主次波长新分光光度法测定天然水硝酸盐

在硫酸介质中,邻苯氨基苯甲酸与硝酸盐(NO_3~-)生成紫红色络合物.本文依据悬浮颗粒对光的吸收性质研究利用该灵敏反应测定 NO_3~—N 新光度法——(?)次双波长法,通过对样品分析,可提高分析灵敏度和精密度,回收良好,且操作简单快速,计算曲线稳定,适合于测定地下水,湖水等天然水体 NO_3~-—N.     

高灵敏度光度法测定地表水中硝酸盐和亚硝酸盐氮

本文详细研究了在硫酸介质中,邻苯氨基苯甲酸与NO_3~-和NO_2~-离子显色体系的光度性质与形成条件。结果表明,显色产物的最大吸收λ_(?)位于560—565nm。在此波长下,表观摩尔吸光系数分别为:ε′NO_3~-=1.07×10~5和ε′NO_2~-=1.77×10~5。符合Beer定律的浓度范围为:0.03—0.15 μg/ml(NO_2~--N)和0.05—0.20 μg/ml(NO_3~--N)。据此,拟定了分光光度联合训定NO_3~--N和NO_2~--N的新方法,应用于地表水的测定,得到了满意的结果。     

Seasonal variation of nitrate-N in surface and ground-waters of South Western Nigeria: a preliminary survey

Two surveys of nitrate-N concentrations in surface and ground water in Ogun and parts of Lagos and Oyo States of south-western Nigeria were undertaken between October 1997 and December 1998, and between July 2000 and May 2001 (covering both dry and rainy seasons). The study was conducted to ascertain the extent of nitrate-N pollution of the surface/ground water in some parts of the three states. Seventy-two water points (33 rivers/streams, 21 wells and 18 boreholes) were sampled three times during each of the two seasons. Nitrate-N was detected in all the river/stream samples analysed with concentrations ranging from 0.5 to 15.3 mg/l and 1.0 to 7.7 mg/l during the rainy and dry seasons, respectively (average value 2.7 and 2.4 mg/l for rainy and dry season, respectively). 98.5% of the rivers/streams sampling points contained nitrate-N in amounts equal to or less than 10 mg/l. 88.1% of wells and 97.2% of boreholes had a nitrate-N content less than 5 mg/l. Nitrate-N concentrations in the sampled wells ranged from 1.4 to 7.4 mg/l and 1.1 to 6.0 mg/l during the rainy and dry seasons, respectively (average value 2.6 and 2.2 mg/l, respectively). The sampled boreholes had a lower nitrate-N concentration ranging from 0.1 to 5.2 mg/l and from below the detection limit to 5.0 mg/l during the rainy and dry seasons, respectively (average value 1.8 and 1.6 mg/l, respectively). Nitrate-N concentrations in boreholes were below detection limit in 22% of the samples. Generally, for most of the sampling points, nitrate-N concentrations were slightly higher during the rainy season compared with the dry season. The present results indicated that nitrate-N concentrations in all the water points (except one) were below the World Health Organization (WHO) maximum acceptable limit in potable waters (10 mg/l). Therefore, contamination of the surface and ground water of the study area is not indicated. This study provides background data against which future changes in nitrate-N concentrations of surface and ground waters in the study area can be measured.     

Contamination potential of nitrogen compounds in the heterogeneous aquifers of the Choushui River alluvial fan, Taiwan

This study aimed to analyze the contamination potential associated with the reactive transport of nitrate-N and ammonium-N in the Choushui River alluvial fan, Taiwan and to evaluate a risk region in developing a groundwater protection policy in 2021. In this area, an aquifer redox sequence provided a good understanding of the spatial distributions of nitrate-N and ammonium-N and of aerobic and anaerobic environments. Equiprobable hydraulic conductivity (K) fields reproduced by geostatistical methods characterized the spatial uncertainty of contaminant transport in the heterogeneous aquifer. Nitrogen contamination potential fronts for high and low threshold concentrations based on a 95% risk probability were used to assess different levels of risk. The simulated result reveals that the spatial uncertainty of highly heterogeneous K fields governs the contamination potential assessment of the nitrogen compounds along the regional flow directions. The contamination potential of nitrate-N is more uncertain than that for ammonium-N. The high nitrate-N concentrations (> or =3 mg/L) are prevalent in the aerobic environment. The low concentration nitrate-N plumes (0.5-3 mg/L) gradually migrate to the mid-fan area and to a maximum distance of 15 km from the aerobic region. The nitrate-N plumes pose a potential human health risk in the aerobic and anaerobic environments. The ammonium-N plumes remain stably confined to the distal-fan and partial mid-fan areas.     

紫外光度法测定硝酸盐氮有关问题的探讨

试验了水样预处理过程中所加氢氧化铝悬浮液的数量,以加１ｍｌ,并作了以活性炭代替树酯的试验,结果表明对测定结果的精密度和准确度均无影响。简化了操作手续,节省了时间。