Opportunities and challenges of China’s inquiry-based education reform in middle and high schools: Perspectives of science teachers and teacher educators

Consistent with international trends, an emergent interest in inquiry-based science teaching and learning in K-12 schools is also occurring in China. This study investigates the possibilities for and the barriers to enactment of inquiry-based science education in Chinese schools. Altogether 220 Chinese science teachers, science teacher educators and researchers (primarily from the field of chemistry education) participated in this study in August 2001. Participants represented 13 cities and provinces in China. We administered two questionnaires, one preceding and one following a 3-hour presentation by a US science educator and researcher about inquiry-based teaching and learning theories and practices. In each of three sites in which the study was conducted (Shanghai, Guangzhou and Beijing), questionnaires were administered, and four representative participants were interviewed. Our coding and analysis of quantifiable questionnaire responses (using a Likert scale), of open-ended responses, and of interview transcripts revealed enthusiastic interest in incorporating inquiry-based teaching and learning approaches in Chinese schools. However, Chinese educators face several challenges: (a) the national college entrance exam needs to align with the goals of inquiry-based teaching; (b) systemic reform needs to happen in order for inquiry-based science to be beneficial to students, including a change in the curriculum, curriculum materials, relevant resources, and teacher professional development; (c) class size needs to be reduced; and (d) an equitable distribution of resources in urban and rural schools needs to occur.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42933/1/10763_2005_Article_1517.pd

Metals in sediment, seagrass and gastropods near a nickel smelter in Greece: Possible interactions

Accumulation of Cd, Co, Cr, Cu, Fe, Mn, Ni and Zn was studied in the sediments, Cymodocen nodosa leaves, roots and stems and in two gastropods from an area adjacent to a ferro-nickel smelting plant and a control site on the east coast of Greece. In the sediment, the metals, with the exception of Cu, have significantly higher concentrations in the polluted than in the clean site. There is a tendency for C. nodosa tissues in the polluted area to have higher concentrations of metals although the differences are not always statistically significant. Co, Mn, Ni and Zn are in higher concentrations in the leaves than in the other tissues, a trend more obvious in the polluted site. Concentrations of metals in the viscera of the gastropods Cerithium vulgatum and Monodonta mutabilis are higher than in the muscle (except for Cd) and significantly higher in the animals from the polluted site. It is suggested that Mn is taken up from the water by C. nodosa leaves, which in the form of detritus enter C. vulgatum. Mn concentrates in the viscera of C. vulgatum in the form of granules. Zn follows the same route with additional amounts being taken by C. vulgatum directly from the water

Transfer of metal detoxification along marine food chains

It has been observed previously that the digestive gland of the carnivorous gastropod mollusc, Murex trunculus, does not accumulate metals which occur in high concentration in the digestive gland of its prey, the detritus-feeding gastropod, Cerithium vulgatum. It is proposed that mechanisms of metal detoxification which operate in C. vulgatum render metals biologically unavailable to M. trunculus. In the present work, this scheme is tested by feeding tissues containing detoxified metals from a gastropod, bivalve and barnacle to carnivorous gastropods. Metals in the prey are accumulated in insoluble granules in the digestive gland of the gastropod, kidney of the bivalve and gut connective tissue of the barnacle. These tissues are fed to the carnivores and the granules pass through the entire length of the gut. They are egested as clean preparations within the faecal pellets and they still contain the metals introduced by the tissues of the prey. This transfer of detoxification between species indicates that the food chain progression of material can result in the reduction of the bioavailability of metals. The observations are recorded by scanning electron microscopy and X-ray microanalysis. © 1990, Marine Biological Association of the United Kingdom. All rights reserved

Heavy metal pollution induced by a ferro-nickel smelting plant in Greece

Seven heavy metals, Co, Cr, Cu, Fe, Mn, Ni and Zn, were measured in marine sediments, plants and invertebrates in the vicinity of a ferro-nickel smelting plant in Greece. The concentrations of metals in the sediment were higher than those found in the average unpolluted Greek coastal sediment. High levels of metals were observed in the gastropod molluscs, particularly Cerithium vulgatum, which concentrated metals more than other invertebrates. © 1989

Heavy metal pollution induced by a ferro-nickel smelting plant in Greece

Seven heavy metals, Co, Cr, Cu, Fe, Mn, Ni and Zn, were measured in marine sediments, plants and invertebrates in the vicinity of a ferro-nickel smelting plant in Greece. The concentrations of metals in the sediment were higher than those found in the average unpolluted Greek coastal sediment. High levels of metals were observed in the gastropod molluscs, particularly Cerithium vulgatum, which concentrated metals more than other invertebrates. © 1989

Mediterranean pollution from a ferro-nickel smelter: Differential uptake of metals by some gastropods

Cadmium, Co, Cr, Cu, Fe, Mn, Ni, and Zn were measured by atomic absorption spectroscopy in the digestive gland of the marine gastropods Cerithium vulgatum, Monodonta spp., Murex trunculus, Conus mediterraneus, and Patella coerulea, sampled during different seasons at four sites near a ferro-nickel smelting plant and two control sites on the east coast of Greece. Near the smelter there were higher concentrations of all metals in Cerithium (except Cu) and Murex, and of Ni and Co in Monodonta, compared with the control sites, which indicated that the plant contaminated the environment. The animals from the contaminated area showed marked differences in concentrations which were associated both with the genera and the sites, while there were no consistent seasonal variations. © 1990

Kinetics of metals in molluscan faecal pellets and mineralized granules, incubated in marine sediments

Marine snails excrete metals via the gut. The sediment-feeding, tower shell Cerithium vulgatum, from a polluted environment, accumulates Cr and Ni to 3500 ppm dry weight in the faecal pellets. Pellets from C. vulgatum and the grazing, top shell Monodonta mutabilis were incubated in surface and deeper anoxic layers of clean and metal-polluted sediment. Pellets retained the original load of metals and in some cases gained Ti, Cr, Mn, Fe and Ni. Effects were modified by sediment properties. Pellets of C. vulgatum are durable, membrane-bound structures and they reduce metal bioavailability to food chains by compartmentalization. Intracellular, phosphate granules bind metals in digestive glands of snails and they are excreted via the gut and faecal pellets. These granules were extracted from digestive glands of both species of snail and incubated in the same sediments. Magnesium phosphate granules from M. mutabilis dissolved but calcium/metal phosphate granules from C. vulgatum remained; they had differentially retained or lost Mn, Fe, Co, Ni and Zn according to the type of sediment

Kinetics of metals in molluscan faecal pellets and mineralized granules, incubated in marine sediments

Marine snails excrete metals via the gut. The sediment-feeding, tower shell Cerithium vulgatum, from a polluted environment, accumulates Cr and Ni to 3500 ppm dry weight in the faecal pellets. Pellets from C. vulgatum and the grazing, top shell Monodonta mutabilis were incubated in surface and deeper anoxic layers of clean and metal-polluted sediment. Pellets retained the original load of metals and in some cases gained Ti, Cr, Mn, Fe and Ni. Effects were modified by sediment properties. Pellets of C. vulgatum are durable, membrane-bound structures and they reduce metal bioavailability to food chains by compartmentalization. Intracellular, phosphate granules bind metals in digestive glands of snails and they are excreted via the gut and faecal pellets. These granules were extracted from digestive glands of both species of snail and incubated in the same sediments. Magnesium phosphate granules from M. mutabilis dissolved but calcium/metal phosphate granules from C. vulgatum remained; they had differentially retained or lost Mn, Fe, Co, Ni and Zn according to the type of sediment

Metals in gastropods-metabolism and bioreduction

In marine gastropods, high concentrations of heavy metals can occur in the digestive gland. The metals are accumulated within intracellular mineralized granules as phosphates and within lysosomal residual bodies in association with sulphur. X-Ray microanalysis shows that in the phosphate granules, an increase in the quantity of metal is associated with a reduction in the magnesium/calcium ratio. However, analyses of the whole digestive gland by atomic absorption spectrometry show that an increase in the quantity of metal can be associated with an increase in the concentration of magnesium. To account for these changes, it is proposed that metals induce the formation of magnesium phosphate in the granules as a source of metal-binding ions. The excess magnesium is displaced from the phosphate granules by the metals and accumulated by the carbonate granules in the interstitial region of the gland. The intracellular metals are stored in a form which renders them unavailable to the general metabolic processes of the animal and also to a carnivore which eats the tissue. Thus, uptake by the first animal results in bioamplification but transfer to the second animal results in bioreduction. © 1990