg translocation factors increased. These results indicated that the increase in POD activity and the modification of mineral nutrient uptake and transfer might play an important role in reducing the detrimental effects of excess copper.

Analysis of Heavy Metal Sources in the Soil of Riverbanks Across an Urbanization Gradient

Regional soil quality issues arising from rapid urbanization have received extensive attention. The riverbank that runs through a city is representative of urbanization gradient transformation. Thirty soil samples in the Yangtze River Delta urban agglomeration were collected and analyzed for the concentrations of seven analytes. Correlation, principle component analysis, cluster analysis and GeoDetector models suggested that the four groups (Cr-Ni-Cu, Cu-Zn-As-Sb, Cd and Pb) shared the same sources in the core urban region; five groups (Cr-Ni-Cu-Zn, As, Cd, Sb and Pb) in the suburbs and three groups (Cr-Ni, Cu-Zn-Cd-Sb-Pb and As) in the exurbs. GeoDetector methods not only validated the results of the three other methods, but also provided more possible impact factors. Besides the direct influences, the interaction effects among factors were quantified. Interactive combination with strong nonlinear increment changed from between-two-weak factors in the central region to between-strong-and-weak factors in the suburbs. In the exurbs, the stronger interaction effects were observed between strong and weak factors. Therefore, the GeoDetector model, which provided more detailed information of artificial sources could be used as a tool for identifying the potential factors of toxic elements and offering scientific basis for the development of subsequent pollution reduction strategies.