SAPONIN ACTIVITY OF DIFFERENT PARTS OF ALFALFA SEEDLINGS

The saponin content of alfalfa of different age was investigated by thin-Iayer- chromatographic densitometric method and by a biological method, by the Trichoderma- bioassay. With the help of the Trichoderma-bioassay the highest level of saponin was determined in the cotyledons of the alfalfa seedlings, independently of the age of the seedlings. Comparing the results obtained by the two methods it was found that the fungistatic activity or toxicity of the saponins of the cotyledons are more intensive than that of the leaves of developed plants

Leaching of copper and nickel in soil-water systems contaminated by bauxite residue (Red mud) from Ajka, Hungary: The importance of soil organic matter

Red mud is a highly alkaline (pH >12) waste product from bauxite ore processing. The red mud spill at Ajka, Hungary, in 2010 released 1 million m3 of caustic red mud into the surrounding area with devastating results. Aerobic and anaerobic batch experiments and solid phase extraction techniques were used to assess the impact of red mud addition on the mobility of Cu and Ni in soils from near the Ajka spill site. Red mud addition increases aqueous dissolved organic carbon (DOC) concentrations due to soil alkalisation, and this led to increased mobility of Cu and Ni complexed to organic matter. With Ajka soils, more Cu was mobilised by contact with red mud than Ni, despite a higher overall Ni concentration in the solid phase. This is most probably because Cu has a higher affinity to form complexes with organic matter than Ni. In aerobic experiments, contact with the atmosphere reduced soil pH via carbonation reactions, and this reduced organic matter dissolution and thereby lowered Cu/Ni mobility. These data show that the mixing of red mud into organic rich soils is an area of concern, as there is a potential to mobilise Cu and Ni as organically bound complexes, via soil alkalisation. This could be especially problematic in locations where anaerobic conditions can prevail, such as wetland areas contaminated by the spill

Trace and rare earth element dispersal downstream of the Ajka red mud spill, Hungary

Between 600,000—700,000m³ of caustic (pH>13) red mud suspension were released from the Ajkai Timfoldgyar Zrt alumina plant on the 4th October 2010. This study highlights the dispersal of key red mudderived contaminants in downstream fluvial sediments from surveys undertaken within two months of the spill. Source samples contain abundant V (>1000mg/kg), Cr (>800mg/kg), Ni (>250mg/kg) and As (>80mg/kg). Red mud-affected samples are also particularly enriched above reference sites in rare earth elements which include Ce (>400mg/kg), La, Nd and Pr (all >100mg/kg). The combined signal of these provides a useful tracer of red mud dispersion in the 3076km² Marcal catchment. A comparison of the bulk physico-chemical properties of the spill material at Ajka is made with other notable tailings failures elsewhere. The implications for system management and recovery along with the effects of emergency management (e.g. gypsum dosing) on metal availability downstream of the site are also discussed

Trace and rare earth element dispersal downstream of the Ajka red mud spill, Hungary

Between 600,000—700,000m³ of caustic (pH>13) red mud suspension were released from the Ajkai Timfoldgyar Zrt alumina plant on the 4th October 2010. This study highlights the dispersal of key red mudderived contaminants in downstream fluvial sediments from surveys undertaken within two months of the spill. Source samples contain abundant V (>1000mg/kg), Cr (>800mg/kg), Ni (>250mg/kg) and As (>80mg/kg). Red mud-affected samples are also particularly enriched above reference sites in rare earth elements which include Ce (>400mg/kg), La, Nd and Pr (all >100mg/kg). The combined signal of these provides a useful tracer of red mud dispersion in the 3076km² Marcal catchment. A comparison of the bulk physico-chemical properties of the spill material at Ajka is made with other notable tailings failures elsewhere. The implications for system management and recovery along with the effects of emergency management (e.g. gypsum dosing) on metal availability downstream of the site are also discussed

Trace and rare earth element dispersal downstream of the Ajka red mud spill, Hungary

Between 600,000—700,000m³ of caustic (pH>13) red mud suspension were released from the Ajkai Timfoldgyar Zrt alumina plant on the 4th October 2010. This study highlights the dispersal of key red mudderived contaminants in downstream fluvial sediments from surveys undertaken within two months of the spill. Source samples contain abundant V (>1000mg/kg), Cr (>800mg/kg), Ni (>250mg/kg) and As (>80mg/kg). Red mud-affected samples are also particularly enriched above reference sites in rare earth elements which include Ce (>400mg/kg), La, Nd and Pr (all >100mg/kg). The combined signal of these provides a useful tracer of red mud dispersion in the 3076km² Marcal catchment. A comparison of the bulk physico-chemical properties of the spill material at Ajka is made with other notable tailings failures elsewhere. The implications for system management and recovery along with the effects of emergency management (e.g. gypsum dosing) on metal availability downstream of the site are also discussed

Contaminant mobility and carbon sequestration downstream of the Ajka (Hungary) red mud spill: The effects of gypsum dosing

A number of emergency pollution management measures were enacted after the accidental release of caustic bauxite processing residue that occurred in Ajka, western Hungary in October, 2010. These centred on acid and gypsum dosing to reduce pH and minimise mobility of oxyanion contaminants mobile at high pH. This study assessed the effectiveness of gypsum dosing on contaminant mobility and carbon sequestration through assessment of red mud and gypsum-affected fluvial sediments via elemental analysis and stable isotope analysis. There was a modest uptake of contaminants (notably As, Cr, and Mn) on secondary carbonate-dominated deposits in reaches subjected to gypsum dosing. C and O stable isotope ratios of carbonate precipitates formed as a result of gypsum dosing were used to quantify the importance of the neutralisation process in sequestering atmospheric carbon dioxide. This process was particularly pronounced at sites most affected by gypsum addition, where up to 36% of carbonate-C appears to be derived from atmospheric in-gassing of CO 2. The site is discussed as a large scale analogue for potential remedial approaches and carbon sequestration technologies that could be applied to red mud slurries and other hyperalkaline wastes. The results of this work have substantial implications for the aluminium production industry in which 3-4% of the direct CO 2 emissions may be offset by carbonate precipitation. Furthermore, carbonation by gypsum addition may be important for contaminant remediation, also providing a physical stabilisation strategy for the numerous historic stockpiles of red mud