Does improved waste treatment have demonstrable biological benefits?

Since 1972, 10 benthic surveys and 9 static fish bioassays have been conducted to assess the impact of AVTEX Fibers, Inc. effluent on the lower South Fork of the Shenandoah River. AVTEX (formerly FMC Corp.) is a rayon and polyester fibers plant located in Front Royal, Virginia. Benthic samples were taken at four stations, one above and three below the plant discharges. Single surveys in 1972 and 1973 indicated a severe impact on the benthic community along the right side of the river, below the plant, as a result of the channelized effluent. Diversity values (¯d) were low (0–2.42) and numbers of taxa and organisms were reduced. A fish bioassay in 1973 indicated the effluent to be acutely toxic at the 34.5% level (mixture of effluent and river water). In early 1974, FMC Corp. constructed an activated sludge treatment system to reduce BOD and supplement the neutralization and chemical precipitation (zinc hydroxide and liquid-solid separation) facilities that had been used to treat waste waters since 1948. After the new equipment was placed in operation, the previously stressed area became more stable. In 1975 and 1976 the stressed area exhibited greater ¯d values (1.19–3.39) and an increased number of taxa and organisms. Bioassays showed the effluent to be acutely toxic to fish only once since 1973. The major improvements in the effluent were a 70% reduction in BOD₅ and a 60% reduction in the amount of zinc entering the river. Community conditions in 1977 indicated a partial remission of improvement, probably due to drought conditions.The rehabilitation of damaged ecosystems is a process important to all biologists. An important factor in encouraging industry to participate in this activity is evidence that improved waste treatment will often have demonstrable biological benefits rather soon. As data accumulate on the recovery process it may be possible to predict the degree of rehabilitation and time required more precisely.     

RUNOFF,EROSION, AND SOLUTES IN THE LOWER TRUCKEE RIVER,NEVADA, DURING 19691

The Truckee River heads in the Sierra Nevada at Lake Tahoe, and terminates in Pyramid Lake. During the 1969 water year, flow about 9 miles upstream from the mouth (974,000 acre-ft) was almost four times the long-term average, due mainly to heavy winter rains and spring snowmelt. A short period of low-altitude rainfall produced the highest concentrations of suspended sediment, whereas a much longer subsequent period of snowmelt yielded a much greater total quantity of material. The upper 90 percent of the basin yielded about 260 acre-feet (630,000 tons) of sediment at the Nixon gage, whereas an estimated 2,800 acre-feet (6.8 million tons) was contributed by erosion of about 200 acres of river bank below the gage. Solute content at the gage ranged from 80 to 450 mg/l, dominated by calcium, sodium, and bicarbonate, plus silica in the most dilute snowmelt and chloride in the most concentrated low flows. Solute load totaled about 130,000 tons, of which the principal constituents in Pyramid Lake-sodium plus equivalent bicarbonate and chloride-amounted to almost 40,000 tons. The total solute load during a year of average flow may be 45,000-55,000 tons, including 18,000-22,000 tons of principal lake constituents.     

Temporal Trends in Water Chemistry in the Turkey Lakes Watershed Ontario,Canada, 1982-1999

The Turkey Lakes Watershed (TLW) was established in 1980 as asite for study of the ecosystem effects of acidic deposition, andsince then there has been 40% reduction in North AmericanSO₂ emissions. Monitoring records for bulk deposition,shallow and deep ground water, two headwater streams and two lakeoutflows have been tested to identify statistically significantmonotonic trends. The TLW appears to be responding to decliningacidifying emissions because the most prevalent chemical trendacross sample types/stations was decreasing SO₄ ^2-. Increasing pH was detected in four of the seven data sets, butonly the H⁺ decrease in bulk deposition was of a magnitudeto be an important ionic compensation for the SO₄ ^2-decline. There is little evidence of acidification recovery inTLW waters however. Increasing alkalinity was found only in theoutflow of the penultimate lake of the basin, and in fact, deepground water and the other lake outflow had decreasing alkalinitytrends (i.e., continuing acidification). For the surface waterstations, the greater part of the ionic compensation fordeclining SO₄ ^2- was decreasing base cations, and as aresult, these waters are probably becoming more dilute with time,although only the headwater streams exhibited decliningconductivity. Five of seven data sets had increasing dissolvedorganic carbon concentrations. Increasing NO₃ ^- wasimportant in ground waters. Drought has strongly influencedtrends and delayed recovery by mobilizing S stored in catchmentwetlands and/or soils.     

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.     

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。