Estuary planning and management: the case of Vouga Estuary (Ria de Aveiro), Portugal

Estuarine areas often concentrate complex and conflicting sets of natural, economic and social resources and activities with multiple challenges to planning and management approaches as well as to governance practices. Using a set of integration factors depicted from the literature review, the paper analyzes the main features of the new set of the Portuguese estuary types of plans and assesses their potential added value, while focusing the analysis on the estuary of the Vouga River (Ria de Aveiro). The results are twofold. On the one side, their uniqueness, by treating the estuary as a planning unit, integrating the water resources and the land use planning systems and by establishing mandatory rules for the estuary uses, embodies relevant potential for reducing boundary tensions and to improve integrative approaches. On the other side, while at the level of plan content the contribution of the Portuguese Estuary Land Use and Management Plans (Planos de Ordenamento de Estuário) legislation brings strong new prospects for integration, at the level of planning process and implementation, further efforts should be undertaken. Their added value, especially in complex institutional and societal estuarine contexts, such as the Ria de Aveiro, strongly depends on more robust participation schemes through which knowledge, institutions, aims and measures are articulated in a collective vision and shared governance process.     

Using a Multi-Component Indicator Toward Reducing Phytoplankton Bloom Occurrences in the Swan River Estuary

The Swan River estuary is an icon of the city of Perth, Western Australia, running through the city centre and dividing the northern from the southern part of the city. However, frequent phytoplankton blooms have been observed in the estuary as a result of eutrophication. The Index of Sustainable Functionality (ISF), a composite index able to indicate for sustainable health of the estuary, was applied, taking into account the hydrology and highly seasonal nature of the estuary to inform the management of the estuary, towards the aim of reducing bloom occurrences. The study period was from the beginning of intensive monitoring in 1995 to mid-2009. The results emphasize the importance of physical controls on the ecology of the estuary. No significant trend in the estuary's low functionality was found, indicating that despite extensive restoration efforts, the frequency of algal bloom occurrences has remained relatively stationary and other mitigating factors have maintained an annual average ISF value at around 70 % functionality. We identified that the low flow season consistently performs the worst, with (high) temperature found as the most dominant variable for phytoplankton growth and bloom. Thus in managing the estuary, vigilance is required during periods of high temperature and low flow. Focusing on the risk of phytoplankton bloom, a nutrient reduction program that is in place is a long term solution due to high concentrations in the estuary. Other management measures need to be considered and adopted to effectively reduce the occurrences of future phytoplankton blooms.     

Transboundary Pollution between Guangdong Province and Hong Kong: Threats to Water Quality in the Pearl River Estuary and Their Implications for Environmental Policy and Planning

The Pearl River (Zhujiang) is the largest river system in southern China. The river, which is approximately 2200 km long, discharges into the South China Sea through an extensive deltaic area to the west of Hong Kong. Water quality in the river is under threat from a variety of sources associated with industrializationand urbanization in the Pearl River Delta Region (PRDR). Hong Kong's location on the eastern bank of the Pearl River estuary means that the quality of its western marine waters is likely to be increasingly influenced by the Pearl's pollution burden. Little published material exists on pollution in the Pearl River, or the potential impacts of transboundary pollution on marine water quality in Hong Kong. This paper focuses on this issue of transboundary water pollution between the Delta Region and Hong Kong. Specifically, we present the results of a preliminary analysis of water quality data for the Pearl River. The paper demonstrates that the major potential problem affecting the Pearl River is organic pollution, and that the principal sources of pollution affecting the Pearl River estuary, and consequently Hong Kong's western waters, are the Shenzhen River, the upstream Guangzhou section of the Pearl River, and the Dongguan Canal. We estimate that less than 5% of untreated domestic sewage discharges affecting the estuary derive from Hong Kong itself. The paper also discusses the implications of transboundary pollution in the context of environmentalpolicy making in Hong Kong and argues that more extensive and effective co-operation and collaboration between Hong Kong and mainland agencies should be developed to address these concerns.     

Potential Impacts and Management Implications of Climate Change on Tampa Bay Estuary Critical Coastal Habitats

The Tampa Bay estuary is a unique and valued ecosystem that currently thrives between subtropical and temperate climates along Florida’s west-central coast. The watershed is considered urbanized (42 % lands developed); however, a suite of critical coastal habitats still persists. Current management efforts are focused toward restoring the historic balance of these habitat types to a benchmark 1950s period. We have modeled the anticipated changes to a suite of habitats within the Tampa Bay estuary using the sea level affecting marshes model under various sea level rise (SLR) scenarios. Modeled changes to the distribution and coverage of mangrove habitats within the estuary are expected to dominate the overall proportions of future critical coastal habitats. Modeled losses in salt marsh, salt barren, and coastal freshwater wetlands by 2100 will significantly affect the progress achieved in “Restoring the Balance” of these habitat types over recent periods. Future land management and acquisition priorities within the Tampa Bay estuary should consider the impending effects of both continued urbanization within the watershed and climate change. This requires the recognition that: (1) the Tampa Bay estuary is trending towards a mangrove-dominated system; (2) the current management paradigm of “Restoring the Balance” may no longer provide realistic, attainable goals; (3) restoration that creates habitat mosaics will prove more resilient in the future; and (4) establishing subtidal and upslope “refugia” may be a future strategy in this urbanized estuary to allow sensitive habitat types (e.g., seagrass and salt barren) to persist under anticipated climate change and SLR impacts.     

Use of Sediment Risk and Ecological/Conservation Value for Strategic Management of Estuarine Environments: Sydney Estuary,Australia

Sediment mantling the floor of Sydney estuary contains a wide range of chemicals at highly elevated concentrations over extensive areas. Appropriate sediment management decisions are urgently required to prevent further degradation of sediment quality and to minimize resulting adverse ecological effects. The objective of the present work was to provide a systematic, estuary-wide assessment of sediment risk and ecological/conservation value throughout the harbor to guide sediment management decisions. Sediment risk is the likelihood of sediment chemistry causing adverse biological effects to bottom-dwelling animals and was conducted using national sediment quality guidelines (SQGs) for single contaminants and the mean SQG quotient approach to assess chemical mixtures. Sediment risk was negligible at the mouth of the estuary, but increased strongly landwards. The ecological/conservation value assessment was conducted to identify sites that warrant different levels of protection and was conducted using the value of ecological communities and priority waterway use. Consideration of these two parameters combined enabled the estuary to be prioritized for management attention. The prioritization and identification of appropriate management strategies were determined through the use of management matrices also based on sediment risk and ecological/conservation value. A computer package is being developed to provide managers with information on sediment risk, ecological/conservation value, the urgency and the type of management intervention required for any location in Sydney estuary, in real-time. This approach to estuarine management is unique and will greatly improve effective management of Sydney estuary, and other harbors in urgent need of management action and protection.     

Study of Fractionation and Potential Mobility of Metal from the Guadalquivir Estuary: Changes in Mobility with Time and Influence of the Aznalcollar Mining Spill

This study analyzed the evolution of metal levels in surface sediments from the Guadalquivir estuary between 1997 and 2002 and assessed the impact of the April 1998 Aznalcollar tailings dam failure and subsequent cleanup on metal concentrations in surface sediments. We also analyzed metal distribution with time in five chemical fractions of the surface sediments: exchangable, carbonate, reducible, oxidizable, and residual. This work showed that the April 1998 Aznalcollar tailings dam failure caused a considerable increase in the concentrations of Cd, Zn, Cu, and Pb in the surface sediments of the Guadalquivir estuary. It was also found there was a change in the distribution of Cd, Zn, Cu, and Pb between the chemical fractions of the sediment after the failure of the dam. There were increases in the percentages of Cd in the carbonate fraction, of Zn and Pb in the reducible fraction, and of Cu in the oxidizable fraction, whereas the percentages of these elements associated with the residual fraction decreased. In 1999, there was a decrease in the metal concentrations in the surface sediments from the Guadalquivir estuary, and by 2000 the chemical distribution and metal levels had returned to levels similar those before the dam failure.     

Spatiotemporal variability of wet atmospheric nitrogen deposition to the Neuse River Estuary, North Carolina

Excessive nitrogen (N) loading to N-sensitive waters such as the Neuse River estuary (North Carolina) has been shown to promote changes in microbial and algal community composition and function (harmful algal blooms), hypoxia and anoxia, and fish kills. Previous studies have estimated that wet atmospheric deposition of nitrogen (WAD-N), as deposition of dissolved inorganic nitrogen (DIN: NO3-, NH3/NH4+) and dissolved organic nitrogen, may contribute at least 15% of the total externally supplied or "new" N flux to the coastal waters of North Carolina. In a 3-yr study from June 1996 to June 1999, we calculated the weekly wet deposition of inorganic and organic N at eleven sites on a northwest-southeast transect in the watershed. The annual mean total (wet DIN + wet organics) WAD-N flux for the Neuse River watershed was calculated to be 956 mg N/m2/yr (15026 Mg N/yr). Seasonally, the spring (March-May) and summer (June-August) months contain the highest total weekly N deposition; this pattern appears to be driven by N concentration in precipitation. There is also spatial variability in WAD-N deposition; in general, the upper portion of the watershed receives the lowest annual deposition and the middle portion of the watershed receives the highest deposition. Based on a range of watershed N retention and in-stream riverine processing values, we estimate that this flux contributes approximately 24% of the total "new" N flux to the estuary.     

A Modeling System to Assess Land Cover Land Use Change Effects on SAV Habitat in the Mobile Bay Estuary

Estuarine ecosystems are largely influenced by watersheds directly connected to them. In the Mobile Bay, Alabama watersheds we examined the effect of land cover and land use (LCLU) changes on discharge rate, water properties, and submerged aquatic vegetation, including freshwater macrophytes and seagrasses, throughout the estuary. LCLU scenarios from 1948, 1992, 2001, and 2030 were used to influence watershed and hydrodynamic models and evaluate the impact of LCLU change on shallow aquatic ecosystems. Overall, our modeling results found that LCLU changes increased freshwater flows into Mobile Bay altering temperature, salinity, and total suspended sediments (TSS). Increased urban land uses coupled with decreased agricultural/pasture lands reduced TSS in the water column. However, increased urbanization or agricultural/pasture land coupled with decreased forest land resulted in higher TSS concentrations. Higher sediment loads were usually strongly correlated with higher TSS levels, except in areas where a large extent of wetlands retained sediment discharged during rainfall events. The modeling results indicated improved water clarity in the shallow aquatic regions of Mississippi Sound and degraded water clarity in the Wolf Bay estuary. This integrated modeling approach will provide new knowledge and tools for coastal resource managers to manage shallow aquatic habitats that provide critical ecosystem services.     

Assessing the Effects of Nutrient Management in an Estuary Experiencing Climatic Change: The Neuse River Estuary, North Carolina

Eutrophication is a serious water quality problem in estuaries receiving increasing anthropogenic nutrient loads. Managers undertaking nutrient-reduction strategies aimed at controlling estuarine eutrophication are faced with the challenge that upstream freshwater segments often are phosphorus (P)-limited, whereas more saline downstream segments are nitrogen (N)-limited. Management also must consider climatic (hydrologic) variability, which affects nutrient delivery and processing. The interactive effects of selective nutrient input reductions and climatic perturbations were examined in the Neuse River Estuary (NRE), North Carolina, a shallow estuary with more than a 30-year history of accelerated nutrient loading and water quality decline. The NRE also has experienced a recent increase in Atlantic hurricanes and record flooding, which has affected hydrology and nutrient loadings. The authors examined the water quality consequences of selective nutrient (P but not N) reductions in the 1980s, followed by N reductions in the 1990s and an increase in hurricane frequency since the mid-1990s. Selective P reductions decreased upstream phytoplankton blooms, but increased downstream phytoplankton biomass. Storms modified these trends. In particular, upstream annual N and P concentrations have decreased during the elevated hurricane period. Increased flushing and scouring from storms and flooding appear to have enhanced nutrient retention capabilities of the NRE watershed. From a management perspective, one cannot rely on largely unpredictable changes in storm frequency and intensity to negate anthropogenic nutrient enrichment and eutrophication. To control eutrophication along the hydrologically variable freshwater–marine continuum, N and P reductions should be applied adaptively to reflect point-source–dominated drought and non–point-source–dominated flood conditions.     

Perceptions about Environmental Use and Future Restoration of an Urban Estuary

Recent interest in restoring urban ecosystems has engendered studies on public perceptions of these ecosystems and future land use. This paper examines the perceptions of people using the waterfront area of the New York/New Jersey harbour estuary about their use of the area, and how this environment could be improved. Pollution was viewed as the most important problem in New Jersey, and removing pollution was rated the most important way to improve the waterfront habitat. Using the remaining undeveloped area for natural habitat and to improve quality of life were rated as the most important uses of the waterfront. People valued the waterfront for walking, providing open green space, and as a place to commune with nature without people. Management options people favoured were removing pollution and cleaning up rubbish and adding educational signs and information brochures about the remaining, natural habitat. Age, income and education influenced which activities people said they undertook. For improvements to the waterfront: Hispanics rated adding educational signs and creating information brochures higher, Blacks rated building promenades as more important, and Asians and Whites rated improving habitat for birds and butterflies more important than others. The data indicate that the public has a firm understanding of the big picture (pollution in the region and locally), habitat improvement, and of the small improvements that can be done locally. Planners and managers could move forward on three fronts: source reduction, wildlife habitat improvement, and amenity (signs, brochures, cleaning up rubbish) development. Understanding how people use an environment, and wish to improve it, can provide valuable information for future restoration and management of urban environments generally, as well as for structuring a citizen advisory committee.     

A LOOK AT THE HUDSON RIVER ESTUARY1

This paper provides background information on the effect of tide waves upon the movement of water in the Hudson River estuary. Computations based on records from three continuous stage recorders and current-meter discharge measurements made throughout a tidal cycle show that peak discharge rates in the estuary at Poughkeep-sie may be as great as 500,000 cubic feet per second and that total daily tidal volumes as great as 20 billion cubic feet move in the estuary. Computation of water movement in the estuary requires precise field data and continued efforts are needed to perfect the data-collection system and the computation procedure in order to adequately define water movement in the Hudson estuary.     

WATER QUALITY AND SOURCE OF FRESHWATER DISCHARGE TO THE CALOOSAHATCHEE ESTUARY,FLORIDA1

ABSTRACT: The Caloosahatchee River has two major sources of freshwater one from its watershed and the other via an artificial connection to Lake Okeechobee. The contribution of each source to the freshwater discharge reaching the downstream estuary varies and either may dominate. Routine monitoring data were analyzed to determine the effects of total river discharge and source of discharge (river basin, lake) on water quality in the downstream estuary. Parameters examined were: color, total suspended solids, light attenuation, chlorophyll a, and total and dissolved inorganic nitrogen and phosphorus. In general, the concentrations of color, and total and dissolved inorganic nitrogen increased, and total suspended solids decreased, as total discharge increased. When the river basin was the major source, the concentrations of nutrients (excepting ammonia) and color in the estuary were relatively higher than when the lake was the major source. Light attenuation was greater when the river basin dominated freshwater discharge to the estuary. The analysis indicates that water quality in the downstream estuary changes as a function of both total discharge and source of discharge. Relative to discharge from the river basin, releases from Lake Okeechobee do not detectably increase concentrations of nutrients, color, or TSS in the estuary.     

长江入海口北支沿海滩涂养殖区底泥重金属污染特征及趋势评价

对长江入海口北支沿海滩涂养殖区底泥重金属污染的总体水平进行调查,结果表明,滩涂养殖区底泥重金属含量满足海洋沉积物质量一类标准要求,污染程度属于安全Ⅰ级水平,重金属潜在生态危害属轻微级别,6种重金属潜在生态危害由大到小排序依次为Cd﹥Hg﹥Cu﹥Cr﹥Pb﹥As,2005年～2011年,底泥重金属污染程度均处于安全的Ⅰ级水平。     

垃圾微波裂解及资源化利用技术

概述了我国城市垃圾处理现状,介绍了国内外现有城市垃圾处理技术,对各种垃圾处理工艺进行了简要评述;并介绍了一种先进的垃圾微波裂解及资源化利用技术,分析了该技术的特点、先进性和经济性等。     

海洋溢油和含油废水排放的对策

海洋是人类赖以生存的第二大场所。开发海洋石油资源必须做到既要把石油资源开采出来，又要保护海洋生态环境不遭受污染。概述了溢油的污染机理、计算方法、预防措施。     

A Review of Habitat Connectivity Research for Pacific Salmon in Marine,Estuary, and Freshwater Environments

Long‐term conservation planning for diadromous fishes would benefit from a better understanding of both the role of connectivity among environments and habitat variability in the expression of life‐history diversity. Most of the scientific knowledge on habitat fragmentation and connectivity has been developed in terrestrial systems in the discipline of landscape ecology. Research on habitat connectivity in aquatic systems (e.g., salmonid research that spans the spectrum of habitats from freshwater to the sea) is uncommon and largely focused on barriers to fish passage. Here, we present a review of the literature characterizing current research patterns on habitat connectivity within and among environments for Pacific salmon. We found this topic is still incipient: the literature is dominated by studies of freshwaters, with few articles focusing on habitat needs in estuary and marine systems. Pan‐environment studies are rare, pointing to a gap in our understanding of complex habitat relationships that might be significant in the development of long‐term conservation and restoration plans for Pacific salmon, particularly in light of the potential impact of climate change.     

Epipellic Algae Profile of the Mixohaline Mangrove Swamp of Qua Iboe River Estuary (Nigeria)

The epipellic algae of Qua Iboe Estuary was studied in late summer (between January and February) of 1999. Physicochemical analysis of the tidal mud flats of the Estuary revealed a mixohaline habitat characterized by its high acidity (pH 4.72±0.02) and rich nutritive salts content. The results of the phytoplankton studies revealed variation in the density of the microalgae within the microalgal Orders. The epipellic algae community was predominated by pinnate diatoms. The mean densities of the phytoplanktons ranged from 102.75 organism/ha, 34.25 organism/ha, 21.25 organism/ha to 1.00 organism/ha of Pennales, Centrales, Zygnematales and Blue-Green algae, respectively. Their densities, however, decreased with increase in sampling distance from the low tide level. At the species level, Actinoptychus undulatus and Tabellaria sp. predominate the microalgae community. The occurrence of the freshwater diatom, A. undulatus, in an otherwise harsh salty epipellic habitat confirms the adaptive potential of some freshwater phytoplankton to marine ecosystem. Other phytoplankter present in the epipellic habitat of the estuary were Amphora ovalis, Campylodis cibrosus, Cymbella lanceolata, Navicular radiosa, N. rhynocephala, Pleurosignma sp., Pinnularia viridis, Stephanodiscus sp., Closterium sp., Oscillatoria nigroviridis and Nodularia spumigena.     

Chaotic Behavior and Pollution Dispersion Characteristics in Engineered Tidal Embayments: A Numerical Investigation1

Abstract: This paper presents a numerical investigation of approaches to enhance the mixing and dispersion processes in tidal areas by effecting changes in the natural estuary system. It compares the impact of various estuary modifications stemming from human intervention to pollutant dispersion and chaotic flow within the estuary including the implications of alteration of the original channel shape, change of the channel bathymetry, and modification of the tidal signal. Our findings indicate that chaotic flow analysis is similar in many regards, but not all, to conventional dispersion analysis. Specifically, we conclude that (1) simplification of the flow regime reduces chaotic flow patterns and tracer particle dispersion, (2) creation of extensively protruding barriers and/or installation of barriers on opposite sides of the main stem of the estuary enhances particle dispersion and chaotic mixing, (3) installation of underwater berms has relatively minor beneficial, but highly localized, effects on chaotic regime and particle dispersion, and (4) increasing the tidal signal amplitude was shown to increase chaotic and dispersion properties of the estuarine system. A parametric study investigating the effect of several geometrical configurations and tidal signals on characteristics of chaotic flows concludes the paper.     

Estimating Relevance of Organic Carbon,Nitrogen, and Phosphorus Loads to a Blackwater River Estuary1

Abstract: In blackwater river estuaries, a large portion of external carbon, nitrogen, and phosphorus load are combined in complex organic molecules of varying recalcitrance. Determining their lability is essential to establishing the relationship between anthropogenic loads and eutrophication. A method is proposed in which organic C, N, and P are partitioned into labile and refractory forms, based upon first‐order decay estimated by biochemical oxygen demand relative to total organic carbon, and C:N and C:P ratios as a function of organic carbon lability. The technique was applied in developing total maximum daily loads for the lower St. Johns, a blackwater Atlantic coastal plain river estuary in Northeast Florida. Point source organic nutrients were determined to be largely labile. Urban runoff was found to have the highest relative labile organic N and P content, followed by agricultural runoff. Natural forest and silviculture runoff were high in refractory organic N and P. Upstream labile C, N, and P loads were controlled by autochthonous production, with 34‐50% of summer total labile carbon imported as algal biomass. Differentiation of labile and refractory organic forms suggests that while anthropogenic nutrient enrichment has tripled the total nitrogen load, it has resulted in a 6.7‐fold increase in total labile nitrogen load.     

Environmental impact assessment for Xiaolangdi Yellow River multi-purpose economic-cumenvironmental improvement project

Summary The Yellow River is renowned for its life-endangering floods, a problem augmented by the continuous heavy siltation of its lower flood plain. Major dam and reservoir projects have both positive and negative environmental impacts, and their construction requires careful environmental consideration. This paper outlines the key findings of environmental impact assessment reports related to the Xiaolangdi Yellow River dam/reservoir project. The authors conclude that the project, as planned, should provide an optimal mix of both economic and environmental benefits.This paper is modified from a presentation given to the 1993 Annual Meeting of the International Association for Impact Assessment (IAIA) in Shanghai, China.