Size fraction and class composition of phytoplankton in the Antarctic marginal ice zone along the 140°E meridian during February–March 2003

We investigated the size fraction and pigment-derived class compositions of phytoplankton within the euphotic zone of the Antarctic marginal ice zone between 63.3°S and 66.5°S along the 140°E meridian on two consecutive cruises in the late austral summer and early austral autumn of 2003. We observed significant temporal and spatial variations in phytoplankton size and taxonomic composition, although chlorophyll a concentrations were generally below 1 μg l⁻¹ during both periods. Microphytoplankton (>20 μm), mainly diatoms, were prominent in the euphotic zone in the southernmost area around 66.5°S during late summer. In the rest of the study area during both cruises, the phytoplankton community was dominated by pico- and nano-sized populations (<20 μm) throughout the euphotic zone. The small-size populations mostly consisted of diatoms and haptophytes, although chlorophytes were dominant in extremely cold water (−1.5°C) below the overlying warm water around 65.5°S during late summer. From late summer to early autumn, chlorophytes declined in abundance, probably due to increasing temperature within the euphotic zone (−1 to 0°C). These pico- and nano-phytoplankton-dominated populations were often accompanied by relatively high concentrations of ammonium, suggesting the active regeneration of nutrients within the small-size plankton community.     

Upper-ocean hydrodynamics along meridional sections in the southwest Indian sector of the Southern Ocean during austral summer 2007

This paper addresses analysis of surface meteorological and hydrographic data collected along the transects Durban–India Bay, Antarctica (Track-1) and Prydz Bay–Mauritius (Track-2) during February–March 2007 as part of the International Polar Year project (IPY#70). Strong winds (>12 m s⁻¹) resulted in enhanced turbulent heat loss north of 45°S. Whereas a highly stable marine atmospheric boundary layer (MABL) and strong winds facilitated the release of latent heat of condensation along Track-1, a highly unstable MABL and strong winds resulted in large turbulent heat loss from the sea surface along Track-2, in the 40–45°S belt. The northern and southern branches of Subantarctic Front on both tracks coalesce, while the Agulhas Retroflection Front (AF) and South Subtropical Front (SSTF) merge between 43° and 44°S on Track-2. The southern branch of the Polar Front (PF2) meanders 550 km southward towards the east. The Subtropical Surface Water, Central Water, and Mode Water are located north of 43.5°S, while the Subantarctic Surface Water, Antarctic Surface Water, Antarctic Intermediate Water, and Circumpolar Deep Water are encountered in the region of the Antarctic Circumpolar Current (ACC). Baroclinic transport relative to 1000 db reveals that the ACC is enhanced by 10 × 10⁶ m³ s⁻¹ eastward, and a four-fold increase in transport occurs south of the ACC. Nearly 50% of the ACC transport occurs in the 100–500 m slab. We discuss the effects of the feedback of AC and hydrological fronts on the MABL.     

Seasonal and long-term sea level variability in the marginal seas of the Arctic Ocean

One of the parameters useful for monitoring large-scale climate variability in the Arctic Ocean is sea level. It integrates virtually all static and dynamic processes in the hydrosphere and atmosphere of the Arctic. Previously unavailable mean monthly sea level data at 44 coastal and island stations in the Kara, Laptev, East Siberian and Chukchi seas covering years from 1950 to 1990 were used to analyse seasonal and inter-annual variability. Sea level has a significant annual cycle with an average seasonal amplitude (from peak to peak) in the coastal zone of the Arctic seas on the order of 20 - 30 cm. The analysis of inter-annual and inter-decadal changes has shown that at nearly all stations in the Kara, Laptev, East Siberian and Chukchi seas from the beginning of the 1950s through the end of 1980s there is a positive trend in sea level variability. The main contribution to the sea level rise was in the 1980s; on average for the coastal zone of Siberian shelf the sea level in the 1980s was 5-6 cm higher than in the previous decades. A reasonable agreement between observed decadal mean sea level values and the results of diagnostic model simulations suggests that this rise in the Arctic seas is connected with the reorganization of large-scale circulation of the Arctic Ocean, rather than the regional lowering of the coasts, as has been suggested previously.     

Seasonal diet of black-backed jackal in the Eastern Karoo,South Africa

The ability of small canids to consume a variety of resources in an opportunistic manner has been cited as a reason for their wide distribution across many habitats. Black-backed jackals Canis mesomelas have varied diets that reflect changes in food availability as a result of seasonal fluctuations in resources. Seasonal fluctuations can include variations in food type availability, as well as variations in the phenology of food resources (i.e. ungulate birth peaks). Additionally, the presence of apex predators can affect opportunistic predator diets through the provision of carrion. We investigated the diet of black-backed jackals on a reserve in the semi-arid Karoo, South Africa. Ungulates (>5 kg) were the dominant prey item across all seasons, reflecting either active predation or scavenging. Most seasonal comparisons in percent occurrence of prey groups revealed significant seasonal fluctuations in black-backed jackal diet. However, in terms of biomass consumed, the diet remained stable, dominated by small ungulates across all seasons with no clear seasonal change in ungulate composition. These results suggest that in this study black-backed jackals, although being opportunistic in terms of diet composition, had a seasonally stable food resource, most likely facilitated by the presence of cheetahs Acinonyx jubatus providing scavenging opportunities.     

60年来黄河流域径流量时空变化(英文)

Water discharge data of the Yellow River over the past 60 years was analyzed using the continuous wavelet transform (CWT) and Mann-Kendall (MK) test methods to identify spatial and temporal variation patterns. Potential connections between water discharge in the Yellow River Basin and El Ni o/Southern Oscillation (ENSO) were also examined by the cross wavelet and wavelet coherence methods. CWT results show that the periodic oscillations in water discharges had occurred at the temporal scales of 1-, 2to 4-, 6to 8and 10to 22-year. It was also found that at the annual timescale (1-year) the phase relations between water discharge and ENSO were indistinct probably due to the strong influence by human disturbances. However, over the longer time scales, the phase relation becomes much clearer with an anti-phase relation being found mainly at inter-annual scale (2to 8-year) and in-phase relation at decadal scale (16to 22-year). According to the MK test results water discharge at most stations except Tangnaihai have decreased significantly and the abrupt change occurred in the mid-1980s or the early 1990s. The changes in water discharge were found to be influenced by both climate changes and human activities. Before 1970 the change in water discharge was positively related to precipitation variations in the river basin, but after 1970 the decrease in water discharge has been largely caused by various human activities including constructions of reservoirs, water abstraction and water-soil conservation with water abstraction being the main cause.     

1950-2008年黄河入海水沙变化(英文)

Based on hydrological data observed at Lijin gauging station from 1950 to 2008, the temporal changes of water discharge and sediment load of the Yellow River into the sea were analyzed by the wavelet analysis, and their impacts on the estuary were investigated in different periods based on the measured coastline and bathymetry data. The results show that: (1) there were three significant periodicities, i.e. annual (0.5-1.0-year), internnual (3.0-6.5-year) and decadal (10.1-14.2-year), in the variations of w...     

黑河流域气候变化对水资源的影响

1IntroductionThe climate conditions of temperature and precipitation are of primary importance for arid region and a change of climate in the direction to warmer or colder, wetter or drier would have large water resources, biological and socio-economic consequences (Raino Heino, 1994; Guido V etal., 2001).Since last century, there has been a warming trend for global climate with greenhouse gases such as CO2 continually increasing. The trend got intensified particularly in the late 20th centu…     

Impact of climate change and variability on water resources in Heihe River Basin

Studies indicate that the climate has experienced a dramatic change in the Heihe River Basin with scope of temperature rise reaching 0.5-1.1oC in the 1990s compared to the mean value of the period 1960-1990, precipitation increased 18.5 mm in the 1990s compared to the 1950s, and 6.5 mm in the 1990s compared to the mean value of the period 1960-1990, water resources decreased 2.6×108 m3 in the 1990s compared to the 1950s, and 0.4×108 m3 in the 1990s compared to the mean value of the period 1960-1990. These changes have exerted a greater effect on the local environment and socio-economy, and also made the condition worsening in water resources utilizations in the Heihe Rver Basin.     

Acidity and organic carbon in lake water: variability and estimation of means

The demand for a single value to characterize the pH (and other chemical variables) of a lake, in order to calibrate palaeolimnological reconstructions, requires an answer to the question of whether means should be of untransformed or log data. The temporal frequency distributions of acidity and organic carbon in seven rivers and lakes (surface samples) in Norway are approximately lognormal. Thus log means describe the distributions better than untransformed means. Estimated standard deviations, which are similar for the rivers and lakes, are independent of the mean values. Restricting observations to the autumn does not result in better estimation of mean annual values.     

Distribution characteristics of planktonic nano－and microalgae in the Prydz Bay and its adjacent Southern Indian Ocean，during austral summer

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Perceptions of climate variability and livelihood adaptations relating to gender and wealth among the Adi community of the Eastern Indian Himalayas

The impacts of extreme weather events and climate variability on natural resource dependent farmers will further increase their vulnerability. This study describes how Adi farmers in Arunachal Pradesh (India) perceive and adapt to climate variability, and how this is influenced by gender and wealth. A total of 65 male and 71 female Adi farmers were interviewed or participated in focus group discussions. Both men and women have noticed there are fewer rainy days, longer summers, shorter winters and more erratic rainfall. However, some perceptions of change were gender and/or wealth class specific. Adi women noticed changes across areas they control including collecting forest foods, crop harvesting, and fermenting and storing of food. Men noted climate variability had made hunting wild game and marketing agricultural produce more difficult. Wealthy people were better placed to adapt to climate variability than poorer people because they could intensify their production systems. They switched to rainfed maize with improved varieties and horticultural cash crops which need more costly inputs. Wealthy people, particularly men, also received more advice and training than poorer people. Poorer farmers, particularly poor women, adapted predominantly by diversifying activities, such as using drought tolerant oil seeds and subsistence horticultural crops, accessing forest-based resources, rearing pigs and poultry, increasing fishing and the making of handicrafts. Storage, exchange and pooling of local resources were further strategies of the poor. This deeper understanding of Adi livelihood adaptation strategies will help increase their resilience by improving targeting of location specific extension services and adaptation policies.     

气候变化和人类活动对白洋淀水源区径流的影响(英文)

As the largest wetland in the North China Plain(NCP),the Baiyangdian Lake plays an important role in maintaining water balance and ecological health of NCP.In the past few decades,the decreasing streamflow in the Baiyangdian Basin associated with climate variability and human activities has caused a series of water and eco-environmental issues.In this study,we quantified the impacts of climate variability and human activities on streamflow in the water source area of the Baiyangdian Lake,based on analyses of hydrologic changes of the upper Tanghe river catchment(a sub-basin of the Baiyangdian Basin) from 1960 to 2008.Climate elasticity method and hydrological modeling method were used to distinguish the effects of climate variability and human activities.The results showed that the annual streamflow decreased significantly(P>0.05) by 1.7 mm/a and an abrupt change was identified around the year 1980.The quantification results indicated that climate variations accounted for 38%-40% of decreased streamflow,while human activities accounted for 60%-62%.Therefore,the effect of human activities played a dominant role on the decline of the streamflow in the water source area of the Baiyangdian Lake.To keep the ecosystem health of the Baiyangdian Lake,we suggest that minimum ecological water demand and integrated watershed management should be guaranteed in the future.     

Features and spatial distribution of circumpolar deep water in the southern Indian Ocean and the effects of Antarctic circum polar current

The data from the Southern Ocean observations of World Ocean Circulation Experiment(WOCE) are used for analysis and illustration of the features and spatial distributions of Circumpolar Deep Water(CDW) in the southern Indian Ocean.It is learnt from the comparison among the vertical distributions of temperature/salinity/oxygen along the 30°E,90°E and 145°E sections respectively that some different features of CDW and the fronts can be found at those longitudes,and those differences can be attributed to the zonal transoceanic flow and the merizonal movement in the Circumpolar Deep Water.In fact,the zonal transoceanic flow is the main dynamic factor for the water exchange between the Pacific Ocean and the Indian Ocean or between the Atlantic Ocean and the Indian Ocean,and for the effects on the spatial distributions of the physical properties in CDW.     

辽宁营口大辽河口水鸟多样性及季节动态

营口市大辽河口湿地是东亚-澳大利西亚迁飞区水鸟的重要栖息地。2019年,采用样线法和定点观察法,对大辽河口湿地水鸟进行监测,运用指数分析方法研究湿地水鸟多样性。结果表明:共记录到湿地水鸟5目10科45种230355只,其中,鸻形目29种,国家Ⅰ级保护动物2种,国家Ⅱ级保护动物5种,IUCN濒危物种2种,易危物种2种,近危物种2种,个体数量超过全球数量1%标准的有13种。从居留型来看,以旅鸟为主,其个体数量占水鸟个体总数的90.06%。大辽河口湿地水鸟多样性季节差异明显,春季的水鸟个体数量最高,8月的水鸟多样性指数最高,3月的水鸟均匀度指数最高。营口大辽河口湿地水鸟多样性高,种群数量大,已达到国际重要湿地的标准,应尽快纳入国家湿地保护体系。     

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu

The delta evolution and erosion process of the abandoned Yellow River Delta (AYRD) have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model. In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance (Dc) with the average range value (Ao) of grain size parameter. Filtering method (removing data that not at a sampling station) is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta (AS) is better than that in the northern part of the abandoned Yellow River Delta (AN). Sediment in the area is found to be anisotropy at the northeast-southeast direction. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between Dc, Ao, sediment transport and delta evolution shows a close link between Dc and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.     

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu

The delta evolution and erosion process of the abandoned Yellow River Delta (AYRD) have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model. In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance (D _c) with the average range value (Ao) of grain size parameter. Filtering method (removing data that not at a sampling station) is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta (AS) is better than that in the northern part of the abandoned Yellow River Delta (AN). Sediment in the area is found to be anisotropy at the northeast-southeast direction. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between D _c, Ao, sediment transport and delta evolution shows a close link between D _c and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.     

Environmental and socioeconomic dynamics of the Indian Ocean tsunami in Penang,Malaysia

This paper addresses some of the environmental and socioeconomic dimensions of the 2004 Indian Ocean tsunami on Penang, Malaysia. We aim to offer wide access to unique and perishable data, while at the same time providing insight to ongoing debates about hazards, vulnerability and social capital. Our social survey examines some of the dynamics that shaped the tsunami impact, response and recovery process. While in terms of lives lost Penang may not conform to arguments surrounding vulnerable environments, the recovery process is more marked by social disparities in terms of the ability to access resources. Our physical survey records local topography, flow depth and flow direction, and charts the differential impact of the tsunami. Yet measuring hazards is not a straightforward process, and relies on reflexive methodologies and eyewitness accounts.