Watershed Ecology and the Environment最新文献

The coastal area, with its fragile environment and the characteristics of both marine and terrestrial, is getting increasing attention globally, highlighting a critical need to form a systematic management framework. The objectives of this article are to illustrate the status quo of Chinese regional ecological civilization and land-sea integrated development, then combine resilience theory and sustainable development goals (SDGs) of United Nations together for selecting social-ecological indicators to build a resilience assessment matrix applying to the coastal urban area, further explore the core mechanisms of coastal resilience evolution. Accordingly, we suggest a new method of evaluation matrix with 12 indicators, representing the function of the target system in four phases (prepare, absorb, recover and adapt) and three domains (economic, natural resources and eco-environment) respectively, which focusing on the dynamic progress instead of the static situation of the typical and unique urbanizing area is exactly one of its improvements in comparison with other existing assessment tools. The key findings reveal the dificient resilience of Dapeng New District in dealing with the rapid urbanization stressor, as well as its asymmetrical performance among three subsystems within the temporal scope of 2014–2016. Another contribution reflected in the regime shifts of land-sea integration, which uncovers the states of critical functions in the target system, correspondingly outlines how to integrate the land use, water management, and biodiversity conservation into resilience-based management and sustainability for the coastal zone, namely the Land-Water-Biodiversity Nexus. Our scope is taking the typical coastal zone, Shenzhen Dapeng New District, Greater Bay Area of China, as an example, and to promote the research technology in other coastal urban regions.

Microplastics irrespective of their myriad sources eventually are discharged into the world's oceans, posing a serious threat to marine life. Evidence has shown the increasing threat posed by accumulation of microplastics along shore lines and sandy beaches to the species that inhabit these ecosystems. This study evaluates the species at potential risk due to microplastic pollution along the coastal regions of India, through a combination of existing literature and original observations. The harmful effects of microplastics on various classes of aquatic and coastal species through both direct ingestion and indirect consumption by the process of bio-accumulation, have been discussed in this study. The species at risk in other ecosystems such as freshwater lakes, brackish water sites, swamplands and marshlands have also been covered. The various species recorded at these ecosystems were evaluated on the basis of their potential risk of consumption of microplastics. Potential routes for bioaccumulation of microplastics through trophic transfer have been proposed, with special emphasis on the routes involving those species at risk, in order to fill the existing knowledge gaps. Further studies in the Indian scenario are therefore necessary, in order to truly gauge the impact of the bioaccumulation in specific species and on the coastal ecosystem as a whole.

The process of leaf litter breakdown is essential as a main energy source for aquatic life in stream ecosystems. This process is complicated due to the interaction among the stream's physical, chemical, and biological characteristics as well as the composition of litter. This study investigated the variation of litter breakdown rates with different water qualities and microbial activities influenced by dam operation. Litter bags were installed along Nakatsugawa River, which is regulated by Takizawa Dam, and Arakawa River in Saitama Prefecture, central Japan, during autumn and winter. Three dominant leaf species were studied, namely Quercus serrata, Carpinus cordata, and Acer mono. The factors possibly affecting the litter breakdown process were: (1) a 4 °C higher water temperature downstream than upstream of the dam in the Nakatsugawa; (2) high bacterial productivity in the Nakatsugawa; (3) high silt deposition on the litters in the Arakawa; and (4) low contents of Dissolved Organic Carbon (DOC) and nutrients in the Arakawa. In the Nakatsugawa, neither a contribution of the dam to a higher breakdown rate nor recovery of the rate to upstream conditions far downstream was found. However, the breakdown rate was lower in the Arakawa than in the Nakatsugawa. Inorganic deposition on litter, DOC, Na⁺, Mg²⁺, Ca²⁺ and NO₃⁻ were believed to play a main role in litter breakdown.

The Alternative Stable States Model describes the two contrasting conditions of shallow lakes that occur in response to external phosphorus (P) loading: 1) a clear-water, macrophyte-dominated state during times of lesser external P loading, and 2) a turbid, phytoplankton-dominated state during periods of greater P loading. Determination of the P loading rate that distinguishes the two stable states, i.e. the threshold phosphorus loading rate (TPL), is fundamental to shallow-lake science and management. We used data from nine shallow subtropical lakes in Florida (USA) to generate a parsimonious model that predicts the TPL from the hydraulic detention time (HDT). The model reveals that the TPL is more sensitive to changes in HDT in lakes with short (<1 year), as opposed to long (>10 years) HDTs. We compared our results with published data from 54 geographically distributed shallow aquatic systems and found that the Florida-based HDT-TPL model has general applicability. Given many lakes worldwide are shallow, our findings have the potential to improve understanding and management of numerous aquatic ecosystems around the globe.

The assessment of resilience for people, places, and systems to climate-change hazards is essential for understanding how to reduce disaster risks. Globally, a number of resilience assessment methodologies have been developed and implemented by a variety of entities, including national and local organizations, donor agencies, and academic researchers. In Bangladesh, although a number of resilience studies have been conducted, it has never been determined whether these assessments rightfully addressed conceptual understanding, methodological approaches, and disciplinary underpinnings, and maintained compliance with on-going research communications standards. To unpack this gap, we systematically reviewed 38 articles to characterize how the resilience to climate change, of coastal communities in Bangladesh, is being assessed. To operationalize the study, we have presented a brief overview of the assessment tools and then applied an analytical framework containing six criteria: comprehensiveness of dimensions, scalar relationships, temporal dynamism, addressing uncertainties of climate change by modeling and scenario-making, participatory approaches, and action plans. The overview analysis shows diverse traditions of methodological underpinnings, and reveals authors' often incomplete conceptual understandings of resilience. Results of the review analysis reveal extensive inadequacy regarding multiple dimensionality, scalar and temporal scales, and more importantly, addressing the uncertainty of climate change. In relation to comprehensiveness, current literature has failed to consistently comply with global research communication in regard to the criteria of institutional and infrastructural dimensions. More attention needs to be placed on temporal and scalar dynamics. Most importantly, the uncertainty issue is virtually overlooked in the literature, and iterative processes and the development of alternate states of planning through scenario analysis are also critical, for risk reduction and adaptation to climate-change impacts. Substantial emphasis should be given to include all possible stakeholders in the planning and implementation of any climate-change adaptation or mitigation program.

There is a crucial need to achieve a more sustainable management of the world's water resources with serious water scarcity and water pollution. The trans-basin movement of water faces major environmental and engineering challenges and remains controversial. Therefore, improved management of water within basins offers more feasible options to enhance the efficiency of water use. This paper aimed to find out the bottlenecks of integrated catchment management, summarizes the research frontier about integrated catchment management and put forwards some measures, mainly include taking the interaction impacts among water, land and other factors into consideration, evaluating the effectiveness and impacts on different systems of decisions and policies based on appropriate methods, and strengthening watershed management capacity. This paper provides decision-making information for integrated catchment management. The government should strengthen the scientific research in the relationship between water sector and other sectors, and account trans-basin water resources flow. Moreover, participation of different stakeholders is one of key points to promote the success of integrated water resources management (IWRM). Much of the evidence in this paper is from the Heihe River Basin, which is the second largest inland river basin in China. While this evidence comes from a specific area, the integrated economic and environmental modeling presented in this paper can usefully be applied to river basin management elsewhere. Indeed, the international collaboration of researchers evident in this paper is a testament to the worldwide interest in freshwater management issues.

Mangrove wetlands are under increasing pollution pressure from human activities due to rapid industrialization and urbanization of coastal regions. Many pollutants such as heavy metals may be accumulated via food chains to hazardous levels which will thus bring potential health issues to humans. In the present study, three species of crabs (Sesarma dehaani, Sesarma plicata, Macrophthalmus japonicus) and associated sediments from three mangrove habitats with different vegetation were collected from the mangrove wetlands in Qi'ao Island, South China to investigate the levels, bioaccumulation and dietary exposure of heavy metals including copper (Cu), zinc (Zn), manganese (Mn), cadmium (Cd) and chromium (Cr). Metal concentrations in sediment samples were 65–91, 212–247, 506–1256, 0.6–1.3, and 8.8–14 mg/kg dry weight for Cu, Zn, Mn, Cd and Cr, respectively. The spatial heterogeneity of these metals in mangrove sediments was observed with a descendant order of metal concentrations as Mn > Zn > Cu > Cr > Cd at each site. Species-specific and tissue-specific accumulation of metals was also found in mangrove crabs, both in the degree of accumulation of particulate metals and the tissues in which they were most abundant. All biota-sediment accumulation factors (BSAF) values >1 for Cd in each crab species suggested that the native mangrove crabs tended to be good tools for the monitoring of Cd pollution in mangrove forests. Results of the estimated daily intake (EDI) and target hazard quotient (THQ) suggested that consumption of the mangrove crabs in Qi'ao Island might subject local residents to potential health risks as far as the metals are concerned.

Urban runoff from traffic areas is a major source of pollution that degrades the quality of adjacent surface waters. Green infrastructure provided by the substantial amount of roadside land at urban fringe areas can be used to better manage and infiltrate this urban runoff. When establishing urban green areas, recycled materials should be preferred in order to achieve economically feasible and environmentally responsible solutions. Wastewater treatment plants within e.g. the EU yield substantial amounts of solids containing nutrients and metals that need to be utilised in a sustainable way. However, soil composted from such sewage sludge is being used widely in constructing green infrastructure, such as parks and road verges, which may jeopardise their use for stormwater management even though the effects of sewage sludge at road verges on the quality of runoff waters have not been subjected to scientific examination. Biochar has been suggested to retain pollutants and may also meet the criteria of being recycled material. We established artificial biofilter structures, mimicking road verges, in large-scale field lysimeters under cold climatic conditions in southern Finland to study the ability of biochar to retain pollutants leaching from composted sewage sludge and from infiltrating artificial stormwater. The topmost 15 cm consisted of an organic layer of either natural peat (Peat) or soil composted from sewage sludge either mixed with birch-derived biochar (3% by volume) or without this biochar (Comp+bc and Comp, respectively). At the end of the 1st growing period grasses growing in the lysimeters had taken up to 32% of phosphorus in the top soil containing compost. Leaching of phosphorus did not differ between the treatments, while nitrogen (N) leaching was ten time larger from Comp than Peat. Leaching of heavy metals, such as nickel and copper, was also significantly higher from compost soils than peat, but biochar significantly reduced metal leaching from compost (up to 50%). Two years after establishment, lysimeters were irrigated with artificial stormwater mimicking runoff from roads with heavy traffic. Comp leached more N compared to Peat. However, biochar significantly reduced N load infiltrated through the compost by 44%. Mixing sewage sludge-originated compost with biochar, and adding a 5 cm thick layer of biochar underneath the organic soil layer can substantially reduce leaching of N and heavy metals. However, given the substantial amount of roadsides in urban fringe areas, the extensive use of sewage sludge and other N-rich materials in such areas should be considered carefully.