Toxicity assessment of fresh and weathered petroleum hydrocarbons in contaminated soil- a review.

Soil contamination with total petroleum hydrocarbons (TPH) is widespread throughout the globe due to the massive production of TPH anthropogenically and its occurrence in the soil. TPH is toxic to beneficial soil organisms and humans and thus has become a serious concern among the public. Traditionally TPH toxicity in the soil is estimated based on chemical fractions and a range of bioassays including plants, invertebrates and microorganisms. There is a large inconsistency among ecotoxicology data using these assays due to the nature of TPH and their weathering. Therefore, in this article, we critically reviewed the weathered conditions of TPH, the potential fate in soil and the bioindicators for the assessment of the ecotoxicity. Based on the current research and the state-of-the-art problem, we also highlighted key recommendations for future research scope for the real-world solution of the ecotoxicological studies of hydrocarbons.

Assessment of chromium hyper-accumulative behaviour using biochemical analytical techniques of greenhouse cultivated Sonchus asper on tannery waste dump site soils.

Keeping the sources of pollution such as chromium (Cr) under a safe limit is a daunting challenge due to the negative impact of heavy metal bioaccumulation in vegetation and the concomitant human health exposure. We took a closer look at Sonchus asper by cultivating in the green house. It resulted in 80% germination when cultivated over nine different soils collected from the tannery dump site. The biochemical analytical techniques such as mass spectrometry indicated significant bioaccumulation of Cr in the plant tissue. As per the ICP-MS analysis, this annual herb resulted in the accumulation of 601 mg kg-1 of total Cr with 212 mg kg-1 in its shoot from soil samples containing up to 41 mg kg-1 of hexavalent Cr. The energy dispersive X-ray (EDX) spectroscopy of S. asper revealed a higher level of S element indicating a sulfate-Cr binding relation. Elevated content of Cr in soil (73,721 ± 65 mg kg-1) caused biochemical changes in the shoot of S. asper as indicated by the disappearance of Fourier transform infrared spectroscopy (FTIR) bands at 935 and 872 cm-1 and further revealing aliphatic -CH2 appearing as anti-symmetry νa(CH2) and symmetric vibration νs(CH2) at the band of 2920 and 2850 cm-1, respectively.