Application of biochar in heavy metal remediation suffers from lack of long-term stability. Phosphate-solubilizing bacteria (PSB) are able to elevate P release and the subsequent reaction with Pb to form stable pyromorphite. This study investigated the feasibility of applying PSB modified biochar to enhance immobilization of Pb2+. An alkaline biochar produced from rice husk (RB) and a slightly acidic biochar produced from sludge (SB) were selected. It showed that the biochars can effectively remove Pb2+ via adsorption, i.e., aqueous Pb concentrations after RB and SB addition were reduced by 18.61 and 53.89% respectively. The addition of PSB increased the Pb2+ removal for both biochars (to 24.11 and 60.85%, respectively). In particular, PSB significantly enhanced the formation of stable pyromorphite on surface of SB. This is due to that the evenly distributed PSB enhanced P release and regulated pH on the biochar surface. Moreover, small particles (<0.074 mm) showed their higher ability to induce the formation of pyromorphite, for both RB and SB. Nevertheless, SB demonstrated higher capability of sorption, together with its more abundant P content, which provided a more suitable platform to attract PSB to immobilize heavy metals. Therefore, the combination of biochar and PSB is a promising candidate material for heavy metal remediation. However, the types and particle size distribution of biochar should be addressed.

Qinghai-Tibetan Plateau is the most sensitive region to global warming on Earth. Qinghai Lake, the largest lake on the plateau, has experienced evident area variation during the past several decades. To quantify the area changes of Qinghai Lake, a satellite-based survey based on Landsat images from the 1980s to 2010s has been performed. In addition, meteorological data from all the seven available stations on Qinghai-Tibetan Plateau has been analyzed. Area of Qinghai Lake shrank ~2% during 1987–2005, and then increased ~3% from 2005–2016. Meanwhile, the average annual temperature increased 0.319 °C/10 y in the past 50 years, where the value is 0.415 °C/10 y from 2005–2016. The structural equation modeling (SEM) shows that precipitation is the primary factor influencing the area of Qinghai Lake. Moreover, temperature might be tightly correlated with precipitation, snow line, and evaporation, thereby indirectly causes alternations of the lake area. This study elucidated the significant area variation of water body on the Qinghai-Tibetan Plateau under global warming since 1980s.