沙漠微生物矿化覆膜及其稳定性的现场试验研究

Field experimental study on stability of bio-mineralization crust in the desert

将微生物诱导矿化技术应用于原位沙漠覆膜的形成,使得流动沙丘经结皮固定而成为半固定、固定沙丘,从根本上阻断沙尘暴的源头。在内蒙古乌兰布和沙漠腹地选择两个微生物矿化试验区域(TP1和TP3),分别用于两种不同矿化菌种诱导生成碳酸钙覆膜。研究沙漠微生物矿化覆膜的现场试验方法及工艺,对原位矿化覆膜的强度及其在沙漠环境中的长期稳定性进行跟踪检测。采用沙漠土中自行提取的葡萄球菌和传统的巴氏芽孢杆菌两种不同的微生物矿化菌种,通过现场贯入试验检测7、14、28、60、210 d后矿化覆膜沿深度发展的贯入阻力,并将覆膜厚度为2 cm处的平均贯入阻力换算成覆膜层强度,总结覆膜强度随时间的发展变化规律。现场观测结果显示,不同微生物菌种诱导生成的矿化覆膜均在试验的第4天开始形成,到第7天覆膜层具有稳定的强度和厚度,现场检测覆膜的平均厚度为2.0～2.5cm,经自源葡萄球菌诱导生成的矿化覆膜(TP1)的强度是巴氏芽孢杆菌诱导生成的矿化覆膜(TP3)强度的1.05倍。当经历冬春交替后覆膜层强度都有不同程度的降低,明显地TP3较TP1区域表面剥落更为严重,第210天检测TP3的平均厚度为0.7～1.0 cm,覆膜强度较第7天时降低19%,覆膜内碳酸钙含量较第7天检测时降低15%～30%。而TP1在第210天时的强度较第7天时强度降低仅2%。因此,微生物诱导矿化技术可以应用于沙漠原位覆膜的形成,且沙漠自源葡萄球菌经诱导生成的矿化覆膜层具有更好的强度表现和稳定性。

Microbial induced calcite precipitation(MICP)technology is applied to the formation of in-situ bio-mineralization crust on the surface of desert,which enables floating dune to be semi-fixed and fixed,hinders wind erosion,and fundamentally blocks the source of sandstorm.Two bio-mineralization test plots(TP1 and TP3)were built using two different microbial strains on the Aeolian sand surface in Ulan Buh desert,Inner Mongolia Autonomous Region of China.The field-scale experiment methods and processes were designed to evaluate and analyze the strength of bio-mineralization crust and its long-term stability in the desert environment.Staphylococcus,extracted from local Aeolian sand,and Sporoscarcina pasteurii,a traditional bio-mineralized bacterium,were used to induce the formation of calcium carbonate crystals.Through penetration tests in site,the penetration resistance developed along the depth of bio-mineralization crust was recorded on the 7th,14 th,28th,60th and 210 th day.The strength of bio-mineralization crust was converted according to the value of average penetration resistance at 2.0 cm of the crust.The variation of strength of bio-mineralization crust with mineralization time was summarized.From visual observation in site,the bio-mineralization crust began to form on the 4th day.The average thickness ranges from 2.0 cm to 2.5 cm on the 7th day,and the strength of bio-mineralization crust induced from Staphylococcus was 1.05 times than that of Sporoscarcina pasteurii.For the bio-mineralization crust TP3 induced from Sporoscarcina pasteurii after freeze-thaw cycles on the 210 th day,the average thickness decreased from 0.7 cm to 1.0 cm,the strength was reduced by 19%and the content of calcium carbonate was reduced by 15%-30%compared with that on the 7th day.However,the strength of bio-mineralization crust TP1 induced from Staphylococcus on the 210th day was reduced only by 2%,which is a little less than that on the 7th day.MICP technology can be applied to the formation of in situ bio-mineralization crust in desert.The bio-mineralization crust developed from Staphylococcus has better strength performance and long-term stability in desert environment than that from Sporoscarcina pasteurii.