Arsenic-phosphorus interactions in the soil-plant-microbe system: dynamics of uptake, suppression and toxicity to plants

High arsenic (As) concentrations in the soil, water and plant systems can pose a direct health risk to humans and ecosystems. Phosphate (Pi) ions strongly influence As availability in soil, its uptake and toxicity to plants. Better understanding of As(V)-Pi interactions in soils and plants will facilitate a potential remediation strategy for As contaminated soils, reducing As uptake by crop plants and toxicity to human populations via manipulation of soil Pi content. However, the As(V)-Pi interactions in soil-plant systems are complex, leading to contradictory findings among different studies. Therefore, this review investigates the role of soil type, soil properties, minerals, Pi levels in soil and plant, Pi transporters, mycorrhizal association and microbial activities on As-Pi interactions in soils and hydroponics, and uptake by plants, elucidate the key mechanisms, identify key knowledge gaps and recommend new research directions. Although Pi suppresses As uptake by plants in hydroponic systems, in soils it could either increase or decrease As availability and toxicity to plants depending on the soil types, properties and charge characteristics. In soil, As(V) availability is typically increased by the addition of Pi. At the root surface, the Pi transport system has high affinity for Pi over As(V). However, Pi concentration in plant influences the As transport from roots to shoots. Mycorrhizal association may reduce As uptake via a physiological shift to the mycorrhizal uptake pathway, which has a greater affinity for Pi over As(V) than the root epidermal uptake pathway

The role of plant growth promoting bacteria on arsenic removal: a review of existing perspectives

Phytobial remediation is an innovative tool that uses plants and microbes to mitigate Arsenic (As) contamination of the environment. Recently, plant growth-promoting bacteria (PGPB) that assists phytoremediation has been highly touted for both improving plant metal tolerance and promoting plant growth while achieving the goal of large-scale removal of As. This review focuses on the PGPB characteristics influencing plants and the mechanisms in which they function to overcome/lessen As-induced adversities. Several recent examples of mechanisms responsible for increasing the availability of As to plants and coping with As stresses facilitated by PGPB will be reviewed. Although drawbacks to phytoremediation have been reported, encouraging results have been developed with regular monitoring. Introducing PGPB-assisted phytoremediation of As in a field requires an assessment of the environmental effects of PGPB, especially with respect to the impacts on indigenous bacteria

Heavy metals in chrome-tanned shaving of the tannery industry are a potential hazard to the environment of Bangladesh

During the tannery production process, huge quantities of waste especially chrome shaving are produced and are being discharged directly into the environment of Bangladesh. To know the concentration of some heavy metals in chrome shaving, the samples were collected, digested, and analyzed. Among the determined metals e.g. zinc (Zn), lead (Pb), and chromium (Cr), the Cr concentration was very high. The average concentration of Cr was 13,832.70 mg Kg−1 dry weight which was equivalent to almost 1.383%. Chromium in leather shavings poses a critical problem for disposal or management. Recovery of Cr and management of chrome shaving are strongly suggested

Conversion of waste plastic (low density polyethylene) to alternative resources

Plastic pollution has become one of the top issues at present throughout the world. In Asian continent plastic pollution is found at the highest rate and Bangladesh is ranking as the 10th number of plastic wastes producer. To minimize the plastic pollution its management is necessary. To do that we tried to convert the plastic wastes as alternative resources for example plastic tiles or plastic tobs. The study was conducted at Jashore University of Science and Technology campus where polyethylene plastic wastes are found available. Molten LDPE were mixed with varying proportion of sand to conduct two experiments. First one is the preparation of plastic tiles and the second one is the making of tobs. Both of the two experiments kept in incubation under water for 7 and 14 days and experimental characterization such as water absorption variation, compressive strength, SEM, FTIR and EDX were done using standard procedures. Density and water absorption changes with the increase in plastic percentage in both the two experiments. In the 1st experiment, compressive strength was done and showed that at the increase of plastic % up to 45% tiles could bear maximum load above 3000 psi that match the standard concrete tiles strength. In the case of EDX analysis, C, O and Hg showed at the highest peak than other elements in both the two experiments. In the surface internal structure of the 1st experiment, some structural deformation was noticed but in the 2nd experiments some cracks and cavities formation found on the naked eye. In the chemical structure of the 1st experiment showed C-O stretching, C=C stretching, O=C=O stretching whereas in the 2nd experiment, most of the tob samples showed C-O stretching, O-H stretching, C=C stretching and N-H stretching. The plastic tiles could be used in rare or rural area and plastic tobs could be used as decorative purposes. From the results, we found the satisfactory output of the product and could be used as alternative resources