Simon M. Hutchinson

China's Yangtze Estuary: I. Geomorphic influence on heavy metal accumulation in intertidal sediments

Five intertidal sites along the coast of the Yangtze Estuary, China were examined for concentrations of heavy metals including Cu, Zn, Pb, Ni, Mn and Fe in bulk surficial and core sediments. Differences in heavy metal concentrations are apparent between the sites, which are dependent on site-specific metal inputs and sediment grain size. With the exception of site A (Shidongkou), where the highest concentrations of Cu, Zn, Pb occur due to direct pollutant input from the nearby sewage outlet, heavy metal concentrations at other sites are largely determined by particle size characteristics. Clay-rich sediments, together with a downstream location relative to the sewage outlets, result in elevated concentrations of heavy metals at site C (Donghai). Within the intertidal zone at site C, the vegetated, upper marsh zone exhibits higher heavy metal concentrations in comparison with the bare mudflat. Monthly sampling (May to September) in the Scirpus marsh at site C records a temporal variation in heavy metal concentrations. Both of them can be related to the spatial and temporal variability of sediment grain size. A geomorphic understanding of the heterogeneity of sediment grain size is, therefore, vital to the assessment of sediment pollution in intertidal sediments. The present study reveals that the levels of heavy metals found in the Yangtze Estuary are relatively moderate compared with other estuaries in Asia and Europe. This is related to both the diluting effects of the huge volume of water and sediment in the estuary and a shorter period of industrialisation.

Historical record and sources of polycyclic aromatic hydrocarbons in core sediments from the Yangtze Estuary, China

Polycyclic aromatic hydrocarbons (PAHs) in a sediment core taken from intertidal flat in the Yangtze Estuary were determined by gas chromatography-mass spectrometry. The results indicate that the total concentration of PAHs ranged from 0.08 to 11.74 microg/g. The concentration levels of total and individual PAHs changed dramatically with depth. The concentrations of PAHs were relatively high above 35 cm depth and remained constantly low below this depth. The historical record of PAHs in the core shows subsurface maximum (one or more peak values), followed by decreased levels to the surface and with depth. And, PAH sediment record in the core profile is in agreement with historically sewage discharge events during the 1980s to 1990s. The distribution of target molecule acenephthene, the fluoranthene/pyrene ratio, the proportion of 2-3-ring and 4-5-ring PAHs, and alkylated naphthalene to parent naphthalene in the core profile show that the sources in this area are characterized by petroleum-derived PAH contamination (mainly sewage discharge and the river runoff) and the incorporation of atmospheric inputs. Studies indicate the PAH profile pattern in this site in comparison with other regions appear to reflect its particular local position (near the sewage outlet). Moreover, physico-chemical conditions and sedimentation rate as well as biodegradation also affect the PAH concentration levels in the core sediments.

Towards a sustainable coast: an integrated coastal zone management framework for Shanghai, People's Republic of China

Abstract This paper proposes an integrated coastal zone management (ICZM) framework in the context of the current pressures and management problems of the coastal zone in Shanghai, Peoples Republic of China. The main issues in the coastal zone caused by human activities are addressed and the drawbacks of the present coastal zone management are identified. The proposed ICZM framework is developed in view of the existing situation in this coastal zone which lies at the mouth of the Yangze estuary. Besides providing a general framework, the paper lays particular emphasis on discussing the implementation of cross-sectoral management, strategic environmental assessment, systematic scientific research and public involvement in this ICZM system. The innovation of management approaches at the local level will hopefully be conducive to the achievement of sustainable development in the coastal zone of the most developed area in China whose wetland areas are also of international importance.

Diagenesis of magnetic minerals in the intertidal sediments of the Yangtze Estuary, China, and its environmental significance

In this study, diagenesis of iron oxides in intertidal sediments of the Yangtze Estuary, China, has been investigated by combined environmental magnetic and geochemical methods. The results indicated that the magnetic properties of the sediments were dominated by ferrimagnetic magnetite. The content of Fe, DCB- and AOD-extractable iron oxides correlated positively with the concentration of fine grained magnetite near the superparamagnetic/stable single domain (SP/SSD, approximately 0.03 microm) boundary, and with anti-ferromagnetic minerals (hematite/goethite). The magnetic parameters for core SDK indicated a substantial decrease in magnetite concentration from a depth of approximately 20 cm toward the surface, together with a shift in the grain-size distribution of magnetic minerals toward the coarse end, suggesting selective dissolution of fine grained magnetite under reducing conditions. The reduction of iron oxides inferred from magnetic measurements was supported by the similar decrease in the concentration of Fe and Mn and a lower ratio of Mn/Fe. Magnetic measurements on another core from elsewhere also indicated substantial reductive dissolution of iron oxides. In conjunction with the results of heavy metal analysis, it was suggested that the dissolution of iron oxides had a direct effect on the cycling of heavy metals. Therefore, magnetic measurements may provide useful information as to early diagenesis within intertidal sediments, which greatly influences the behavior of heavy metals in coastal environments.

Last Millennium hydro-climate variability in Central–Eastern Europe (Northern Carpathians, Romania)

Proxy-based reconstructions of climate variability over the last millennium provide important insights for understanding current climate change within a long-term context. Past hydrological changes are particularly difficult to reconstruct, yet rainfall patterns and variability are among the most critical environmental variables. Ombrotrophic bogs, entirely dependent on water from precipitation and sensitive to changes in the balance between precipitation and evapotranspiration, are highly suitable for such hydro-climate reconstructions. We present a multi-proxy analysis (testate amoebae, plant macrofossils, stable carbon isotopes in Sphagnum, pollen, spores and macroscopic charcoal) from an ombrotrophic peat profile from the Rodna Mountains (northern Romania) to establish a quantitative record of hydro-climatic changes. We identify five main stages: wet surface mire conditions between AD 800 and 1150 and AD 1800 and 1950, and drying of the mire surface between AD 1300 and 1450, AD 1550 and 1750 and AD 1950 and 2012. Our multi-proxy reconstructions suggest that conditions during the Medieval Climate Anomaly (MCA) period (AD 900–1150) were considerably wetter than today, while during most of the ‘Little Ice Age’ (LIA; AD 1500–1850), they were dry. Mire surface conditions in the Rodna Mountains have dried markedly over the last 40 years mainly as a result of anthropogenic climate change approaching the driest conditions seen over the last 1000 years. There is a marked difference between current hydro-climatic conditions (dry mire) and those of the MCA (wet mire). This implies that for the study region, the MCA cannot provide analogous climatic conditions to the contemporary situation. Our reconstructions are in partial agreement with water table estimates elsewhere in central and eastern Europe but generally contrast with those from NW Europe, especially during LIA. We suggest that these distinctive regional differences result from fluctuations in large-scale atmospheric circulation, which determine the relative influences of continental and oceanic air masses.

High mountain region of the Northern Romanian Carpathians responded sensitively to Holocene climate and land use changes: A multi-proxy analysis

A high-altitude lake sediment sequence (Buhăiescu Mare, 1918 m a.s.l.) in the subalpine zone of the Rodna Mountains was analysed through a multi-proxy approach to determine the sensitivity of high mountain habitats to climate, fire and land use changes. The early Holocene regional forests were dominated by Pinus (sylvestris and mugo) and replaced by Picea abies from 9800 cal. yr BP. After an extended hiatus in the profile (c. 9800–4200 cal. yr BP), probably because of the physical removal of sediments through avalanche or high-flow events, P. abies, Abies alba and Fagus sylvatica forests developed after 4200 cal. yr BP. The timberline and treeline reacted sensitively to past changes in climate and human impact. The site was probably situated above the treeline throughout most of the investigated period. However, a treeline ecotone or krummholz zone may have sporadically reached the lake’s elevation in the early Holocene. A decline in timberline and treeline elevation was noted during the last 1200 years, and more evidently over the past 200 years, with replacement by subalpine shrubs (Alnus viridis) and alpine herbaceous communities. Because these vegetation changes were associated with an increased prevalence of pollen-based anthropogenic indicators, charcoal particles and abiotic indicators, human-induced fires and clearance and resultant erosion inputs to the lake are implied. Effects of current warming on the altitude range of trees are not yet visible, probably because land use has more strongly contributed to changes in land cover than the climate fluctuations of the last millennium in the Rodna Mountains.

Assessment of Lead contamination in Peatlands using field portable XRF

Ombrotrophic peatlands are highly sensitive to atmospheric heavy metal deposition. Previous attempts to quantify peatland lead pollution have been undertaken using the inventory approach. However, there can be significant within-site spatial heterogeneity in lead concentrations, highlighting the need for multiple samples to properly quantify lead storage. Field portable x-ray fluorescence (FPXRF) continues to gain acceptance in the study of contaminated soil, but has not thus far been used to assess peatland lead contamination. This study compares lead concentrations in surface peat samples from the South Pennines (UK) derived using (a) FPXRF in the field, (b) FPXRF in the lab on dried samples and (c) ICP-OES analysis. FPXRF field and lab data are directly comparable when field measurements are corrected for water content, both can be easily used to estimate acid extractable lead using regression equations. This study is a successful demonstration of FPXRF as a tool for a time- and cost-effective means of determining the lead content of contaminated peatlands, which will allow rapid landscape scale reconnaissance, core logging, surface surveys and sediment tracing.

Establishing the sediment stratigraphy of reservoirs in the southern Pennines, UK

Abstract Reservoirs in the southern Pennines have been investigated to determine their potential for reconstructing a history of atmospheric pollution. A selection procedure has been used to identify sites with the best chance of obtaining a usable sedimentary record prior to sample collection. Five reservoirs were selected for core collection and sediment analysis using magnetic susceptibility (χlf), particle size, spheroidal carbonaceous particle (SCP) analysis and radiometric dating. Analysis reveals that largely undisturbed sedimentary records exist in the deepest zones of these reservoirs, thus reservoir sediments represent a valuable resource for investigating pollution histories in the southern Pennines.

Magnetic normalization of particle size effects in a heavy metal pollution study of intertidal sediments from the Yangzte Estuary

Magnetic, granulometric and geochemical analyses were conducted on an intertidal sediment core from the Yangtze Estuary to evaluate the possibility of normalizing samples for particle size effects in a heavy metal pollution study by means of magnetic proxies. It has been found that the magnetic parameterϰARM, indicating fine grained ferrimagnetic minerals, correlates well with the clay content and organic matter concentration of the sediments.ϰARM also shows significant relationship with heavy metals. ThereforeϰARM is proposed as a proxy for clay content in the sediments, and can be used to compensate for the particle size effect in sedimentary heavy metal records, where magnetic minerals are not subject to significant post-depositional alteration.

Interdisciplinary cooperation and studies in geoscience in the Carpathian Basin

An interdisciplinary approach to geoscience is particularly important in this vast research field, as the more innovative studies are increasingly crossing discipline boundaries and thus benefitting from multiple research methods and viewpoints. Grasping this concept has led us to encourage interdisciplinary cooperation by supporting and promoting the creation of “meeting places” able to provide a framework for researchers and scholars involved in geoscience research to find common grounds for discussion and collaboration. Most recently, this was achieved by organizing the 1st Workshop on “Interdisciplinarity in Geosciences in the Carpathian Basin” (IGCB) held in the Department of Geography at the University of Suceava (Romania), between the 18 th and 22 nd October 2012. This event brought together both an international group of scientists and local researchers which created opportunities for collaboration in research topics such as geography, environment, geology and botany, biology and ecology in the Carpathian Basin.