福州盆地不同土地利用方式下土壤磁化率特征

Characteristics of Soil Magnetic Susceptibility Under Different Patterns of Land Use in Fuzhou Basin

福州盆地不同土地利用方式下的土壤磁化率研究表明,福州城市土壤表层土的磁化率平均值为230×10-8m3/kg,频率磁化率均值仅为0.74%,表现出磁化率高,频率磁化率低的特征,表明土壤中有较多人类活动产生的粗粒磁性矿物颗粒物输入.工业区、商业区、生活文化区和城市风景区的磁化率平均含量分别为326×10-8,297×10-8,156×10-8,113×10-8m3/kg,表现出工业区>商业区≥生活文化区>城市风景区的特征,土壤磁化率影响因素呈现多元性特征.城郊农业用地的磁化率相对城市用地的磁化率低,表层土壤的平均值为106×10-8m3/kg,与20cm以下的磁背景值较为接近,并且随深度变化不大,表明农业用地化肥和农药的过量使用并不严重,重金属未在土壤中大量累积,不同用地类型的磁化率特征规律为果园土>林地土>菜园土>水稻土.

Study on magnetic susceptibility of soils under different land use types inFuzhou basin shows that the average magnetic susceptibility of urban topsoil in Fuzhou is230×10^-8 m^3/kg, and the mean frequency susceptibility is only 0.74%. The result uncovers the characteristic of high magnetic susceptibility and low frequency susceptibility, indicatingthat many coarse-grained magnetic particles produced by human activities enter into the soil. The average values of magnetic susceptibility in industrial zone, commercial zone, culturalzone and scenic zone are 326×10^-8, 297×10^-8, 156×10^-8, 113×10^-8 m^3/kg, respectively, indicating that the variation in different function zones presents industrial zone〉commercialzone≥cultural zone〉scenic zone. This reflects the diversity of influence factors to soil mag- netic susceptibility. The soil magnetic susceptibility of agricultural land in suburbs is gener-ally low and it changes little with the increasing of depth, which is close to the backgroundvalue below 20 cm. This indicates that the use of fertilizers and pesticides in the soil of agri- cultural land is not seriously superfluous. Thus, there is no abundant accumulation of heavy metal in soil. The values of magnetic susceptibility of different agricultural land uses from high to low are soil in orchard, woodland, kaleyard and paddy field.