高一化学教学中实施研究性学习的探索

本文根据国家教育部制定的《全日制普通高级中学课程计划(试验修订稿)》所提出的新的培养目标，在“研究性学习”课程的实践中，煞合化学学科特点，选择“环境保护”为突破口，联系本地区实际开展环境教育活动。就“研究性学习”课题的选择、实施进行了探索，提出了我们的认识和见解。     

IMPACT OF COAL SURFACE MINING AND RECLAMATION ON SURFACE WATER CHEMICAL CONCENTRATIONS AND LOAD RATES IN THREE OHIO WATERSHEDS1

ABSTRACT: Information is lacking on the watershed scale effects of mining and reclaiming originally undisturbed watersheds for coal on surface water chemical concentrations and load rates for a variety of constituents. These effects were evaluated on three small, geologically dissimilar watersheds subjected to surface mining in Ohio. Comparisons were made between phases of land disturbances using ratios of average concentrations and load rates: Phase 1 (natural), subphases of Phase 2 (mining and reclamation), and subphases of Phase 3 (partial reclamation and final condition) using 4,485 laboratory analyses of 34 constituents. Average concentration and load rate ratios were categorized into three classes—minor, moderate, and substantial. Mining and reclamation (M/R) affected flow duration curves in different ways‐baseflow changes were variable, but high flows generally increased. The average concentration ratios for all sites were classified as 15 percent “minor,” 36 percent “moderate,” and 49 percent “substantial” (average ratio of 2.4.) Generally load rate ratios increased due to mining and reclamation activities (average ratio of 3.3). Minor, moderate, and substantial impacts were found on average for 7 percent, 23 percent, and 70 percent, respectively, of load rate ratios. The impact of M/R on average load rates was not necessarily the same as on average concentrations due to changed hydrology and can be opposite in effect. The evaluation of the impacts of M/R requires knowledge of changing hydrologic conditions and changing supplies and rates of release of chemicals into streams. Median sediment concentration ratio is an indicator of average constituent load rate ratio of a wide variety of chemical constituents and is useful for development of best management practices to reduce chemical loads. The site at which diversion ditches were not removed during final reclamation sustained large chemical load rates, and removal of diversions at the other mined site reduced load rates. Revegetation of poorly reclaimed areas decreased chemical load rates. Chemical load rates were sensitive to geology, mining, and reclamation methods, diversions, and changing hydrology, concentration flow rate regressions, and watershed areas.     

The Sensitivity of Headwater Streams in the Hindu Kush Himalayas to Acidification

Water, Air, &; Soil Pollution: Focus - The mountain ecosystems of the Hindu Kush Himalayas are generally considered to be pristine despite little available data to confirm it. Is there any...     

Chemical Variation and Catchment Characteristics in High Altitude Lochs in Scotland,U.K.

Previous research has established clear relationshipsbetween the chemical composition of surface waters andthe nature of their contributing catchments. Theserelationships are particularly strong when broadenvironmental gradients are considered. However, forfreshwaters at higher altitudes, some of the catchmentprocesses that mediate chemical composition are lessinfluential than those at lower altitudes. The waterchemistry of 85 upland lochs in Scotland, U.K. is examinedto assess differences in chemical composition along arelatively short altitude gradient. Principal componentsanalysis identifies the main gradients of variationwithin the dataset. A series of digital datasets is usedto characterise the catchments according to a range ofattributes including soils and landcover. Multivariatestatistical analysis is undertaken to examine the extentto which the catchment attributes can explain variationin surface water chemistry in upland systems. Theseempirical relationships may be used in the development ofregionalisation procedures, which will allow upscaling ofknowledge from individual sites to regions.     

Restoration of a Small High Mountain Lake after Recent Tourist Impact: The Importance of Limnological Monitoring and Palaeolimnology

The natural Park of Peñalara consists of a small mountainousarea near Madrid and includes a series of water bodies (fromsmall mountain lakes to temporary ponds and peat bogs), the mostknown of them being the so-called `Laguna Grande dePeñalara'. Due to growing numbers of visitors theenvironmental conditions of this lake started to decline in theearly 1970s because of: (1) the start of severe soil erosionprocesses; (2) the increase of nutrient load; and (3) theintroduction of a non-native fish species. Since the area wasprotected in 1990, several conservation and restoration projectsincluded in an integrated management plan have been developed. Here we summarise some of the results of these efforts: (1) controlled access of livestock and visitors to the area; (2) palaeolimnology studies aimed at inferring recent changes in thewatershed; and (3) monitoring of the limnological features of thesystem. Restoration of this lake and its watershed is intendedto serve as a model for the management of other severely alteredhigh mountain lakes.     

Geochemistry of Iron and Sulfur in the Zone of Microbial Sulfate Reduction in Mine Tailings

The cycling of iron and sulfur in mine tailings depends on various chemical and microbial reactions. The present study was undertaken in order to assess the role played by populations of sulfate-reducing bacteria (SRB) on the fate of Fe and SO₄ ^2- in Cu–Zn and Au tailings. Samples were taken along a 50-cm deep profile at all sites and analyzed for SRB populations, solid-phase mineralogy and porewater geochemistry. Results indicated that the Cu–Zn tailings were highly oxidized near the surface, as shown by the very low pH, high redox potential, large concentrations of soluble Cu, Zn and sulfate in the porewaters, and the depletion of pyrite. On the other hand, Au tailings were more pH neutral, slightly anoxic, and showed low concentrations of Fe and SO₄ ^2- in the porewaters and very little pyrite oxidation. SRB populations in the Cu–Zn tailings increased with depth, just below the oxic/anoxic interface and were linked to a decline of sulfate and DOC concentrations around the same depths. However, large concentrations of dissolved Fe were also observed around the same depth intervals. Our results suggest that SRB could be involved in sulfate reduction in the Cu–Zn tailings, because the solubility of sulfate was not controlled by the precipitation of sulfate-rich minerals. However, the presence of soluble Fe in the reduced portion of the tailings was also indicative of the presence of iron reducing bacteria (IRB). These bacteria were not enumerated in the present study, but their co-occurrence with SRB has been reported in the past in similar mining environments. The decline of sulfate and the release of soluble iron into the porewaters were also paralleled by a pH increase and the generation of alkalinity. In the Au tailings, SRB populations were generally constant throughout the depth profile and could not be ascribed to sulfate reduction in the porewaters. The solubilities of sulfate and iron in these tailings were partially controlled by jarosite and Fe-oxide minerals. It is then clear that SRB populations could be recovered from various mining sites, but their activity cannot be ascertained based on microbial enumeration and geochemical data.     

RELATIONSHIPS BETWEEN FLOOD FREQUENCIES AND RIPARIAN PLANT COMMUNITIES IN THE UPPER KLAMATH BASIN,OREGON1

ABSTRACT: This study was conducted in the Klamath Basin of southwestern Oregon to evaluate the dependency of riparian plant communities upon infrequent flooding. Plant communities were sampled with 1 m² quadrats along established cross‐sections. Data collected for purposes of hydraulic modeling included channel and floodplain elevations (i.e., cross‐sectional profiles) and water surface elevations associated with specific discharges. The elevational distribution of hydrophytic plant communities relative to modeled return periods provided the basis for establishing relationships between these variables for nine sites. Results indicate that, on average, a peak flow frequency of 4.6 years (range of 3.1 to 7.6 years) was needed to sustain riparian plant communities at seven of nine sites. At two sites, results indicated return periods of more than 25 years were needed; these results possibly were influenced by local geomorphic conditions (a narrow steep channel in one case and an incised channel in the other). Overall, these results tend to confirm a strong dependency of riparian plant communities on overbank flows.     

苯砜基乙酸酯类化合物对大型蚤急性毒性的结构信息指数

为了建构结构信息指数回归模型，研究了苯砜基乙酸酯类化合物结构与其对大型Sao急性毒性的关系，在邻接矩阵基础上，提出一种新的原子生物活性特征值αi,由αi建构结构信息指数G，将其用于苯砜基乙酸酯类化合物对大型Sao急性毒性的研究，化合物对大型的稳定性和预测能力，由方程得出的以预测值与测定值之间能较好地吻合，用Jackknife法检验，模型具有总体稳健性，G是一种结构选择性、性质相关性俱佳的拓扑指数。     

染料在干污泥上的吸附平衡和动力学

本文研究了染料活性嫩黄 KD- 3G、直接深棕 M和酸性媒介棕 RH在干活性污泥上的吸附平衡和吸附动力学。结果表明 :所试染料的吸附等温线数据都可用 Freundlich方程描述 ;对于 Langmuir方程 ,只有酸性媒介深棕 RH的等温线数据能与之拟合。染料的吸附过程遵循二级吸附动力学模型 ,也能用 Lagergren一级速率方程描述。在吸附温度为 1 5℃、2 0℃、2 5℃、35℃和 45℃时 ,活性嫩黄 KD-3G、直接深棕 M和酸性媒介棕 RH的一级吸附速率常数分别为 0 .0 0 2 8～ 0 .0 0 3 2 min- 1、0 .0 1 5～ 0 .0 4 0 min- 1、0 .0 0 7～ 0 .0 1 2 min- 1 ,二级吸附速率常数分别为 0 .0 0 0 2 7～ 0 .0 0 0 4 7g/ (mg· min)、0 .0 0 6 5～ 0 .0 2 90 g/ (mg· min)、0 .0 0 3 0～ 0 .0 1 3 2 g/ (mg· min)。由二级吸附速率方程计算得到的平衡吸附量与实验值的相对误差在 1 0 %以内 ,这表明两者的符合程度较高。上述温度范围内 ,当染料质量浓度为50 mg/ L时 ,活性嫩黄 KD- 3G、直接深棕 M和酸性媒介棕 RH的平衡吸附量分别为 1 6.5～ 1 9.2 mg/ g、1 4 .3～ 1 6.0 mg/ g、7.2～ 9.6 mg/g。试验溶液的温度对吸附速率常数有影响