Characterization of landscape pattern based on land economic niche change: A case study in Ganzhou,Gansu Province,China

Land use change has a profound impact on biodiversity and ecological processes, and is closely related to changes in landscape patterns. This paper introduces the theory and method of land economic niche into landscape ecology, which provides a new method for spatial characterization of urban and rural spatial landscape patterns. Based on this theory, this paper analyzes the landscape pattern of Ganzhou District by using Landsat images as data source in 1995, 2000, 2005,2010 and 2015. We calculated the land economic niche by applying the niche potential theory. Combined with the theory of landscape ecology, we explored the effects of the land economic niche change on the landscape pattern at a county scale.The results show that economic niche of construction land, watershed and farmland increased during 1995–2015, and grassland declined significantly. The economic niche of farmland, construction land, watershed and grassland show a negative correlation with the number of patches(NP), fragmentation index(FN) and the fractal dimension index(FD), and had a positive correlation with the aggregation index(AI). There was no significant correlation between the forest land economic niche and landscape metrics. The change of land economic niche has a driving effect on the landscape pattern of the county, which can represent the economic development direction of Ganzhou District. The land economic niche is closely related to the landscape type which can directly obtain an economic benefit.     

Geochemical constraints on CO2-rich mantle source for the Kocebu Seamount,Magellan Seamount chain in the western Pacific

The alkaline oceanic island basalts(OIBs) with under-saturated SiO_2 and high contents of CaO and alkaline are usually attributed to mantle sources different from typical tholeiitic OIBs.Based on the results of high pressure and temperature experiment study,the genesis of silica under-saturated alkaline basaltic melts could be explained by the role of CO_2, thus,the genetic relationship of alkaline basalts with CO_2 has become a topic of relevance because it is closely related to the deep carbon cycle.The Magellan Seamount chain in the West Pacific Seamount Province has wide distribution of alkali basalts.For the first time,we collected alkaline basalt samples from the Kocebu Seamount of the Magellan Seamount chain and found that magmatic apatites widely occur in the less evolved volcanic rock samples,and the high contents of phosphorus should be a feature of the alkaline OIB s of the Magellan Seamounts.Compared with typical OIBs,these alkaline volcanic rocks have higher CaO and P_2 O_5, lower SiO_2 content,negative anomaly of high field strength elements(HFSEs),more distinctly negative anomaly of potassium(K) and the ubiquity of titanaugite,indicating a CO_2-rich mantle source.Based on the relatively high K2 O and TiO_2 contents and La/Yb ratio and low MgO content of these alkaline rocks,we suggest that the volcanic rocks of the Magellan Seamounts are originated from carbonated eclogites derived possibly from ancient subducted altered oceanic crust.     

Dynamic Diurnal Changes in Green Algae Biomass in the Southern Yellow Sea Based on GOCI Images

Macroalgae blooms of Ulva prolifera have occurred every summer in the southern Yellow Sea since 2007, inducing severe ecological problems and huge economic losses. Genesis and secular movement of green algae blooms have been well monitored by using remote sensing and other methods. In this study, green algae were detected and traced by using Geostationary Ocean Color Imager(GOCI), and a novel biomass estimation model was developed from the relationship between biomass measurements and previously published satellite-derived biomass indexes. The results show that the green algae biomass can be determined most accurately with the biomass index of green algae for GOCI(BIGAG), which is calculated from the Rsurf data that had been atmospherically corrected by ENVI/QUAC method. For the first time, dynamic changes in green algae biomass were studied over an hourly scale. Short-term biomass changes were highly influenced by Photosynthetically Available Radiation(PAR) and tidal phases, but less by sea surface temperature variations on a daily timescale. A new parameter of biomass changes(PBC), calculated by the ratio of the biomass growth rate to movement velocity, could provide an effective way to assess and forecast green tide in the southern Yellow Sea and similar areas.     

Some scientific problems facing research on hydrological processes in an inland river basin

The challenge is put forward to scientific hydrology by the advancement of water sciences; that is, how should we carry out a multidisciplinary, integrated and cooperative research on hydrological processes in the basin, regional and global scales, in order to better understand the role water plays in the changes of the natural resources and environment of the earth, and to understand the hydrosphere and its interactions with the atmosphere, lithosphere and biosphere. How the changes and transformation of the components of the water cycle and water balance occur in an inland river basin has yet to be understood. We also need to understand what the interactions of water cycle, ecosystems and environment are, and what the responses and feedback of the changes to global change and to human activities are. The water cycle in an inland river basin characterizes the runoff generation region of the mountains upstream, the artificial oases region of water resources exploitation and utilization midstream and the natural desert oases region of runoff dissipating downstream. The mountain hydrological processes are discussed from water cycle, energy balance, water balance and ecological processes. The interactions of water and vegetation are discussed in relation to ecohydrology, and the hydrological processes in the ground water-soil-vegetation layer are discussed from the concept of the critical zone newly put forward abroad. The basic frame is put forward to carry out the field measurement, experiment and studies of hydrological processes in a typical inland river basin. __________ Translated from Advances in Earth Science, 2007, 22(9): 940–953 [译自: 地球科学进展]     

Interaction of Freshly Precipitated Silica Gel with Aqueous Silicic Acid Solutions under Ambient and Near Neutral pH-conditions: A Detailed Analysis of Linear Rate Law

Interaction of freshly precipitated silica gel with aqueous solutions was studied at laboratory batch experiments under ambient and near neutral pH-conditions. The overall process showed excellent reversibility: gel growth could be considered as an opposite process to dissolution and a linear rate law could be applied to experimental data. Depending on the used rate law form, the resulting rate constants were sensitive to errors in parameters/variables such as gel surface area, equilibrium constants, Si-fluxes, and reaction quotients. The application of an Integrated Exponential Model appeared to be the best approach for dissolution data evaluation. It yielded the rate constants k _dissol ∼ (4.50 ± 0.68) × 10⁻¹² and k _growth ∼ (2.58 ± 0.39) × 10⁻⁹ mol m⁻² s⁻¹ for zero ionic strength. In contrast, a Differential Model gave best results for growth data modeling. It yielded the rate constants k _dissol ∼ (1.14 ± 0.44) × 10⁻¹¹ and k _growth ∼ (6.08 ± 2.37) × 10⁻⁹ mol m⁻² s⁻¹ for higher ionic strength (I ∼ 0.04 to 0.11 mol L⁻¹). The found silica gel solubility at zero ionic strength was somewhat lower than the generally accepted value. Based on the and standard Gibbs free energy of silica gel formation was calculated as and −850,318 ± 20 J mol⁻¹, respectively. Activation energies for silica gel dissolution and growth were determined as and respectively. An universal value for growth of any silica polymorph, is not consistent with the value for silica gel growth, which questions the hypothesis about one unique activated complex controlling the silica polymorph growth.     

Morphological characters and multi-element isotopic signatures of carbonates from Chinese loess-paleosol sequences

Morphological characters and multi-element isotopic compositions of carbonates from the loess-paleosol sequences in Northwestern China are examined to explore the origin of the minerals. Samples are collected from various sections ranging from Holocene to 0.9 Ma within the sequences and fractions with grain sizes >45 and <2 μm are separated from the bulk soil and examined by SEM and TEM. The results show that the grains >45 μm exhibit an almost perfect spherical shape while those <2 μm are dominated by nano-rods having diameters of 30-50 nm and lengths of 0.3-2 μm, presumably indicating the detrital origin of the coarse fractions and the authigenic characters of the fine ones. Such implications are corroborated by the multi-elemental isotopic compositions of the carbonate minerals. A comparison of the δ¹³C and δ¹⁸O values between minerals and biologically originated samples indicates that the <2 μm fractions have a similar composition to those of coexisting land snail shells. Additional differences between the two size fractions also manifest in the ratios of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, ²⁰⁸Pb/²⁰⁴Pb, and ⁸⁷Sr/⁸⁶Sr. These results suggest the utility of fine carbonate particles in the soil profile in reconstructing a potentially higher resolution δ¹³C and δ¹⁸O time series to elucidate the paleoclimatic fluctuation in the Chinese Loess Plateau during Pleistocene. The discovery of the nano-rod calcite in Chinese loess, together with previous findings of the similar mineral form in Asian dust, strongly suggests the possibility that these highly reactive CaCO₃ form may alter the aerosol properties during transport.     

南四湖及主要入湖河流沉积物中磷的赋存形态研究

应用沉积物磷形态SMT提取方法,分析了南四湖及主要入湖河流丰水季节表层沉积物、独山湖及微山湖区沉积岩芯中磷的含量及形态组成变化,研究了磷的埋藏演化过程与人为污染特征.结果表明,老运河表层沉积物中磷的含量最高,为13068.3 mg/kg,以OP及NaOH-P为主,其富集系数分别为6.5和9.0,主要是与来自济宁市的废水污染有关.其余表层沉积物以HCl-P为主;受人为污染的影响,NaOH-P、OP产生一定程度的富集,其富集系数分别为1.0.3.7、1.3～6.0;部分沉积物中高含量的有机质加重了OP的富集.独山湖及微山湖沉积岩芯中以HCl-P和OP为主;20世纪60年代末期以来,随着湖泊生产力的提高及早期成岩过程中有机质的矿化分解,独山湖及微山湖沉积岩芯中TOC含量自下而上呈指数增加,这也导致了沉积物中OP的增加;独山湖及微山湖沉积岩芯6～0 cm和5～0 cm较高的OP及NaOH-P含量,指示了20世纪80年代中期以来磷的人为污染过程.     

The status of the passive treatment systems for acid mine drainage in South Korea

This study was performed to investigate the operating status, evaluate the problems, and discuss possible improvement methods of passive treatment systems for acid mine drainage (AMD) in South Korea. Thirty-five passive treatment systems in 29 mines have been constructed from 1996 to 2002 using successive alkalinity producing systems (SAPS) as the main treatment process. We investigated 29 systems (two for metal mines), 19 of which revealed various problems. Overflows of drainage from SAPS, wetland, or oxidation ponds were caused by the flow rate exceeding the capacities of the facilities or by the reduced permeability of the organic substance layer. Leakages occurred at various parts of the systems. In some cases, clogged and broken pipes at the mouths of the mine adits made the whole system unusable. Some systems showed very low efficiencies without apparent leakage or overflow. Even though the systems showed fairly good efficiencies in metal removal ratios (mainly iron) and pH control; sulfate removal rates were very poor except in three systems, which may indicate very poor sulfate reductions with sulfate reducing bacteria (SRB) as a means.     

Holocene environmental and climatic changes inferred from Wulungu Lake in northern Xinjiang, China

Sedimentological, geochemical and palynological data from Wulungu Lake in northern Xinjiang, China, are used to reconstruct environmental and climate changes since 9550 cal yr BP. High abundance of Sparganium and Poaceae, low Md (median diameter) and δ¹³C_organic values indicate aridity between 9550 and 6730 cal yr BP. High Md and δ¹³C_organic values, and the prevalence of desert-steppe and steppe vegetation between 4200 and 560 cal yr BP, indicate that effective moisture increased after 6730 cal yr BP, peaking at 4200 and 560 cal yr BP. Low Md values, a negative excursion of δ¹³C_org, and the transition from steppe to desert vegetation since 560 cal yr BP reflect a decrease in effective moisture during the latest Holocene. Late Holocene human activities were indicated by sharp increase in the abundance of Pediastrum then. Variations in carbonate contents indicate that temperature was generally high between 9550 and 7740 cal yr BP, low between 7740 and 6730 cal yr BP, intermediate between 6730 and 560 cal yr BP, and low during the last 560 yr. Regional comparison indicates that the Asian monsoon did not extend to Wulungu Lake and westerlies were the main factor in determining the moisture availability during the Holocene.     

青藏线冻土区“阴阳坡”问题及其辐射机制

青藏线(包括青藏铁路和青藏公路)格-拉段基本呈南北走向, 对其进行的长期地温监测表明, 在多年冻土地区, 两条线路绝大部分路段的路基出现了所谓的 "阴阳坡"现象. 在多年冻土地区, 尤其是高含冰量的多年冻土区, 阴阳坡的出现给路基的稳定性带来了极大的危害. 在分析青藏线沿线太阳辐射特点的基础上指出, 青藏高原上强烈的太阳辐射, 再加上边坡坡向以及太阳总辐射特殊的日变化规律导致了青藏线上的"阴阳坡"现象. 对于如何消除阴阳坡问题, 减缓其危害性, 给出了两条建议: 1)在路基边坡或者路面喷涂热反射材料;2)适当降低路基高度并减小路基边坡的坡度.