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运用137Cs和210Pbex联合示踪技术,考察深圳特区内外典型区域137Cs和210Pbex面积活度的背景值与变化特征,以及典型区农用土壤侵蚀速率、分布特征和主要影响因素.结果表明:①在城市化剧烈的人为扰动作用下,深圳市的地表土壤环境已经大部分不具备自然土壤的基本属性.深圳市137Cs面积活度背景值介于99～653 Bqm2之间,仙湖植物园的137Cs实测面积活度背景值最大〔为(653±81)Bqm2〕,南澳新大村的137Cs实测面积活度背景值最小〔为(99±47)Bqm2〕.②随着海拔升高,210Pbex的实测面积活度背景值呈增加趋势,这和低纬度地区亚热带海洋性季风气候的水汽运动有关.③深圳市南澳新大村和公明水库陡坡农用地种果造成的土壤侵蚀已达到了极剧烈的程度,土壤平均侵蚀速率分别高达6 150和40 530 t(km2.a).深圳市农用土壤侵蚀具有分布面积广、人为扰动较剧烈、产流产沙集中、侵蚀强度较大等特征.人为扰动主导的土地开发与陡坡种果是造成城市水土流失的主要影响因素.④深圳市近30年来快速城市化活动加速了城市土壤侵蚀的发生和发展,亟待加强开发建设项目水土保持、陡坡还林还草等生态治理工作.
137Cs and 210Pbex combined tracing techniques were used to investigate the background value and variation characteristics of 137Cs and 210Pbex area activities in typical areas both inside and outside of Shenzhen Special Economic Zone and the agricultural soil erosion rate, distribution characteristics and main influencing factors in typical areas.The results showed: Due to the violent anthropogenic disturbances, the surface soil environment in Shenzhen has largely failed to possess the basic properties of natural soils.The background activity of 137Cs in Shenzhen ranged from 99-653 Bqm2, and the measured area of 137Cs in Xianhu Botanical Garden (653 ± 81) Bqm2〕, the minimum background activity of 137Cs measured in Xin’amu Village of Nan’ao was 〔〔〔〕 (99 ± 47) Bqm2〕 .②With the elevation of 210Pbex The background value of measured area activity showed an increasing trend, which was related to the water vapor movement in the subtropical maritime monsoon climate at low latitudes.③The soil erosion caused by the species of farmland in steep slopes of Xin’nan Village and Gongming Reservoir in Shenzhen City reached a very severe degree, The average soil erosion rates were as high as 6 150 and 40 530 t (km2.a), respectively.Agricultural erosion in Shenzhen had a wide distribution area with more severe human disturbance, concentrated runoff and sediment yield, Etc .. The rapid development of urban soil erosion in Shenzhen in recent 30 years has accelerated the occurrence and development of urban soil erosion and the urgent need to strengthen the development Soil and water conservation projects, steep slopes also grassland and other ecological management work.