Salinity in Colonial Irrigation: British India and south-eastern Australia

Salinity is an environmental phenomenon that affects the world's arid and semi-arid regions, where it causes soil degradation and problems for agriculture. Salinity began to attract serious attention in the irrigated districts of the Murray Valley in south-eastern Australia in the 1960s. However, observations that the south-eastern Australian landscape was affected by naturally occurring salts predates this period of awareness by more than half a century. Drawing on documentary history, the present paper reveals what soil chemists in New South Wales in the 1890s already understood of the potential dangers of salinity. These scientists were aware of the experience of their colonial colleagues in British India, where the seriousness of the problem had been recognised by the 1870s. Using evidence from India and south-eastern Australia in the nineteenth and early-twentieth centuries, the paper outlines the opposing worldviews of scientists and engineers in New South Wales about the potential dangers of intensive irrigation. It offers an explanation as to why that understanding was insufficient to prevent the growth of the problem.     

Audiomagnetotelluric investigations of shallow sedimentary basins in northern Sudan

Audiomagnetotelluric (AMT) investigations were carried out to study shallow sedimentary basins in northern Sudan and southern Egypt. Unlike recordings in settled areas, the natural variations (atmospherics) in the eastern Sahara were completely unperturbed by cultural noise, usually yielding very high data quality. Typical recordings and spectra are presented. The atmospherics show distinct daily variations, with maximum amplitudes in the local afternoon/night hours. As a sort of calibration, AMT measurements together with DC-resistivity and electromagnetic soundings were conducted at several groundwater boreholes. Under favourable conditions, a vertical anisotropy may be resolved by joint inversion of DCR and AMT data. The results of a case study in the Es Safya basin (NW Sudan) are presented. The investigations were aimed at determining basement depths and groundwater levels, as well as the direction and dip of major bounding faults. 2-D modelling and inversion revealed the overall conductivity structure of this shallow graben. The AMT method proved to be a valuable tool for a comparatively swift reconnaissance study of shallow structures.     

不同初始盐分浓度下土壤盐结皮的形成过程及其对蒸发的影响机理

土壤盐结皮对土壤水文过程具有重要影响,初始盐分浓度（Initial salt concentration, ISC）的差异会对盐结皮的形成过程产生不同程度的影响,从而导致土壤蒸发的差异。但目前不同ISC下盐结皮形成过程对土壤蒸发的影响机理尚不明确。因此,通过试验模拟与理论分析相结合,动态监测及分析不同ISC下砂土的盐结皮形成、蒸发、土壤表面温度动态变化过程,以期阐明不同ISC下盐结皮形成过程及其对土壤蒸发的影响机理。结果表明：ISC越高,盐结皮在土壤表面出现的时间越早,覆盖率越大,且在同样光照强度和光照时间条件下土表温度增幅越小,蒸发量也越小;对数函数能较好地拟合不同ISC与累积蒸发量之间的关系（R²>0.90）;随着ISC的增加,盐结皮对土壤蒸发抑制效率从24.14%（10 g·L^-1）增大到71.99%（250 g·L^-1）。ISC会显著影响盐结皮形成的过程,并通过影响土表温度的变化进而导致土壤蒸发出现巨大差异。     

A Raman investigation on the boron form occurring in salt lake brine during evaporation

Boron resources are abundant in Da Qaidam salt lake of Qaidamu Basin. It has been given great attention for the polyborate species present in brine. In this study, the Raman spectroscopy was applied to investigate the existing-form of boron in brine during evaporation. The prepared solutions of MgO·2B2O3-H2O, MgO·2B2O3-MgCl2 -H2O, and MgO·2B2O3-MgSO4-H2O was also evaporated and recorded to study the influence of boron concentration, pH, and electrolytes on the borate speciation in brine. The mononborates of B(OH)3 and B(OH)4- were found to be the only forms present in the original salt lake brine. Brine evaporation promotes the formation of polyborate anions B3O3(OH)4-, B5O6(OH)4-, and B6O7(OH)62- and also disappearance of the B(OH)4- ion in brine with boron concentration of more than 11 g/L in B2O3. The pentaborate ion of B5O6(OH)4- was sensitive to the solution pH and found to be appeared under the pH value of 8.0. While the hexaborate ion of B6O7(OH)62- was observed more dependent on the electrolyte of magnesium chloride due to its special properties, such as promoting boron accumulation, lowering solution pH, and also the strong af?nity for water molecules, which is beneficial to the polymerization of borate ions in brine. The interaction mechanisms among polyborate anions during evaporation had also been proposed.     

1960-2005年新疆地区蒸发皿蒸发与实际蒸发之间的关系

Pan evaporation,an indictor of potential evaporation,has decreased during the last several decades in many parts of the world;the trend is contrary to the expectation that the increase of actual evaporation will accompany global warming,known as the pan evaporation paradox.What is the essential relationship between pan evaporation and actual evaporation? This is still an uncertain problem.In this paper,the trends of pan evaporation and actual evaporation are investigated using observational data and observation-constrained simulation results using NCAR Community Land Model(CLM) in Xinjiang from 1960 to 2005.Our analysis suggests that the decreasing trend of annual pan evaporation accompanies the increasing trend of annual actual evaporation,the tendencies of them both have statistical significance(at 99% level and at 95% level,respectively).We also find that there is the same turning point in precipitation,pan evaporation and actual evaporation of 1986,and either before the point or after,pan evaporation has inverse trend comparing with actual evaporation and precipitation.The above analysis indicates that pan evaporation and actual evaporation have complementary relationship.These results support the issue of evaporation paradox described by Brutsaert and Parlange(1998) and suggest that decrease of pan evaporation indicates an increase of actual evaporation in Xinjiang in the past half century.The correlation analysis shows that diurnal temperature range(DTR),wind speed,low cloud cover and precipitation are the most likely driving forces for the reduced pan evaporation and the ascending actual evaporation.     

Comparison of pan evaporation and actual evaporation estimated by land surface model in Xinjiang from 1960 to 2005

Pan evaporation,an indictor of potential evaporation,has decreased during the last several decades in many parts of the world;the trend is contrary to the expectation that the increase of actual evaporation will accompany global warming,known as the pan evaporation paradox.What is the essential relationship between pan evaporation and actual evaporation? This is still an uncertain problem.In this paper,the trends of pan evaporation and actual evaporation are investigated using observational data and observation-constrained simulation results using NCAR Community Land Model(CLM) in Xinjiang from 1960 to 2005.Our analysis suggests that the decreasing trend of annual pan evaporation accompanies the increasing trend of annual actual evaporation,the tendencies of them both have statistical significance(at 99% level and at 95% level,respectively).We also find that there is the same turning point in precipitation,pan evaporation and actual evaporation of 1986,and either before the point or after,pan evaporation has inverse trend comparing with actual evaporation and precipitation.The above analysis indicates that pan evaporation and actual evaporation have complementary relationship.These results support the issue of evaporation paradox described by Brutsaert and Parlange(1998) and suggest that decrease of pan evaporation indicates an increase of actual evaporation in Xinjiang in the past half century.The correlation analysis shows that diurnal temperature range(DTR),wind speed,low cloud cover and precipitation are the most likely driving forces for the reduced pan evaporation and the ascending actual evaporation.     

Managed Temporary Labour Migration of Pacific Islanders to Australia and New Zealand in the Early Twenty-first Century

ABSTRACT

Circular migration was one of several enduring themes in Graeme Hugo’s highly productive research career. Although his specialist field was Asian population movement, during the 2000s he became increasingly interested in labour migration in the Pacific Islands. This paper reviews the development of two managed circular migration schemes targeting Pacific labour that emerged following the UN High-level Dialogue on International Migration and Development in 2006. New Zealand’s Recognised Seasonal Employer (RSE) scheme and Australia’s Seasonal Worker Program (SWP) have attracted international attention as the kind of ‘best practice’ temporary labour migration schemes that Hugo had in mind when he emphasised the positive contributions that circular forms of mobility could make to development in both source and destination countries. The two schemes have transformed mobility between the participating countries and have played a major role in the negotiations over a free-trade agreement between Pacific Forum countries, including Australia and New Zealand. Although the schemes have been in operation for almost 10 years, this paper argues that they are not becoming ‘business as usual’; they embody complex systems of relationships between multiple stakeholders that require ongoing management to ensure that they do not become traps for low-skilled, low-paid ‘permanent’ temporary workers.     

宁夏引黄灌区蒸散发量的计算模拟

为了解宁夏引用耗排黄河水量的问题,针对水域、裸地-植被域和不透水域等不同土地利用类型,采用了Penman公式、Noilhan-Planton模型和Penman-Monteith公式等对相应土地利用类型的蒸散发量进行计算模拟,从而确定了区域蒸散发量的计算模拟方法。依据计算模拟结果和试验观测数据对区域蒸散发量的计算模拟方法进行了验证。基于以上研究,以宁夏引黄灌区为例,对宁夏引黄灌区2000年的蒸散发量和1991-2000年间蒸散发量的变化趋势进行了计算模拟,并就降雨量对区域蒸散发量的影响关系进行了分析。模拟结果表明,2000年宁夏引黄灌区(不计黄河干流河道本身的蒸发)的总蒸散发量为4.59×109m3,计入黄河干流河道本身的蒸发则总蒸散发量为4.97×109m3;1991-2000年10年间区域总蒸散发量和区域农田蒸散发量呈增加趋势,天然林草灌木地和荒地蒸散发量呈下降趋势;区域总蒸散发量、农田蒸散发量、林草灌木地蒸散发量等与降雨量有着较好的相关关系,并随着降雨量的增加呈递增趋势。     

Definition and measurement of salinity in salt lakes

Salinity is the most important chemical attribute of athalassic salt lakes. Even so, some confusion persists of what salinity means and how to measure it. For sal lakes, salinity is best defined as the sum total of all ion concentrations, or total ion concentration. Ideally, it is recommended that salinities be expressed on a mass per mass basis and as ppt (parts per thousand). Direct measurements of salinity can only be derived from full ionic analyses. Indirect measurements can be derived by determinations of density, conductivity, freezing point depression and total dissolved solids or matter.     

全球主要河流流域碳酸盐岩风化碳汇评估

碳酸盐岩风化吸收的大气CO₂主要以HCO₃ ^-形式连续地经由河流从大陆输送到海洋,成为陆地生态系统的重要碳汇。目前主要河流流域的碳酸盐岩风化碳汇估算存在不确定性,分布格局尚不清晰。基于GEMS-GLORI全球河流数据库提供的全球10万km ²以上主要河流流域多年平均监测数据,利用水化学径流法估算出全球主要河流流域碳酸盐岩对CO₂的吸收速率为0.43±0.15 Pg CO₂ yr ^-1,平均CO₂吸收通量为7.93±2.8 t km ^-2 yr ^-1。CO₂吸收通量在不同气候带下差异显著,热带和暖温带CO₂年吸收速率占全球主要河流流域年吸收速率的62.95%。冷温带CO₂年吸收速率占全球主要河流流域的33.05%,仅次于热带地区。本文划分出全球CO₂吸收通量的9个关键带,关键带的交汇处CO₂吸收通量较高。喀斯特出露流域碳酸盐岩对CO₂吸收通量的均值为8.50 t km ^-2 yr ^-1,约为非喀斯特流域的3倍。全球喀斯特出露流域碳酸盐岩风化碳汇在全球碳循环、水循环及碳收支平衡估算研究方面占据重要地位。     

Wilderness survey and evaluation in Australia

Increasing pressures on and interest in remote and natural lands have necessitated the formulation of wilderness protection and management policies by many Australian nature conservation authorities. Planners and managers require detailed information on variation in wilderness quality and the capacity to assess the impact on wilderness of development proposals or management strategies. To meet these demands advances have been made in techniques of wilderness identification and analysis, and a national inventory of remote and natural land in Australia has been commenced. This paper reviews these developments, discussing the newly established National Wilderness Inventory and its implications for wilderness protection in Australia.     

Issues of Spatial and Temporal Variability in Climate Impact Studies

The accuracy of impact estimates relating climate change to regional-scale agricultural production is constrained by the temporal and spatial resolution of climate change projections. Several techniques have been used to compensate for these limitations in order to provide reasonable estimates of the impact of climate change on crop yield. One approach assumes that variability over time can substitute for spatial variability, thereby reducing the need to estimate the impacts at a spatially dense network of stations—an assumption that has not been generally tested. This study evaluates this assumption using methods similar to those employed in the climate impact literature. The findings suggest that current practices are generally defensible if the goal is to provide a range of possible crop responses to climate change. However, the results also show that the assumption is highly sensitive to specific interactions at the soil-plant-atmosphere interface and, consequently, does not hold under certain circumstances.