Land Ocean Interaction Research Articles

Nutrient budgets in the Piratininga-Itaipu lagoon system (southeastern Brazil): effects of sea-exchange management

The Piratininga-Itaipu Lagoon System and its drainage basin, located on the southeastern coast of Brazil, Niterói (RJ), has been the target of an intense process of urbanization over the last four decades. As a result of this process, both the lagoon and the adjacent sea area have shown signs of eutrophication due to the release of large quantities of domestic sewage semi (or not) treated. In an attempt to minimize these effects, in 2008 the government re-established a connection between the Piratininga lagoon and the sea. To evaluate changes and variations in the balance of dissolved inorganic nutrients, before and after interventions, the geochemical model of two stoichiometric mass balance boxes of the "LOICZ Program” (Land-Ocean Interactions in the Coastal Zone) was used. The salt and water balance showed different water residence times in the Piratininga lagoon for the two periods: 2005-2006 (before the opening of the connection between the Piratininga lagoon and the sea) and 2009-2010 (after the opening of the connection with the sea). The first period showed a value about two times higher than that obtained for 2009-2010, τ = 83 and 39 days respectively. The water residence time of the Itaipu lagoon did not show great variations between the two periods (τ = 9 and 8 days). For the period of 2005-2006, before the opening of the connection with the sea, both the lagoons were autotrophic (∆DIP > 0) and nitrogen loss was predominant (∆DIN < 0). The second period (2009-2010) was characterized by changes only in the trophic state of the Piratininga lagoon, which became heterotrophic (∆DIP > 0).

Temporal-spatial variation of DOC concentration, UV absorbance and the flux estimation in the Lower Dagu River, China

Dissolved organic carbon (DOC) is an important component for both carbon cycle and energy balance. The concentration, UV absorbance, and export flux of DOC in the natural environment dominate many important transport processes. To better understand the temporal and spatial variation of DOC, 7 sites along the Lower Dagu River were chosen to conduct a comprehensive measurement from March 2013 to February 2014. Specifically, water samples were collected from the Lower Dagu River between the 26th and 29th of every month during the experimental period. The DOC concentration (CDOC) and UVabsorbance were analyzed using a total organic carbon analyzer and the ultraviolet-visible absorption spectrum, and the DOC export flux was estimated with a simple empirical model. The results showed that the CDOC of the Lower Dagu River varied from 1.32 to 12.56 mg/L, consistent with global rivers. The CDOC and UV absorbance showed significant spatial variation in the Dagu River during the experiential period because of the upstream natural processes and human activities in the watershed. The spatial variation is mainly due to dam or reservoir constructions, riverside ecological environment changes, and non-point source or wastewater discharge. The seasonal variation of CDOC was mainly related to the source of water DOC, river runoff, and temperature, and the UV absorbance and humification degree of DOC had no obvious differences among months (P<0.05). UV absorbance was applied to test the CDOC in Lower Dagu River using wave lengths of 254 and 280 nm. The results revealed that the annual DOC export flux varied from 1.6 to 3.76 × 105 g C/km2/yr in a complete hydrological year, significantly lower than the global average. It is worth mentioning that the DOC export flux was mainly concentrated in summer (~90% of all-year flux in July and August), since the runoff in the Dagu River took place frequently in summer. These observations implied environment change could bring the temporal-spatial variation of DOC and the exports, which would further affect the land-ocean interactions in the Lower Dagu River and the global carbon cycle.

Provenance study of the Holocene sediments in the Changjiang (Yangtze River) estuary and inner shelf of the East China sea

The source to sink process of terrigenous sediment from East Asia continent to the marginal seas is crucial for the understanding of land–ocean interaction and marine sedimentary process in the West Pacific continental margin. This paper presents element geochemical and Sr–Nd isotopic records of core CM97 in the Changjiang (Yangtze River) Estuary and core MD06–3040 on the inner shelf of East China Sea, aiming to reconstruct the Changjiang sediment source–to–sink transport process and its major controlling mechanism during the Holocene. Driven by the asynchronous evolution of the Indian and East Asian summer monsoon, the provenance of sediments accumulated in the Changjiang Estuary gradually changed from the upper catchment during the late glacial period to the mid–lower valley in the early–mid Holocene. With the intensive agricultural cultivation and urbanization development in the catchment during the late Holocene, the major source of Changjiang sediment into the sea shifted back to the upper catchment, again. The high–frequency ENSO activity may superimpose the effect of human disturbances on sediment source–to–sink process in the late Holocene. Therefore, the Holocene provenance evolution of Changjiang sediments in the East China Sea witnessed the changes of governing sediment erosion process within a large catchment from monsoon climate–dominated to anthropogenic driving. Our study also suggests the strong effect of hydrodynamics in coastal and shelf environments on sedimentary geochemical compositions, which deserves more attention in further sediment provenance study.

Reprint of Recent coastal environmental management based on new concept of Satoumi which promotes land-ocean interaction: A case study in Japan

Environmental conservation and management policy first emphasized on water pollution control in Japan. However, this kind of passive conservation policy is gradually being shifted to an active approach such as Satoumi, which includes the restoration of biodiversity, biological productivity, habitat and a well-balanced nutrient cycle between land and sea. Many Satoumi creation activities were also characterized by activities which promote interactions between land and sea. In this paper, a case study of Ago Bay in Shima City, Mie Prefecture, Japan, is introduced in which land-sea interaction at two sites was improved by promoting water exchange across dikes constructed for land development and land reclamation. Tidal flat restoration experiments conducted in Ago Bay clearly showed that the promotion of tidal exchange between the sea and wetland area on the inner side of dikes improved both deteriorated sediment quality and macro-benthos conditions. Along with the results of this case study, future tidal flat restoration in Japan is also discussed.

Recent coastal environmental management based on new concept of Satoumi which promotes land-ocean interaction: A case study in Japan

Environmental conservation and management policy first emphasized on water pollution control in Japan. However, this kind of passive conservation policy is gradually being shifted to an active approach such as Satoumi, which includes the restoration of biodiversity, biological productivity, habitat and a well-balanced nutrient cycle between land and sea. Many Satoumi creation activities were also characterized by activities which promote interactions between land and sea. In this paper, a case study of Ago Bay in Shima City, Mie Prefecture, Japan, is introduced in which land-sea interaction at two sites was improved by promoting water exchange across dikes constructed for land development and land reclamation. Tidal flat restoration experiments conducted in Ago Bay clearly showed that the promotion of tidal exchange between the sea and wetland area on the inner side of dikes improved both deteriorated sediment quality and macro-benthos conditions. Along with the results of this case study, future tidal flat restoration in Japan is also discussed.

Land-ocean-human interactions in intensively developing coastal zone: Demonstration of case studies

Land-Ocean-Human (L-O-H) interactions in intensively developing coastal zones are demonstrated using four case studies in the western Bohai Sea, China. Three aspects of L-O-H interactions are discussed: 1. Coastlines are the result of Land-Ocean (L-O) interactions, but human activities have changed many coastlines from natural to artificial. In recent years, sea reclamation projects have moved the land and its coastline towards the sea, leading to hydrodynamic changes and affecting both the topography and sediment-erosion dynamics in western Bohai Bay (case study 1). 2. Estuaries are key areas for L-O interactions; river sediments, together with ocean power, shape the topography of the estuarine delta, while river nutrients impact offshore biological productivity. However, due to irrigation and reservoir construction up-stream, runoff and sediments have decreased resulting in increased coastal erosion in the Yellow River Delta (case study 2). Rivers carry industrial and agricultural point and non-point source pollution into the sea, causing marine pollution in Jinzhou Bay (case study 3). 4. Sea-level rise caused by global climate change enhances the role of the ocean. At a local scale, in Binhai New Area, sea-level change is also influenced by vertical land movement along with some land subsidence caused by over-exploitation of groundwater. Rising sea levels exacerbate storm surges and floods, and increase the risk of socio-economic and ecological impacts (case study 4). Because of rapid economic growth in Chinese coastal areas, L-O-H interactions have become the most significant factors changing natural and artificial environments. If the coastal zone is to be developed sustainably, human activities must be regulated.

Zonal‐mean circulation response to reduced air–sea momentum roughness

The impact of uncertainties in surface‐layer physics on the atmospheric general circulation is comparatively unexplored. Here, the sensitivity of the zonal‐mean circulation to reduced air–sea momentum roughness (Z0m) at low flow speed is investigated with the Community Atmosphere Model (CAM3). In an aquaplanet framework with prescribed sea‐surface temperatures, the response to reduced Z0m resembles the La Niña minus El Niño response to El Niño Southern Oscillation variability, with (i) a poleward shift of the midlatitude westerlies extending all the way to the surface, (ii) a weak poleward shift of the subtropical descent region and (iii) a weakening of the Hadley circulation, which is generally also accompanied by a poleward shift of the intertropical convergence zone (ITCZ) and tropical surface easterlies. Mechanism‐denial experiments show this response to be initiated by the reduction of tropical latent and sensible heat fluxes, effected by reducing Z0m. The circulation response is elucidated by considering the effect of the tropical energy fluxes on the Hadley circulation strength, the upper tropospheric critical‐layer latitudes and the lower tropospheric baroclinic eddy forcing. The ITCZ shift is understood via moist static energy budget analysis in the Tropics. The circulation response to reduced Z0m carries over to more complex set‐ups with seasonal cycle, full complexity of atmosphere–ice–land–ocean interaction and a slab ocean lower boundary condition. Hence, relatively small changes in the surface parametrization parameters can lead to a significant circulation response.

Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13C, 14C) and molecular organic geochemistry (lignin, leaf waxes). High-resolution age models (137Cs, 210Pb) of downcore lake sediment records (n=11) along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels). Comparison with earlier published Mackenzie River depth profiles shows that (i) lake sediments reflect the riverine surface suspended load, and (ii) hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale) riverine fluxes and may prove instrumental in shedding light on past behaviour of arctic rivers, as well as how they respond to a changing climate.

Temporal–spatial variation and partitioning prediction of antibiotics in surface water and sediments from the intertidal zones of the Yellow River Delta, China

As special zones, the intertidal zones of the Yellow River Delta (YRD) are highly variable along with time and space. Fluvial–marine and land–ocean interactions which frequently occur in these areas have a great impact on the fate of pollutants. Antibiotics, which contribute to antibiotic-resistant genes (ARGs), are widely detected in wastewater, natural water, soil, sediments, and even drinking water. Therefore, it is meaningful to investigate the occurrence and fate of antibiotics in these special zones. In this study, eight antibiotics belonging to tetracyclines (TCs), fluoroquinolones (FQs), and macrolides (MLs) were detected in the surface water and sediments from the intertidal zones of YRD during two seasons. Two models were established to predict the partitioning coefficients of norfloxacin (NOR) and erythromycin (ETM) using physicochemical properties of sediments, respectively. The total concentrations of these antibiotics were 82.94–230.96ng·L−1 and 40.97–207.44ng·g−1, respectively, in the surface water and sediments. Seasonal variation was mainly influenced by the frequency of antibiotics use and environment factors. The regions with river supply exhibited the highest concentrations of antibiotics in surface water and sediments. Meanwhile, particle-size fractions, cation exchange capability (CEC), and metal ions content played dominant roles in the partitioning behaviors of NOR and ETM between the surface water and sediments. Both models established in this study featured accuracy and feasibility, which provided the methods for predicting the partitioning coefficients of emerging contaminants similar in structures to NOR and ETM in the intertidal zones.

An assessment of transport timescales and return coefficient in adjacent tropical estuaries

Transport timescales (TTS), namely residence time and exposure time, were computed for adjacent shallow meso-tidal tropical estuarines system using the Lagrangian model D-Waq Part coupled with the hydrodynamic model Delft3D-Flow, and the Constituent-oriented Age and Residence time Theory, CART. The main results are threefold: (a) The TTS differs more between releases at high or low tide than between those at spring and neap tides. The exposure time was also calculated and found to be larger than the residence time by a few days. (b) The exposure and residence times were used to evaluate the return coefficient (r) for different scenarios. As with residence and exposure times, the return coefficient was found to differ more between releases at high or low tide than between those at spring and neap tides. (c) For the Caravelas Estuary, where the river inflow was low (~4m3s−1), the residence time was found to be much larger than for the Peruípe Estuary, where the river discharge was greater and nearly constant during the sampling period (~20m3s−1). These results shows the importance of advection in decreasing TTS in the Peruípe Estuary compared to the Caravelas Estuary. The influence of the advection and dispersion agrees with previous simple estimates obtained using the newly modified Land Ocean Interaction Coastal Zone (LOICZ) model by Andutta et al. (2014).

Complex coastal change in response to autogenic basin infilling: An example from a sub‐tropical Holocene strandplain

AbstractThick bay‐fill sequences that often culminate in strandplain development serve as important sedimentary archives of land–ocean interaction, although distinguishing between internal and external forcings is an ongoing challenge. This study employs sediment cores, ground‐penetrating radar surveys, radiocarbon dates, palaeogeographic reconstructions and hydrodynamic modelling to explore the role of autogenic processes – notably a reduction in wave energy in response to coastal embayment infilling – in coastal evolution and shoreline morphodynamics. Following a regional 2 to 4 m highstand at ca 5·8 ka, the 75 km2 Tijucas Strandplain in southern Brazil built from fluvial sediments deposited into a semi‐enclosed bay. Holocene regressive deposits are underlain by fluvial sands and a Pleistocene transgressive–regressive sequence, and backed by a highstand barrier‐island. The strandplain is immediately underlain by 5 to 16 m of seaward‐thickening, fluvially derived, Holocene‐age, basin‐fill mud. Several trends are observed from the landward (oldest) to the seaward (youngest) sections of the strandplain: (i) the upper shoreface and foreshore become finer and thinner and shift from sand‐dominated to mud‐dominated; (ii) beachface slopes decrease from &gt;11° to ca 7°; and (iii) progradation rates increase from 0·4 to 1·8 m yr−1. Hydrodynamic modelling demonstrates a correlation between progressive shoaling of Tijucas Bay driven by sea‐level fall and sediment infilling and a decrease in onshore wave‐energy transport from 18 to 4 kW m−1. The combination of allogenic (sediment supply, falling relative sea‐level and geology) and autogenic (decrease in wave energy due to bay shoaling) processes drove the development of a regressive system with characteristics that are rare, if not unique, in the Holocene and rock records. These findings demonstrate the complexities in architecture styles of highstand and regressive systems tracts. Furthermore, this article highlights the diverse internal and external processes and feedbacks responsible for the development of these intricate marginal marine sedimentary systems.

Arctic in Rapid Transition: Priorities for the future of marine and coastal research in the Arctic

Understanding and responding to the rapidly occurring environmental changes in the Arctic over the past few decades require new approaches in science. This includes improved collaborations within the scientific community but also enhanced dialogue between scientists and societal stakeholders, especially with Arctic communities. As a contribution to the Third International Conference on Arctic Research Planning (ICARPIII), the Arctic in Rapid Transition (ART) network held an international workshop in France, in October 2014, in order to discuss high-priority requirements for future Arctic marine and coastal research from an early-career scientists (ECS) perspective. The discussion encompassed a variety of research fields, including topics of oceanographic conditions, sea-ice monitoring, marine biodiversity, land-ocean interactions, and geological reconstructions, as well as law and governance issues. Participants of the workshop strongly agreed on the need to enhance interdisciplinarity in order to collect comprehensive knowledge about the modern and past Arctic Ocean's geo-ecological dynamics. Such knowledge enables improved predictions of Arctic developments and provides the basis for elaborate decision-making on future actions under plausible environmental and climate scenarios in the high northern latitudes. Priority research sheets resulting from the workshop's discussions were distributed during the ICARPIII meetings in April 2015 in Japan, and are publicly available online.

Balanço de Massa para Nutrientes Inorgânicos (N e P) no Estuário do Rio Itajaí-Açu, SC

This work aimed to determine the dissolved inorganic nutrient flows and calculate a budget for N and P in the Itajai-Acu River Estuary, SC, Brazil. Flows were calculated according to the method developed by LOICZ (Land Ocean Interactions in the Coastal Zone), based on the balance of water, salt and N and P in the estuary. Data were collected weekly at seven sampling sites between 2003 and 2004 and the balances were calculated for the lowest and highest period of the river discharge (97 and 228 m3.s-1). The results showed a hydraulic residence time ranging between 12.4 h and 23 h for the surface layer of the system and between 58 h and 65 h for the bottom layer. The estuary was a sink for phosphate, removing 50% of the computed entries and this was attributed to adsorption to suspended particulate material, since the primary productivity is low. The estuary showed no conservative increase of ammonia and nitrite, related to mineralization and nitrification of organic matter, and low variation for nitrate. The sewage was shown to be an important component of the flows, accounting for 28-42% of P inputs and 23-30% of N inputs to the estuary.

陆源人类活动对近海生态系统的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 陆源人类活动对近海生态系统的影响 DOI: 10.5846/stxb201511182334 作者: 作者单位: 中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室,中国科学院生态环境研究中心城市与区域生态国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重点国际合作项目(41420104004);科技基础性工作专项(2013FY111100);中国科学院重点部署项目(KZZD-EW-TZ-12) Impacts of land-based human activities on coastal and offshore marine ecosystems Author: Affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:随着海岸带快速城市化和经济发展,人类活动对近海生态系统的影响日益增加。通过对国内外大量相关文献的分析和与国际专家的研讨,分别从海洋资源开发、海岸带城市化和环境变化等几个方面概述了陆源人类活动对近海生态系统的影响。目前陆源人类活动导致近海生态系统出现的主要问题有:海洋生物资源过度捕捞、海岸带富营养化、海洋酸化、珊瑚礁退化、海洋垃圾、以及海岸带矿产开采等高强度开发活动引发的重金属和持久性有机污染物污染等。这些问题会直接导致海洋生物群落结构变化、影响水质、降低海洋生物多样性,最终影响海洋生态系统服务功能,威胁海洋生态系统健康。这些问题的根源多来自陆地,必须将海洋和陆地作为一个有机整体,整合海陆系统相互作用的科学计划,推进海洋资源和近海生态系统的可持续管理。 Abstract:With rapid urbanization and economic development along the coast, the impacts of land-based human activities on coastal and offshore marine ecosystems have been significantly increased. This paper presented the impacts through literature synthesis and discussions with international experts, which are mainly caused by the exploitation of marine resources, coastal urbanization, and environmental change. Over exploitation of marine biotic resources, coastal eutrophication, ocean acidification, coral reef degradation, marine litter, and increasing pollution of heavy metals and persistent organic pollutants due to intensive coastal industrialization have become the major challenges and problems for coastal and offshore ecosystems. With changes in marine biological community structure, deteriorating water quality, and declining marine biodiversity, those chanllenges and problems will change the functioning of marine ecosystem services and thus threaten the health of the marine ecosystem. Since the major issues of coastal and offshore ecosystems stem from land-based activities, land and ocean should be considered as a single system when addressing them. Therefore, scientific plans on land-ocean interactions should be integrated to conserve and to ensure the sustainable use of marine resources and the sustainable management of coastal ecosystems. 参考文献 相似文献 引证文献

Effect of enhanced reactive nitrogen availability on plant-sediment mediated degradation of polycyclic aromatic hydrocarbons in contaminated mangrove sediment

As land–ocean interaction zones, mangrove systems receive substantial polycyclic aromatic hydrocarbons (PAHs) from sewage and combustion of fossil fuel. In this study, we investigated the relationship between dissolved inorganic nitrogen (DIN) availability and degradation rate of phenanthrene, a typical PAH compound, in mangrove plant-sediment systems, using Avicennia marina as a model plant. After 50day incubation, phenanthrene removal ratios in sediments ranged from 53.8% to 97.2%. In non-rhizosphere sediment, increasing DIN accessibility increased microbial biomass and total microbial activity, while enhancements in population size of phenanthrene degradation bacteria (PDB) and phenanthrene degradation rates were insignificant. In contrast, the presence of excessive DIN in rhizosphere sediment resulted in a significantly large number of PDB, leading to a rapid dissipation rate of phenanthrene. The differences in degradation rates and abundances of degrader in sediment may be explained by the enhanced root activity due to the elevation in DIN accessibility.

Land Ocean Interaction - Measuring and Modelling Fluxes from River Basins to Coastal Seas

The UK Land-Ocean Interaction Study (LOIS) provided a major opportunity to measure and model the processes controlling the fluxes of materials between river basins and coastal seas. The main programme of research took place between 1992 and 1998, funded by the UK Natural Environment Research Council, and involved approximately 360 coastal researchers contributing to more than 70 collaborative projects. This book presents accessible summaries of key results of this research. The ten chapters of the book are written by leading contributors to the programme, and cover aspects of the physical, sedimentological, chemical and biological processes controlling fluxes between river catchments and coastal seas in temporate environments. Major overarching themes for all of the chapters include the persistence, storage, degradation and transport of pollutants from catchment to coastal sea, and an emphasis on the relevance of research for river and coastal water quality management. The chapters also describe a number of important technological advances in the measurement of processes and longer term monitoring of the fluvial, estuarine and coastal environments. Approaches to monitoring were also transferred between disciplines, in many cases for the first time. The rivers and coastal programme of LOIS was unique in its scale and inter-disciplinarity and its results are of lasting value. This book provides a useful and important summary of many of its results and an effective introduction to the research for those who want to delve more deeply into the data and published papers. It will be of interest to scientists, environmental managers and scientific policy makers. This title belongs to European Water Research Series ISBN: 9781900222105 (Print) ISBN: 9781780402222 (eBook)

Land–Ocean Interactions in the Coastal Zone: Past, present &amp; future

Abstract The Land–ocean Interactions in the Coastal Zone (LOICZ) project was established in 1993 as a core project of the International Geosphere–Biosphere Programme (IGBP) to provide the science knowledge to answer “How will changes in land use, sea level and climate alter coastal systems, and what are the wider consequences?” In its first phase of operation (1993–2003) LOICZ began a fundamental investigation focused on biophysical dimensions, including seminal assessments of coastal seas as net sources or sinks of atmospheric CO2, river discharge to the oceans, and biogeochemical modelling. In the second generation of LOICZ (2004–2014), increased attention was paid to the human dimensions of the coast, involving the inclusion of cross-cutting themes such as coastal governance, social-ecological systems, ecological economics and activities around capacity building and the promotion of early career scientists. This paper provides a synthesis of this work and looks forward to the future challenges for the project. With the transition to Future Earth, there is a paradigm shift emerging. The new vision is to support transformation to a sustainable and resilient future for society and nature on the coast, by facilitating innovative, integrated and solutions-oriented science. Realising this vision takes LOICZ into a third generation: to be at the forefront of co-designing, co-producing and co-implementing knowledge for coastal resilience and sustainability. LOICZ as Future Earth Coasts will continue to address ‘hotspots’ of coastal vulnerability, focusing on themes of dynamic coasts, human development and the coast, and pathways to global coastal sustainability and constraints thereof.

Carbon sink mechanism and processes in the Arctic Ocean under arctic rapid change

The Arctic Ocean plays a key role in the global carbon cycle and budget. This semi-closed ocean and its vast and shallow marginal shelf seas surrounded by widespread tundra makes it a unique area to study the carbon source, sink and budget, with consideration of land-ocean interaction and land and ocean as a whole. Over the last three decades because of global warming, sea ice has rapidly decreased. This has induced air-ice-sea-land multi-geosphere interaction that has greatly affected the carbon source and sink in the arctic areas. Such rapid change has not only led to the release of methane and carbon dioxide in degraded permafrost but has also altered the physical, biological and microbial carbon pumps. This process may be attributed to changes of freshwater input, water mixing and circulation, terrestrial fluvial transport, and nutrient supply to the Arctic Ocean. In this review paper, we discuss how global warming and rapid sea ice retreat affects the Arctic carbon sink and source, with a focus on the biological pump, terrestrial carbon input, and carbon burial in the Arctic Ocean.

Investigation of seasonal variability of CDOM fluorescence in the southern changjiang river estuary by EEM-PARAFAC

The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant. Moreover, land-ocean interactions strongly impact the estuary, and harmful algal blooms (HABs) frequently occur in the area. In October 2010 and May 2011, water samples of chromophoric dissolved organic matter (CDOM) were collected from the southern Changjiang River Estuary. Parallel factor analysis (PARAFAC) was used to assess the samples’ CDOM composition using excitation-emission matrix (EEM) spectroscopy. Four components were identified: three were humic-like (C1, C2 and C3) and one was protein-like (C4). Analysis based on spatial and seasonal distributions, as well as relationships with salinity, Chl a and apparent oxygen utilization (AOU), revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1, C2 and C3 in autumn. In spring, microbial processes and phytoplankton blooms were also important factors that impacted the three components. The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component. CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs. Microbial processes and phytoplankton blooms were also important sources of CDOM, especially in spring. The fluorescence intensities of the four components were significantly higher in spring than in autumn. On average, C1, C2, C3, C4 and the total fluorescence intensity (TFI) in the surface, middle and bottom layers increased by 123%–242%, 105%–195%, 167%–665%, 483%–567% and 184%–245% in spring than in autumn, respectively. This finding corresponded with a Chl a concentration that was 16–20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn. The humification index (HIX) was lower in spring that in autumn, and the fluorescence index (FI) was higher in spring than in autumn. This result indicated that the CDOM was labile and the biological activity was intense in spring.

Regional initiatives for interlinking global coastal scientific research projects

LOICZ (Land Ocean Interactions in the Coastal Zone) (see http://www.loicz.org/) is a core research project of International Geosphere Biosphere Program (IGBP) (and previously also the International Human Dimensions Program (IHDP) involving scientists from across the globe investigating biogeochemical as well as social, economic and governance related coastal zone research. Since 2003, its focus on human dimensions allows better informing the scientific community, policymakers, managers and other stakeholders on the relevance of global environmental change in the coastal zone. LOICZ has six existing regional nodes: in South Asia (Chennai, India), Southeast Asia (Singapore), East Asia (Yantai, China), Latin America (Rio de Janeiro) and North America (Louisiana, USA). The four upcoming nodes include Arctic (Canada), West Africa (Nigeria), Caribbean (Trinidad & Tobago) and China (Taiwan). Each regional node coordinates and promotes global change research at the regional and local level as well as facilitates links and exchanges between international, national and local science and policy.