浅谈行业环境监测站的任务与作用

我国环境问题日趋严重，环境污染和生态破坏已成为社会发展的制约因素。然而，有些企业忽视环境保护工作，取消或合并环境监测站，削弱环境监测力量。针对这种情况，从行业环境监测站的任务、作用和不可取代性方面阐述了强化行业环境监测站建设的必要性。     

THE FLOOD HAZARD AND DYNAMICS OF THE URBAN RESIDENTIAL LAND MARKET1

ABSTRACT: Literature on the flood hazard/residential land market relationship is full of contradictory findings, many of which are counter-intuitive to the belief that flooding has a negative impact on house prices. This research advances a conceptual framework through which these relationships might be re-examined. Based on the expected utility model, the theoretical framework integrates the economic notion of capitalization with spatial and temporal characteristics of the flood hazard. Four communities with different flood regimes are used to test the effect of flooding on the residential real estate market. Results show that, (1) there is an identifiable relationship between characteristics of the flood hazard and changes in house values; (2) the length of the recovery period is dependent on characteristics and expectations of flooding, attributes of the real estate market, and availability of capital to fuel recovery; and (3) dynamics of the urban market and spatial extent of the flood hazard influence these relationships. Further research is now necessary to examine these findings under different spatial, temporal, hydrological, and socio-economic conditions.     

EXAMINING LAND USE INFLUENCES ON STREAM HABITATS AND MACROINVERTEBRATES: A GIS APPROACH1

ABSTRACT: Geographic Information Systems (GIS) were used to assess the relationships between land use patterns and the physical habitat and macroinvertebrate fauna of streams within similar sized watersheds. Eleven second or third order watersheds ranging from highly urbanized to heavily forested were selected along Lake Superior's North Shore. Land use patterns within the watersheds were quantified using readily available digital land use/land cover information, with a minimum mapping resolution of 16 ha. Physical habitat features, describing substrate characteristics and stream morphology, were characterized at sample points within each stream. Principle component and correlation analyses were used to identify relationships between macroinvertebrates and stream physical habitat, and between habitat and land use patterns. Substrate characteristics and presence of coarse woody debris were found to have the strongest correlations with macreinvertebrate assemblage richness and composition. Agricultural and urban land use was correlated with substrate characteristics. Algal abundance, associated with macroinvertebrate compositional differences, was correlated with housing density and non-forest land covers. The use of readily available spatial data, even at this relatively coarse scale, provides a means to detect the primary relationships between land use and stream habitat quality; finer-resolution GIS databases are needed to assess more subtle influences, such as those due to riparian conditions.     

Trends and issues in land and water resources management: Setting the agenda for change

The classical model of a paradigm shift is used to explore changes that are occurring in public lands and water resources management. Recent policy developments suggest that the traditional paradigm, which is characterized by sustained yield, is in the process of being invalidated. While no new paradigm has been fully accepted, the emerging paradigm does appear to be based on two principles: ecosystem management and collaborative decision making. Implementation of these two principles is likely to require extensive revision of traditional management practices and institutions. Failure to address these issues could result in adoption of the rhetoric of change without any lasting shift in management practices or professional attitudes.     

Changes in wetlands on nonfederal rural land of the conterminous United States from 1982 to 1987

Recent wetland area trends were estimated from the National Resources Inventory (NRI) for nonfederal rural lands for the period 1982–1987. NRI-based estimates of wetland area for states comprising the conterminous United States were highly correlated with estimates made by the US Fish and Wildlife Service and with estimates of coastal salt marsh wetlands made by the National Oceanic and Atmospheric Administration. Net wetland area declined by 1.1% (≈363,200 ha) during the five-year study period. Conversion to open water, primarily caused by natural flooding in western inland basins, was responsible for altering extensive wetland areas (≈171,400 ha). Of the human-induced wetland conversions, urban and built-up land was responsible for 48% of the wetland loss, while agricultural development was indicated in 37% of the converted wetland area. A decrease in rural land, and increases in both population, and urban and built-up land were associated with wetland loss among states. Potential reasons for wetland loss were different in 20 coastal states than in 28 inland states. Proportionately, wetland loss due to development was three times greater in coastal states than inland states, while agriculturally induced wetland losses were similar in both groups. The proportionate declines of forested vs nonforested wetlands were not significantly different among states.     

Improving lake riparian source area management using surface and subsurface runoff indices

Sensitivity indices, which rank factors pertinent to surface and subsurface runoff pathways, were used to identify phosphorus source areas in riparian zones of 15 northern Minnesota lakes. Watershed models were first developed using a geographic information system (GIS). Empirical models were then developed correlating water quality with land use, lake morphometry, and riparian sensitivity. Base models of forested, cultivated, pasture/open, wetland and residential land use within 100, 200, 400, and 2000 m of the study lakes were regressed on total phosphorus and chlorophyll-a. Area-weighted groundwater and surface runoff sensitivity indices were then incorporated into each model and tested for significance. Within the 200-m buffer, the total phosphorus base model was improved by including the groundwater index alone. The chlorophyll-a base model at 200 m was improved by including: (1) the groundwater index alone, and (2) both the groundwater and surface runoff sensitivity indices. Results suggest that surface and subsurface runoff analysis of potential source areas can improve decision making for lake riparian management.     

Initial decision analysis (IDA): a participatory approach for developing resource policies

Initial decision analysis (IDA) is a microcomputer based decision-making technique that is organized so that a rational, step-by-step, procedure can be followed to use existing knowledge to develop resource policies. The IDA process provides a systematic way for participants to define their own problem and to explore jointly alternative solutions. IDA is particularly suited to resolving complex problems involving many groups with conflicting interests. IDA is illustrated with data from the US Forest Service's Draft Environmental Impact Statement for the 1985 to 2030 Resource Planning Act Program for the United States. Four policy options are evaluated: maximization of timber production, of grazing, and of wilderness, and a dominant use policy that concentrates timber management on productive sites. Policies were evaluated using a new mathematical satisficing procedure. Mathematical satisficing of simulated policy consequences showed that, for selected performance standards, current RPA policies are superior to the four alternative policies examined.     

Application of the randomized response technique to marine park management: an assessment of permit compliance

Marine product collecting permits are useful management tools for providing information on usage patterns. Unfortunately, usage parameters based on permit issuance are invariably inaccurate because of permit noncompliance. Since noncompliance is a prosecutable offense, any attempt to estimate the rate of noncompliance by direct survey techniques is met with misleading and evasive responses. It has been shown elsewhere that randomized response designs reduce survey response bias to incriminating questions by ensuring respondent anonymity. With the use of the randomized response survey technique, estimates of permit noncompliance were determined for the Capricornia Section of the Great Barrier Reef Marine Park. Noncompliance with the requirement to obtain the prescribed permit was found to be low whereas, once a permit was obtained, noncompliance with specific permit conditions was considered high. Reasons for the high rate of noncompliance with specific conditions are presented, and it is recommended that marine park managers should not unreservedly base management decisions on usage data derived simply from permit issuance.     

EFFECTIVENESS OF DROUGHT POLICIES FOR MUNICIPAL WATER MANAGEMENT1

During the 1976–77 drought, three principal mechanisms were used to reduce water use in Utah communities: price increases, maximum monthly use restrictions, and restrictions on outdoor watering times. A regression model was developed to explain observed changes in water use, with price, type of restriction, household size, and summer rainfall as independent variables. For an average system, a 1 percent increase in price would reduce water use by 0.07 to 0.09 percent. A 1 percent increase in outdoor watering time restriction reduces use by 0.064 to 0.075 percent. A 1 percent increase in quantity restrictions leads to a reduction in water use of 0.014 to 0.054 percent. The effectiveness of rationing policies is influenced by system characteristics. For example, outdoor watering time restrictions were less effective in systems with above average household size and below average monthly use.     

LONG-TERM PATTERNS OF WATER QUALITY IN A MANAGED WATERSHED IN OREGON: 1. SUSPENDED SEDIMENT1

The cumulative effects of forest management activities on water quality at a downstream point were monitored from 1972-1980 during development of a watershed for timber resources. Suspended sediment concentration and turbidity were measured at two hydrologic stations which bracketed a 10-km reach of the Middle Santiam River in the Western Cascades of Oregon as it flowed through an 8000-ha block of intensively managed forest land. Slope failures often accompany road building and harvesting in steep forested watersheds and pose the most serious threat to water quality. Although 180 km of road were constructed and 3400 ha of old-growth forests were harvested from slopes averaging over 60 percent, long-term changes in sediment yields remained undetectable during the period of measurement. The geologic characteristics of the basin and the road construction and maintenance techniques as prescribed by Oregon's forest practice regulations helped to minimize the occurrence of slope failures so that long-term changes in suspended sediment export rates did not occur. Throughout the nine-year measurement period, seven slope failures which added sediment directly to streams produced measurable short-term responses at the downstream sampling location, but these erosion events were too small and too infrequent to produce long-term changes in sediment yield from the watershed.