碳酸氧镧改性生物炭材料的合成及对磷酸盐去除性能

为高效去除废水中过量的磷酸盐为目的,该研究将研究利用艾草生物质与镧溶液共生共热的方法制成具有大量纳米级碳酸氧镧突起的镧基复合生物炭材料,研究了材料投加量、初始磷酸盐浓度、吸附时间、初始溶液pH值和共存离子对其吸附磷酸盐性能的影响及饱和磷吸附镧基复合生物炭材料（La-CB2-P）对生菜种子发芽率的试验。试验结果表明：La-CB2最佳投加量为1 g/L,最佳吸附温度为25 ℃,对磷酸盐的吸附主要为多分子层吸附,Langmuir模型模拟最大吸附容量为126.82 mg/g,并在12h内达到吸附平衡,酸性至中性水环境中La-CB2吸附性能更优,并对碱性水环境的pH值具有缓冲作用,在pH值为3时La³⁺浸出率为7.66%,其他pH值条件下仅为0.029%左右,在磷吸附过程中La-CB2的DOC溶出量随着初始溶液pH值的升高呈先增后减的趋势,在多种共存阴离子中对磷酸盐具有很强的选择性吸附,水体中的腐殖酸会大幅度降低La-CB2对磷酸盐的吸附性能。饱和磷吸附镧基复合生物炭材料（La-CB2-P）能够作为磷缓释肥显著促进生菜发芽,对La-CB2在富营养水体的磷吸附及资源回收提供了大量的理论基础。

Synthesis and phosphate removal performance of La2O2CO3 modified biochar materials

Agricultural droughts have frequently occurred in the arid and semi-arid areas in China. Frequent drought and delayed sowing have also posed the a huge impact on the crop yield and economic losses in the tens of billions of every year. It There is a high demand to clarify the uneven annual distribution of precipitation. In this study, the translation in-variance method was used to improve the applicability of the soil moisture agriculture drought index (SMADI), in order to accurately monitor the occurrence of agricultural drought for the sustainable development of the social economy. Then, the drought grading criteria of the soil moisture agriculture drought index modified (SMADIM) was were modified by comprehensive analysis of the objective drought index. The reliability of SMADIM was finally verified from the regional, and temporal scales, as well as the timeliness of drought response. The results show that the SMADIM changed significantly the situation as the overestimation of drought in the low vegetation coverage areas, indicating the a wider scope than the SMADI. The correlation between SMADIM and soil moisture data of 0-10cm depth was 0.77 (P<0.01). The A better correlation of SMADIM was achieved with the damaged area, affected disaster and crop failure area. Specifically, the SMADIM correlation with the area of failed harvest was much better than SPEI (0.43) and VCI (0.07). Therefore, the SMADIM can be expected to accurately measure the major droughts in the typical regions. For instance, the severe and moderate drought were accounted for 26.58%, and 49.53%, respectively in Zhangye City in 2001. The drought and mild were accounted for 72.44%, and 26.46%, respectively, in Xilinguole League in 2018. Meanwhile, the seasonal drought was ranked in the descending order in the whole year: spring, autumn, winter and summer drought. The proportion of occurrence of no, mild, medium, severe and extreme drought in the arid and semi-arid regions during spring were 7.82%, 19.91%, 32.78, and 25.99%, respectively, while in summer were 20.69%, 26.73%, 20.78%, 18.84%, and 12.98%, respectively. Among them, the correlation coefficients between SMADIM and VCI that lagged by 0, 30 and 60 d in spring were 0.60, 0.69 and 0.70, respectively. Once the agricultural drought occurred occurs in spring, the SMADIM can be expected to capture the agricultural drought up to 30 d ahead of VCI. The relationship between VCI and SMADIM that lagged by 30 d was marginally significant in summer and winter. In autumn, the correlation coefficient between VCI and SMADIM with a lag of 60 d was significantly higher than that with a lag of 0 d and 30 d. It infers that the SMADIM captured the drought information up to 60 d earlier than VCI in the fall drought. In winter, the lagged 60 d correlation coefficient relationship between SMADIM and SPEI was 0.65, which was higher than that lagged 0 and 30 d, indicating the more sensitive SMADIM to agricultural droughts. Consequently, the SMADIM was more sensitive to the agricultural drought, where the response was 30-60 d earlier than that of VCI and SPEI. The finding can also provide the a new approach to accurately monitor the agriculture drought.