Effects of Microbial Inoculums on Soil Enzyme Activity and Microbial Diversity in a Reclaimed Mining Area

Through a pot experiment, effects of various microbial inoculums on soil microbial diversity and enzyme activity in a typical reclaimed mining area in Shanxi Province were discussed based on quantitative analysis of PLFA, soil urease, phosphatase and sucrase activity. The results showed that the application of microbial inoculums increased microorganism quantity in rhizosphere of rape by 2.3% -66.4%, and quantities of bac- teria, gram-positive bacteria, gram-negative bacteria, fungi and actinomycetes in the treatments with microbial inoculums were significantly higher than the contrast （P 〈0.05）, while there was no obvious change in protist quantity. In comparison with the contrast, the application of various mi- crobial inoculums also improved soil urease, sucrase and phosphatase activity by 4.2% - 61.4%, 18.0% - 32.5% and 64.2% - 199.0% respec- tively. It indicated that the application of microbial inoculums can improve soil microbial diversity and enzyme activity, so it is an effective way to sl^eed UP ecoloQical restoration of soil.

Adsorption and desorption of Cd in reclaimed soil under the influence of humic acid:characteristics and mechanisms

Exogenous humus can change the content and migration activity of cadmium(Cd)in soil.Humic acid(HA)is an important soluble humus component in soil.In order to explore the relationship between cadmium pollution mechanism and ecological environment of humic acid in reclaimed soil,the characteristics of humic acid adsorbing cadmium in alkaline conditions were studied.This study employed reclaimed soil from the Huainan mining area,China.The adsorption and desorption characteristics as well as influence mechanisms on the heavy metal cadmium(Cd)were explored under the influence of HA.The results show that:(1)When Cd concentration was low(0.2–10 mg/L),HA had little effect on Cd adsorption and desorption in reclaimed soil.When the Cd concentration was high(15–80 mg/L),HA had a great influence on the adsorption and desorption of Cd in reclaimed soil.The addition of HA can inhibit the adsorption of Cd by reclaimed soil and effectively improve the desorption capacity of Cd by reclaimed soil.(2)The kinetic curves of Cd adsorption and desorption of reclaimed soil with added HA show that both processes(adsorption and desorption)include two stages:rapid reaction and slow reaction.The adsorption of Cd by reclaimed soil under the influence of HA was 18.18%lower than that of normal reclaimed soil,and the increase of Cd desorption was 50.29%.(3)The factors affecting the adsorption and desorption of Cd in the soil were analyzed with gray theory,and their importance can be ordered as follows:Cd concentration>HA concentration>pH>temperature.Considering the influence of HA,a multi-factor coupling function model of adsorption and desorption of Cd in soil is established.This model provides theoretical guidance for the scientific prediction and evaluation of Cd environmental pollution risks in soil and will be useful for developing a new solution for engineering remediation of high concentration Cd contaminated soil.

Performance evaluation and calibration of capacitance sensor for estimating the salinity of reclaimed land

Generally,soil moisture and salinity in reclaimed land are monitored using soil dielectric sensors such as time domain reflectometry,frequency domain reflectometry,and capacitance.The soil dielectric sensor measures apparent dielectric permittivity.However,apparent dielectric permittivity is affected by soil moisture,salinity,and texture.In this study,performance evaluation and calibration of a dielectric sensor(5TE;METER Group,Inc.,Pullman,WA,USA)for monitoring soil salinity were performed.Laboratory calibration tests were completed,incorporating various levels of dry density,water content,and salinity.The soil salinity was determined by the electrical conductivity(EC)1:5 method.The volumetric water content as measured by the sensor was affected by dry density and water content.Generally,it linearly increased as dry density and water content increased.However,when dry density or water content was high,the measured value of the sensor increased nonlinearly.The bulk EC measured by sensor had no specific correlation with EC 1:5.The EC 1:5 measurement had a linear relationship with the gradient ofθandθs.Therefore,it can be estimated with a simple linear equation usingθfrom the soil test andθs from the capacitance sensor.The R 2 value of the EC 1:5 estimation equation was 0.98.The proposed equation requiresθfrom the gravimetric sample andθs from the sensor.Therefore,in the case of monitoring salinity using a sensor,it is recommended to measure the water content with a tensiometer.