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갯벌 매립사업 환경평가 개선방안에 관한 연구 맹준호|조광우|김호석|박하늘|홍재상|유재원|이창근
Abstract
Tidal flats play many important roles in maintaining coastal environment by eliminating inorganic salts and organic matters from land, by purifying sea water, and by providing enriching microalgae to animals through food chains in tidal flat ecosystem. In addition it is noticed that salt plants in the tidal flat works as ʹcarbon sink.
These values of tidal flat have been recognized for a long time, but ʹpreservationʹ has been a dead word for tidal flat in Korea because of urgent demand for ʹdevelopment.ʹ Therefore, how to properly implement environmental assessment on tidal flat reclamation is very important. But current methods of environmental assessment on tidal flat reclamation lack of clear guidelines and do not provide enough information to understand and predict potential impacts of tidal flat development on environment.
So far, environmental assessment on tidal flats has been implemented without properly evaluating functions, values, and economic cost‐benefit of tidal flats. Lack of thoughtful survey, in turn, contributed to excessive tidal flat development. If the current environmental assessment on tidal flat development continues, it will continue to destroy tidal flat. Therefore, to minimize impacts of tidal flat reclamation on environment, the study researched following alternatives: improving EA on tidal flat ecosystem, tidal flat value assessment and economic assessment, and mitigation measures of tidal flat reclamation.
First, the study provided methodology to survey profiles of tidal flat ecosystem. It proposed measures to improve survey planning, identification of environmental characteristics, range of survey site, survey period, map‐making of habitats of investigation sites, survey of coastal environmental quality and monitoring based upon examining problems of existing survey. Furthermore, it showed methods to predict impacts in the form of checklists.
Second, it showed alternatives to existing value assessment of tidal flat ecosystem by examining existing problems of value assessment of pollution purification and marine biota production. In the case of evaluation of marine biota production, the study estimated an ecosystem model to reflect energy flow among ecosystem constituents and examine food chains in tidal flat ecosystem. In the case of value assessment of pollution purification, existing problems were identified as follows;
1) Most of studies rely on BOD removal value of Odum.
2) Attempts to assess value based upon measured function have been not made enough.
3) Most studies based on the field or laboratory are heavy on limited functional groups (mainly microorganisms).
4) Functions of meiobenthos or macrobenthos have been ignored. Particularly, roles of the latter have been underestimated and, high standing crops to other biota and effects of producing crops have been dropped in assessing functions of purification.
To solve these problems, this study assessed the value by calculating standing and production crops of biological constituents in tidal flat ecosystem and converting the amount of carbon removed from them according to cost basis of the function of pollution purification of sewage processing terminal. The result shows that the amount reduced by tidal flat ecosystem amounted to about 1000 ton C/㎢/year. This has the value of about 34,000,000(KRW) per ha. In other words, it has 3.3 to 95 times as much as value range (3,600,000 to 12,000,000 (KRW)) of purification set by Ministry of Maritime Affairs and
Fisheries.
Third, it proposed an alternative to improve economic assessment of tidal flat reclamation. In order to implement effective economic assessment of tidal flat reclamation, the study proposed following improvements;
1) Comprehensive review of diverse functions of tidal flat
2) Development indicators capable of estimating ecological, socio‐cultural, and economic functions of tidal flat
3) Development and application of diverse value assessment methods
4) Thoughtful analysis of stakeholder related to tidal flat
5) Establishment of long‐term planning for tidal flat management
Problem of existing economic assessment of tidal flat development is that economic benefits of development is inflated while environmental and indirect costs are rarely scrutinized. Therefore, there needs to examine the latter more carefully. In addition, diverse alternatives need to be discussed in current economic assessment. Alternatives to develop harbors and industrial complexes in places other than tidal flats should be considered in economic assessment.
This study aimed at proposing alternatives to evaluate ecosystem and economic assessment of tidal flat reclamation as to minimize adverse impacts of tidal flat reclamation projects on environment. Eventually, alternatives discussed in the study will contribute to sustainable coastal development through rational environmental impact assessment on tidal flat.
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An increasing amount of information is being collected on the ecological and socio-economic value of goods and services provided by natural and semi-natural ecosystems. However, much of this information appears scattered throughout a disciplinary academic literature, unpublished government agency reports, and across the World Wide Web. In addition, data on ecosystem goods and services often appears at incompatible scales of analysis and is classified differently by different authors. In order to make comparative ecological economic analysis possible, a standardized framework for the comprehensive assessment of ecosystem functions, goods and services is needed. In response to this challenge, this paper presents a conceptual framework and typology for describing, classifying and valuing ecosystem functions, goods and services in a clear and consistent manner. In the following analysis, a classification is given for the fullest possible range of 23 ecosystem functions that provide a much larger number of goods and services. In the second part of the paper, a checklist and matrix is provided, linking these ecosystem functions to the main ecological, socio–cultural and economic valuation methods.
Lack of basic understanding of ecosystem structure and function forms a major impediment to successful conservation of coastal ecosystems. This paper provides a description of the fauna and examines faunal succession inSalicornia -vegetated sediments of southern California. Environmental attributes (vegetation and sediment properties) and macrofaunal (animals ≥0·3mm) community structure were examined in sediments of five natural, southern CaliforniaSalicornia spp. marshes (Tijuana Estuary, San Diego Bay, Mission Bay, Upper Newport Bay and Anaheim Bay) and in createdSalicornia marshes 16 months to 10 years in age, located within four of the bays. Oligochaetes and insects were the dominant taxa in both natural (71 to 98% of total fauna) and created (91 to 97%) marshes. In San Diego, Newport and Anaheim Bays, macrofaunal densities were generally higher in the created marshes (88000 to 290000 ind m−2) than in their natural counterparts (26000 to 50000 ind m−2). In the youngest system, Mission Bay, the reverse was true (natural: 113000 vs created: 28000 ind m−2). Similar species numbers were recorded from the created and adjacent natural marshes. Insects, especially chironomids, dolichopodids, and heleids, as well as the naidid oligochaete, Paranais litoralis, characterize early successional stages. Enchytraeid and tubificid oligochaetes reflect later succession evident in natural and older created marshes. Sediment organic matter (both combustible and below-ground plant biomass) was the environmental variable most commonly associated with densities of various macrofaunal taxa. These relationships were generally negative in the natural marshes and positive in the created marshes. Within-bay comparisons of macrofauna from natural Salicornia- vs Spartina -vegetated habitat in San Diego and Mission Bays revealed lower macrofaunal density (San Diego Bay only), proportionally fewer oligochaetes and more insects, and no differences in species richness in the Salicornia habitat. The oldest created Salicornia marsh (San Diego Bay) exhibited an assemblage intermediate in composition between those of the natural Salicornia- and Spartina- vegetated marshes. These results suggest: (a) faunal recovery following Salicornia marsh creation can require 10 or more years, (b) high macrofaunal variability among bays requires marsh creation reference site selection from within the same bay, and (c)Spartina -based research should not be used for Salicornia marsh management decisions.
Tidal flats in China occur on a larger scale and are associated with two different types of coast. The total length of coastline represented by tidal flat is about 4000 km long. The tidal flat coast is dominated by tidal processes and is often associated with a large sediment supply.
Uses both an economic willingness-to-pay and an energy analysis method of establishing the social value of a wetlands system. The economic approach considers the commercial, recreational and storm protection value of wetlands. The energy analysis evaluates the energy processed by the wetlands system. These methods are applied to the wetlands system in S Louisiana. -Authors
Economic valuation can be defined as the attempt to assign quantitative and monetary values to goods and services provided by environmental resources or systems, whether or not market prices are available to assist us. When market prices are not available (e.g., for flood control services, for disaster mitigation services, for erosion avoidance…), the value is established by the willingness to pay for the good or service, whether or not we actually make any payment. A major problem in assessing the value of ecosystems arises when the services provided, such as climate change regulation or biodiversity conservation, benefit the global community. However, this short introduction will not deal with valuation of ecosystems global services. Why estimate ecosystem value? Environmentalists sometimes question the need to always put a price tag on nature and assert that nature has an intrinsic value, that it is our long-term life support system and that this is reason enough to protect it. They are of course totally right but the reality of life on this planet unfortunately shows that many people do not share this view. Especially (but not only) those who suffer from hunger and understandably try to get the most out of wetlands in the short term. If they are hungry today, they will not care about what happens tomorrow -even less in 20 years from now! But people in developing countries do not have the privilege of this short-term approach. People in developed countries often also have restricted vision and prefer to maximize their immediate benefits rather than to secure them for the long term. This being a realistic view of life on Earth, we have to work with it. We therefore think that when one cannot reasonably expect to change a situation in the short term, it is better to try to make the best of it and exert influence to mitigate its negative effects on the environment.
Energy (biomass) and energy flows (production, inputs, transfers and respiration) were calculated for seven compartments (phytoplankton, benthic primary producers, zooplankton, benthic macro- fauna, fish, birds and particulate organic matter (POM)) of the Dublin Bay system. The resultant model was analysed with the SCOR network analysis package. The most prominent feature of the model was the importance of the allochthonous input of POM and the processing through the macroinvertebrates. Network analysis suggested that Dublin Bay showed the characteristics of a coastal:estuarine system, although the total system energy throughput was rather low. Indices of the system itself suggested that it was in an immature, developing stage (sensu Odum 1969) which would show low resilience and thus be sensitive to external perturbations.
For decades researchers have concentrated on proving that C is exported from salt marshes to coastal waters, with limited success. Yet, the C retained in the marsh soils may be equally important. Presumptions that minor amounts of C are stored in salt marsh soils are based upon measurements of low percentages of C in many marshes. Simply measuring the organic matter content of marsh soils provides little indication of the amount or rate of C stored, as this parameter is based upon the percent by mass of the soil. The critical parameter to calculate is C density, derived from percent organic matter and bulk density. (The latter is often neglected in marsh soil studies.) Calculation of C density reveals that minerogenic soils with high bulk densities may have C densities or C storage rates equivalent to more organic soils with low bulk densities. A global average soil C density of 0.055 ± 0.004 g cm-3 has been calculated from 107 measurements reported for salt marshes around the world (Gulf of Mexico, NE and NW Atlantic, Mediterranean and NE Pacific). Assuming an average marsh soil depth of 0.5 m and using inventories of marsh area available for Europe, Scandinavia, Africa, Canada and the U.S., the C stored globally in salt marshes is greater than 430 ± 30 Tg C. The global carbon storage could be twice this as there are no marsh inventories available for Asia or South America. Rates of C storage can be calculated from 96 C density measurements where soil accretion rates also were measured. Globally, marshes sequester an average of 210 g CO2 m-2 yr-1, an order of magnitude greater than rates reported for peatlands. Salt marsh C storage can have regional importance. At a magnitude of 5 Tg C yr-1, tidal wetlands comprise 1--2 percent of the C sink (300--580 Tg C yr-1) estimated for the coterminous U.S. In the Bay of Fundy restoration of salt marshes reclaimed for agricultural land could enable sequestration of an additional 240 to 360 Gg C yr-1, equivalent to 4 to 6 percent of Canada's targeted reduction of 1990-level emissions of CO2 under the Kyoto Protocol. The C sink in salt marsh soils has advantages over those in freshwater wetlands or terrestrial soils. Presence of abundant sulfate limits release of the potent greenhouse gas, methane, which can be released in substantial quantities from freshwater wetland soils. In salt marshes, turnover of C occurs on time scales of hundreds to thousands of years, whereas the C content of terrestrial soils reaches equilibrium in decades to 100 yr. In many marshes C sequestration will continue or perhaps increase with higher rates of sea level rise accompanying global warming, as soil accretion rates will be greater. However, human impacts on many salt marshes (altering hydrological regimes or displacing sediment supplies), such as those of the Mississippi Delta, limits their sustainability in the face of higher rates of sea level rise and the future of these C sinks is threatened. Future research on C storage in salt marshes must be directed at local controls, for there is as much variability in a single region (e.g., Long Island Sound or the Bay of Fundy) as there is globally. Intensive sampling at multiple elevations in a single marsh reveals C densities to be significantly greater at higher elevations, but rates of C accumulation decline with elevation. Controlling for this variability in elevation reveals that C density decreases with average annual temperature, thus greater understanding of local processes are critical to detect global patterns.