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首页> 外文期刊>Journal of the American Water Resources Association >NITROGEN AND PHOSPHORUS CONCENTRATIONS IN FOREST STREAMS OF THE UNITED STATES
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NITROGEN AND PHOSPHORUS CONCENTRATIONS IN FOREST STREAMS OF THE UNITED STATES

机译：美国森林流域的氮和磷浓度

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摘要

Seventy to eighty percent of the water flowing in rivers in the United States originates as precipitation in forests. This project developed a synoptic picture of the patterns in water chemistry for over 300 streams in small, forested watersheds across the United States. Nitrate (NN_3~-) concentrations averaged 0.31 mg N/L, with some streams averaging ten times this level. Nitrate concentrations tended to be higher in the northeastern United States in watersheds dominated by hardwood forests (especially hardwoods other than oaks) and in recently harvested watersheds. Concentrations of dissolved organic N (mean 0.32 mg N/L) were similar to those of NO_3~-, whereas ammonium (NH_4~+) concentrations were much lower (mean 0.05 mg N/L). Nitrate dominated the N loads of streams draining hardwood forests, whereas dissolved organic N dominated the streams in coniferous forests. Concentrations of inorganic phosphate were typically much lower (mean 12 mg P/L) than dissolved organic phosphate (mean 84 mg P/L). The frequencies of chemical concentrations in streams in small, forested watersheds showed more streams with higher NO_3~- concentrations than the streams used in national monitoring programs of larger, mostly forested watersheds. At a local scale, no trend in nitrate concentration with stream order or basin size was consistent across studies.
机译：美国河流中百分之七十至八十的水来自森林中的降水。该项目概述了全美国小型森林流域中300多个溪流的水化学模式。硝酸盐（NN_3〜-）浓度平均为0.31 mg N / L，有些物流的平均浓度是此水平的十倍。在美国东北部，以硬木森林（尤其是橡树以外的硬木）为主的流域和最近收获的流域中的硝酸盐浓度往往较高。溶解态有机氮的浓度（平均0.32 mg N / L）与NO_3〜-相似，而铵态氮（NH_4〜+）的浓度低得多（平均0.05 mg N / L）。硝酸盐在排泄硬木森林的氮流中占主导地位，而溶解的有机氮则在针叶林中占主导地位。无机磷酸盐的浓度（平均12 mg P / L）通常比溶解的有机磷酸盐（平均84 mg P / L）低得多。在较小的森林流域中，溪流中化学物浓度的频率显示，NO_3〜-浓度较高的溪流比用于较大的，主要是森林流域的国家监测计划中使用的溪流更多。在局部范围内，各研究中硝酸盐浓度与水流顺序或流域规模的趋势均不一致。

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