Risk Assessment of Heavy Metal Pollution in Farmland Soils at the Northern Foot of the Qinling Mountains, China.

To provide scientific basis for the prevention and control of heavy metal pollution, a field investigation, sample collection and analysis of the heavy metal content in farmland soils at the northern foot of the Qinling Mountains were conducted. Based on the comparative analysis of the single pollution index method, the Nemerow comprehensive pollution index method, the geological accumulation index method, the potential ecological hazard index method, and the geological accumulation index method were used to comprehensively analyze and evaluate the risk of soil heavy metal pollution. The results showed that the heavy metal pollution of farmland soil at the northern foot of the Qinling Mountains was severe, among which Hg and Cr pollution was relatively obvious. Taking the soil screening values of agricultural land as the standard, the quantity of element Hg in agricultural soils at the northern foot of the Qinling Mountains was higher than the relevant screening value. In the two sample sites investigated, the intensity of the heavy metal accumulation index in Baoqizhai Village was Hg > Cr > Cu > As > Pb, and in Dayangyu Village it was Cr > Cu > As > Pb. Among them, in Baoqizhai Village it shows the heavy pollution caused by Hg (Igeo= 3.42) and the light pollution caused by Cr (Igeo < 1) in the two areas. Hg is mostly affected by mining activities and its atmospheric subsidence. At the same time, Cr is mainly derived from the weathering of rock parent material and is also affected by anthropogenic factors to a certain extent. The accumulation of heavy metals in the farmland soil around the northern foot of the Qinling Mountains was relatively high, posing a threat to the surrounding soil environment. Therefore, it is urgent to control farmland soil environmental pollution.

Critical assessment of plasma tar reforming during biomass gasification: A review on advancement in plasma technology.

The contamination of producer gas with tar due to inefficient removal methods remains a major challenge in the bioenergy industry and a critical barrier, hindering commercial applications of biomass gasification technology. Single syngas treatment through primary and secondary tar removal method is insufficient to produce a tar free syngas. Currently widely applied tar removal methods are catalytic reforming and plasma reforming. Though both methods have hindrances of fast catalyst deactivation due to coke deposition and reduced syngas selectivity with large quantities of undesired liquid products from plasma reforming. Our review paper showed that hybrid plasma catalysis could be a breakthrough in tar reforming methods and overcome major drawbacks. Though, very little work on review articles have reported merging non-thermal plasma and heterogeneous catalyst. Plasma catalysis offers an inexpensive viable future technology of tar reforming through biomass gasification. The article assessed in-depth the synergistic effect created during the interaction of energetic plasma species and catalyst radicals in tar reforming. Review results show that merging plasma with catalysts noticeably Nickel, Non-nickel metal catalyst and zeolites gave pleasant results of tar conversion efficiency, improved gas selectivity and improved catalyst stability.