成都市干性降落物与道路粉尘的化学组成对比研究

为了弄清大气中微粒子的化学组成的特征，我们自2001年12月在成都市采集了干性降落物和道路粉尘，并对其水溶性阴离子成分进行了比较。通过分析认为干性降落物对道路粉尘的化学组分有影响。同时道路混凝土的污染物亦可进入道路粉尘。     

垃圾焚烧烟气中氯化氢的干法去除研究

采用干态固定床实验装置系统，研究去除垃圾焚烧炉烟气中HCl气体的主要影响因素及其规律。结果表明：选择适当的摩尔比α和颗粒度较细小的吸收剂，吸收效率和吸收剂利用率会提高；温度对净化效率影响不大；HCl气体浓度(ρHCl)对吸收剂的吸收效率(ηHCl)显著影响，ρHCl升高，则ηHCl增大；含有少量杂质的工业碱性废渣的利用率要大于纯化学试剂吸收剂；HCl气体排放标准在75mg／m^3时，可采用干法去除垃圾焚烧炉烟气中的HCl气体。     

SEDIMENT RESUSPENSION AND DRAWDOWN IN A WATER SUPPLY RESERVOIR1

ABSTRACT: The magnitudes and patterns of sediment resuspension are assessed in Cannonsville Reservoir, New York, to quantify and characterize this internal source of sediment. The assessment is based on analyses of sediment trap collections from 10 sites over the spring to fall interval of two years. Temporal and spatial patterns in sediment deposition are demonstrated to be driven by resuspension/redeposition processes. Sediment that had been resuspended and redeposited represented 80 to 96 percent, on average, of the depositing solids collected along the main axis of the lake. About 90 percent of the redeposited sediment was inorganic. Increased resuspension caused by drawdown of the reservoir surface and fall turnover resulted in 10 to 50‐fold increases in deposition rates compared to levels observed when the reservoir was full and strongly thermally stratified. Elevated levels of redeposition from resuspension in the reservoir have been driven by both higher water column concentrations of suspended solids and settling velocities. Recurring longitudinal and lateral gradients in resuspension are delineated, establishing that resuspended solids are transported from the riverine to the lacustrine zone and from near‐shore to pelagic areas. Resuspension is demonstrated to cause increases in inanimate particle (tripton) concentrations. Higher tripton levels have been observed in years with greater drawdown. Water quality impacts of the resuspension phenomenon are considered.     

ACIDIFICATION AND FISH OCCURRENCE IN THE UPPER CHEAT RWER DRAINAGE,WEST VIRGINIA1

ABSTRACT: The decline of many fish populations within the mid-Appalachian region has been attributed to stream acidification as a result of acid precipitation. Many previous attempts to examine relationships between fish occurrence and acidification have been hindered by a lack of data on water quality and fish distributions. To assess relationships between water quality and bedrock type in the upper Cheat River drainage, we used EPA STORET water quality data (1969–1993) and calculated mean pH and mean alkalinity of streams associated with four bedrock types (Hampshire, Chemung, Mauch Chunk, and Pottsville). We examined the relationship between fish occurrence and bedrock type for 53 headwater streams. We found that acidity in headwater streams associated with Pottsville and Mauch Chunk groups often exceeded biological thresholds for acid-sensitive fish species (pH < 5.5). Streams associated with the Pottsville group typically had fewer cyprinid species and fewer total species than those associated with Mauch Chunk, Chemung, and Hampshire bedrock types. The congruent occurrence of streams with low buffering capacity, streams with pH > 5.5, and streams with low fish species richness indicate that acidification has influenced fish distributions in the upper Cheat River drainage.     

The Appalachian Mountains' Copper Basin and the concept of environmental susceptibility

The Copper Basin is located within the southern Appalachian Mountains primarily in extreme southeastern Tennessee, USA. It has long been known for its copper mining/smelting and associated chemical industry, as well as its severely injured environment. Virtually all previous commentary on the environmental degradation at this location have focused on human activities and their destructive impact. This article approaches the subject from a different angle, one that emphasizes the interaction between man and nature. The site's physical setting, industrial history, and environmental history are briefly reviewed. The theory then presented here is that certain of the Copper Basin's natural features made its environment unusually vulnerable to the negative impact of copper mining and smelting, especially as practiced around the turn of the century. These features are identified. This reasoning provides the basis for the concept of environmental susceptibility, which is defined and discussed. A few of its applications are mentioned. This study offers a new perspective on the Copper Basin, as well as insights for those whose work involves investigating the man/nature relationship—both past and present.     

A strategy for integrated monitoring

Administrative machinery has been set up to regulate and control most of the emissions that are known to have severe local consequences, such as the discharge of raw sewage into rivers and lakes and the smokestack emission of air pollutants. Now, the nature of environmental degradation is usually different. We are faced with pollutants and effects with more subtle cause-effect relationships, often characterized by larger geographic areas of interest and longer term potential damage; the potential risk is now more chronic than acute. Acid rain and climate change are good examples, in that they are associated with a variety of pollutants from a number of sources and damage to ecosystems occurs over many years. It is argued that monitoring programs should evolve to reflect the changing nature of the environmental problems they are addressing. It is now necessary to consider interactions among many pollutants, mixing among the various media, and potentially affecting many components of the ecosystem in both indirect and direct ways. Here, integrated monitoring and analysis is presented as a unifying strategy to bring together different measurement methodologies in different disciplines, addressing environmental questions of complexity beyond the scope of many existing activites that have a classical narrower focus. The underlying concept is of nested networks, each tier being composed of sites selected for specific purposes but arranged to maximize the number of common sites where more multidisciplinary questions can be addressed.     

Synthesis and characterization of multi-walled carbon nanotubes from silkworm cocoons to use as the cathode material for Al-air battery

ABSTRACT

Carbon nanotubes have been synthesized by chemical vapor deposition at 850°C using silkworm cocoons as a precursor. The impregnation method with 3 wt% ferrocene as a catalyst was utilized for growth of carbon nanotubes. The flow rates of C₂H₂, H₂, and N₂ were fixed at 100, 150, and 350 ml/min, respectively. Morphology, microstructure and quality of the synthesized carbon nanotubes were investigated by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques. Results showed that the prepared carbon nanotubes were multiwalled and good graphitic quality. When used as the cathode material for aluminum-air battery, prepared carbon nanotubes cathode exhibited higher current density than commercial graphite cathode. Based on our study, there is a successful conversion of silkworm cocoons into value-added nanomaterial products, promoting the natural biotechnological materials.     

STREAM CHEMISTRY IN THE SOUTHERN BLUE RIDGE: FEASIBILITY OF A REGIONAL SYNOPTIC SAMPLING APPROACH1

ABSTRACT: A pilot study, which was conducted in the Southern Blue Ridge geographical province of the Southeastern U.S., demonstrated the feasibility of a probability-based regional synoptic design for the National Stream Survey, which is a project aimed at estimating the number and percentage of streams in various regions of the U.S. that are acidic or at risk from acid deposition. Estimated population distributions for key chemical variables were not appreciably affected by week-to-week variability in stream chemistry during the spring index period chosen for the study. Differences were observed in estimated acid neutralizing capacity (ANC), nitrate, and pH frequency distributions between spring and summer. Observations made at the downstream node did not represent the chemistry of the entire reach for some variables (ANC and nitrate) as indicated by differences in chemical concentrations between upstream and downstream sampling locations. Coefficients of variation in chemical species were low enough to provide a reasonably stable classification of streams based on ANC. Although median ANC, sulfate, and nitrate concentrations were quite low in the region, the probability of finding streams with ph < 6.3 is less than 1.3 percent at the α= 0.05 confidence level.     

Watershed surveys to support an assessment of the regional effects of acidic deposition on surface water chemistry

Through the Direct/Delayed Response Project (DDRP), the United States Environmental Protection Agency is attempting to assess the risk to surface waters from acidic deposition in three regions of the eastern United States: the Northeast Region, the Southern Blue Ridge Province, and the Mid-Appalachian Region. The central policy question being addressed by the DDRP is: Within the regions of concern, how many surface water systems (lakes, streams) will become acidic due to current or altered levels of acidic sulfur deposition, and on what time scales? The approach taken by the DDRP is to select a statistically representative set of watersheds in each region of concern and to project the future response of each watershed to various assumed levels of acidic deposition. The probability structure will then be used to extrapolate the watershed-specific results to each region. The data will be used also for statistical investigation of hypothesized relationships between current surface water chemistry and watershed characteristics. Because the needed terrestrial data base was not available, regional watershed surveys were conducted to meet the specific data needs of the DDRP. Maps (1∶24,000) of soils, vegetation, land use, depth to bedrock, and bedrock geology were made for each watershed. The soils were grouped into sampling classes based on their hypothesized response to acidic deposition. Randomized sampling of these classes provided regional means and variances of soil properties that can be applied to individual watersheds. Because of DDRP's need for consistency within and among regions, unique quality control/quality assurance activities were developed and implemented. After verification and validation, the DDRP data base will be made publicly available. This will be a unique and useful resource for others investigating watershed relationships on a regional scale. The results of these surveys and the conclusions of the DDRP will be presented in several future papers. The current paper gives an overview of the context, rationale, logistical considerations, and implementation of these surveys, with special emphasis on the field activities of watershed mapping and soil sampling. This discussion should be useful to those planning, implementing, and managing survey activities in support of regional assessments of other environmental concerns, who are likely to face similar choices and constraints.     

THE RELATIONSHIP OF WATER QUALITY AND FISH OCCURRENCE TO SOILS AND GEOLOGY IN AN AREA OF HIGH HYDROGEN AND SULFATE ION DEPOSITION1

ABSTRACT: A survey of 61 headwater streams and their watersheds on Pennsylvania's Laurel Hill, an area of high hydrogen ion and sulfate deposition, was conducted in May and June 1983. Trout were absent from 12 or 20 percent of the streams. No fish were present in 10 streams. Thirty-three streams appeared to contain viable trout populations, 10 streams had other interferring cultural impacts and 6 streams had nonviable trout populations. Significant differences in water quality were noted among streams with and without fish. The streams having no fish as a group had significantly lower pH and alkalinity and higher dissolved aluminum than those with fish. Attempts were made to correlate soil type and geology with the presence or absence of trout. Watersheds with a major percentage of very stony land soil classifications always contained no trout or were culturally impacted. On the other hand, watersheds with a major percentage of Upshur (limestone derived) soils always supported trout. Watersheds with more than 30 percent Pocono Group bedrock supported trout in every case but two, while in every case but one, watersheds with more than 30 percent Pottsville Group bedrock did not support trout. Acid runoff episode data indicate severe transient acidification attributable to atmospheric deposition. It appears that a combination of very stony land, 30 percent Pottsville Group bedrock and high deposition of hydrogen ions and sulfate may result in transient acidification and absence of fish populations from headwater streams on Pennsylvania's Laurel Hill.