Effects of Anthropogenic Disturbance on Sediment Organic Carbon Mineralization Under Different Water Conditions in Coastal Wetland of a Subtropical Estuary

The changes in soil organic carbon(C) mineralization as affected by anthropogenic disturbance directly determine the role of soils as C source or sink in the global C budget. The objectives of this study were to investigate the effects of anthropogenic disturbance(aquaculture pond, pollutant discharge and agricultural activity) on soil organic C mineralization under different water conditions in the Minjiang River estuary wetland, Southeast China. The results showed that the organic C mineralization in the wetland soils was significantly affected by human disturbance and water conditions(P 0.001), and the interaction between human disturbance activities and water conditions was also significant(P 0.01). The C mineralization rate and the cumulative mineralized carbon dioxide-carbon(CO_2-C)(at the 49th day) ranked from highest to lowest as follows: Phragmites australis wetland soil aquaculture pond sediment soil near the discharge outlet rice paddy soil. This indicated that human disturbance inhibited the mineralization of C in soils of the Minjiang River estuary wetland, and the inhibition increased with the intensity of human disturbance. The data for cumulative mineralized CO_2-C showed a good fit(R~2 0.91) to the first-order kinetic model C_t = C_0(1 – exp(–kt)). The kinetic parameters C_0, k and C_0 k were significantly affected by human disturbance and water conditions. In addition, the total amount of mineralized C(in 49 d) was positively related to C_0, C_0 k and electrical conductivity of soils. These findings indicated that anthropogenic disturbance suppressed the organic C mineralization potential in subtropical coastal wetland soils, and changes of water pattern as affected by human activities in the future would have a strong influence on C cycling in the subtropical estuarine wetlands.     

Green space planning and land use: An assessment of urban regional and green structure planning in Greater Copenhagen

Geografisk Tidsskrift, Danish Journal of Geography 106(2):7–20, 2006

In its Regional Plan of 2005, The Greater Copenhagen Authority (abbreviated as “HUR” in Danish) places special emphasis on the future recreational values associated with the regional green structure. In this paper, the development of the urban green structure in Greater Copenhagen is elaborated upon, focusing on land use changes and the effectiveness of regionally coordinated planning measures. EU MOLAND data are used to analyse the development of the region's green structure during the period 1954 to 1998. Analysis of two “green wedges” within the green structure illustrates that the development of the green recreational areas is the result of both formal and more informal planning initiatives. Development has shown equal phases that correspond to the applied regional planning measures and the general economic conditions. However, local preferences in the involved municipalities likewise have played an important role and have resulted in different urbanisation pressure within the two wedges. Land use has transformed from an agricultural to a primarily recreational landscape. In some areas, however, urbanisation pressure has resulted in residential and green industrial areas instead of the planned recreational land use. Based on its historical development it is concluded that future preservation and development of the green structure in Greater Copenhagen requires regional planning measures to be incorporated into municipal plans. In this way the increasingly independent municipalities will comply to objectives of the Regional Plan 2005.     

Petrochemistry of Jurassic and Cretaceous tholeiites from Kong Karls Land, Svalbard, and their relation to Mesozoic magmatism in the Arctic

A study of the whole-rock geochemistry and mineral chemistry of high-TiO₂ Upper Jurassic and medium-TiO₂ Lower Cretaceous basalts from Kong Karls Land, Svalbard, is presented. Geochemical criteria indicate that the basalts are initial rifting tholeiites with weak signs of crustal contamination. The Upper Jurassic basalts appear to be associated with the Olga Rift, part of a trans-Barents rift system which failed to link the proto-Atlantic and proto-Arctic basins. The Lower Cretaceous basalts may be more closely related to initial rifting tholeiites on Franz Josef Land and Spitsbergen generated during the rifting stage of opening of the Canada Basin. During break-up of the Barents Shelf, the sequence of magma types corresponds to the pre-, syn- and post-rifting stages established in other areas of continental break-up. Evidence for a possible hot-spot or plume trail, extending from Siberia to the Yermak Plateau over 250 Ma, is assembled.     

Luminescence chronology of river adjustment and incision of Quaternary sediments in the alluvial plain of the Sabarmati River, north Gujarat, India

River adjustment and incision in the Sabarmati basin, Gujarat, India have been examined at a site near Mahudi. Towards this, the morphostratigraphy and depositional chronometry of the middle alluvial plains were investigated. The upper fluvial sequence, along with the overlying aeolian sand and riverbed scroll plains, provide clues to the evolution of the present Sabarmati River. Sedimentological analyses of the upper fluvial sequence indicate its deposition by a meandering river system during what is believed to be a persistent wetter phase. Luminescence chronology bracketed this sequence to between 54 and 30 ka, which corresponds to Oxygen Isotope Stage-3, during which the SW monsoon was enhanced. The overlying aeolian sand has been dated to 12 ka, indicating that dune accretion occurred simultaneously with the strengthening of the SW monsoon during the Early Holocene. Adjustment of the Sabarmati along a N–S transect is placed around 12 ka and the incision is bracketed between 12 and 4.5 ka. River adjustment could have been tectonic; however, the incision was facilitated by the availability of continuous flow in the river caused by the SW monsoon. The basin experienced two tectonic events at about 3 and 0.3 ka, as demonstrated by the morphology of the scroll plains.     

Monitoring of water stress in wheat using multispectral indices derived from Landsat-TM

Detection of crop water stress is crucial for efficient irrigation water management. Potential of Satellite data to provide spatial and temporal dynamics of crop growth conditions makes it possible to monitor crop water stress at regional level. This study was conducted in parts of western Uttar Pradesh and Haryana. Multi-temporal Landsat data were used for detecting wheat crop water stress using vegetation indices (VIs), viz. vegetation water stress index (VWSI) and land surface wetness index water stress factor (Ws_LSWI). The estimated water stress from satellite data-based VIs was validated by water stress factor (Ws) derived from flux-tower data. The study observed Ws_LSWI to be better index for water stress detection. The results indicated that Ws_LSWI was superior over other index showing RMSE = 0.12, R² = 0.65, whereas VWSI showed overestimated values with mean RD 4%.     

Distribution and sources of pre-anthropogenic lead isotopes in deep ocean water from FeMn crusts

The lead isotope composition of ocean water is not well constrained due to contamination by anthropogenic lead. Here the global distribution of lead isotopes in deep ocean water is presented as derived from dated (ca. 100 ka) surface layers of hydrogenetic Fe-Mn crusts. The results indicate that the radiogenic lead in North Atlantic deep water is probably supplied from the continents by river particulates, and that lead in Pacific deep water is similar to that characteristic of island and continental volcanic arcs. Despite a short residence time in deep water (80–100 a), the isotopes of lead appear to be exceedingly well mixed in the Pacific basin. There is no evidence for the import of North Atlantic deep water-derived lead into the Pacific ocean, nor into the North Indian Ocean. This implies that the short residence time of lead in deep water prohibits advection over such long distances. Consequently, any climate-induced changes in deep-water flow are not expected to result in major changes in the seawater Pb-isotope record of the Pacific Ocean.     

Late quaternary deformation and palaeoseismicity: Insight into geomorphotectonic evolution of Kachchh, western Indian Subcontinent

Kachchh in western Indian Shield, according to the Bureau of Indian Standard (IS:1893:2002), falls in Seismic Zone V. This is intriguing considering that the region is far away from active Plate margin. Apart from the recent incidences of earthquakes, there are several pre-historic/archaeological records of earthquakes in the region. Beyond these, the geological evidence of earth-movements (causing earthquakes) is provided by the occurrence of several’ active’ faults, which are considered geological markers of palaeoseismicity. There are records of innumerable incidences of faulting in the region in not so distant geological past. Study of fault features especially the scarp faces marking abrupt change in physical relief proves that the different levels of topography in the entire terrain are fault-bound features. Studies also confirm that the topographic difference between the high and ’sunken’ features have formed due to uplift and relative down-sagging during the geomorphotectonic evolution of the terrain. Features that make the region unique are: (i) restriction of fault-related deformation zone to a narrow strip between the southern margin of Thar Desert and the south coast line of the Kachchh Peninsula; (ii) overall sub-horizontality of bedding and other topographic and planation surfaces over the entire region; (iii) evidence of fault-controlled geomorphology indicating vertical movement along fault planes; (iv) evidence constraining the time of geomorphological evolution of the terrain only during the Late Quaternary, making it the youngest neotectonically evolved terrain in the Precambrian Indian Shield.