| 河南省部分市售农用化肥中溶解性离子浓度及同位素组成 |
| 摘要点击 2099 全文点击 854 投稿时间：2022-01-25 修订日期：2022-05-16 |
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| 中文关键词 农用化肥 硫酸盐 硫和氧同位素 氮同位素 水体污染 |
| 英文关键词 agricultural fertilizers sulfate sulfur and oxygen isotopes nitrogen isotope water contamination |
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| 中文摘要 |
| 农用化学肥料提供作物生长所需营养元素，不能被吸收的组分滞留在土壤中，对周围地表水和地下水水质构成潜在影响.农用化肥中元素含量以及稳定同位素组成常用来衡量和计算其对地表水和地下水硝酸盐和硫酸盐污染的贡献.但农用化肥种类繁多，其水溶性离子浓度及同位素组成尚不清楚.在收集河南省内部分市售农用化肥基础上，通过分析水溶态化肥（1 g农用化肥溶解于1 L纯水）离子浓度及溶解性硫酸盐（SO42-）硫和氧同位素（δ34 S和δ18 O）及固体化肥中总氮（TN）含量和氮同位素（δ15 N），说明农用化肥元素和同位素组成特征.结果表明，化肥溶液pH值范围3.6~10.2，均值为6.7±1.5（n=30，1σ），溶解态SO42-和硝酸盐（NO3-）浓度范围分别为4.38~827.29 mg ·L-1和1.34~208.90 mg ·L-1，ρ（SO42-）和ρ（NO3-）中位值分别为192.80 mg ·L-1和13.51 mg ·L-1，均值分别为（256.19±239.93） mg ·L-1（n=30）和（37.07±53.21） mg ·L-1（n=29），铵盐（NH4+）浓度范围为1.12~701.83 mg ·L-1，ρ（NH4+）中位值为277.05 mg ·L-1，均值为（282.55±226.44） mg ·L-1（n=30）；化肥溶解态SO42-的δ34 S和δ18 O值范围分别为-3.5‰~19.0‰和6.7‰~18.5‰，中位值分别为4.1‰和10.1‰，均值分别为（5.8±5.5）‰（n=22，1σ）和（10.7±2.7）‰（n=22，1σ）；化肥TN含量和δ15 N值范围分别为0.5%~38.9%和-2.7‰~3.4‰，中位值分别为13.3%和0.0‰，均值分别为（14.8±9.3）%（n=25）和（0.0±1.5）‰（n=24，1σ）；化肥中溶解态SO42-具有较低δ34 S均值和较高δ18 O均值，可能与化肥生产过程中使用硫酸作为原料有关，造成化肥溶液pH与溶解态SO42-浓度呈负相关关系（P<0.05）；化肥TN的δ15 N值靠近大气N2的δ15 N组成，显示化肥原料中NO3-/NH4+多由N2合成的特征.结果指出河南省境内施用的农用化肥中溶解态SO42-、NO3-和NH4+的浓度范围及其溶解态硫酸盐的δ34 S和δ18 O及总氮的δ15 N组成特征，为研究农用化肥对区内地表水和地下水中SO42-和NO3-污染的贡献提供科学依据. |
| 英文摘要 |
| Agricultural fertilizers (AFs) have provided vegetation with necessary nutrients, but unabsorbed constituents have been retarded in soil, potentially affecting the quality of adjacent surface water and groundwater. AFs element contents and stable isotope compositions have often been utilized to assess and calculate AFs pollution to nitrate and sulfate in surface water and groundwater; however, due to various AFs applied, the dissolved ion concentrations and isotope ratios are still unknown. This study collected commercial AF widely utilized in Henan province, China, to constrain their ion concentrations and isotope values. The dissolved ions (1 g AFs dissolved in 1 L ultrapure water), sulfate sulfur, and oxygen isotope values(δ34S and δ18O) were analyzed, and total nitrogen (TN) contents coupled with nitrogen isotope values(δ15N) in solid AFs were determined to elucidate their elemental and isotopic compositions. These characteristics provided a scientific basis for further assessing their contributions to surface water and groundwater contaminations. The results indicated that pH values in the AFs solutions varied from 3.6 to 10.2, with a mean value of 6.7±1.5 (n=30, 1σ). Sulfate (SO42-) and nitrate (NO3-) concentrations ranged from 4.38 mg·L-1 to 827.29 mg·L-1 and from 1.34 mg·L-1 to 208.90 mg·L-1, with median values of 192.80 mg·L-1 and 13.51 mg·L-1 and average values of (256.19±239.83) mg·L-1 (n=30) and (37.07±53.21) mg·L-1 (n=29), respectively. Dissolved sulfate δ34S and δ18O values in AFs varied from -3.5‰ to 19.0‰ and from 6.7‰ to 18.5‰, with median values of 4.1‰ and 10.1‰ and mean values of (5.8±5.5)‰ (n=22, 1σ) and (10.7±2.7)‰ (n=22, 1σ), respectively. TN and δ15N values in AFs ranged from 0.5% to 38.9% and from -2.7‰ to 3.4‰, with median values of 13.3% and 0.0‰ and average values of (14.8±9.3)% (n=25) and 0.0±1.5‰ (n=24, 1σ), respectively. The lower averaged δ34S values and positive averaged δ18O values potentially resulted from sulfuric acids added as raw materials, giving rise to a negative relationship between pH values and SO42- concentrations (P<0.05). The δ15N values of AFs were close to that of air N2, corresponding to the fact that NO3--N and NH4+-N were synthesized via air N2. Our results revealed the dissolved ion concentrations of SO42-, NO3-, and NH4+ and their δ34S, δ18O, and δ15N values of typically applied AFs in Henan province, which provided the scientific basis for studying the AFs contributions to SO42- and NO3- pollutions in surface water and groundwater surroundings. |
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