The effect of climate change on extreme waves in front of the Dutch coast

Coastal safety may be influenced by climate change, as changes in wave conditions (height, period, direction) may increase the vulnerability of dunes and other coastal defences. Dune erosion depends on mean water level, storm surge height and wave conditions. In this paper, we investigate the change in wave conditions in the North Sea in a changing climate. Until now, the effect of climate change on annual maximum wave conditions has been investigated, while events with higher return periods are actually most damaging for the coast (e.g. severe dune erosion). Here, we use the 17-member Ensemble SimulationS of Extreme weather under Non-linear Climate changeE (ESSENCE) change of climate change simulations, to analyse A1b-induced changes in the mean wave climate, the annual maxima and wave conditions with return periods of up to 1:10,000?years in front of the Dutch coast. The mean wave climate is not projected to differ between 1961–1990 and 2071–2100, with both wave height (H _s) and wave period (T _m) remaining unaltered. In the annual maximum conditions, a decrease is projected; especially, the annual T _m maximum decreases significantly by 0.3 to 0.6?s over the whole study area. Furthermore, we find that the direction of the annual maximum wave conditions shifts from north and north-west to west and south-west for both H _s and T _m. This is induced by a similar shift in the direction of the extreme wind speeds. Despite the decrease in annual maximum conditions, the return H _s and T _m are not projected to change significantly as a result of climate change in front of the Dutch coast for the period 2071–2100 relative to 1961–1990.     

Eutrophication assessment of the Baltic Sea Protected Areas by available data and GIS technologies

Concerning increased degradation of marine ecosystems, there is a great political and institutional demand for an array of different tools to restore a good environmental status. Thereby, eutrophication is acknowledged as one of the major human induced stressors which has to be monitored and reduced. The present study concentrates on an assessment of the eutrophication status of the Baltic Sea Protected Areas by use of available data and GIS technologies. Two geodata layers were used for analysis: (1) a map on the eutrophication status of the Baltic Sea generated by the Helsinki Commission applying the HELCOM Eutrophication Assessment Tool (HEAT), and (2) modelled data on atmospheric nitrogen deposition made available by the European Monitoring and Evaluation Programme (EMEP). The results yielded comprehensive and conclusive data indicating that most of the BSPAs may be classified as being 'affected by eutrophication' and underlining the need to decrease the overall emissions of nutrients.     

Atmospheric input of nitrogen into the North Sea: ANICE project overview

The aim of the atmospheric nitrogen inputs into the coastal ecosystem (ANICE) project is to improve transport–chemistry models that estimate nitrogen deposition to the sea. To achieve this, experimental and modelling work is being conducted which aims to improve understanding of the processes involved in the chemical transformation, transport and deposition of atmospheric nitrogen compounds. Of particular emphasis within ANICE is the influence of coastal zone processes. Both short episodes with high deposition and chronic nitrogen inputs are considered in the project. The improved transport–chemistry models will be used to assess the atmospheric inputs of nitrogen compounds into the European regional seas (the North Sea is studied as a prototype) and evaluate the impact of various emission reduction strategies on the atmospheric nitrogen loads. Assessment of the impact of atmospheric nitrogen on coastal ecosystems will be based on comparisons of phytoplankton nitrogen requirements, other external nitrogen inputs to the ANICE area of interest and the direct nitrogen fluxes provided by ANICE. Selected results from both the experimental and modelling components are presented here. The experimental results show the large spatial and temporal variability in the concentrations of gaseous nitrogen compounds, and their influences on fluxes. Model calculations show the strong variation of both concentrations and gradients of nitric acid at fetches of up to 25 km. Aerosol concentrations also show high temporal variability and experimental evidence for the reaction between nitric acid and sea salt aerosol is provided by size-segregated aerosol composition measured at both sides of the North Sea. In several occasions throughout the experimental period, air mass back trajectory analysis showed connected flow between the two sampling sites (the Weybourne Atmospheric Observatory on the North Norfolk coast of the UK and Meetpost Noordwijk, a research tower at 9 km off the Dutch coast). Results from the METRAS/SEMA mesoscale chemistry transport model system for one of these cases are presented. Measurements of aerosol and rain chemical composition, using equipment mounted on a commercial ferry, show variations in composition across the North Sea. These measurements have been compared to results obtained with the transport–chemistry model ACDEP which calculates the atmospheric inputs into the whole North Sea area. Finally, the results will be made available for the assessment of the impact of atmospheric nitrogen on coastal ecosystems.     

Dispersion assessment of particulate substances from deep-sea mining activities by means of model simulations

Ocean Dynamics - The model study aims at the assessment of effects of mining activities of manganese nodules in the deep-sea. A Lagrangian transport model is applied on a global scale to estimate...     

The importance of submerged macrophytes as indicators for the nutrient concentration in a small stream (Rotbach, Bavaria)

The relationship between the macrophyte vegetation and the nutrient concentration of the water and the sediment of a stream was studied. The small stream is fed by calcareous groundwater. The alteration in the macrophyte vegetation of the stream Rotbach from oligotrophic community towards more eutrophic species is associated with an increasing concentration of nutrients in the sediment. Particularly the concentration of SRP-P in the interstitial water changes significantly.

In terms of the macrophyte vegetation the stream can be divided into 4 floristic zones, A-D. The zones are labelled in a sequence according to their sediment's nutrient content. The chemical analyses of the water and the sediment show the highest concentrations in zone D. It is characterized by the presence of Zannichellia palustris. The zones A-C have almost the same very low nutrient concentration in the water but show a different content of nutrients in the sediment, particularly of the SRP-P in the interstitial water. Zone A which is dominated by Chara hispida shows the lowest SRP-P in the interstitial water. Within zone B which is characterized by Mentha aquatica and Nasturtium officinale and even more in zone C where Chara hispida is less abundant and Elodea canadensis occurs, the SRP-P content is elevated.

The nutrient concentration in the sediment is clearly associated with changes in the macrophyte vegetation of the stream Rotbach.     

Metasomatism of ferroan granites in the northern Aravalli orogen,NW India: geochemical and isotopic constraints,and its metallogenic significance

The late Palaeoproterozoic (1.72–1.70 Ga) ferroan granites of the Khetri complex, northern Aravalli orogen, NW India, were extensively metasomatised ~900 Ma after their emplacement, at around 850–830 Ma by low-temperature (ca. 400 °C) meteoric fluids that attained metamorphic character after exchanging oxygen with the surrounding metamorphic rocks. Albitisation is the dominant metasomatic process that was accompanied by Mg and Ca metasomatism. A two-stage metasomatic model is applicable to all the altered ferroan intrusives. The stage I is represented by a metasomatic reaction interface that developed as a result of transformation of the original microcline–oligoclase (An_12–14) granite to microcline–albite (An_1–3) granite, and this stage is rarely preserved. In contrast, the stage II metasomatic reaction front, where the microcline-bearing albite granite has been transformed to microcline-free albite granite, is readily recognisable in the field and present in most of the intrusives. Some of them lack an obvious reaction interface due to the presence of stage II albite granites only. When studied in isolation, these intrusives were incorrectly classified and their tectonic setting was misinterpreted. Furthermore, our results show that the mafic mineralogy of metasomatised granites has a significant impact on the characterisation of such rocks in the magmatic classification and discrimination diagrams. Nevertheless, the stage I metasomatised granites can be appropriately characterised in these diagrams, whereas the characterisation of the stage II granites will lead to erroneous interpretations. The close spatial association of these high heat producing ferroan granites with iron oxide–copper–gold (IOCG), U and REE mineralisation in the region indicates a genetic link between the metasomatism and the mineralisation. World-class IOCG, U and REE deposits are associated with metasomatised ferroan granites, suggesting that such a relationship may act as a critical first-order exploration target for undiscovered mineral deposits.     

Urban and suburban storm water runoff as a source of polycyclic aromatic hydrocarbons (PAHs) to Massachusetts estuarine and coastal environments

Urban and suburban storm water runoff from ten locations in eastern Massachusetts was analyzed for 39 polycyclic aromatic hydrocarbons (PAHs) compounds. Similar profiles in PAH composition were observed for groups of samples and appear to reflect land use. The largest group includes, urban storm water from areas with a mix of industrial, commercial, and residential use. Fluoranthene, phenanthrene, pyrene, chrysene, and benzo (b) fluoranthene were the predominant compounds in this group, but lighter molecular weight PAHs were also present. Sources of PAHs to storm water include a combination of petroleum and combustion. The profile of PAH compounds in local atmospheric deposition was similar to urban storm water, but differed in several of the predominant compounds. PAHs in storm water could increase the levels of these compounds in nearshore sediments and may be the most important source of high molecular weight PAHs to these environments.     

Phytoplankton response to climate changes in Lake Baikal during the Holocene and Kazantsevo Interglacials assessed from sedimentary pigments

Lake Baikal, an ancient pristine lake in Siberia, has accumulated sediment deposits that span 25 million years. These deposits have the potential to provide a long-term record of climate changes and their interaction with the ecology of the lake. In order to investigate whether sedimentary phytoplankton pigments could be used to reconstruct past changes in total phytoplankton abundance and productivity, we compared the spatial variability in sedimentary pigment distributions in Holocene cores from three separate regions of the lake; Vidrino in the south, Posolski on Selenga Delta and Continent Ridge in the north. Furthermore, we present the first continuous sedimentary pigment and organic carbon sequence of the Kazantsevo interglacial (roughly a time equivalent to the European Eemian, and Marine Isotopic Stage MIS5e) at a resolution of approximately 150 years. Results of the spatial study showed marked differences in the sediment pigment deposition. Lowest chlorophyll a plus its degradation products versus organic carbon ratios (Chlas/TOC) indicating lowest production, but highest variability with time (indicating strongest climatic oscillations) were found at Continent Ridge. The study of sedimentary pigments deposited during the last two interglacial periods at Continent Ridge showed Chlas/TOC ratios 50–1000 times higher during the Kazantsevo Interglacial compared to the glacial periods, whereas the TOC content was only five times higher, thus indicating the significance of the Chlas/TOC ratio for the reconstruction of the phytoplankton abundance and productivity. Strong oscillations occurred during the Kazantsevo Interglacial within centennial time scales. Chlorophyllb plus its degradation products provided additional information on the past development of Chlorophyceae. Highest Chlas/TOC ratios were found during the early Holocene at approximately 9 kyr BP. Indications of short phytoplankton production maxima were also found during the late Atlantic (6 kyr BP) and at the Subboreal/Subatlantic transition (3 kyr BP). From this we conclude that sedimentary chlorophyll a is a reliable indicator of phytoplanktonic response to climate changes and may serve for␣validation of future climate scenarios in continental regions.     

Assessing physical vulnerability in large cities exposed to flash floods and debris flows: the case of Arequipa (Peru)

Understanding the physical vulnerability of buildings and infrastructure to natural hazards is an essential step in risk assessment for large cities. We have interpreted high spatial resolution images, conducted field surveys, and utilized numerical simulations, in order to assess vulnerability across Arequipa, south Peru, close to the active El Misti volcano. The emphasis of this study was on flash floods and volcanic or non-volcanic hyperconcentrated flows, which recur on average every 3.5 years across the city. We utilized a geographic information system to embed vulnerability and hazard maps as a step to calculate risk for buildings and bridges along the Río Chili valley and two tributaries. A survey of ~1,000 buildings from 46 city blocks, different in age, construction materials, and land usage, provided architectural and structural characteristics. A similar survey of twenty bridges across the three valleys was based on structural, hydraulic, and strategic parameters. Interpretation of high spatial resolution (HSR) satellite images, which allows for quick identification of approximately 69 % of the structural building types, effectively supplemented field data collection. Mapping vulnerability has led us to pinpoint strategic areas in case of future destructive floods or flows. Calculated vulnerability is high if we examine structural criteria alone. We further consider physical setting with the most vulnerable city blocks located on the lowermost terraces, perpendicular or oblique to the flow path. Statistical analysis conducted on 3,015 city blocks, considering nine criteria identified from HSR images, indicated that building-type heterogeneity and the shape of the city blocks, along with building and street network density, are the most discriminant parameters for assessing vulnerability.