Kinetics, biochemical and factorial analysis of chromium uptake in a multi-ion system by Tradescantia pallida (Rose) D. R. Hunt

Assessment of the mutagenic potential of the water of an urban river by means of two Tradescantia-based test systems

River pollution can be caused by anthropogenic or natural factors. When testing water quality for the presence of toxic substances, higher plants as bioindicators for the genotoxic effects of complex mixtures are effective and appropriate. Hence, in this work the Tradescantia (clone 02) stamen hair mutations (Trad-SHM) and Tradescantia micronuclei (Trad-MCN) were used to determine mutagenic and clastogenic potential of an urban river. A significant increase in the level of all studied endpoints as well as morphological changes, including pink cells (PC) and colorless cells (CC) in stamen hairs, stunted hairs (SH), tetrads with micronuclei (MN) and MN in tetrads of pollen microspores in the Tradescantia was observed compared to the negative control (tap water). As an example riverine system, part of the River Hrazdan (Armenia) flowing through a highly urbanized and industrial area was studied. The positive control (10 mM CrO₃) showed the highest genotoxicity for the SHM assay (PC: 5.1 / 1000, CC: 17.9 / 1000) and for the MCN assay (12 MN / 100 tetrads and 9.4 ± 0.53 tetrads with MN). Genetic responses were analyzed in conjunction with the concentrations of select elements in the riverine water. Reasons for observing such a high level of genetic markers in the riverine water and applicability of the Tradescantia (clone 02) test-systems in environmental risk assessment and biomonitoring are discussed.

Temporal and spatial trends of a floating islands system's efficiency

Floating Treatment Systems (FTWs) are known to be an efficient means to treat eutrophic surface waters, but most of the studies are related to the use of FTWs at the laboratory, microcosm or mesocosm level. It is necessary to expand these studies to larger surface areas and to introduce new supporting materials, substrates and plants adapted to the different regional conditions. This study aimed to evaluate the efficiency of temporal and spatial remediation of a floating island system, set up in a 400m² experimental area delimited in an urban reservoir located on the main campus of the Federal University of Campina Grande-PB, Brazil. The experiment was carried out in three stages and 16 physicochemical and biological variables were monitored at thirteen sampling points regularly distributed in the study area, for a period of eight months. Temporally, the variables turbidity, electrical conductivity and total, fixed and volatile dissolved solids tended to decrease. Spatially, considering the 13 sampling points in sequence, the trend of reductions were found in the total dissolved solids, volatile dissolved solids and electrical conductivity. The trend of elevation was more substantial for the concentrations of ammonia-nitrogen and orthophosphate. In addition, occasional substantial reductions was found in variables that did not show statistical trends, such as chemical oxygen demand and total phosphorus. This study demonstrated the importance of expanding the scale of evaluation of floating island systems, finding significant results in terms of reduction of pollutants and adaptation of new structures and plants to adverse environmental conditions.

Chromium-Induced Reactive Oxygen Species Accumulation by Altering the Enzymatic Antioxidant System and Associated Cytotoxic, Genotoxic, Ultrastructural, and Photosynthetic Changes in Plants

Chromium (Cr) is one of the top seven toxic heavy metals, being ranked 21st among the abundantly found metals in the earth’s crust. A huge amount of Cr releases from various industries and Cr mines, which is accumulating in the agricultural land, is significantly reducing the crop development, growth, and yield. Chromium mediates phytotoxicity either by direct interaction with different plant parts and metabolic pathways or it generates internal stress by inducing the accumulation of reactive oxygen species (ROS). Thus, the role of Cr-induced ROS in the phytotoxicity is very important. In the current study, we reviewed the most recent publications regarding Cr-induced ROS, Cr-induced alteration in the enzymatic antioxidant system, Cr-induced lipid peroxidation and cell membrane damage, Cr-induced DNA damage and genotoxicity, Cr-induced ultrastructural changes in cell and subcellular level, and Cr-induced alterations in photosynthesis and photosynthetic apparatus. Taken together, we conclude that Cr-induced ROS and the suppression of the enzymatic antioxidant system actually mediate Cr-induced cytotoxic, genotoxic, ultrastructural, and photosynthetic changes in plants.