PII: S0043-1354(99)00111-6

ÐResults are presented from a study into the e€ects of scuba diving on water column structure in perennially ice-covered Lake Fryxell, Antarctica. General theoretical predictions are compared with results, which assess potential impacts from diving activities on water quality parameters related to disruptions to water column stability and dissolved gas concentrations. Potential mechanisms of water column disturbance are considered including: (1) mixing due to diver motion, (2) mixing by diverexhaled bubble plumes and (3) changes of water column gas concentrations due to dissolution of diverexhaled gases. Data (temperature, dissolved oxygen, speci®c conductance, pH, dissolved organic carbon, salinity) were collected from two control holes and one dive hole immediately before and 2.5 d after dive activities. Variability in measured parameters did not di€er signi®cantly between sampling sites either before or after diving; and di€erences between control holes and dive hole observations, on a depth-by-depth basis, were within the range of expected statistical ̄uctuations. Preand post-dive virus-like particle, bacterial, ciliate, photoand heterotrophic ̄agellate densities also did not di€er signi®cantly. An apparent lack of long-term trends indicative of water column destabilization over the past 18 ys of diving is discussed, along with recent evidence for deep mixing in this lake. Although all potentially a€ected parameters have not been considered, theoretical model results and an analysis of ®eld data suggest that diving impacts on physicochemical properties and microbial distributions in a closed-basin, ice-covered lake occur at spatiotemporal scales other than those considered in this study. # 1999 Elsevier Science Ltd. All rights reserved Key wordsÐscuba diving, impact assessment, disturbance, dissolved gases, water quality, Antarctica, polar lakes, strati®cation, stability

本文介绍了一项关于水肺潜水对南极洲常年被冰覆盖的弗莱克塞尔湖水体结构影响的研究结果。将一般理论预测与研究结果进行了比较，该研究评估了潜水活动对与水体稳定性破坏和溶解气体浓度相关的水质参数的潜在影响。考虑了水体扰动的潜在机制，包括：（1）潜水员运动引起的混合，（2）潜水员呼出的气泡羽流引起的混合，以及（3）潜水员呼出气体溶解导致的水体气体浓度变化。在潜水活动前和活动后2.5天，从两个对照孔和一个潜水孔收集了数据（温度、溶解氧、电导率、pH值、溶解有机碳、盐度）。在潜水前或潜水后，测量参数的变异性在采样点之间没有显著差异；并且在逐个深度的基础上，对照孔和潜水孔观测值之间的差异在预期的统计波动范围内。潜水前后病毒样颗粒、细菌、纤毛虫、光合和异养鞭毛虫的密度也没有显著差异。讨论了过去18年潜水过程中明显缺乏表明水体不稳定的长期趋势，以及该湖深层混合的最新证据。尽管并非所有可能受影响的参数都已考虑在内，但理论模型结果和现场数据分析表明，在一个封闭盆地、被冰覆盖的湖泊中，潜水对物理化学性质和微生物分布的影响发生在本研究未考虑的时空尺度上。#1999年爱思唯尔科学有限公司。保留所有权利。关键词 - 水肺潜水，影响评估，扰动，溶解气体，水质，南极洲，极地湖泊，分层，稳定性