Organic nitrogen in precipitation over Eastern North America
Organic nitrogen in precipitation over Eastern North America
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DOI：
10.1016/s1352-2310(02)00403-x
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发表时间：
2002-09
影响因子：
5
通讯作者：
W. Keene;J. Montag;J. Maben;M. Southwell;J. Leonard;T. Church;J. Moody;J. Galloway
中科院分区：
文献类型：
--
作者：
W. Keene;J. Montag;J. Maben;M. Southwell;J. Leonard;T. Church;J. Moody;J. Galloway
开发了一种测量技术来可靠地定量环境中仅潮湿的降水中的有机氮(ON)。样品在采集过程中被冻结，随后被分成两份等分。一组在−170°C下储存，通过高温燃烧转化为NO并用化学发光法检测总氮(TN)；另一组用CHCl3灭菌，冷藏，用自动比色法测定NH4+，用离子色谱法测定NO2−和NO2−。ON是由差异推断出来的。对在不同温度下储存30天和41天的成对未经处理的等分进行的分析表明，在室温下NH4+大量转化为ON，在冷藏样品中NH4+的显著损失(16%和23%)(可能是生长在瓶壁上的生物群)。冷冻和灭菌样品中的分析物是稳定的。在弗吉尼亚州夏洛茨维尔(VA)、特拉华州纽瓦克(DE)和新罕布夏州纽卡斯尔(NH3.1、4.2和0.6μM N)采集的降水的体积加权浓度以及对体积加权TN的相应贡献(分别为6.5%、7.8%和2.6%)处于北美东部和其他地区公布的数值的下限。方法上的差异是这些报告的样本统计数据之间存在明显差异的原因。按体积加权的浓度一般在春季最高，在夏季最低。由于保存不充分的样品中未测量的NH4+和NH4+的损失的综合影响，目前根据国家网络数据对大气N向北美东部的湿沉降的估计可能被低估了10-20%。
A measurement technique was developed to reliably quantify organic nitrogen (ON) in ambient, wet-only precipitation. Samples were frozen during collection and subsequently divided into two aliquots. One set was stored at −170°C and analyzed for total N (TN) via high-temperature combustion to NO and detection by chemiluminescence; the other set was sterilized with CHCl3, stored refrigerated, and analyzed for NH4+by automated colorimetry and for NO3−, and NO2−by ion chromatography. ON was inferred by difference. Analysis of paired, untreated aliquots stored for 30 and 41 days at different temperatures revealed substantial conversion of NH4+to ON at room temperature and significant losses (16% and 23%) of NH4+(presumably to biota growing on bottle walls) in refrigerated samples. Analytes in frozen and sterilized samples were stable. Volume-weighted ON concentrations for precipitation sampled at Charlottesville, Virginia (VA), Newark, Delaware (DE), and New Castle, New Hampshire (NH; 3.1, 4.2, and 0.6μM N, respectively) and corresponding contributions to volume-weighted TN (6.5%, 7.8%, and 2.6%, respectively) are at the lower limit of published values for eastern North America and elsewhere. Methodological differences contribute to the apparent variability among these reported sample statistics. Volume-weighted ON concentrations were generally highest during spring and were lowest during summer. Due to the combined influence of unmeasured ON and loss of NH4+from inadequately preserved samples, current estimates for the wet deposition of atmospheric N to eastern North America based on data from national networks may be underestimated by 10–20%.