Post-glacial regional climate variability along the East Antarctic coastal margin—Evidence from shallow marine and coastal terrestrial records

We review the post-glacial climate variability along the East Antarctic coastline using terrestrial and shallow marine geological records and compare these reconstructions with data from elsewhere. Nearly all East Antarctic records show a near-synchronous Early Holocene climate optimum (11.5–9 ka BP), coinciding with the deglaciation of currently ice-free regions and the optimum recorded in Antarctic ice and marine sediment cores. Shallow marine and coastal terrestrial climate anomalies appear to be out of phase after the Early Holocene warm period, and show complex regional patterns, but an overall trend of cooling in the terrestrial records. A Mid to Late Holocene warm period is present in many East Antarctic lake and shallow coastal marine records. Although there are some differences in the regional timing of this warm period, it typically occurs somewhere between 4.7 and 1 ka BP, which overlaps with a similar optimum found in Antarctic Peninsula terrestrial records. The differences in the timing of these sometimes abrupt warm events in different records and regions points to a number of mechanisms that we have yet to identify. Nearly all records show a neoglacial cooling from 2 ka BP onwards. There is no evidence along the East Antarctic coastline for an equivalent to the Northern Hemisphere Medieval Warm Period and there is only weak circumstantial evidence in a few places for a cool event crudely equivalent in time to the Northern Hemisphere's Little Ice Age. There is a need for well-dated, high resolution climate records in coastal East Antarctica and particularly in Terre Adélie, Dronning Maud Land and Enderby Land to fully understand the regional climate anomalies, the disparity between marine and terrestrial records, and to determine the significance of the heterogeneous temperature trends being measured in the Antarctic today.     

Invertebrate community response to experimental lime (Ca(OH)2) treatment of an eutrophic pond

Calcium hydroxide (Ca(OH)₂), or hydrated lime, has recently been reintroduced in western Canada as a treatment to reduce macrophytes and algae in eutrophic waters. We examined the effects and recovery of aquatic invertebrates of the Ca(OH)₂ treatment (250 mg L^–1) of one half of a divided eutrophic pond compared to the untreated half. Nine weeks following treatment, total invertebrates on the untreated side were present at 1917 ± 555 individuals m^–2, and on the treated side at 822 ± 186 individuals m^–2. Notably, Chironomidae represented 13% of invertebrates on the untreated half, but dominated numerically with 72% on the treated half of the pond. The remaining five most abundant taxa in the untreated side were 88%–99% less abundant in the treated half of the pond. Diversity and evenness were twice as high for the untreated half as for the treated half of the pond. Because macrophytes were also extirpated with the Ca(OH)₂ treatment, macrophyteassociated taxa were absent or at low numbers in the treated half. The death of organisms on the treated side of the pond may have been caused (directly or indirectly) by the pH shock associated with Ca(OH)₂ treatments. Slow recolonization by most invertebrates during the year of treatment was probably due to the lack of heterogeneous macrophyte habitat. Follow-up sampling 3 years later indicated that the pond completely regained the abundance and biological diversity of flora and fauna.     

First record of Odontaster penicillatus populations (Philippi, 1870) (Echinodermata: Asteroidea) in the Atacama and Antofagasta regions,Chile (Southeast Pacific)

We report for the first time the presence of local populations of the starfish Odontaster penicillatus in the regions of Atacama and Antofagasta, Chile. This finding indicates an extension of the distribution limit of 500 km with respect to the last observation made in 2007 in Isla Grande de Atacama. A total of 121 specimens of O. penicillatus were recorded at depths of between 8 m and 24 m. They were associated with rocky substrate and with different species of barnacles, sponges and bryozoans. The presence of O. penicillatus expands the knowledge of the benthic biodiversity of the region, and the development of studies on its ecological importance will be promoted.     

The Class 0 source Barnard 1c

We present our most recent results from an ongoing study of the Class 0 source Barnard 1c in Perseus. This source is of particular interest because it exhibits evidence of strong alignment of grains all the way to the core’s centre, which is contrary to all other low-mass protostellar cores observed to date. Our goal is to clarify the source of poor alignment in other sources by identifying the source of strong alignment in B1c. A central cavity has been identified in N₂H⁺ emission; its anticorrelation with C¹⁸O emission suggests that heating in the centre has released CO from grain mantles, in turn destroying N₂H⁺. We present sensitivity-limited, high spatial resolution polarimetry data from the SubMillimeter Array and discuss the potential implications of these data.     

THE HUMAN GEOGRAPHY OF SOUTHEAST ASIA: AN ANALYSIS OF POST-WAR DEVELOPMENTS

This paper reviews the directional shifts in human geographical research on Southeast Asia from 1945 to the present. It first begins with an overview of the identity of the region as conceived in various cultural traditions, such as the Greek, Arabic and Indian traditions. This is followed by an evaluation of regional geographies of Southeast Asia in the post-war period, highlighting the pre-eminence of the geostrategic definition of the region and the failure to come to grips with its rich cultural-historical identity. The paper then goes on to show that, arising from the changes in conceptual developments and methodologies in geography, the early regional emphasis then shifted to systematic concerns, with a movement away from ‘encyclopaedic’ to ‘adjectival’ geography (economic, urban, population, political, cultural and historical) and a greater emphasis on issues concerning national development. Since the 1980s, there have also been fewer regional works on Southeast Asia and though there are now many more indigenous geographers within the region, much of their research is based on their own national or provincial areas. However, this may shift again, given that rapid economic growth has now given the region prominence. Certainly, there is renewed multi-disciplinary interest in Southeast Asia.     

Constructing Community Through Maps? Power and Praxis in Community Mapping*

Despite the growing practice of community mapping, empirical research remains limited. Extant studies have focused primarily on “counter‐maps” and indigenous maps, leaving many locally produced maps and their authors' perspectives unexplored. This article identifies the mapping process as critical to the definition and understanding of community mapping. It links critical cartography literature to goals of community‐mapping practitioners through themes of inclusion, transparency, and empowerment. The discussion highlights the social construction and practice of “community,” the relationship between maps and power, the definitional difficulties associated with community mapping, and the figurative and literal boundaries that constrain community cartography. Finally, it points to areas for further research and exploration.     

Gross erosion,net erosion and gross deposition of dust by wind: field data from 17 desert surfaces

Wind erosion measurements were carried out in Nellis Dunes Recreation Area, southern Nevada, USA. Gross erosion (the total mass of sediment effectively blown away from a surface), gross deposition (the total mass of sediment effectively depositing on a surface) and net erosion (the difference in sediment mass before and after an event) were measured for 1 year, on 17 different types of surfaces developed on loose dune sand, compacted sand, loose silt, compacted and/or aggregated silt, rock‐covered sands and silts, mixtures of sand, silt and clay, exposed petrocalcic horizons, gravelly substrata and bedrock. Results showed that net erosion, which is the type of erosion measured in field and laboratory experiments, strongly differs from gross erosion. Activity on a surface is much higher than classic net erosion measurements suggest. Future studies on wind erosion should better acknowledge the distinction between the two types of process. Also, a grain diameter of maximum susceptibility to wind erosion (‘optimum deflation diameter’) near 70 µm as proposed by the aeolian literature only exists for net wind erosion. No such optimum diameter was found for gross wind erosion within the particle range 0–100 µm delineating the transport modes of suspension and modified saltation. In addition, desert surfaces predominantly composed of sand did not show an optimum deflation diameter (for net erosion) around 70 µm. Instead, there was a preferential grain size around 15 µm at which particles were most vulnerable to net emission. Desert surfaces poor in sand showed the classic value of 70 µm. This suggests that interactions exist between the type of surface and the susceptibility of particles to wind erosion. This study is solely based on field data. Although results are supported by two previous wind tunnel studies, more wind tunnel experiments documenting the interactions between gross erosion and gross deposition are necessary. Copyright © 2010 John Wiley & Sons, Ltd.     

International Pellet Watch: Global monitoring of persistent organic pollutants (POPs) in coastal waters. 1. Initial phase data on PCBs, DDTs, and HCHs

Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale.