In situ radiometric mapping of soil erosion and field-moist bulk density on cultivated fields

Abstract. Recent developments in in situγ ray spectrometry offer a new approach to measuring the activity of radionuclides such as ¹³⁷Cs and ⁴⁰K in soils, and thus estimating erosion or deposition rates and field moist bulk density (ρ_m). Such estimates would be rapid and involve minimal site disturbance, especially important where archaeological remains are present. This paper presents the results of a pilot investigation of an eroded field in Scotland in which a portable hyper pure germanium (HPGe) detector was used to measure γ ray spectra in situ. The gamma (γ) photon flux observed at the soil surface is a function of the ¹³⁷Cs inventory, its depth distribution characteristics and ρ_m. A coefficient, Q_Cs, derived from the forward scattering of ¹³⁷Cs γ ray photons within the soil profile relative to the ¹³⁷Cs full energy peak (662 keV), was used to correct the in situ calibration for changes in the ¹³⁷Cs vertical distribution in the ploughed field, a function of tillage, soil accumulation and ρ_m. Based on only 8 measurements, the agreement between in situγ ray spectrometry and soil sample measurements of ¹³⁷Cs inventories improved from a non significant r²=0.05 to a significant r²=0.62 (P<0.05). Erosion and deposition rates calculated from the corrected in situ¹³⁷Cs measurements had a similarly good agreement with those calculated from soil cores. Mean soil bulk density was also calculated using a separate coefficient, Q_K, derived from the forward scattering γ photons from ⁴⁰K within the soil relative to the ⁴⁰K full energy peak (1460 keV). Again there was good agreement with soil core measurements (r²=0.64; P<0.05). The precision of the in situ¹³⁷Cs measurement was limited by the precision with which Q_Cs can be estimated, a function of the low ¹³⁷Cs deposition levels associated with the weapons testing fallout and relatively low detector efficiency (35%). In contrast, the precision of the in situ ρ_m determination was only limited by the spatial variability associated with soil sampling.     

可控止回阀水力特性的测试研究

本文运用水流相似原理，对可控止回阀的流阻系数曲线和动水力矩，进行了系统的水力模型试验研究，为该阀的节能效益和技术开发的可行性，提供了必要的科学依据，其流阻系数值为０．１９，优于液控蝶阀。     

灌水量对不同类型晚稻生育及产量影响的初步研究

采取盆栽遮雨人工定量灌水的方法,探讨了常规晚稻和杂交晚稻前后两大生育时期不同灌水量对生育和产量的影响.结果表明:两类型晚稻品种前后两个生育时期节水灌溉都能达到高产之目的,但不同类型和不同生育时期的最佳灌水量和节水效果不同.     

保定市工业废水农灌的研究

本文论述了保定市工业废水经农灌土地处理,对土壤、地下水和农作物品质的影响。结果表明:以造纸、食品、轻纺和化工为主的工业废水在重金属常年不超出农灌标准下,宜于在非盐化土壤灌溉;废水中硫化物超标,通过土壤生物区系,能降低毒性;废水中常规有机物,农灌后利大于害;只要在土壤容量允许内,可具有二级污水处理工艺不能完成的效果。     

植物活体水分探测仪的研制及测试初报

利用NIM插件探测器及金硅面垒探头组装了植物活体水分探测仪;筛选并分析了仪器的最佳工作条件;检测了春小麦、玉米、苜蓿、豌豆、红豆草叶片鲜重的变化。结果表明;叶片水分随时间损失大的,其抗旱性差。叶片保水的秩序为:红豆草、豌豆>苜蓿>春小麦>玉米。     

绵阳官司河流域水土流失综合报告

报告简述域地质地貌水文气象土壤，植被等地理因素的概况及其与土壤侵蚀的关系，指出本流域由于长防林的建立，发挥了保持水土作用，水土流失不严重，属轻度－中度侵蚀，最大侵蚀模数小于７４００［ｔ／（ｋｍ＾２．年］，全区平均侵蚀模数１７５４．４２［ｔ／ｋｍ＾２．年］；确定了水土流失类型，即片蚀，沟蚀，母质侵蚀三大类；分析了水土流失的原因：以泥岩和灰白砂岩，第四纪冰碛物堆积土侵蚀最高测定不同精植被类型的土壤质地     

甘肃省水资源时间序列模型及其变化规律研究

水文水资源序列是一个具有周期变化、随机变化和递增或递减趋势变化的复杂时间序列。作为一种近似,可以把水文序列{Qt}分为趋势序列{Nt}、周期序列{Pt}和随机性的平稳时间序列{St},即式:Qt=Nt+Pt+St。采用时间序列分析的方法,建立了甘肃省水资源的时间序列模型,分析了其变化规律,结果表明,甘肃省水资源呈明显下降趋势,并存在一定的周期变化规律。     

木捆排排型参数对其运行水阻力影响的试验研究

本文研究了木捆排在无限水域中的运行水阻力问题,提出了排型参数(L/B)和(B/T)对木捆排运行水阻影响程度的试验数据和图表,探讨了降低木捆排运行水阻力的途径及措施。