Sedimentary evolution and environmental history of Lake Van (Turkey) over the past 600,000 years

The lithostratigraphic framework of Lake Van, eastern Turkey, has been systematically analysed to document the sedimentary evolution and the environmental history of the lake during the past ca 600,000 years. The lithostratigraphy and chemostratigraphy of a 219 m long drill core from Lake Van serves to separate global climate oscillations from local factors caused by tectonic and volcanic activity. An age model was established based on the climatostratigraphic alignment of chemical and lithological signatures, validated by 40Ar/39Ar ages. The drilled sequence consists of ca 76% lacustrine carbonaceous clayey silt, ca 2% fluvial deposits, ca 17% volcaniclastic deposits and 5% gaps. Six lacustrine lithotypes were separated from the fluvial and event deposits, such as volcaniclastics (ca 300 layers) and graded beds (ca 375 layers), and their depositional environments are documented. These lithotypes are: (i) graded beds frequently intercalated with varved clayey silts reflect rising lake-levels during the terminations; (ii) varved clayey silts reflect strong seasonality and an intralake oxic–anoxic boundary, for example, lake-level highstands during interglacials/interstadials; (iii) CaCO3-rich banded sediments are representative of a lowering of the oxic-anoxic boundary, for example, lake-level decreases during glacial inceptions; (iv) CaCO3-poor banded and mottled clayey silts reflect an oxic–anoxic boundary close to the sediment-water interface, for example, lake-level low-stands during glacials/stadials; (v) diatomaceous muds were deposited during the early beginning of the lake as a fresh water system; and (vi) fluvial sands and gravels indicate the initial flooding of the lake basin. The recurrence of lithologies (i) to (iv) follows the past five glacial/interglacial cycles. A 20 m thick disturbed unit reflects an interval of major tectonic activity in Lake Van at ca 414 ka BP.

Late Glacial and Holocene environmental history of the Pirin Mountains (SW Bulgaria): a paleolimnological study of Lake Dalgoto (2310 m)

Diatoms, Cladocera, and chironomids preserved in the sediments of Lake Dalgoto were studied to reconstruct the history of the lake ecosystem in the context of the vegetation history as represented by the pollen stratigraphy. Younger Dryas silty sediments at the base of the core are characterized by low diversity of aquatic organisms. The transition to the Holocene is indicated by a sharp change from silt to clay-gyttja. The migration and expansion of trees at lower elevations between 10200 and 8500 14C-yr BP, along with higher diversities and concentrations of aquatic organisms and the decreased proportion of north-alpine diatoms, point to rapidly rising summer temperatures. After 6500 14C-yr BP the expansion of Pinus mugo in the catchment coincides with signs of natural eutrophication as recorded by an increase of planktonic diatoms. In the late Holocene (4000–0 14C-yr BP) Pinus peuce and Abies are reduced and Picea expands. Cereal grains and disturbance indicators suggest late-Holocene human modification of the vegetation.

Accessibility as a determinant of environmental dynamics in socio-economic disparities in mainland Southeast Asia

Access and accessibility are important determinants of people’s ability to utilise natural resources, and have a strong impact on household welfare. Physical accessibility of natural resources, on the other hand, has generally been regarded as one of the most important drivers of land-use and land-cover changes. Based on two case studies, this article discusses evidence of the impact of access to services and access to natural resources on household poverty and on the environment. We show that socio-cultural distances are a key limiting factor for gaining access to services, and thereby for improved household welfare. We also discuss the impact of socio-cultural distances on access to natural resources, and show that large-scale commercial exploitation of natural resources tends to occur beyond the spatial reach of socio-culturally and economically marginalised population segments. We conclude that it is essential to pay more attention to improving the structural environment that presently leaves social minority groups marginalised. Innovative approaches that use natural resource management to induce poverty reduction – for example, through compensation of local farmers for environmental services – appear to be promising avenues that can lead to integration of the objectives of poverty reduction and sustainable environmental stewardship.

Mainstreaming a Decade's Experiences in Watershed Management to Meet the Challenges of Environmental Change in the Hindu Kush-Himalayas

Like other mountain areas in the world, the Hindu Kush-Himalayan (HKH) region is particularly vulnerable to climate change. Ongoing climate change processes are projected to have a high impact on the HKH region, and accelerated warming has been reported in the Himalayas. These climate change impacts will be superimposed on a variety of other environmental and social stresses, adding to the complexity of the issues. The sustainable use of natural resources is crucial to the long-term stability of the fragile mountain ecosystems in the HKH and to sustain the socio-ecological resilience that forms the basis of sustainable livelihoods in the region. In order to be prepared for these challenges, it is important to take stock of previous research. The ‘People and Resource Dynamics Project’ (PARDYP), implemented by International Centre for Integrated Mountain Development (ICIMOD), provides a variety of participatory options for sustainable land management in the HKH region. The PARDYD project was a research for development project that operated in five middle mountain watersheds across the HKH – two in Nepal and one each in China, India, and Pakistan. The project ran from 1996 to 2006 and focused on addressing the marginalisation of mountain farmers, the use and availability of water, issues relating to land and forest degradation and declining soil fertility, the speed of regeneration of degraded land, and the ability of the natural environment to support the growing needs of the region’s increasing population. A key learning from the project was that the opinion of land users is crucial to the acceptance (and, therefore, successful application) of new technologies and approaches. A major challenge at the end of every project is to promote knowledge sharing and encourage the cross-fertilization of ideas (e.g., in the case of PARDYP, with other middle mountain inhabitants and practitioners in the region) and to share lessons learned with a wider audience. This paper will highlight how the PARDYP findings, including ways of addressing soil fertility and water scarcity, have been mainstreamed in the HKH region through capacity building (international, regional, and national training courses), networking, and the provision of backstopping services. In addition, in view of the challenges in watershed management in the HKH connected to environmental change, the lessons learned from the PARDYP are now being used by ICMOD to define and package climate change proof technology options to address climate change adaptation.

An ice-core based history of Siberian forest fires since AD 1250

Forest fires play a key role in the global carbon cycle and thus, can affect regional and global climate. Although fires in extended areas of Russian boreal forests have a considerable influence on atmospheric greenhouse gas and soot concentrations, estimates of their impact on climate are hampered by a lack of data on the history of forest fires. Especially regions with strong continental climate are of high importance due to an intensified development of wildfires. In this study we reconstruct the fire history of Southern Siberia during the past 750 years using ice-core based nitrate, potassium, and charcoal concentration records from Belukha glacier in the continental Siberian Altai. A period of exceptionally high forest-fire activity was observed between AD 1600 and 1680, following an extremely dry period AD 1540-1600. Ice-core pollen data suggest distinct forest diebacks and the expansion of steppe in response to dry climatic conditions. Coherence with a paleoenvironmental record from the 200 km distant Siberian lake Teletskoye shows that the vegetational shift AD 1540-1680, the increase in fire activity AD 1600-1680, and the subsequent recovery of forests AD 1700 were of regional significance. Dead biomass accumulation in response to drought and high temperatures around AD 1600 probably triggered maximum forest-fire activity AD 1600-1680. The extreme dry period in the 16th century was also observed at other sites in Central Asia and is possibly associated with a persistent positive mode of the Pacific Decadal Oscillation (PDO). No significant increase in biomass burning occurred in the Altai region during the last 300 years, despite strongly increasing temperatures and human activities. Our results imply that precipitation changes controlled fire-regime and vegetation shifts in the Altai region during the past 750 years. We conclude that high sensitivity of ecosystems to occasional decadal-scale drought events may trigger unprecedented environmental reorganizations under global-warming conditions.

Deposition History of Polychlorinated Biphenyls to the Lomonosovfonna Glacier, Svalbard: A 209 Congener Analysis

A 37 m deep ice core representing 1957–2009 and snow from 2009 to 2010 were collected on the Lomonosovfonna glacier, Svalbard (78.82° N; 17.43° E) and analyzed for 209 polychlorinated biphenyl (PCB) congeners using high-resolution mass spectrometry. Congener profiles in all samples showed the prevalence of tetra- and pentachlorobiphenyls, dominated in all samples by PCB-44, PCB-52, PCB-70 + PCB-74, PCB-87 + PCB-97, PCB-95, PCB-99, PCB-101, and PCB-110. The ∑PCB flux varied over time, but the peak flux, 19 pg cm–2 year–1 from 1957 to 1966, recurred in 1974–1983, 1998–2009, and 2009–2010. The minimum was 5.75 pg cm–2 year–1 in 1989–1998, following a 15 year decline. Peak ∑PCB fluxes here are lower than measured in the Canadian Arctic. The analysis of all 209 congeners revealed that PCB-11 (3,3′-dichlorobiphenyl) was present in all samples, representing 0.9–4.5% of ∑PCB. PCB-11 was not produced in a commercial PCB product, and its source to the Arctic has not been well-characterized; however, our results confirm that the sources to Lomonosovfonna have been active since 1957. The higher fluxes of ∑PCB correspond to periods when average 5 day air mass back trajectories have a frequency of 8–10% and reach 60° N or beyond over northern Europe and western Russia or the North Sea into the U.K