<Emphasis Type="Italic">Deepwater Horizon</Emphasis> Oil Spill Impacts on Salt Marsh Fiddler Crabs (<Emphasis Type="Italic">Uca</Emphasis> spp.)

The Deepwater Horizon oil spill was the largest marine oil spill in US waters to date and one of the largest worldwide. Impacts of this spill on salt marsh vegetation have been well documented, although impacts on marsh macroinvertebrates have received less attention. To examine impacts of the oil spill on an important marsh invertebrate and ecosystem engineer, we conducted a meta-analysis on fiddler crabs (Uca spp.) using published sources and newly available Natural Resources Damage Assessment (NRDA) and Gulf of Mexico Research Initiative (GoMRI) data. Fiddler crabs influence marsh ecosystem structure and function through their burrowing and feeding activities and are key prey for a number of marsh and estuarine predators. We tested the hypothesis that the spill affected fiddler crab burrow density (crab abundance), burrow diameter (crab size), and crab species composition. Averaged across multiple studies, sites, and years, our synthesis revealed a negative effect of oiling on all three metrics. Burrow densities were reduced by 39 % in oiled sites, with impacts and incomplete recovery observed over 2010–2014. Burrow diameters were reduced from 2010 to 2011, but appeared to have recovered by 2012. Fiddler crab species composition was altered through at least 2013 and only returned to reference conditions where marsh vegetation recovered, via restoration planting in one case. Given the spatial and temporal extent of data analyzed, this synthesis provides compelling evidence that the Deepwater Horizon spill suppressed populations of fiddler crabs in oiled marshes, likely affecting other ecosystem attributes, including marsh productivity, marsh soil characteristics, and associated predators.     

桂西地区二叠系合山组铝土岩的沉积环境*

桂西地区二叠系合山组铝土岩的沉积环境存在海相、陆相之争。通过对桂西二叠系铝土岩的区域调查及钻孔样品微量元素地球化学数据的分析,认为桂西二叠系铝土岩产出于陆相环境。从铝土岩分布情况看,桂西二叠纪各孤立碳酸盐岩台地上均广泛分布铝土岩沉积,该区域产出特征证明矿层是在碳酸盐岩台地全部暴露地表的环境下形成的。从铝土岩层与下伏茅口组灰岩的接触关系来看,铝土岩层底部存在茅口组灰岩砾石,在部分剖面尚见下伏茅口组灰岩中充填铝土岩等现象,说明铝土岩矿化过程直接于茅口组灰岩的古喀斯特面上完成。此外,在矿层中发现古植物根茎化石也是铝土岩形成于陆相环境的有力证据。从微量元素地球化学结果来看,来自铝土岩层样品的硼含量均小于10×10^-6,Sr/Ba值范围为0.29~1.61,平均值为0.92,Rb/K值范围为0.0011~0.0025,平均值为0.0017,以上指标结合V/Zr-Zr/Cu图解的判别,结果均指示铝土岩形成于陆相淡水环境。     

Effects of heavy metal (Pb) concentration on some growth parameters of plants grown in lead polluted soil under organic fertilizer amendment

This study investigated morphological variation and biomass accumulation that occurred in Sida acuta and Chromolaena odorata plants grown in lead polluted soil under organic fertilizer amendment. The study was carried out in the screen house at the Biological Gardens of the Obafemi Awolowo University, Ile-Ife, Osun State. The experiment was a factorial combination of one heavy metal (Pb) at five levels of concentration (0, 200, 400, 800 and 1,000 mg/kg) in a completely randomized design, and were replicated three times for each of the two plants and two levels (0 g/kg and 9.4 g/kg) of organic fertilizer (OBD-Plus). Each pot was filled with 5 kg of air-dried and sieved soil and placed on a plastic tray for the collection of excess water. Two weeks after planting, seedlings of uniform height were transplanted from the nursery to experimental pots at the rate of one seedling per pot and grown for 10 weeks. The growth parameters of the plants were biomonitored for 7 weeks. After 10 weeks of treatment, the plants were harvested and dried to calculate the biomass accumulation. The two plant species performed better under fertilizer application than without it. For each of the plant species the growth parameters decreased as the levels of Pb concentration increased. Furthermore, the plants' biomass decreased significantly (p<0.05) as the levels of Pb concentration increased. The organic fertilizer helped to improve the plants' performance in lead-polluted soil.     

Discussion on applying an analytical method to optimize the anti-freeze design parameters for underground water pipelines in seasonally frozen areas

Adopting the quasi-three-dimensional (Quasi-3D) numerical method to optimize the anti-freeze design parameters of an underground pipeline usually involves heavy numerical calculations. Here, the fitting formulae between the safe conveyance distance (SCD) of a water pipeline and six influencing factors are established based on the lowest water temperature (LWT) along the pipeline axis direction. With reference to the current widely used anti-freeze design approaches for underground pipelines in seasonally frozen areas, this paper first analyzes the feasibility of applying the maximum frozen penetration (MFP) instead of the mean annual ground surface temperature (MAGST) and soil water content (SWC) to calculate the SCD. The results show that the SCD depends on the buried depth if the MFP is fixed and the variation of the MAGST and SWC combination does not significantly change the SCD. A comprehensive formula for the SCD is established based on the relationships between the SCD and several primary influencing factors and the interaction among them. This formula involves five easy-to-access parameters: the MFP, buried depth, pipeline diameter, flow velocity, and inlet water temperature. A comparison between the analytical method and the numerical results based on the Quasi-3D method indicates that the two methods are in good agreement overall. The analytic method can be used to optimize the anti-freeze design parameters of underground water pipelines in seasonally frozen areas under the condition of a 1.5 safety coefficient.     

Progress in China’s sustainable development research: Contribution of Chinese geographers

Sustainable development has always been a hotspot in Chinese geographical research. Herein, we conduct a systematic statistical analysis of the contribution of Chinese geographers to sustainable development research using bibliometric methods. Based on the review of a vast amount of literature, we identify the main research teams, research funding sources, journals, and key research fields. The findings are as follows: (1) the resources and environmental institutes of the Chinese Academy of Sciences have a significant influence on sustainable development research; (2) China’s central government foundations (the National Natural Science Foundation of China and National Social Sciences Fund) are the main research funding sources; (3) most of the highly cited articles are published in journals sponsored by the Geographical Society of China; and (4) sustainable development theory and its research areas are being constantly enriched and perfected. Based on the statistics of keywords, the theory, research methods, research regional scales, and key research areas are summarized and expounded.     

Channel deformations of the Irkut river in the Tunkinskaya depression

We examine the intrasecular morphodynamics of the Irkut river within the Tunkinskaya depression and the associated partitions between depressions. An analysis is made of the changes in the channel pattern in plan, and a typization is provided for the channel processes for three time intervals: 1914, 1975 and 2015. We identified eleven morphodynamically uniform reaches of the channel: three, one and seven of them are of the adapted, incised and broad-floodplain types, respectively. The types of morphodynamical development of the river are systematized, and reaches with a different degree of deformation are identified within the most mobile broad-band segment of the river in conditions of free meandering. It is ascertained that the reaches of the braided type and the reach with sharp loop-like bends are the most stable, which is, in either case, due to the consolidation of vegetation by the high floodplain which made it possible to stabilize the movement of the channel in plan. The most strongly altered reaches are determined, where river channel displacements were accompanied by a complete change of the morphodynamical types of bends; the macrobends mainly experienced a regular breakthrough or were complicated by lower-order bends. We identified the reaches with lower-order (local) changes where the development of the bends (for the most part, of the loop-like type) changed into a new evolutionary cycle). We determined the role played by the influence of the territory’s geologo-geomorphological structure, hydrological conditions and natural processes of channel evolution on the dynamics of homogeneous reaches, and on morphological changes within them. The period of the most significant channel deformations, from 1914 to 1976, was determined, which is accounted for by an enhancement in anthropogenic pressure and by the associated increase in suspended load, and the period of decrease in the magnitude of manifestations of channel deformations from 1976 to 2015.     

Extreme phases of denudation and questions of geomorphological security of the Upper Angara region

An analysis is made of the manifestations of fluvial and aeolian processes in the southern, developed areas of Irkutsk oblast belonging to the upstream part of the Angara basin. We examine the formation probability and the recurrence frequency of disastrous geomorphological events. The study revealed their association with positive (fluvial processes) and negative (aeolian processes) extremes and anomalies of atmospheric moistening. It is shown that at the time of an extreme event the rate of the processes and the volumes of transported material increase abruptly (by an order of magnitude), and the affected areas show an increase. The criteria for an extreme fluvial event can be represented by a spasmodic buildup of gullies and appearance of new gullies, an abrupt increase in soil losses due to erosion of agricultural lands reaching 100?200 m³/ha, death of crops, releases of mud flows, and destruction of roads, dams, bridges and other structures. The geomorphological consequences of the 1960 summer storm rains are considered to exemplify the disastrous fluvial events. The extremes of aeolian processes have the character of hurricanes encompassing most of the agricultural areas of Irkutsk oblast. The hurricanes are accompanied by a powerful removal of aeolian material from north-west to south-east to the water area of Baikal, to windward slopes and watershed divides of the mountain ranges along the eastern coast. The finest dust particles are transported to neighboring areas of Buryatia, Mongolia and China. The negative consequences of extreme aeolian events include agricultural crop destruction or damage, soil deflation, pollution of surface waters by deflation products, fires, damage to power transmission lines or even death of people. The findings were used in zoning the Upper Angara region according to the degree of geomorphological security of the territory.     

Forecasting the water inflow into the Krasnoyarsk and Sayano-Shushenskoe reservoirs in the second quarter of the year

We consider the various methods of constructing models intended to forecast the average water inflow, in the second quarter of the year, into two reservoirs on the Yenisei river. To solve modeling problems used a new computer technology implemented in the specialized “Stochastic Modeling” software package. Independent data were employed to verify the variants of the models for the formation of variability in quarterly inflow as generated based on different algorithms. A more sophisticated and robust model for forecasting the inflow was constructed as an ensemble of partial models. Based on aggregate results of modeling, we suggest the method of constructing a forecast of the average (for the second quarter) lateral inflow into the Krasnoyarsk reservoir and the inflow into the Sayano-Shushenskoe reservoir by use of observational data accumulated by Srednesibirskoe UGMS (Weather Control and Environmental Monitoring Service), based on an ensemble of partial models. It is established that such an operation reduces the probability of forecasting errors implying an arbitrary selection of models. We constructed forecasts of the aforementioned characteristics using real-time data for 2015. It is stated that the solution of the forecasting problem can be facilitated by using additional information.     

Typology of countries of the world according to the development level of international tourism

A multifactor tourism typology of countries of the world having a structural-functional character has been developed. It provides insight into the typological features of the global spatial structure of international tourism, reflecting the intensity of international tourism flows, their geography, the importance of the tourism industry for the national economy as well as the general attributes of territorial organization of international tourism, and the dynamics of its development. Five main types of touristic types of countries have been identified. The following indicators were used for characterization of the countries and their comparison: the size of the territory, and the population size; the general level of socioeconomic development; the level and character of development of international tourism; the characteristic properties of touristic demand; the orientedness of tourism flows; characteristics of touristic offer; the degree of influence of international tourism on the national economy; characteristics of the state policy in the sphere of tourism, and touristic specialization. The first type includes the economically highly developed countries with mature national systems of international tourism forming the center of the world’s touristic space. The second type is represented by countries belonging to the semi-periphery of the world’s touristic space with an intensely forming state-supported polyfunctional system of international tourism. The third type includes moderately developed countries of the semi-periphery of the world’s touristic space with a polyfunctional system of international tourism in the stage of transformation and formation of a civilized travel market. The fourth type comprises small island states of the Caribbean Basin which belong to the semi-periphery and, in part, to the “advanced” periphery of the world’s touristic space. The fifth type combines developing countries belonging to the periphery of the world’s touristic space, with a weakly developed market of international tourism.     

Influence of melioration in natural ecological processes of a small river valley (Poland)

On the basis of the topographic maps from 1933, 1951 and 1962 (sc 1:10 000, 1:25 000 and 1:100 000, respectively) and the satellite image from 2014 (sc 1:10 000), we determined changes in the channel of the small Brynica river (Southern Poland) as well as in the land-use pattern along this river valley after its melioration. Terrain regulation and drainage brought about an intensification of the overland runoff, and a decrease in irrigation of the territory. Due to soil overdrying, some tracts of the valley are experiencing a moisture deficiency. Peat drying can lead to negative consequences, because shallow peats mostly occur on the study territory. Disappearance of peaty soils acts to decrease the degree of suitability of the riverside territories for economic purposes as well as their capacity for recovery. The schematic map of vegetation distribution along the river valley prior to and after melioration as compiled from results of field observations displays differences between mosaic quasi-natural vegetation and areas of typical agrocenoses. The preservation of the natural values along the Brynica valley is possible through balanced economic management, while the differentiation of topography contributes to creating favorable conditions for the formation of biodiversity.