Spatial Distribution of Soil Total Nutrients of Farmland in Liaoning Province

[Objective]The aim was to reveal the spatial distribution characteristics of total nutrients in soil and provide a theoretical basis for farmland management and improvement of crop yield. [Method]GIS technique was used to analyze the spatial distribution characteristics of total C,total N,total P and total K for different soil layers in Liaoning Province. [Result]The results showed that the content of total C,total N,total P decrease from east to west,but the content of total K was high in north district of Liaoning Province. The content of total C,total N,total P and total K was higher in soil surface （0-20 cm） than the lower （20-40 cm）. Total K varied less with soil depth,and its mean content was respectively 17.64 g/kg and 17.08 g/kg for soil surface and soil lower layer. [Conclusion]The results of the distribution of soil total nutrients in different soil layers supplied a theory basis for farmland management.

Total N,total P and organic matters content in floodplain soils of Xianghai Nature Reserve

Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from the Huolin River channel.

Characteristics of Soil Organic Carbon, Total Nitrogen, and C/N Ratio in Chinese Apple Orchards

Soil organic carbon and nitrogen are used as indexes of soil quality assessment and sustainable land use management. At the same time, soil C/N ratio is a sensitive indicator of soil quality and for assessing the carbon and nitrogen nutrition balance of soils. We studied the characteristics of soil organic carbon and total nitrogen by investigating a large number of apple orchards in major apple production areas in China. High apple orchard soil organic carbon content was observed in the provinces of Heilongjiang, Xinjiang, and Yunnan, whereas low content was found in the provinces of Shandong, Henan, Hebei, and Shaanxi, with the values ranging between 6.44 and 7.76 g·kg-1. Similar to soil organic carbon, soil total nitrogen content also exhibited obvious differences in the 12 major apple producing provinces. Shandong apple orchard soil had the highest total nitrogen content (1.26 g·kg-1), followed by Beijing (1.23 g·kg-1). No significant difference was noted between these two regions, but their total nitrogen content was significantly higher than the other nine provinces, excluding Yunnan. The soil total nitrogen content for Xinjiang, Heilongjiang, Hebei, Henan, and Gansu was between 0.87 and 1.03 g·kg-1, which was significantly lower than that in Shandong and Beijing, but significantly higher than that in Liaoning, Shanxi, and Shaanxi. Six provinces exhibited apple orchard soil C/N ratio higher than 10, including Heilongjiang (15.42), Xinjiang (13.38), Ningxia (14.45), Liaoning (12.24), Yunnan (11.03), and Gansu (10.63). The soil C/N ratio was below 10 in the remaining six provinces, in which the highest was found in Shaanxi (9.47), followed by Beijing (8.98), Henan (7.99), and Shanxi (7.62), and the lowest was found in Hebei (6.80) and Shandong (6.05). Therefore, the improvement of soil organic carbon should be given more attention to increase the steady growth of soil C/N ratio.

^(137)Cs tracing of the spatial patterns in soil redistribution,organic carbon and total nitrogen in the southeastern Tibetan Plateau

The southeastern Tibetan Plateau,which profoundly affects East Asia by helping to maintain the stability of climate systems,biological diversity and clean water,is one of the regions most vulnerable to water erosion,wind erosion,tillage erosion,freeze-thaw erosion and overgrazing under global climate changes and intensive human activities.Spatial variations in soil erosion in terraced farmland(TL),sloping farmland(SL)and grassland(GL)were determined by the^(137)Cs tracing method and compared with spatial variations in soil organic carbon(SOC)and total nitrogen(total N).The^(137)Cs concentration in the GL was higher in the 0-0.03 m soil layer than in the other soil layers due to weak migration and diffusion under low precipitation and temperature conditions,while the^(137)Cs concentration in the soil layer of the SL was generally uniform in the 0-0.18 m soil layer due to tillage-induced mixing.Low^(137)Cs inventories appeared at the summit and toe slope positions in the SL due to soil loss by tillage erosion and water erosion,respectively,while the highest^(137)Cs inventories appeared at the middle slope posi-tions due to soil accumulation under relatively flat landform conditions.In the GL,the^(137)Cs data showed that higher soil erosion rates appeared at the summit due to freeze-thaw erosion and steep slope gradients and at the toe slope position due to wind erosion,gully erosion,freeze-thaw erosion and overgrazing.The^(137)Cs inventory generally increased from upper to lower slope positions within each terrace(except the lowest terrace).The^(137)Cs data along the terrace toposequence showed abrupt changes in soil erosion rates between the lower part of the upper terrace and the upper part of the immediate terrace over a short distance and net deposition on the lower and toe terraces.Hence,tillage erosion played an important role in the soil loss at the summit slope positions of each terrace,while water erosion dominantly transported soil from the upper terrace to the lower terrace and resulted in net soil deposition on the flat lower terrace.The SOC inventories showed similar spatial patterns to the^(137)Cs inventories in the SL,TL and GL,and significant correlations were found between the SOC and^(137)Cs inventories in these slope landscapes.The total N inventories showed similar spatial patterns to the inventories of,37Cs and SOC,and significant correlations were also found between the total N and^(137)Cs inventories in the SL,TL and GL Therefore,^(137)Cs can successfully be used for tracing soil,SOC and total N dynamics within slope landscapes in the southeastern Tibetan Plateau.

左氧氟沙星杂质N的全合成工艺

化合物((S)-(-)-2,3-二氢-3-甲基-9,10-双(4-甲基-1-哌嗪基)-7-氧代-7H-吡啶并[1,2,3-de][1,4]苯并噁嗪-6-羧酸)是抗菌药左氧氟沙星的杂质N,可作为左氧氟沙星生产过程中的杂质对照品。针对其合成难度大的问题,设计了左氧氟沙星杂质N(6)的合成工艺。以左氧氟沙星中间体环合酯((S)-(-)-2,3-二氢-3-甲基-9,10-二氟-7-氧代-7H-吡啶并[1,2,3-de][1,4]苯并噁嗪-6-羧酸乙酯)(1)为原料,先在8位引入硝基,经N-甲基哌嗪的亲核取代反应得到化合物(3),再在氢氧化钠作用下水解、铁粉/氯化铵体系还原、重氮化脱除8-氨基得到目标化合物。该工艺原料易得,反应条件温和,总收率约为35.8%,解决了缺少左氧氟沙星相关研究中杂质N对照品的难题。

N型MOSFET器件总剂量效应通用测试系统设计

抗辐照电机驱动器研发需要准确获取电桥电路金属-氧化物半导体场效应晶体管(Metal Oxide Semiconductor Field Effect Transistor,MOSFET)器件的总剂量效应失效阈值,电流-电压、电容-电压等离线测试方法,无法真实反映器件开关性能随累积剂量增加的连续变化过程。因此,针对MOSFET器件总剂量效应的在线测试需求,设计了基于高速信号采集及存储的通用化测试系统,具备被测样品驱动、高频信号采集、高速数据存储、数据模块管理等功能。利用典型商用MOSFET器件开展了总剂量效应测试,结果显示,当吸收剂量达598.08±41.54 Gy(Si)时,样品采集方波波形开始出现异常,低电平电压升高至0.82 V,高电平电压始终正常;随着累积剂量的增大,低电平电压持续性升高至1.08 V,并进一步升高至1.24 V,但器件开关功能保持正常;当累积剂量达1775.41±219.68 Gy(Si)时,采集波形跳变为2.93 V的直线,无方波信号输出,经判断MOSFET开关功能完全受损。

Does the Total Soil N Determined by Kjeldahl Method Include Fixed NH4^+?

Forty soils from top layer (0-20 cm) were sampled in different regions of China and Kjeldahl, HF-Kjeldahl and double treatment methods were used to determine total N, total N plus fixed ammonium, and total N and the residual fixed ammonium left in soil after determination of total N, respectively, to evaluate if Kjeldahl’s method could include the fixed N by soil minerals. The fixed N by soil minerals was measured by Silva-Bremner procedure to make comparison. Results showed that total N determined by Kjeldahl’s method averaged 1.622 g kg-1, while that by HF- Kjeldahl’s method 1.633 g kg-1, and that by double procedure 1.666 g kg-1. Obviously results obtained by the last two methods, particularly the double treatment method, were higher than Kjeldahl’s, showing that Kjeldahl’s method could not or not fully release N fixed by 2:1 minerals in soil, and therefore the determined results would not be the true “total N” for soils that contained large amount of the fixed N. The mineral fixedN averaged 166 mg kg-1, accounting for 10.1% of the total N while the residual fixed N amounted to 30.4 mg kg-1, equivalent to 1.9% of the total N or 18.3% of the total fixed N. The residual fixed N was correlated neither to organic matter nor to total N, but closely related to the total fixed N with a correlation coefficient of 0.598 (n=40), showing that the fixed N was the sole source of the residues. Soils having high residues of the fixed N were just those containing high fixed N, and soils containing high fixed N were just those containing high amount of 2:1 minerals. As a result, Kjeldahl’s method could not give a true value of the total N for such soils. However, for those containing small or little amount of 2:1 minerals, there was no significant difference in results measured by these methods.

Nondestructive diagnostics of soluble sugar,total nitrogen and their ratio of tomato leaves in greenhouse by polarized spectra-hyperspectral data fusion

Polarized spectra-hyperspectral data fusion technique was used to estimate the soluble sugar(SS),total nitrogen(N),and their ratio(SS/N),of greenhouse tomato leaves.Fresh tomato leaves of five different growth stages(seedling,flowering,initial fruiting,mid-fruiting and picking stage)and five different nitrogen treatments(severe stress 25%,moderate stress 50%,mild stress 75%,normal 100%,and excess 150%)at every stage were collected for spectra acquisition and SS and N determination.Polarized reflectance spectra were acquired with a polarization reflectance spectrum spectro-goniophotometer system and four polarization degree features were extracted.Hyperspectral data were collected with a hyperspectral imaging system and four reflectance spectrum features and eight image features were extracted.Initially,models were built with polarization degree features,image features,and spectral features respectively.Linear and nonlinear fusion methods were comparatively used for modeling based on normalized data of the three sources.The results suggest that the performances of SS/N models are better than those of N and SS models,and the prediction capability of the Support Vector Machine(SVM)models of N and SS/N are superior to those obtained with single kind feature.This work indicates that the polarized spectrum-hyperspectral multidimensional information detecting method can feasibly judge the tomato nutrient stress conditions.Multi-features data fusion analysis technique can enhance the prediction accuracy of spectral diagnostics technology in precision agriculture.

配电网N-1最大供电能力的判定定理

N-1最大供电能力(total supply capability,TSC)是评估配电网的重要指标。该文提出TSC判定定理并证明。定理1:每回馈线均能找到与其具有转带关系的一回馈线/馈线段,使两者负荷互补;且N供一备和不对称分段联络接线的备用馈线负荷最小,对称分段联络接线由同一馈线提供备用的馈线段负荷相等。定理2:任意馈线N-1后,所有与故障馈线相联络馈线都满载。定理3:冗余量最小。冗余量是由严格边界等式约束得到的冗余式的取值。这3个定理分别从N-1前负载特征、N-1后负载特征和数学模型的不同角度进行判定。该文证明以上3个定理,并采用我国常见接线模式和配电网算例验证;进一步给出定理的应用举例。判定定理是TSC理论体系的一个基础性工作。与现有研究相比,判定定理提炼出了TSC点的负荷分布特征,能方便地确定所有达到TSC的系统状态,为规划运行中优化负荷分布提供方向,便于发挥配电网的供电能力。

血清-βCTX和Total-P1NP联检在前列腺癌骨转移监测中的价值

目的:为探讨血清Ⅰ型胶原羧基端肽β特殊序列(-βCTX)和总Ⅰ型胶原氨基端延长肽(Total-P1NP)在前列腺癌骨转移监测中的意义。方法:用电化学发光免疫分析检测血清β-CTX和Total-P1NP水平。结果:发现前列腺癌骨转移组的血清β-CTX明显高于无骨转移组及正常对照组(P均<0.05),而血清Total-P1NP明显低于无骨转移组及正常对照组(P均<0.05)。结论:检测血清β-CTX和Total-P1NP对前列腺癌患者骨转移的及时诊断有重要的参考意义。

硅基N沟道VDMOS不同偏置下总剂量效应研究

通过^(60)Coγ射线辐照试验,研究了不同栅极和漏极偏置下硅基N沟道VDMOS器件的总剂量效应,获得了器件的电学特性与低频噪声特性随辐射总剂量的变化规律。试验结果表明:受辐射诱生的氧化物陷阱电荷与界面陷阱电荷的影响,在栅极偏置为+20 V时,器件的电学特性随累积剂量的增大而退化明显。通过退火试验发现,相比于导通电阻和正向压降,阈值电压、漏电流、亚阈值摆幅和输出电容对于总剂量辐射更加敏感。而在低频噪声特性方面,辐照后器件的沟道电流归一化噪声功率谱密度与正栅极偏置呈现正相关性,与负栅极偏置呈现负相关性。在不同漏极偏置条件下,辐照后器件的沟道电流归一化噪声功率谱密度降低,且基本重合。依据噪声模型,认为N沟道VDMOS内部局域电场分布对辐射感生陷阱电荷的形成影响显著,导致器件Si/SiO_(2)界面或者附近的载流子与陷阱交换引起的沟道电流波动不同,成为低频噪声主要来源。研究结果可为N沟道VDMOS器件的辐射效应评估、筛选和抗辐射加固设计提供参考。

Effect of Reducing Chemical Fertilizer on Rice Yield,Output Value,Content of Soil Carbon and Nitrogen after Utilizing the Milk Vetch

A located field experiment was carried out to study the effects of different amount of chemical fertilizer usage on rice yield,economic benefits of rice,soil carbon（C） and total nitrogen（TN） under ploughing back of Chinese milk vetch for 5consecutive years.Six treatments were included in the experiment,they are CK（unfertilized）,CF（100% chemical fertilizer with the amount of N,P2O5,K2 O being150,75,120 kg/hm^2respectively）,A1（22 500 kg/hm^2 Chinese milk vetch and 100%chemical fertilizer）,A2（Chinese milk vetch and 80% nitrogen and potassium fertilizer and 100% phosphate fertilizer）,A3（Chinese milk vetch and 60% nitrogen and potassium fertilizer and 100% phosphate fertilizer）,A4（Chinese milk vetch and 40% nitrogen and potassium fertilizer and 100% phosphate fertilizer）.The results were as follows：application of fertilizer could increase the yield of rice,while Chinese milk vetch combined with fertilizer application had a much more increase effect in rice yield.Under the condition of milk vetch application with 22 500 kg/hm^2,the early rice yield of the treatment A1 was significantly increased by 7.7% compared with that of CF.And the yield of treatment A3 was basically identical to or slight increase in comparison with that of CF.Decreasing amount of fertilizers cloud improve output value of rice in the case of the utilization of Chinese milk vetch.The treatment A1 increased output value of rice by 5.92% in comparison of CF,and treatment A2 was by 4.08% in the next.Treatment A4 showed much better effect in increasing soil organic carbon and total nitrogen in the paddy soil than those of treatments applying mineral fertilizer only.There was a significant reduction on soil organic carbon and TN in treatment A2 in comparison with that of CF.In general,amount of application of milk vetch with 22 500 kg/hm^2 could replace chemical fertilizer partially,it also could improve rice yield,decrease the production cost,and raise the utilization efficiency of nutrients.

Total synthesis and anticancer activity studies of the stereoisomers of asperphenamate and patriscabratine

All stereoisomers of asperphenamate 1a and patriscabratine 2a were achieved with a high yield,and total synthesis of 2a is firstly described here.The absolute configuration of patriscabratine was determined as(S,S).The compounds 1a-d and 2a-d have been tested by MTT assay in T47D,MDA-MB231,HL60,Hela and SGC-7901 cell lines in vitro.Among them,the(R,S) stereoisomer shows the strongest anticancer effects,while the(S,R) shows the weakest one.

肺癌骨转移患者SPECT/CT最大标准化摄取值及血清ALP N-MID TPINP水平及意义分析

目的:探讨肺癌骨转移患者单光子发射计算机断层成扫描(SPECT)/计算机断层成扫描(CT)最大标准化摄取值(SUVmax)及血清碱性磷酸酶(ALP)、骨钙素N端中分子片段(N-MID)、总Ⅰ型前胶原氨基端前肽(TPINP)水平及意义。方法:选取2021年1月至2022年6月在我院治疗的肺癌患者107例,其中合并骨转移患者37例,无骨转移患者70例,比较合并骨转移和无骨转移患者SUVmax、ALP、N-MID及TPINP差异,同时分析SUVmax、ALP、N-MID及TPINP与临床病理特征的关系,以及ALP、N-MID及TPINP诊断骨转移的价值。结果:骨转移患者ALP、N-MID和TPINP分别为(120.30±33.32)U/L、(19.03±3.54)mg/L和(82.21±26.65)mg/L,明显高于无骨转移患者(P<0.05),而腰椎骨密度(BMD)为(0.82±0.12),明显低于无骨转移患者(P<0.05)。腺癌患者SUVmax为(11.45±1.98),明显低于鳞癌和其他类型患者(P<0.05);肿瘤直径>5cm、TNM分期Ⅲ~Ⅳ期SUVmax分别为(13.38±1.95)和(12.99±2.00),明显高于肿瘤直径≤5cm、TNM分期Ⅰ~Ⅱ期患者(P<0.05)。TNM分期Ⅲ~Ⅳ期ALP、N-MID和TPINP分别为(110.39±21.12)U/L、(18.62±2.22)mg/L和(70.31±17.02)mg/L,明显高于TNM分期Ⅰ~Ⅱ期患者(P<0.05)。ALP、N-MID和TPINP诊断骨转移的ROC曲线下面积分别为0.695、0.734和0.837,P<0.05。结论:相比较无骨转移肺癌患者,肺癌骨转移患者及血清ALP、N-MID、TPINP水平明显升高,而SUVmax无明显差异;SUVmax、ALP、N-MID和TPINP与肺癌患者临床病理特征有一定关系,其中ALP、N-MID和TPINP在诊断肺癌骨转移方面有一定应用价值。

Measurement of the neutron total cross section of carbon at the Back-n white neutron beam of CSNS

To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using ^235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.

血清尿酸、总胆红素联合NT-proBNP对难治性心力衰竭死亡的预测价值

目的 分析血清尿酸、总胆红素(TBil)联合N末端脑钠肽前体(NT-proBNP)对难治性心力衰竭(下称心衰)死亡的预测价值。方法 选择2017年1月至2019年12月杭州市余杭区第二人民医院收治的难治性心衰患者126例为观察组,另择同期本院健康体检者118名为对照组。观察组患者均接受强心、扩血管及利尿治疗,持续2周。分别于治疗前和治疗后检测两组患者血清尿酸、TBil及NT-proBNP水平。根据6个月预后将患者分为死亡组和存活组,比较两组患者血清尿酸、TBil及NT-proBNP水平。采用logistic回归分析难治性心衰死亡的影响因素。采用ROC曲线分析血清尿酸、TBil和NT-proBNP水平预测难治性心衰死亡的效能。结果 观察组治疗前血清尿酸、TBil和NT-proBNP水平高于对照组,差异均有统计学意义(均P<0.05)。随访期间观察组死亡27例(死亡亚组),存活99例(存活亚组)。死亡亚组治疗前和治疗后尿酸、TBil和NT-proBNP水平高于存活亚组,差异均有统计学意义(均P<0.05)。年龄、心衰病程、尿酸、TBil和NT-proBNP均是影响难治性心衰患者死亡的因素(均P<0.05)。尿酸、TBil和NT-proBNP3项指标联合预测死亡的的灵敏度和AUC高于每个指标单独预测。结论 结合尿酸、TBil和NT-proBNP有助于判断难治性心力衰竭患者预后。

A Total and Convenient Synthesis of Orixiarine

A simple total synthesis of the quinoline alkaloid, orixiarine was achieved from N-methylaniline and 1-bromo-3-methyl-2-butanone.

2型糖尿病合并骨质疏松症患者血清N-MID、TP1NP、β-CTX水平与冠状动脉钙化的相关性

目的:探讨2型糖尿病(T2DM)合并骨质疏松症患者血清N端骨钙素(N-MID)、总Ⅰ型胶原氨基端延长肽(TP1NP)、β-胶原降解产物(β-CTX)水平变化及其与冠状动脉钙化的相关性。方法:按照是否合并骨质疏松症将102例T2DM患者分为骨质疏松症组(n=63)与非骨质疏松症组(n=39),比较两组血清N-MID、TP1NP、β-CTX水平;再将T2DM合并骨质疏松患者按是否合并冠状动脉钙化再分为钙化组(n=35)与无钙化组(n=28)。根据钙化程度分为轻度钙化组(n=11)、中度钙化组(n=9)、重度钙化组(n=15)。比较各组血清N-MID、TP1NP、β-CTX水平;分析血清N-MID、TP1NP、β-CTX预测T2DM合并骨质疏松患者冠状动脉钙化的临床意义。结果:骨质疏松症组患者N-MID、TP1NP水平均高于非骨质疏松症组(P<0.05),β-CTX低于非骨质疏松症组(P<0.05)。钙化组患者N-MID、TP1NP均高于无钙化组(P<0.05),β-CTX均低于无钙化组(P<0.05)。重度钙化组N-MID、TP1NP高于轻、中度钙化组(P<0.05),β-CTX低于轻、中度钙化组(P<0.05)。N-MID、TP1NP、β-CTX均是影响冠状动脉钙化的危险因素(P<0.05)。T2DM合并骨质疏松患者冠状动脉的严重程度与血清N-MID、TP1NP均呈正相关(P<0.05),与β-CTX呈负相关(P<0.05)。N-MID、TP1NP、β-CTX中N-MID诊断冠状动脉钙化的效能较高,N-MID约登指数最大时对应截断值为11.22 ng/mL,受试者工作特征曲线(ROC)曲线下面积(AUC)为0.855,敏感度、特异度分别为95.96%、81.00%;N-MID、TP1NP、β-CTX联合诊断冠状动脉钙化的AUC为0.866,敏感度、特异度分别为96.62%、73.30%。结论:T2DM合并骨质疏松症患者存在较高的冠状动脉钙化风险,与N-MID、TP1NP值异常升高及β-CTX值异常降低有关,联合预测冠状动脉钙化的效能较好,值得临床推广。

在随机启动(p,N)-策略控制下不中断多重休假排队系统的性能分析

本文研究在随机启动(p,N)-策略控制下不中断多重休假的M/G/1排队模型.通过运用全概率分解技术和拉普拉斯变换工具,直接讨论了系统从任意初始状态出发在任意时刻t队长的瞬态分布,得到了队长瞬态分布的拉普拉斯变换表达式.基于瞬态分析,使用洛必达法则得到了系统在任意时刻t队长的稳态分布的递推表达式,同时求出了系统其他一些重要排队性能指标,如稳态队长分布的概率母函数、平均稳态队长和附加队长分布的显示表达式等,并讨论了一些特殊情形.最后,通过数值计算实例讨论了系统空闲率和附加平均队长关于一些参数的敏感性以及系统容量的优化设计.

三峡库区黑沟流域AnnAGNPS参数空间聚合效应

农业非点源污染物是长江三峡库区主要污染源之一,已造成令人关注的生态、环境和健康等问题,流域模型(AnnAGNPS)与GIS结合,为空间数据组织和模型参数空间聚合提供技术基础,是其预测和流域规划与管理的有效途径。三峡库区小流域条件下,基于临界源面积(CSA)和最小初始沟道长度(MSCL)值域设定,形成不同流域划分方案,空间离散单元(SDU)水平,即SDU大小及数量,影响输入参数空间聚合效应及模型输出结果。在黑沟小流域(144.4hm2)应用已校准AnnAGNPS模型,设定CSA和MSCL值域为0.5～15hm2及7.5～200m,10种SDU水平、流域尺度和条件下,结果表明:空间参数聚合程度和模型输出结果均随SDU尺度改变而发生变化。土地利用与土壤类型等参数具有明显的聚合效应,径流、泥沙和养分输出具有不同的SDU适宜水平和范围。SDU尺度聚合效应对径流量影响较小,而对泥沙、总N、总P模拟影响较大;径流量、泥沙、总N、总P模拟输出误差可接受SDU尺度范围分别为0.5～18、2～6、0.5～6hm2。因此,应用AnnAGNPS模型,更需要注意不同子模型所需要适宜的SDU尺度水平。