Abstract. Unreasonable mining and smelting of mineral resources, solid waste disposal, sewage irrigation, utilization of pesticides and fertilizers would result in a large number of heavy metal pollutants into the water and soil environment, causing serious damage to public health and ecological safety. In recent years, a majority of scholars tried to use biochar to absorb heavy metal pollutants, which has some advantages of extensive raw material sources, low-cost and high environmental stability. This paper reviewed the definition, properties of biochar, the mechanism of heavy metal sorption by biochar and some related problems and prospects, to provide some technical support for the application of biochar into heavy metal polluted soils.
The East Kunlun Orogenic Belt is considered as one of the important gold mineralization regions in the Tethys tectonic domain. These orogenic gold deposits are related to intermediate-acid intrusions formed at the end of Paleo-Tethys evolution, but the petrogenesis is controversial. This paper presents a new study on the geochemistry of zircon U-Pb, O, S, and Pb isotopic compositions of Asiha quartz diorite, granite porphyry, and sulfides. The geochemical features of quartz diorite and granite porphyry are consistent with the modern adakite, with high content of Sr but low content of Y, Yb, and MgO. Magmatic zircons from these two types of intrusion yielded U-Pb ages of 238.4 ± 1.4 Ma and 240 ± 1.7 Ma, respectively. The high O isotopic composition of Asiha complex may reflect that crust or crustal derivates were incorporated into the magmatic melt, and the Pb isotope characteristics indicates a lower crust origin. The δ34S values of pyrites range from 4.9‰ to 11.6‰. This study infers that the Asiha complex perhaps formed by partial melting of the Paleo-Tethys subducted oceanic crust with seafloor sediments and is markedly different from the traditional adakite. Asiha deposit is an orogenic gold deposit related to adakite-like rocks, which formed in Triassic in the East Kunlun Orogenic Belt.
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