禹城市主要水体硝态氮监测及变化分析

地表水硝态氮(NO3--N)污染与人类健康以及水体生态环境密切相关。以潘庄灌区的禹城市主要水体为例,采集研究区内10个点进行长期监测,主要监测项目包括pH值及NO3--N等水质指标。结果表明,2004年-2009年,禹城市不同水体pH值变化在6.8～8.8之间,符合地下水环境质量标准(GB3838-2002)基本限值。地下水pH值有下降趋势。不同水体pH值最低值多在7月,高值多在10月或1月。2004年-2009年禹城市主要水体硝态氮变化总体呈逐年下降趋势,地下水中硝态氮各年份间变化不大。各采样点灌溉用地表水和地下水中硝态氮含量大多在7月及10月增高,主要原因是小麦或玉米播种前施基肥后随灌溉淋溶进入水体,而受降雨量的影响不大。本研究为该区域水质安全评价提供科学依据。     

Downward movement of nitrate and ammonium nitrogen in a flatland ultisol

Three field trials were conducted in the early and late rainy season on a Piarco Series soil (Aquoxic Tropudults) in Central Trinidad to monitor downward movement of NH ₄ ⁺ -N and NO ₃ ^- -N under flat-tilled and ridge-tilled conditions as affected by mulch application. The first experiment was carried out in the early rainy season under bare-fallowed conditions, while okra (Abelmoschus esculentus) was the test crop used in the two remaining trials, which were conducted during the early and late rainy season periods. The plots were fertilized with urea seven days after crop emergence and 14 days after land preparation for the cropped and bare-fallowed experiments respectively. Soil samples were collected weekly after fertilizer application and analyzed for NH ₄ ⁺ -N, NO ₃ ^- -N and soil water.Urea application increased NH ₄ ⁺ -N levels in the soil and NH ₄ ⁺ -N was the dominant inorganic N form observed for the first four weeks after fertilization. Mulch application decreased NH ₄ ⁺ -N and NO ₃ ^- -N soil levels. Ridging the soil increased downward movement of NH ₄ ⁺ -N and NO ₃ ^- -N. Under bare-fallowed conditions, downward movement of NH ₄ ⁺ -N was noted in the 30 to 45 cm soil layer at seven days after fertilization, while under cropped conditions its movement was restricted to the 15 to 30 cm layer within the same period. In bare-fallowed soil, increased NO ₃ ^- -N and its downward movement was noted after four weeks of fertilization. In the cropped soil, downward movement of NO ₃ ^- -N was observed one week after fertilization in the early rainy season and three weeks after fertilization in the late rainy season.     

亚热带农业小流域暴雨过程硝态氮迁移特征及水文示踪研究

为揭示亚热带丘陵区农业小流域暴雨过程中硝态氮迁移规律及其主要水文输送途径,本研究通过对紫色土丘陵区典型农业小流域典型暴雨过程跨尺度(从3~1 236 hm2)连续监测,分析径流硝态氮迁移动态特征及其尺度效应,并对比δ18O和硝态氮作为示踪剂的端元混合分析(EMMA)解析结果,探讨硝态氮作为暴雨过程水文示踪剂的可行性。结果表明:(1)两场暴雨事件中源头小流域苏荣小流域(含集镇污水)径流中硝态氮浓度最高,而到达梯级小流域出口处(万安小流域)硝态氮浓度最低,林地来水的贡献是较大尺度小流域径流硝态氮浓度降低的主要原因,坡耕地壤中流补给可能是径流消退过程中硝态氮出现浓度峰值的主要原因。(2)EMMA模型解析结果显示:δ18O与硝态氮均能示踪农业小流域径流消退期间壤中流补给过程;但硝态氮在受人居活动强烈影响子流域的示踪应用需谨慎。以农业为主的亚热带丘陵区小流域中,硝态氮具有同时作为环境效应指示剂和水文示踪剂的潜力,但其应用效果仍有待于进一步验证。     

溶解氧对电极生物膜反硝化性能的影响

为确定溶解氧对电极生物膜反硝化性能的影响,设计并运行了一套"电解-电极生物膜反应器"(ER&BER),研究电化学反应器(ER)的电解电流强度对电极生物膜反应器(BER)进水溶解氧(DO)质量浓度及反应器内DO质量浓度梯度的影响.结果表明,电化学反应和微生物的呼吸共同影响BER中DO的消耗.分别单独改变和连续改变ER系统...     

电极生物膜法反硝化工艺条件及过程

为获得具有良好反硝化性能的电极生物膜,以活性污泥为出发菌株,分别以连续和间歇培养方式在石墨电极上生长电极生物膜,研究碳氮比、电流强度、pH等工艺条件对电极生物膜反硝化过程的影响.结果表明:当碳氮比小于3.0时,体系的反硝化速率与碳氮比成正比;而在3.0以后,反硝化速率的增长开始趋于缓慢;电流强度为20mA时,硝酸盐去除效率达到最大值9.26mg/(L.h),继续加大电流,硝酸盐的去除率降低;当pH等于7时,硝酸盐氮的去除负荷最大,为7.89mg/(g.h),而pH小于或大于7时,生物膜的反硝化性能均有所降低.对单纯电极法、单纯生物膜法和电极生物膜法进行比较研究,证明电极生物膜法对硝酸盐的去除是电与生物膜共同作用的结果.     

降水产流非线性驱动下坡地硝态氮产污过程试验

为正确认识坡地氮素流失过程,同时为降水产流非线性驱动下流域污染负荷模型的构建提供理论依据,研发自动化程度高、接近天然降雨的人工模拟降雨产流产污试验装置,试验研究不同降雨强度和前期土壤含水率条件对产流及近地表土壤中硝态氮溶出过程的影响,利用演绎推理法探讨近地表土壤中硝态氮溶出系数与降雨产流及土壤含水率的关系。结果表明：降雨强度越大,前期土壤含水率越高,产流量、累积产流量越大;产流量以幂函数形式随时间不断增加趋于稳定,同时,降雨初期地表产流中硝态氮负荷及累计负荷量也越大;后期随着产流量的增加而呈幂函数形式衰减,最终又随着产流量的稳定而趋于稳定;近地表土壤中硝态氮的溶出系数受控于降雨产流,同时与土壤湿度存在指数函数关系。探讨的降雨产流-溶出系数-土壤含水率的数值关系对模拟高时间分辨率降雨产流非线性驱动下坡地硝态氮产污过程具有一定的参考价值。     

Soil nitrate-N levels required for high yield maize production in the North China Plain

High profile nitrate-nitrogen (N) accumulation has caused a series of problems, including low N use efficiency and environmental contamination in intensive agricultural systems. The key objective of this study was to evaluate summer maize (Zea mays L.) yield and N uptake response to soil nitrate-N accumulation, and determine soil nitrate-N levels to meet N demand of high yield maize production in the North China Plain (NCP). A total of 1,883 farmers’ fields were investigated and data from 458 no-N plots were analyzed in eight key maize production regions of the NCP from 2000 to 2005. High nitrate-N accumulation (≥172 kg N ha⁻¹) was observed in the top (0–90 cm) and deep (90–180 cm) soil layer with farmers’ N practice during maize growing season. Across all 458 no-N plots, maize grain yield and N uptake response to initial soil nitrate-N content could be simulated by a linear plus plateau model, and calculated minimal pre-planting soil nitrate-N content for maximum grain yield and N uptake was 180 and 186 kg N ha⁻¹, respectively, under no-N application conditions. Economically optimum N rate (EONR) decreased linearly with increasing pre-planting soil nitrate-N content (r ² = 0.894), and 1 kg soil nitrate-N ha⁻¹ was equivalent to 1.23 kg fertilizer-N ha⁻¹ for maize production. Residual soil nitrate-N content after maize harvest increased exponentially with increasing N fertilizer rate (P < 0.001), and average residual soil nitrate-N content at the EONR was 87 kg N ha⁻¹ with a range from 66 to 118 kg N ha⁻¹. We conclude that soil nitrate-N content in the top 90 cm of the soil profile should be maintained within the range of 87–180 kg N ha⁻¹ for high yield maize production. The upper limit of these levels would be reduce if N fertilizer was applied during maize growing season.     

The influence of rate and time of nitrate supply on nitrogen fixation and yield in pea (Pisum sativum L.)

The influence of nitrate N supply on dry matter production, N content and symbiotic nitrogen fixation in soil-grown pea (Pisum sativum L.) was studied in a pot experiment by means of¹⁵N fertilizer dilution. In pea receiving no fertilizer N symbiotic nitrogen fixation, soil and seed-borne N contributed with 82, 13 and 5% of total plant N, respectively. The supply of low rates of nitrate fertilizer at sowing (starter N) increased the vegetative dry matter production, but not the seed yield significantly. Nitrogen fixation was not significantly decreased by the lower rates of nitrate but higher rates supplied at sowing reduced the nitrogen fixation considerably. Applying nitrate N at the flat pod growth stage increased the yield of seed dry matter and N about 30% compared to pea receiving no nitrate fertilizer. Symbiotic nitrogen fixation was reduced only about 11%, compared with unfertilized pea, by the lowest rate of nitrate at this application time. The pea very efficiently took up and assimilated the nitrate N supplied. The average fertilizer N recovery was 82%. The later the N was supplied the more efficiently it was recovered. When nitrate was supplied at the flat pod growth stage 88% was recovered, and 90% of this N was located in the seeds.     

施氮方式对葡萄叶柄硝态氮含量及果实品质的影响

为了探讨氮肥不同施肥深度和距干距离对葡萄叶柄硝态氮含量及果实品质的影响,以嫁接在不同砧木1103P和SO4上的桑娇维赛(Vitis vinifera cv.Sangiovese)为试材,进行了试验。结果表明:叶柄硝态氮含量均以在砧木根主体分布区施肥含量的较高;1103P根系分布深而窄,叶柄硝态氮含量较高的施肥组合为深20～30cm,距干40～60cm;SO4根系分布浅而广,叶柄硝态氮含量较高的施肥组合为深10～20cm,距干40～80cm。表面撒施肥料损失大,肥效期短;行中间开沟施肥的效果最差。尿素适当深施可以提高果粒重和可溶性固形物含量,S/1103P在深20～30cm,距干40～60cm组合处,与叶柄硝态氮高峰相吻合;而S/SO4在深20cm,距干60cm处果粒重和可溶性固形物含量较高,与叶柄硝态氮高峰相比施肥深度增加。