Sea spray induced air-sea heat and salt fluxes based on the wavesteepnessdependent sea spray model

Sea spray,which comprises amounts of small ocean droplets,plays a significant role in the air-sea coupling,atmospheric and oceanic dynamics,and climate.However,it remains arduous to arrive at estimates for the efficiency and accuracy of the sea spray induced air-sea heat and salt fluxes.This is because the microphysical process of sea spray evolution in the air is of extreme complexity.In this study,we iteratively calculated the sea spray induced air-sea heat and salt fluxes at various weather condition.To do so,we implemented one novel wave-steepness-dependent sea spray model into a bulk air-sea fluxes algorithm and utilized other sea spray models as comparisons.Based on the improved wave-dependent bulk turbulent algorithm,we observed that despite the negative contribution of sea spray to the sensible heat fluxes,the sea spray positively contributes to the air-sea latent heat fluxes,leading to an overall increase in the total air-sea heat fluxes.The additional heat fluxes caused by sea spray may be the missing critical process that can clarify the discrepancies observed between measured and modelled Tropical Cyclone’s development and intensification.In addition to heat fluxes,we observed that sea spray has significant impacts on the air-sea salt fluxes.As the sea salt particles are one of the main sources of the atmosphere aerosol,our results imply that sea spray could impact global and regional climate.Thus,given the significance of sea spray on the air-sea boundary layer,sea spray effects need to be considered in studies of air-sea interaction,dynamics of atmosphere and ocean.

Variability in salt flux and water circulation in Ota River Estuary, Japan

In this study the sub-tidal and intra-tidal variations of salt fluxes in the upstream section of a shallow estuary （with a water depth of less than 3 m） were investigated. The salt fluxes were estimated based on the cross-sectional average salinity and velocity measured by the fluvial acoustic tomography system （FATS）. The results indicate that the magnitude of seaward fluxes is approximately two times greater than that of landward fluxes under normal conditions. The results of short-term observation in the study area indicate that there is a phase lag of the bottom and surface salinities between the regions with the largest and smallest depths. The vertical shear flux with a peak value of-0.7 m2/s during the ebb tide indicated an important contribution to the total salt flux compared with the advective flux. A phase lag occurred between the vertical shear terms in the regions with the largest and smallest depths, which resulted from the correlation between the vertical variations of the salinity and velocity and the existence of transversal velocity circulations.

Interannual variations in salt flux at 80°E section of the equatorial Indian Ocean

The interannual variations in salt flux on the 80°E section in the equatorial Indian Ocean were explored based on the ORAS5 data,which was quite consistent with the observational data among the four available reanalysis datasets.The results indicated that the area with significant interannual variations in salt flux coincided with that of significant climatological mean salt flux in general and was mainly located in the upper 150 m layer.Specifically,three important areas were identified in the north-south direction,i.e.,(1)the Equatorial Indian Ocean Area(EIOA,3°S–3°N),where the mean salt flux was eastward with the largest value on the section and associated with the most significant interannual variations mainly modulated by the Wyrtki Jets and the Equatorial Undercurrent;(2)the South Equatorial Indian Ocean Area(SEIOA,3°S–6°S),where the mean salt flux changed in the vertical direction from strong eastward flux in the upper layer to weak westward flux in the subsurface layer and associated with significant interannual variations in the upper 100 m layer,which was affected by the South Equatorial Countercurrent;and(3)the North Equatorial Indian Ocean Area(NEIOA,3°N–6°N),where the mean salt flux changed in the north-south direction from strong westward flux to the north of 5°N to weak eastward flux in the south and associated with relatively significant interannual variations,which was mainly influenced by the South Sri Lanka Coastal Current.Two leading interannual variation modes were revealed by the empirical orthogonal function decomposition.The first mode accounted for 39%of the total variance and had four significant spatial antinodes;two of those in-phase antinodes were located at SEIOA and upper 75 m of EIOA,and the other two opposite in-phase antinodes were located at NEIOA and below 75 m of EIOA.The second mode accounted for 17%of the total variance having four antinodes with two dominant out-of-phase antinodes located at the subsurface of EIOA and SEIOA.The temporal components of the two leading modes showed a 1–4 year variation with a main period of 2 years,in which the first mode showed a greater correlation with the Indian Ocean Dipole,while the second mode showed a weak correlation with the Indian Ocean Dipole and the El Niño-Southern Oscillation.Variance analysis showed that the interannual variations in salt flux were mainly determined by the variations in the current,and the spatial distribution was modulated by temporal mean salinity.Composite strong interannual events showed interannual variations in current,and so the salt flux was driven by the interannual anomaly of the wind field and sea surface temperature associated with the Indian Ocean Dipole.

Three-Dimensional Climatological Structures of the Arabian Sea Eddies and Eddy-Induced Flux

This study explores the spatial structure and transport characteristics of eddies in the Arabian Sea(AS)using Argo profiles and satellite measurements.The majority of eddies occur in the northern AS,especially along its northeastern boundary.In contrast,the western AS had a relatively higher eddy kinetic energy compared to the eastern part.Particularly,the strongest energetic eddies were present in the Somali Current system.The composite results revealed the evident thermohaline anomalies caused by cyclonic eddies(CEs)and anticyclonic eddies(AEs)in the upper 300m layers.The anomalous temperature structure within CEs and AEs showed a dominant dipole structure in the near-surface layer and a monopole structure below,with maximum temperature anomalies of approximately−0.8℃and+1.0℃located at depths of 100–150m,respectively.The composited salinity structures for CEs and AEs exhibited monopole vertical structures and sandwich-like patterns.For AEs,large positive salinity anomalies occurred at subsurface layers of 60–180 m with a peak value of about 0.07,and weak negative values were observed above 60m and below 180 m.A similar vertical structure but with an opposite sign operates for CEs.The composited CE and AE caused an equatorward salt flux with values of−8.1×10^(4)and−2.2×10^(4)kg s^(−1),respectively.CEs caused an equatorward heat flux of−7.7×10^(11)W,and AEs induced a poleward flux of 1.5×1011 W.

Double-diffusive Fluxes of Salt and Heat in the Upper Layer of North Pacific Intermediate Water

Almost half of the oceanic water columns exhibit double-diffusion. The importance of double-diffusion in global oceans’ salt and heat fluxes, water-mass formation and mixing, and circulation is increasingly recognized. However, such an important physical process in the ocean has not been well studied. One of the reasons is the difficulty of parameterizing and quantifying the processes. The paper presented here attempts to quantify the double-diffusive fluxes of salt and heat in the ocean. Previous qualitative analysis by applying the water-mass Turner angle, mTu, to the North Pacific Intermediate Water (NPIW) layer showed a favorable condition for salt-fingering in the upper NPIW due to the overlying warm/salty water above the cold/fresh NPIW core, and a doubly-stable condition in the lower NPIW where potential temperature decreases with depth while salinity increases, inducing double stratification with respect to both potential temperature and salinity. The present study gives a quantitative estimate of double-diffusive fluxes of salt and heat contributed by salt-fingering in the upper NPIW layer.

Cross-shore suspended sediment flux in the salt marsh pioneer zone of Chongming eastern beach in the Chang- jiang Estuary in China

Between April 2002 and April 2003,in situ measurements of water depth,current velocity and suspended sediment content were carried out in edge region of East Chongming salt marsh and neighboring bald flat in the Changjiang （Yangtze） Estuary under different weather conditions.Cross-shore suspended sediment flux was calculated and analyzed.The results show that under calm weather conditions,the current velocity process in bald field and salt marsh area varied differently during semidiurnal tidal cycles.Owing to current velocity asymmetry,mean SSC during flood tide phase was 1.8 times higher than that of ebb tide phase.As a result,net onshore sediment flux controlled cross-shore suspended sediment transport process and salt marsh pioneer zone was generally accreting.There was significant positive correlation between total sediment flux and quartic power of maximum water depth.It indicates that tidal ranges dominate suspended sediment transport and sedimentation process in the salt marsh pioneer zone under the calm weather condition.The sedimentation rate on the adjacent mudflat was higher than the salt marsh,which induced stable accreting of salt marsh towards the sea.The wind events enhanced SSC and current velocity during the semidiurnal tides.And the remarkable onshore net sediment flux could occur on the high marsh and mudflat close to the marsh fringe during the short period under the rough weather condition.

Real-time wide-range neutron flux monitor for thorium-based molten salt reactor

A novel full-digital real-time neutron flux monitor(NFM) has been developed for thorium-based molten salt reactor(TMSR).The system is based on the highspeed,parallel,and pipeline processing of the field programmable gate array as well as the high-stability controller area network platform.A measurement range of 10~8 counts per second is achieved with a single fission chamber by utilizing the normalization of the count and Campbell algorithms.With the advantages of using the measurement range,system integrity,and real-time performance,digital NFM has been tested in the Xi'an pulsed reactor fission experiments and was found to exhibit superior experimental performance.

2004-2010年上海崇明东滩湿地生态系统CO_(2)通量数据集

作为微气象学的经典方法之一,涡度相关技术已成为观测陆地生态系统与大气间CO_(2)、水热通量交换的主要手段。本数据集为上海长江河口湿地生态系统国家野外科学观测研究站在上海崇明东滩湿地于2004年9月至2010年12月期间观测累积的通量数据,时间分辨率为半小时,数据项包括气温(T_air)、相对湿度(RH)、土温(T_soil)、光合有效辐射(PAR)、总辐射(Solar)、净辐射(Rn)、降雨量(Precip)、感热通量(Hs)、潜热通量(LE)和二氧化碳净交换量(NEECO_(2))等。本研究观测的生态系统为典型亚热带滨海盐沼类型,优势植物为芦苇和互花米草。本数据集的观测系统架设、设备维护和数据质量控制及处理等均按照FLUXNET规范,数据可靠性高,可为中国滨海盐沼的碳收支、蓝碳估算及生物入侵影响评估等相关研究提供扎实的数据支持。

流体黏性对盐指型双扩散对流扩散通量影响的试验研究

为研究盐指型双扩散对流过程中流体黏性对通量的影响,使用中间有移动挡板的试验水箱形成初始为静止状态的糖-盐双层系统,并通过调整糖、盐组分质量分数设计了一系列密度稳定比相同而流体黏性不同的试验工况,进行了双扩散对流扩散通量变化规律的试验研究。试验结果表明:流体黏性对盐指型双扩散对流扩散通量的影响不可忽略,在双扩散对流强度相同的条件下,试验流体黏性越大,盐指型双扩散对流扩散通量越小;当试验流体的运动黏滞系数均小于1.15 mm2/s时,糖和盐这两种组分跨界面的双扩散对流扩散通量随流体黏性增大而减小的趋势相近,当两种组分的质量分数持续增大时,盐溶液的黏性仍缓慢增大,而糖溶液的黏性迅速变大,此时糖组分的跨界面双扩散对流扩散通量仍会随糖溶液黏性的增大而减小,但盐组分的跨界面双扩散对流扩散通量不再变化;Stern数与流体黏性呈负相关关系。

INTERACTION OF OXIDE FILM WITH MOLTEN FLUX DURING ALUMINUM BRAZING

The interaction of oxide film with molten flux during aluminum brazing has been studied by means of X-ray powder diffraction. The following conclusions have been deduced: The swell- ing of aluminum oxide film is caused by Li^+ inserting into the vacancies of octahedral or tetrahedral structure of 0 atom skeleton in у-Al_2O_3 . The strength of oxide film decreases as the crytallinity increases by the treating of flux containing LiF.

Observations of turbulent mixing and vertical diff usive salt fl ux in the Changjiang Diluted Water

Based on microstructure measurements from a repeated sampling station southwest of the Jeju Island during summer,we studied the hydrography,pycnocline turbulence,and vertical salt fl ux in the Changjiang Diluted Water(CDW).The water column was well stratifi ed with the CDW occupied the surface~20 m.Most of the large turbulent kinetic energy dissipation rate(ε)were found in the bottom boundary layer.Interestingly,intermittent strong turbulence(ε>10^(-6) W/kg)occurred in the pycnocline,which may induce strong mixing events and increase the vertical diff usive salt fl ux at the base of CDW by one order of magnitude.The daily-mean vertical diff usive salt fl ux could reach 4.3(2.1,8.9)×10^(-6) m/s.Both moored velocity measurements and associated wavelet analysis showed the presence of velocity fl uctuations when there was strong pycnocline turbulence.The moderate resolution imaging spectroradiometer(MODIS)satellite images further suggest that the velocity fl uctuations are induced by the prevailing internal solitary waves(ISWs)which are mainly generated at the shelf break of the East China Sea or the topographic features surrounding Jeju Island.The calculated gradient Richardson number denote the occurrence of shear instability in the pycnocline when strong turbulence presents.The presented results have strong implications for the importance of ISWs in infl uencing the vertical diff usion of CDW and changes in other properties.

磨刀门咸潮上溯对河口拦门沙地形变化的响应研究

采用磨刀门河口拦门沙地形变化前后的2005年和2020年实测地形资料,基于FVCOM三维数值模型,对比分析了咸潮上溯对河口拦门沙地形变化的响应,并探讨了拦门沙萎缩对盐分输运的影响机制。结果表明:拦门沙萎缩导致磨刀门水道各取水口表、底层盐度差增大,水体层化程度增强,下游至上游层化增强程度逐渐减小,广昌泵站势能异常最大值增大25.2 J/m^(3),马角水闸、平岗泵站、竹洲头泵站分别增大8.3、2.9、0.2 J/m^(3);拦门沙萎缩后未改变磨刀门水道咸潮上溯规律,半月潮周期盐度峰值依然出现在小潮后的中潮期;拦门沙对咸潮上溯有较大阻碍作用,底层15 psu等盐度线最大上溯距离向陆推进5.1 km,对于取水更为重要的表层0.5 psu等盐度线最大上溯距离向陆推进2.9 km;稳定剪切盐通量显著增大是拦门沙萎缩后咸潮上溯加剧的主要原因,并叠加潮汐震荡盐通量增大的影响。

酚酞基聚醚醚酮/聚乙烯亚胺复合超滤膜的制备与性能研究

目的 制备纯水通量较高的复合超滤膜,实现染料废水的高效快速分离。方法 采用相分离转化法,以丙酮为非溶剂,酚酞基聚醚醚酮和聚乙烯亚胺为研究对象,在室温条件下,开发出一种性能较好的酚酞基聚醚醚酮/聚乙烯亚胺复合超滤膜;分析酚酞基聚醚醚酮(PEEK-WC)质量分数、聚乙烯亚胺(PEI)添加量、改性反应时间等工艺因素对复合超滤膜性能的影响。结果 随着反应沉积时间的增加,复合超滤膜的水通量呈上升趋势;随着聚乙烯亚胺质量分数增加,复合超滤膜的水通量不断增加;复合超滤膜的最优制备条件为PEI与PEEK-WC的质量比为20%,PEEK-WC与NMP的质量比为15%,反应时间为12 h。结论 酚酞基聚醚醚酮/聚乙烯亚胺复合超滤膜具有良好的截留效果和抗细菌污染性。

PTFE中空纤维膜蒸馏高盐废水浓缩实验研究

文章选择工业生产中常见的含氯化钠(NaCl)高盐废水,以疏水性PTFE中空纤维膜组件为载体,采用真空膜蒸馏的方式进行浓缩处理实验研究,研究各操作条件对膜通量和截盐率的影响,并验证实验可行性。实验结果表明,膜下游侧压力增加,膜通量会逐渐降低;废水料液流量和料液温度的增加均有助于提高膜通量;废水料液浓度的增加,会抑制传质过程,降低膜通量。各操作条件对膜截盐率的影响很小,膜截盐率一直保持在99.8%以上,说明PTFE中空纤维膜蒸馏用于高盐废水浓缩具备可行性。

Impact of Wind on Tide-Induced Advective Salt Transport in A Well- Mixed Estuary

The tide-induced net advective salt flux in well-mixed estuaries consists of five terms according to the method from Kjerfve.The term resulted from the vertical variation in salinity can be negligible in well-mixed estuaries with four tide-induced salt flux terms,known as F1−F4.To explore the effects of wind on these salt fluxes,the current-salinity analytical model combined with the perturbation analysis is extended by including wind.Analytical expressions for the four salt fluxes are derived separately in the present model.Under the assumption that only the M_(2) tidal component is accounted for and the salt flux generated by diffusion is not studied,the tide-induced net advective salt flux Q_(sx) is in the seaward direction without the wind effect.By applying the Western Scheldt estuary case,the wind influence on the tidal advection salt flux(TASF)distribution in the F4 term was investigated.The phase difference between zero-order velocity and first-order salinity(Δφ)at the surface layer of the estuary is larger than 90°and smaller than 90°at the bottom layer,which leads to landward TASF in the surface layer and seaward TASF in the bottom layer.The distribution ofΔφis not uniform in the horizontal direction with wind included,which differs from the result without wind.In the case of seaward wind with the speed of 18 m/s,the decrease in the zeroth-order velocity phase(φu)at the surface layer is larger than that of the first-order salinity phase(φs)downstream,which leads to an abnormal seaward TASF in this region.Owing to the surface stress caused by wind,the Stokes compensation flow in the middle and lower reaches increases/decreases with the increase of the landward/seaward wind,while the upstream situation is opposite.Thus,the first-order velocity in the middle and lower reaches increases/decreases with the increase of the landward/seaward wind,while the upstream situation is also opposite.The first-order salinity also increases/decreases with the increase of landward/seaward wind,while the upstream salinity tends to zero.Therefore,the tide-induced net advective salt flux Q_(sx) increases/decreases with the increase of the landward/seaward wind,which is contrary to the usual recognition.

基于传热传质理论的路面除冰盐融冰过程及影响因素分析

为了解决不同环境下路面除冰盐的科学有效使用问题,降低由于除冰盐的滥用导致路面病害与环境污染,从路面除冰盐融冰传热传质机理出发,建立道路除冰盐融冰过程中的物质平衡方程与热通量平衡方程。采用COMSOL有限元软件建立了路面除冰盐融冰温度场模型,考虑多种因素如相变过程、风速、初始温度和太阳辐射的影响,分析融冰过程中温度场的变化规律。研究结果表明:在融冰过程中,盐溶液温度呈现先快速下降后缓慢回升的规律,在固态除冰盐完全溶解的时间段内(Ⅰ阶段),盐溶液温度迅速下降;除冰盐完全溶解后(Ⅱ阶段),盐溶液温度缓慢回升。外界环境温度的上升使得单位质量除冰盐的融冰体积增加,且外界环境温度相比风速和除冰盐用量对盐溶液最终温度的影响更大。风速越高,固体盐溶解溶解所需时间越短,Ⅰ阶段结束后盐溶液体系的温度也更低,盐溶液温度随之下降得更快。由于风速增大将加快盐溶液层与外部环境的换热,除冰盐融冰Ⅱ阶段升温明显,溶解后盐溶液的平均温度更高。另外,较高的除冰盐初始温度可以促进固态盐的溶解,且温度越高,这种促进作用更加明显。同时,随着反应初始温度的增加,融冰反应的终止温度也随之升高。除此之外,研究发现,太阳辐射对于除冰盐融冰过程的影响在Ⅰ阶段不显著,在Ⅱ阶段具有显著影响。研究结论可为道路冬季路面除冰盐的科学有效使用提供技术支撑与理论参考。

A Case Study of Ocean-Atmosphere Interactions during the Passage of an Extra-Tropical Cyclone in the Vicinity of Cape Hatteras, North Carolina

The authors document the interaction of the atmosphere and ocean during the formation and passage of an Extra-Tropical Cyclone, which is a Nor-Easter, winter storm that formed in the southern apex of the Middle Atlantic Bight near Cape Hatteras North Carolina, between February 15 and 18, 1996. While Nor-Easters per se, which have formed along the Atlantic Eastern Seaboard of the United States have been studied for decades, the actual atmospheric-oceanic mechanics and thermodynamics in the formation of a Nor-Easter has never been documented. We report on having done so with in-situ observations and data-based calculations and a numerical model. The in-situ observations were made via a Control Volume consisting of an array of Eulerian Oceanic-Atmospheric Moorings with current meters, temperature and salinity sensors and meteorological towers. We find that Gulf Stream waters were located surrounding the mooring array, and that with the invasion of cold dry atmospheric air, there was a rapid loss of heat from the ocean to the atmosphere via latent and sensible surface heat flux during the cyclogenesis onset of the storm. A unique feature of this storm was that neither satellite nor buoy data showed significant sea surface cooling in the control volume. The findings indicate that storm winds drove warm saline waters from the Gulf Stream across the continental shelf into the control volume, accounting for a 51 cm rise in water level along the coast. This lateral heat advection provided heat to the control volume of 3.4e+18 Joules. On average, the heat loss at the surface of the control volume, via sensible and latent heat fluxes and radiation, was 0.7e+18 Joules, corresponding to a surface heat flux of -600 Watts per Meter2 (W/m2). However, the heat lost by the control volume as latent and sensible heat fluxes was less than the heat it received via lateral heat advection, resulting in the lack of an often-observed sea surface cooling during other winter storms. The serendipitous and detailed observations and calculations reveal a climatological flywheel in this region, documenting the role of ETCs in the global heat balance.

基于SWAP模型的河套灌区向日葵农田土壤水盐通量模拟

为了探究河套灌区节水实施现状条件下农田土壤水盐动态变化规律,利用向日葵田间试验观测资料,对SWAP模型进行参数率定和验证,并利用该模型模拟向日葵生长条件下0~100 cm土层土壤水盐通量及水盐平衡状况。研究结果表明:在灌溉阶段,向日葵根系层土壤水分主要向下渗漏,水分通量和盐分通量为负,土壤盐分被淋洗;在非灌溉阶段,地下水向上补给向日葵根系层土壤,水分通量和盐分通量为正,根系层土壤积盐。2019、2020年模拟期间水分通量累计量分别为52.5、60.6 mm,盐分通量累计量分别为-4.5、-4.9 mg/cm^(2),0~100 cm土层土壤盐分通量分别增加了7.5、7.1 mg/cm^(2)。向日葵现状灌溉条件下0~100 cm土层土壤积盐,可能产生土壤次生盐碱化的风险,向日葵生育期结束后需要进行秋浇淋洗盐分来保证下一年度向日葵的正常生长。

持续强北风天气下长江口盐水入侵对径流量的响应

2014年2月持续强北风下长江口发生了极端严重的盐水入侵事件,影响水源地取水安全.流域上游水库增加径流量是遏制严重盐水入侵的一种方法,本文应用UnFECOM(unstructured quadrilateral grid,finite-differencing,estuarine and coastal three-dimensional ocean numerical model)模式模拟和分析该次盐水入侵对增加不同径流量的响应.考虑实际径流量和风况,模式再现了该次极端严重盐水入侵事件.数值试验结果表明,随着径流量的增加,在2014年2月10—13日盐水入侵最严重时段北港上段的净水体输运仍然向陆,但量值随径流量增加趋于减小;北港上段的净分流比、净水通量和盐通量随着径流量增加而增加;在实际径流量试验中,北港上段分流比为-29%(负号表示净水通量向陆),净水通量为-2300 m^(3)/s,净盐通量为-68 t/s,表明受到持续强北风产生的向陆艾克曼输运作用,北港净水通量和盐通量向陆.当径流量增加3000 m^(3)/s时,北港净分流比和水通量接近零,净盐通量为-34 t/s.当径流量增加8000 m^(3)/s时,北港分流比为21.5%,净水通量为3550 m^(3)/s,净水通量向海输运;净盐通量为-6 t/s,仍向陆输运.在青草沙水库取水口,当径流量增加小于4000 m^(3)/s时,最长连续不宜取水时间下降不明显;当径流量增加值达到5000 m^(3)/s时,最长不宜取水时间下降显著,达到了10.5 d.5000 m^(3)/s的径流量的增加量值和适当的持续时间,对三峡水库的实际调度是较难做到的.预警和预报盐水入侵,在严重盐水入侵来临之前将上游水库蓄至高水位,保证有充足的库容进行水资源调度,是保障水库取水安全的一种有效方法.

和川水库沉积物-水界面氮赋存特征及交换通量分析

为明确氮营养盐在沉积物-水界面的交换过程,以和川水库沉积物为研究对象,分析水库整体氮营养盐污染现状及内源释放特征。采集水库不同点位表层沉积物和上覆水,以此分析氮营养盐空间分布特征及差异性;以原位沉积物柱样沉积物静态释放试验获取沉积物-水界面氮营养盐交换通量,并分析和川水库内源释放对水体营养盐的潜在贡献率。结果表明:和川水库上覆水中总氮含量劣于V类水标准,且空间差异明显;上覆水中氮营养盐以硝酸盐氮为主,间隙水中氮营养盐以氨氮为主,沉积物中氮以有机氮为主;沉积物表现为总氮、氨氮的“源”和硝酸盐氮、亚硝酸盐氮的“汇”;和川水库库区界面交换对上覆水氮营养盐的贡献率较小,TN、NH^(+)_(4)-N、NO^(-)_(3)-N、NO^(-)_(2)-N的潜在贡献率小于10%。