对加拿大东南部湖泊从酸沉降效应中恢复的评价

北美洲SO2排放量的减少激起了人们对加拿大东南部的水生态系统能迅速摆脱酸化的状态的期待.但是只有那些明显减少了排放量的冶炼厂附近的湖泊达到了这种期望值.在临近大西洋的省份魁北克和安大略,受远程污染源影响的湖泊的硫酸根离子(SO2- 4)浓度都有一定降低,但pH和碱度则仅有较少量的提高.对于这种延迟的酸度响应,有如下几种因素可以解释:碱基阳离子含量的下降,干旱加速SO2- 4的迁移,水体内部碱性物质生成机制遭到破坏;同时硝酸盐和有机阴离子含量的提高也可能是其中的原因.对加拿大东南部生物恢复的监测资料非常有限,即使有的话,在萨德伯里(Sudbury)和基拉尼(Killarney)地区以外也很难找到恢复的证据.比如,尽管除了酸化作用外其他因素也对上述现象有一定影响,新思科舍河中的大西洋鲑鱼出现率和安大略湖潜鸟的繁殖成功率实际上正在下降.化学和生物学模型预测,只有比目前法规要求严格的多的SO2排放削减额才能促进广泛的化学恢复和其后的生物恢复,而在加拿大东南部的众多湖泊中重建工业化前的化学与生物学条件或许很难实现.     

Zooplankton proportion estimates from non-uniform sample volumes

The relative abundance of organisms from different taxa provides information about ecosystem health and diversity. When the numbers of sampled organisms are modelled as Poisson counts, and the sample volumes are not uniform, variance for the proportion attributable to each taxon is difficult to compute. We present a method for computing approximate variances for this situation. The point estimates and their standard errors reduce to the standard multinomial maximum likelihood results when sample volumes are uniform. Further, given initial estimates of population densities for the taxa of interest, optimal sample volumes can be computed. The methods are illustrated for zooplankton counts from Andrus Lake, Michigan.     

NATIONAL WATER ASSESSMENT: NEEDED OR NOT?1

ABSTRACT A conceptual framework and the systematic collection of reliable information for application within the framework are the cornerstones of effective water planning. The ideal of strengthening these cornerstones was a driving force behind formation of the Water Resources Council and Council efforts, during its life, to develop the Principles and Standards and to complete two National Water Assessments. The Assessments contained voluminous data but never really became an integral component of the national water planning process. Before being disbanded in 1982, the Council solicited several appraisals of its assessment process. This paper reports one made by the university community in which experiences and opinions were obtained from 108 water research administrators and water policy experts.     

National parks legislative mandate in the United States of America

Natural areas of national parks constitute unique ecological and aesthetic resources. Since the inception of national parks, it has been apparent that they are susceptible to threats that result in significant change and damage. Today, major issues concerning management of parks relate to questions of expanded visitor use and what types of facilities are to be deemed appropriate, that is, the dilemma of preservation versus use. In the United States of America, resolution of this dilemma must, strictly speaking, be based upon intent and meaning of Congressional legislation. The traditional interpretation of legislation in the U.S. has been to provide for a balance of use and preservation. However, extensive review of the literature of national park policy reveals a remarkable lack of elaboration and clarification of legislative meaning. Based upon a critical analysis of pertinent legislation, which has heretofore been ignored, we provide an interpretation of legislative meaning which strongly supports a policy of preservation of park resources.     

PHYTOPLANKTON RESPONSES TO GROUND WATER ADDITION IN CENTRAL FLORIDA LAKES1

ABSTRACT: Phytoplankton were studied in lakes augmented with water from the Floridan aquifer and in control lakes. Augmented lakes exhibited enhanced phytoplankton diversity which was believed to be related to chemical changes in the lakes brought about as a result of ground water addition. In particular, elevated concentrations of inorganic carbon appeared to influence phytoplankton populations.     

Valuation of improved air quality in Utah County,USA

A contingent valuation approach was used to estimate maximum willingness-to-pay for improved air quality in Utah County. Respondents demonstrated a high rate of concern over poor air quality and averaged a willingness-to-pay of $37 per month per household. Noniterative openended questions were used successfully. No information bias was observed but benchmark values did influence bids. Willingness-to-pay for improved air quality was large for both sexes and across all income groups, ages, and occupations.     

Characterisation and analysis of persistent organic pollutants and major, minor and trace elements in Calabash chalk

Analysis of Calabash chalk has been done using energy dispersive X-ray fluorescence spectroscopy (EDXRF), X-ray diffraction (XRD) and pressurised fluid extraction (PFE) followed by gas chromatography (GC) with mass selective detection (MSD). It was found by XRD that the composition of Calabash chalk was an aluminium silicate hydroxide from the kaolin clay group with the possible formula Al(2)Si(2)O(5)(OH)(4). Multi-elemental analysis by EDXRF was able to quantify 22 elements in Calabash chalk including lead at a mean concentration of approximately 40 mg/kg. A range of persistent organic pollutants were identified and quantified in Calabash chalk including alpha lindane, endrin, endosulphan II and p,p'-DDD using PFE-GC-MSD.     

Interactive effects of light and temperature on sporophyte production in the giant kelp Macrocystis pyrifera

Laboratory experiments were conducted in 1984 to test for an interaction between irradiance and temperature in controlling sporophyte production in the giant kelp Macrocystis pyrifera. Gametophytes from plants in the San Onofre kelp forest were cultured under a combination of seven irradiance (2.9 to 30 E m^-2 s^-1) and ten temperature (11° to 20°C) levels. The minimum daily quantum dose for fertility of female gametophytes during the 42 d culture-period was 0.25 E m^-2 d^-1. The saturation quantum dose was approximately 0.60 E m^-2 d^-1. Temperatures between 11° and 20°C had little effect on the fertilityirradiance relationship, except at irradiations near the threshold and saturation levels. Cultures at 0.60 E m^-2 d^-1 had significantly lower fertility after 6 wk at 20°C than at the lower temperatures and there was a trend toward lower fertility at temperatures greater than 15°C in cultures at 0.25 E m^-2 d^-1. These differences were also reflected in the development time for female gametophytes. The 11°C cultures reached 50% fertility slightly faster and the 20°C cultures slower than cultures at intermediate temperatures.     

Nutrient-limited growth of juvenile kelp,Macrocystis pyrifera,during the 1982–1984 “El Niño” in southern California

The relative growth rates of juvenile Macrocystis pyrifera in southern California kelp forests were substantially reduced during the El Niño of 1982–1984. The lower growth rates were correlated with increased temperature and decreased nitrogen availability. Fertilization of juvenile plants with slow-release nitrogen-phosphorus fertilizer increased their growth rates to levels previously observed when temperatures were low and nutrient levels were high. The limitation in growth of M. pyrifera by levels of available nutrients during El Niño was in contrast to the usual limitation of growth by irradiance during non-El Niño years. Thus, there was a shift in the relative importance of factors controlling growth of juvenile M. pyrifera during El Niño.