Factors affecting metal mobilisation during oxidation of sulphidic, sandy wetland substrates

Most metals accumulate as sulphides under anoxic conditions in wetland substrates, reducing their bioavailability due to the solubility of metal sulphides. However, upon oxidation of these sulphides when the substrate is occasionally oxidised, metals can be released from the solid phase to the pore water or overlaying surface water. This release can be affected by the presence of carbonates, organic matter and clay. We compared changes of Cd, Cu and Zn mobility (CaCl2 extraction) during oxidation of a carbonate-rich and a carbonate-poor sulphidic, sandy wetland substrate. In addition, we studied how clay with low and high cation sorption capacity (bentonite and kaolinite, respectively) and organic matter (peat) can counteract Cd, Cu and Zn release during oxidation of both carbonate-rich and carbonate-poor sulphidic sediments. CaCl2-extractability of Cu, a measure for its availability, is low in both carbonate-poor and carbonate-rich substrates, whereas its variability is high. The availability of Cd and Zn is much higher and increases when peat is supplied to carbonate-poor substrates. A strong reduction of Cd and Zn extractability is observed when clay is added to carbonate-poor substrates. This reduction depends on the clay type. Most observations could be explained taking into account pH differences between treatments, with kaolinite resulting in a lower pH in comparison to bentonite. These pH differences affect the presence and characteristics of dissolved organic carbon and the metal speciation, which in turns affects the interaction of metals with the solid soil phase. In carbonate-rich substrates, Cd and Zn availability is lower and the effects of peat and clay amendment are less clear. The latter can also be attributed to the high pH and lack of pH differences between treatments

Soil fertility in flooded and non-flooded irrigated rice systems

The lowland rice system in Asia makes a major contribution to the global rice supply and is often cited as an example of a sustainable system in which two or three crops of rice are grown in sequence under submerged conditions. However, water shortages are becoming critical in some regions for lowland rice cultivation; and there is high potential in exploring rice cultivation under moisture regimes that save water and also increase productivity. The objective of this article therefore is to analyze the consequences of switching growing of rice from flooded to aerobic conditions on soil fertility and its management. Fertility advantages of submerged rice include amelioration of chemical fertility, preferential accumulation of organic matter and improved availability of major, secondary and selected micronutrients, which contribute to the long-term maintenance of soil fertility and sustainability of the lowland rice system. However, the fertility problems under aerobic rice are better addressed with the crop as a component of a cropping system because continuous growing of aerobic rice in sequence does not seem sustainable due to complex, site-specific chemical and biological constraints

Advancing international human resource management scholarship on paternalistic leadership and gender: the contribution of postcolonial feminism

This article aims to inspire international human resource management (IHRM) scholarship that incorporates postcolonial feminist theory, using the under-researched topic of paternalistic leadership and gender to illustrate the opportunities and challenges such an endeavour can present. Paternalistic leadership is utilised because it represents one of the most widely used indigenous frameworks for examining leadership in Chinese contexts. The principal theoretical contribution of this article centres on providing IHRM scholars with postcolonial feminist ideas, perspectives and sites of inquiry for cultivating future research on gender and paternalistic leadership. The salience of postcolonial feminism resides in its capacity to address the representation of non-western women in feminist theory as a universal, transhistorical category, to centralise cultural difference in theorising gender, to shatter binaries reproduced by colonialism and imperialism (e.g. ‘West/East’, 'Western/Third World Woman') and to generate indigenous, localised knowledge on non-western women. Three sites of inquiry are discussed: 1) Chinese feminisms and genders; 2) Chinese cultures and gender norms; 3) voice, agency and the subaltern woman. This article provides research propositions for IHRM scholars seeking to translate postcolonial feminist ideas into empirical research. The article concludes by outlining implications for practice and providing research questions to guide future IHRM scholarship