Estimating Trophic State Proportions of a Regional Lake Population: Are Larger Samples Always Better?

During the summers of 1991–1994, the Environmental Monitoringand Assessment Program (EMAP) sampled 344 lakes throughout thenortheastern United States using a proportional stratified sampling design based on lake size. Approximately one-quarter ofthe 344 lakes were sampled each year (4 years) for totalphosphorus to determine the proportion (and associated95% confidence intervals) of the northeast lake population 1ha (11,076 ± 1,699 lakes) that was in oligotrophic,mesotrophic, eutrophic, or heupereutropic (4 classes) conditionaccording to the total phosphorus criteria of the North AmericaLake Manegement Society. Estimates for the second, third, andfourth yr were developed as cumulative of the previous yrsamples and the current yr samples for the northeast as a wholeand for each of its three ecoregions (4 regions). New confidence intervals were computed for each cumulative yrcondition estimate. This produced a total (4 years × 4classes × 4 regions) of 64 cumulative yr tropic conditionestimates. Confidence intervals for 21% of these estimates didnot shorten with increased sample size. This phenomena raisedquestions about the accuracy of estimates based on cumulativesampling procedures. We explain why and how the phenomenon comesabout with both straight random and proportional randomsampling. Further, we present an example of the effects thisphenomenon has on lake tropic state condition estimates in thenortheastern United States.     

“引江济太”对太湖北部底质及水质总磷的影响

应用GIS技术研究了"引江济太"对太湖北部底质与水质总磷(TP)浓度的影响。研究结果表明,2014—2019年,调水北部沿线4个点位底质TP浓度降幅为59.8%～80.5%;不同点位的水质TP浓度变化存在差异,入湖口点位下降14.1%,沿线其他点位分别上升37.4%、38.6%和45.0%。从空间分布来看,太湖水质TP始终呈明显的"西高东低"分布特点,但底质TP的分布未显示出该类规律。望亭水利枢纽调水情况与入湖口5#点位底质TP浓度呈一定程度的正相关,在调水入湖水量大于出湖水量的年份,5#点位底质TP浓度会偏高。"引江济太"会对太湖北部调水沿线,特别是入湖口附近水域的TP含量产生较大影响,并通过水流迁移与底质再悬浮释放影响下游水域。如何降低望虞河及周边支流的入湖泥沙量将是今后开展科学调水、保障贡湖水源地水质安全的重点研究方向之一。     

氢化物发生原子荧光法测定饮用水中的微量硒

氢化物发生原子荧光法测定饮用水中的微量硒时。仪器条件和试剂的浓度选择很重要。本文对条件的最佳化进行了实验。并对方法的精密度、准确度和检出限进行了讨论。     

沿江施工产生悬浮物对环境影响分析

通过对太仓港围滩吹填工程施工过程泥浆水的采样分析，研究涉及工程施工过程泥浆扩散和演变规律；进而评价吹填工程施工引起悬浮物的增加对水质、水生生物和鱼类的影响。     

Heavy metals in water bodies purified by suspended substrate of rivers

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海滨浴场的卫生细菌学调查及保护对策

从卫生细菌学角度，选用总大量菌群作为指标，对多年的海浴场监测结果进行了综合分析，以期了解近年来秦皇岛海滨浴场的水质变化情况，并提出了可行的保护对策。     

滇池细菌总数与有机碳、氮、磷的调查研究

通过对滇池水体一年多的定点采样工作,重点调查研究了草海、外海表层水中细菌数量及有机营养盐碳、氮、磷的季节变化规律,分析探讨了细菌总数与环境条件和有机营养盐之间的某些关系.对滇池富营养治理提出了一些建议,并提出利用微生物学的方法参与这一研究.     

土壤中总硒与水溶性硒相关性的环境因素

通过对湖北省部分地区土壤中总硒与水溶性硒的调查研究，分析土壤中总硒与水溶性硒的相关性与自然环境因素的关系。从而探讨导致缺硒和富硒疾病的成因。     

炭素行业推行清洁生产的污染物排放系数研究

推行清洁生产、减少污染物排放量，根本的方法是控制物料流失。本研究对炭素制品生产过程中的投入产出进行物料平衡测算，确定各工序物料流失总量及污染物排放系数，提出减少流失、降低排污系数的措施。     

太原市工业区大气中TSP浓度及元素成分分析

采用校正空白称量法对太原市工业区大气中ＴＳＰ浓度进行了测定分析，对该区大气ＴＳＰ浓度随时间变化的规律，超标情况及污染特征进行了研究，同时测定了ＴＳＰ中Ｃｒ、Ｐｂ等１２种元素的含量。