The effectiveness of highly siliceous rocks in the production of environmentally safe crop production

The article presents the results of studying the influence of copper-contaminated soil (typical medium-loamy chernozem) on the ecological safety of grain and the yield of spring wheat when using high-silicate rock - diatomite as a detoxifier. It was found that when diatomite was introduced into soil contaminated with up to 4 MPC Cu at a dose of 5 t/ha, it completely blocked the negative impact of copper on the formation of spring wheat yield. Contamination of the soil with copper up to 10 MPC Cu was accompanied by its accumulation in the grain above the control by 8-35%. The introduction of diatomite into the soil helped to reduce its accumulation in products by 17-50%. Keywords: SOIL CONTAMINATION WITH COPPER, DIATOMITE, ENVIRONMENTALLY SAFE PRODUCTS

Effects of the Silicate Modulus of Water Glass on the Hydration and Mechanical Properties of Alkali-Activated Blast Furnace Ferronickel Slag

Blast furnace ferronickel slag (BFNS), currently an underutilized metallurgical residue, was investigated for use as a precursor for alkaline activation. Water glass solutions with various moduli (0.5, 1.0, 1.5 and 2.0) were used at the same water glass concentration of 10% to investigate the influence of the modulus on hydration and mechanical properties. The results show that the modulus has a certain impact on the hydration and mechanical strength development of alkali-activated BFNS. Increasing the modulus of water glass does not change the type of hydration product and the activity of the Mg-containing phases, but it decreases the amount of C2AS, the Ca/Si and Al/Si ratios of the (N,C)-A(M)-S-H gel. In addition, a high silicate modulus deteriorates the pore structure, which has an adverse effect on the development of compressive strength and splitting tensile strength.

Nutrient budgets in Southern Ocean mode waters controlled by nitrification

<p>Southern Ocean mode and intermediate waters supply nitrate-rich but silicate-poor waters to the lower latitudes, impeding diatom growth throughout the extra-polar ocean and weakening the ocean’s ability to absorb carbon dioxide from the atmosphere. This silicate deficiency is widely attributed to high silicate to nitrate uptake by iron-limited diatoms. Here, we show that nitrification, by rapidly regenerating nitrate in shallow waters, drives the silicate deficiency. Measurements of nitrate dual isotopes and complementary modelling independently suggest that 15-35% of the nitrate within mode waters is generated by nitrification. Our results reveal that without nitrification, the silicate deficiency would disappear, which would allow the diatomaceous niche to expand. Nitrification therefore provides a key buffering service that mitigates against change in the silicate deficit and subsequently restricts diatom dominance to the polar ocean. This insight highlights the critical importance for understanding Southern Ocean processes, such that the large-scale effects of ongoing environmental change may be realised.</p>

Combined artificial high-silicate medium and LED illumination promote carotenoid accumulation in the marine diatom Phaeodactylum tricornutum

Background Diatoms, which can accumulate large amounts of carotenoids, are a major group of microalgae and the dominant primary producer in marine environments. Phaeodactylum tricornutum, a model diatom species, acquires little silicon for its growth although silicon is known to contribute to gene regulation and play an important role in diatom intracellular metabolism. In this study, we explored the effects of artificial high-silicate medium (i.e. 3.0 mM sodium metasilicate) and LED illumination conditions on the growth rate and pigment accumulation in P. tricornutum, which is the only known species so far that can grow without silicate. It’s well known that light-emitting diodes (LEDs) as novel illuminants are emerging to be superior monochromatic light sources for algal cultivation with defined and efficient red and blue lights. Results Firstly, we cultivated P. tricornutum in a synthetic medium supplemented with either 0.3 mM or 3.0 mM silicate. The morphology and size of diatom cells were examined: the proportion of the oval and triradiate cells decreased while the fusiform cells increased with more silicate addition in high-silicate medium; the average length of fusiform cells also slightly changed from 14.33 µm in 0.3 mM silicate medium to 12.20 µm in 3.0 mM silicate medium. Then we cultivated P. tricornutum under various intensities of red light in combination with the two different levels of silicate in the medium. Higher biomass productivity also achieved in 3.0 mM silicate medium than in 0.3 mM silicate medium under red LED light irradiation at 128 μmol/m2/s or higher light intensity. Increasing silicate reversed the down-regulation of fucoxanthin and chlorophyll a under high red-light illumination (i.e. 255 μmol/m2/s). When doubling the light intensity, fucoxanthin content decreased under red light but increased under combined red and blue (50:50) lights while chlorophyll a content reduced under both conditions. Fucoxanthin accumulation and biomass productivity increased with enhanced red and blue (50:50) lights. Conclusion High-silicate medium and blue light increased biomass and fucoxanthin production in P. tricornutum under high light conditions and this strategy may be beneficial for large-scale production of fucoxanthin in diatoms.

Revolution of Malaysia’s Kaolin to Metakaolin towards various application: A Mini Review

The transformation of kaolin to metakaolin was studied in various state in Malaysia which is Segamat, Nitar, Lenggor, Ipoh, Bidor, Mersing, Sabah, and Sarawak. In Segamat, the kaolin has a light colour due to the high silicate composition and also contain high mineral such as kaolinite and quartz existed as impurities. Aluminum rich kaolin is bright in color with elevated plasticity and is commonly used in the ceramic, plastic, dye, fabric, pesticide, pharmaceutical and beauty industry. For Nitar and Lenggor, production of metakaolin occurs at 510°C and formation of mullite occur at 900°C. Both clays show good crystallization of pseudohexagonal to hexagonal kaolinite particles. Moreover, the classification of clay and the sizing are the significant characteristic to be determined using the method of the beneficiations. The method of beneficiations is crucially important to increase the quality of clay to meet the requirement for industry application. In Ipoh and Sarawak, the primary deposit is dominated by kaolin and the mixture of granites and diorites produced from weathering. On the other hand, in Bidor, the primary deposit is a mixture of kaolinite, muscovite and smectite also formed by weathering. The increasing amount of illite in secondary kaolin deposits in the Mersing area due to the marine deposition of those deposits where illite formed by the absorption of clay minerals from the seawater by pottasium. Kaolin in Kg Gading, Bongawan Sabah were treated with sodium hexametaphosphate to remove impurities in natural kaolin. The transformation of kaolin to metakaolin was conducted at 800°C for 5 hours.

ON THE FACTORS AFFECTING THE PRODUCTIVITY OF THE SOUTHERN MAKASSAR STRAIT

An investigation of the upwelling in the Southern Makassar Strait was conducted by LON (Lembaga Oseanologi Nasional) as part of its research program in ecology and oceanography of the Indonesian waters. It consists of observation on one monitoring station and two oceanographical cruises in the region. The result of the monitoring station indicates clearly the occurrence of upwelling and its effect on the hydrology of the region. During the southeast monsoon the upwelled water causes a decrease in temperature and dissolved oxygen and an increase in salinity, density and nitrate-nitrogen, particularly seen at the lower boundary of the homogeneous layer. During the northwest monsoon the upwelled water is replaced by the Jawa Sea water with high temperature, low oxygen, low salinity, low density, very high phosphate, and high silicate. The observation on the oceanographical cruises reveals the precence of two other types of surface waters in the region. They are the East Kalimantan Coastal Water and the South Sulawesi Coastal Water, each is formed by mixing process of sea water and land drainage along the coast of the two islands respectively. Originally they are characterized by low salinity, low oxygen, high temperature, high phosphate, low nitrate and high silicate. Their salinity and dissolved oxygen increase due to mixing with the upwelled water and the high activity of phytoplankton respectively.

Recovering of Iron from Feebly-Magnetic Iron Tailings Containing High Silicate

In this study, the main aims were to recovery iron from iron tailings containing high silicate and reduce the tailing grade by using combined separating technology. Experimental studies were carried out on the iron tailings in Dahongshan samples, which contain 27.78% of iron. Through the experiment, the first is pre-classification by high-frequency vibrating, and then the iron is recovered by strong magnetic separation of one rough, one scavenger and a gravity concentrating with Slon and chute. The iron concentrate which the grade of Fe is 53.08% and the recovery of 68.45% is obtained and the grade of tailings reduce from 27.78% to 13.80%. Iron tailings get a comprehensive utilization, which has a better effect.

Properties of Alkli-Activated Slag Cement Compounded with Soluble Glasses with a High Silicate Modulus

Properties of alkali-activated slag cements compounded with soluble glasse with a high silicate modulus Ms=2.6 were detailedly studied in this paper, including compressive strength and flexure strength characterictics at the ages of 3,7,28 days and flow values of fresh cement mixtures on a jolting table. As a result, with the compressive strength at the age of 28 days of 95.6-107.8 MPa has been developed, and the flow values and strength characteristics of alkali-activated slag cement mortars increased with increase in a water to cement (alkaline activator solution to slag) ratio, and the flow value (determined on the cement mortar mixtures) would reach 145 mm. Moreover, the development speed of strength characteristics of mortar specimens would be affected negatively by increasing of water demand (requirement).

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.