EVALUATING THE ACCURACY OF RAINFALL CATCH BY THREE DIFFERENT GAGES1

ABSTRACT: A U.S. standard gage, a weighing-type recording gage, a standard gage fitted with an Alter windshield, and a pit gage were installed to evaluate the accuracy and wind effects on rainfall catch. The study was conducted at the Stephen F. Austin Experimental Forest, about 20 km SW of Nacogdoches, Texas. A recording anemometer was also installed at a height corresponding to the standard gage orifice. Based on data from 67 storms collected over a one-year period (July 1995-August 1996), all three conventional gages consistently caught less rainfall than the reference pit gage with an average percent deficiency greater than 10 percent. However, the recording gage caught 2.7 percent less and the shielded gage caught 1 percent more than the standard gage—differences less than those reported elsewhere. The deficiencies were highly correlated with storm intensity, duration, or total rainfall. When the correction for wind effect on angle of raindrop inclination is included, the percent catch deficiency of the standard gage was reduced from 11 percent to 6 percent. The remaining errors may be attributed to wind effects (streamline vs. turbulent flow), nonrandom errors, or other unknown sources.     

Recruitment of Hornbill-Dispersed Trees in Hunted and Logged Forests of the Indian Eastern Himalaya

Abstract:  Hunting of hornbills by tribal communities is widespread in logged foothill forests of the Indian Eastern Himalaya. We investigated whether the decline of hornbills has affected the dispersal and recruitment of 3 large-seeded tree species. We hypothesized that 2 low-fecundity tree species , Chisocheton paniculatus and Dysoxylum binectariferum (Meliaceae) bearing arillate fruits, are more dispersal limited than a prolifically fruiting drupaceous tree Polyalthia simiarum (Annonaceae), which has potential dispersers other than hornbills. We estimated the abundance of large avian frugivores during the fruiting season along transects in 2 protected and 2 disturbed forests. We compared recruitment of the tree species near (<10 m) and far (10–40 m) from parent trees at protected and disturbed sites. Median abundance of Great ( Buceros bicornis ), Wreathed ( Aceros undulatus ), and Oriental Pied Hornbills ( Anthracoceros albirostris ) were significantly lower in disturbed forests, but sites did not differ in abundances of the Mountain Imperial Pigeon ( Ducula badia ). Overall, tree species showed more severely depressed recruitment of seedlings (77% fewer) and juveniles (69% fewer) in disturbed than in protected forests. In disturbed forests, 93% fewer seedlings of C. paniculatus were beyond parental crowns, and a high number of all seedlings (42%) accumulated directly under reproductive adults. In contrast , D. binectariferum and P. simiarum were recruitment rather than dispersal limited, with fewer dispersed seedlings surviving in disturbed than in protected forests. Results are consistent with the idea that disturbance disrupts mutualisms between hornbills and some large-seeded food plants, with the caveat that role redundancy within even small and specialized disperser assemblages renders other tree species less vulnerable to loss of regular dispersal agents.     

A Comparison of the Precipitation Chemistry Measurements Obtained by the CAPMoN and NADP/NTN Networks

Precipitation chemistry measurementsobtained by the Canadian Air and PrecipitationMonitoring Network (CAPMoN) and the U.S. NationalAtmospheric Deposition Program/National Trends Network(NADP/NTN) have been examined using more than 7 yrof collocated data from two sites, namely, Sutton,Quebec, Canada and State College, Pennsylvania, U.S.A.In the case of the CAPMoN data, weeklyprecipitation-weighted mean concentrations, totalsample depths and total standard gauge depths werecomputed from daily data and compared to thecorresponding weekly sampling data of the NADP/NTNnetwork. Seasonal and annual precipitation-weightedmean concentrations and deposition values were alsocomputed for both networks and compared. Statisticallysignificant between-network biases were found to existin the weekly results for most of the measuredvariables, particularly standard gauge depth, sampledepth, pH, H⁺, NO₃ ^-,NH₄ ⁺,Na⁺; the NADP/NTN values were consistently lowerthan those of CAPMoN with the exception of pH andNa⁺. The magnitude of the biases was less than35% of the median CAPMoN weekly value for the 7 yr. For most of the measured parameters, thevariability of the between-network differencesrepresented less than 20% of the median CAPMoN weeklyvalue. Both the between-network biases andvariabilities were functions of several physicalparameters, the most dominant being the sample depthand the ionic concentration. For seasonal and annualdeposition values, statistically significantbetween-network biases were found for H⁺,SO₄ ^2-, NO₃ ^-,Ca²⁺,NH₄ ⁺ for both periods; for Mg²⁺ andK⁺ for seasonal data; and Cl^- for yearlydata, with the NADP/NTN deposition values being lowerthan those of CAPMoN. The relative biases ranged from7 to 37%. Part of the between-network bias in thedeposition estimates was directly attributable to astrong bias in the standard gauge depths of the two networks.     

Pseudomonas flava WD-3对人工湿地污染物的去除及Monod模型模拟

为确保寒冷地区冬季人工湿地的污水处理效果,采用从南四湖人工湿地中分离筛选出的耐低温菌Pseudomonas flava WD-3为研究对象,研究其在冬季不同梯度接种量(菌悬液的浓度为4.575×108个·m L-1)和水力停留时间时在复合垂直流人工湿地中连续3个月内的污水处理效果,采用简化的Monod动力学模型对该菌在人工湿地中对污染物的去除进行模拟并验证,并讨论了该菌的投加量和水力停留时间与污染物去除的关系.结果表明,Pseudomonas flava WD-3对污水中的有机污染物以及氮磷等营养物具有明显的去除效果.菌株的最佳投加量为6.0%,且其对污水中COD、NH3-N、TP的去除率分别介于:85.82%~87.00%、73.91%~84.18%和82.04%~85.38%,平均去除效率分别为未投加该菌的1.49、1.46、1.76倍,最佳水力停留时间为7d.简化的Monod模型对Pseudomonas flava WD-3在冬季对人工湿地中污染物去除的预测较为准确,同时,该菌的投加量和水力停留时间均与去除率呈正相关的一级反应关系.     

丹东市区酸雨状况综述

通过对丹东市区降水时间及空间变化趋势的分析,总结酸雨污染现状,找出丹东市区酸雨变化特征。     

宁南山区林地土壤原位矿化过程中碳氮转化耦合特征

为了解宁南山区典型植被恢复模式之一——人工林地土壤碳氮转化的特征以及二者的关系,运用PVC顶盖埋管法进行1 a的原位矿化培养实验,每隔2个月采样,研究柠条、山桃、山杏林地中土壤有机碳、可溶性有机碳和微生物量碳与土壤有机氮、无机氮以及净氨化速率、净硝化速率、净矿化速率和微生物固定速率在一年中的变化特征以及碳氮耦合关系.结果表明在原位培养过程中,61~120 d碳氮的变化最明显,主要受到土壤水分的影响;土壤有机碳和全氮极显著正相关,土壤微生物量碳氮、可溶性有机碳氮显著正相关;土壤有机碳转化速率显著影响净氨化速率、净硝化速率和MBN转化速率,且符合一元线性回归方程;柠条地培养一年后土壤微生物商(MBC/SOC)、MBN/SON显著升高,而且净硝化速率、净矿化速率显著大于山桃和山杏.     

Characterization of heavy metal desorption from road-deposited sediment under acid rain scenarios

Road-deposited sediments(RDS) on urban impervious surfaces are important carriers of heavy metals.Dissolved heavy metals that come from RDS influenced by acid rain,are more harmful to urban receiving water than particulate parts.RDS and its associated heavy metals were investigated at typical functional areas,including industrial,commercial and residential sites,in Guangdong,Southern China,which was an acid rain sensitive area.Total and dissolved heavy metals in five particle size fractions were analyzed using a shaking method under acid rain scenarios.Investigated heavy metals showed no difference in the proportion of dissolved fraction in the solution under different acid rain pHs above3.0,regardless of land use.Dissolved loading of heavy metals related to organic carbon content were different in runoff from main traffic roads of three land use types.Coarse particles(150 μm) that could be efficiently removed by conventional street sweepers,accounted for 55.1%-47.1%of the total dissolved metal loading in runoff with pH 3.0-5.6.The obtained findings provided a significant scientific basis to understand heavy metal release and influence of RDS grain-size distribution and land use in dissolved heavy metal pollution affected by acid rain.     

基于标准分析军用飞机实验室淋雨试验参数设计

目的对军用飞机淋雨试验进行降雨参数设计,为军用飞机实验室淋雨试验参数设计提供参考。方法采用逐一分析,横向对比的方法,对国军标中部分与淋雨试验相关的六个标准,以及国外的三个标准,在降雨强度、雨滴直径及降雨方向等的参数设置进行分析。结果总结降雨强度设计的规律以及各标准在实验室淋雨试验设计时的作用,给出飞机水密性淋雨试验和除雨性能淋雨试验的部分降雨参数设计。结论给出的降雨强度参数符合各标准的要求,所总结的规律建立在深层理解各个标准的基础上,为军用飞机实验室淋雨试验参数设计提供了参考。     

2012年-2016年乐亭酸雨变化特征及影响因素分析研究

利用2012年-2016年乐亭国家基本气象站气象观测资料,分析了乐亭酸雨变化特征和降水量、风向、风速等气象因素对酸雨的影响.结果表明:年平均降水pH值和年酸雨频率呈下降趋势、平均K值呈上升趋势;秋季酸雨程度在四季中最严重,平均pH值为4.50,酸雨频率为38.4%;月平均pH值和酸雨频率呈现波动;酸雨平均pH值随降水量的增加而下降,酸雨频率随降水量的增加不断上升;月平均风速越大,月平均pH值越大,酸雨频率越小;酸雨发生时地面主导风向为NE、ENE、E,与上游地区燃煤型钢铁企业有一定关系.     

采用人工地震波对大跨度刚构桥的地震响应分析

为获得大跨度刚构桥在多维多点地震激励下的响应特征,基于功率谱模型合成了满足给定相关函数的多维多点人工地震波。采用有限元软件SAP2000分别在线性与非线性领域对某大跨度刚构桥进行计算分析,研究刚构桥在多维多点地震下的响应特点。结果表明,多点激励下刚构桥主梁的横向弯矩往往较一致激励下的大;考虑非线性特性后,刚构桥在三向地震作用下的响应并不等于单向地震响应的简单叠加,且刚构桥的墩顶比墩底部位更易形成塑性铰,建议在实际工程中重视刚构桥墩顶部位的延性设计。