Mahidol University International College

About: Mahidol University International College is a based out in . It is known for research contribution in the topics: Tourism & Corporate governance. The organization has 240 authors who have published 485 publications receiving 6095 citations.

The Effect of Corporate Governance on Corporate Social Responsibility

Abstract: Motivated by agency theory, we explore the effect of corporate governance quality on corporate social responsibility (CSR), using the governance standards provided by Institutional Shareholder Services (ISS). Our evidence reveals that firms with more effective governance make significantly less investment in CSR. It appears that managers tend to over-invest in CSR and are forced to reduce CSR investments when corporate governance is more effective. In particular, an improvement in governance quality by one standard deviation translates into a decline in CSR investments by 7.16%. Our fixed-effects analysis also shows that, within firms, when governance quality improves over time, CSR investments decline significantly. Using the passage of the Sarbanes-Oxley Act of 2002 as an exogenous shock that improves the quality of corporate governance, we demonstrate that high-quality governance is not merely associated with, but rather brings about, lower CSR investments.

Phytoremediation potential of charophytes: bioaccumulation and toxicity studies of cadmium, lead and zinc.

Abstract: The ability for usage of common freshwater charophytes, Chara aculeolata and Nitella opaca in removal of cadmium (Cd), lead (Pb) and zinc (Zn) from wastewater was examined. C. aculeolata and N. opaca were exposed to various concentrations of Cd (0.25 and 0.5 mg/L), Pb (5 and 10 mg/L) and Zn (5 and 10 mg/L) solutions under hydroponic conditions for 6 days. C. aculeolata was more tolerant of Cd and Pb than N. opaca. The relative growth rate of N. opaca was drastically reduced at high concentrations of Cd and Pb although both were tolerant of Zn. Both macroalgae showed a reduction in chloroplast, chlorophyll and carotenoid content after Cd and Pb exposure, while Zn exposure had little effects. The bioaccumulation of both Cd and Pb was higher in N. opaca (1544.3 μg/g at 0.5 mg/L Cd, 21657.0 μg/g at 10 mg/L Pb) whereas higher Zn accumulation was observed in C. aculeolata (6703.5 μg/g at 10 mg/L Zn). In addition, high bioconcentration factor values (> 1000) for Cd and Pb were observed in both species. C. aculeolata showed higher percentage of Cd and Pb removal (> 95%) than N. opaca and seemed to be a better choice for Cd and Pb removal from wastewater due to its tolerance to these metals.

Phytoextraction and accumulation of lead from contaminated soil by vetiver grass: Laboratory and simulated field study

Abstract: A soil-culture study was conducted to investigate the phytoextraction of lead (Pb) in two species of vetiver grass (Vetiveria zizanioides and V. nemoralis) irrigated with an increasing level of Pb(NO3)2 (5, 7, 9 and 11 g L-1) for 12 weeks. In a laboratory study, the removalof lead from soil was correlated with lead accumulation by roots and shoots of both species of vetiver grass. High concentration of lead (9—11 g L-1) resulted in decrease of growth, total chlorophyllcontent and biomass of V. zizanioides, while V. nemoralis died after one week of application. Toxicity symptoms (e.g., burning leaf margins, shoot die back) occurred in vetiver grass at a high concentration of lead. Based on the data V. zizanioides tolerated and accumulated the greatest amount of lead most effectively. A simulated field experiment was conducted to examine the efficiency of vetiver grass in removing lead from contaminated soil. The vetiver grasses, V. zizanioides and V. nemoralis, were grown in soil contaminated with Pb(NO3)2 (5, 7, 9, and 11 g L-1) for 3 months. The removal of lead from soil was correlated with lead accumulation by roots and shoots of both grass species. The grass roots took up more lead than the shoots. V. zizanioides could uptake more lead from soil than V. nemoralis. The effects of lead on the biomass of V. zizanioides and V. nemoralisshowed that in both species, the biomass was decreased when the lead concentration was increased. In comparison, V. zizanioidesshowed greater biomass than V. nemoralis.

Influences of Cadmium and Zinc Interaction and Humic Acid on Metal Accumulation in Ceratophyllum Demersum

Abstract: Interactions between Zn and Cd on the accumulation of these metals in coontail, Ceratophyllum demersum were studied at different metal concentrations. Plants were grown in nutrient solution containing Cd (0.05–0.25 mg l−1) and Zn (0.5–5 mgl−1). High concentrations of Zn caused a significant decrease in Cd accumulation. In general, adding Cd solution decreased Zn accumulation in C. demersum except at the lowest concentration of Zn in which the Zn accumulation was similar to that without Cd. C. demersum could accumulate high concentrations of both Cd and Zn. The influence of humic acid (HA) on Cd and Zn accumulation was also studied. HA had a significant effect on Zn accumulation in plants. 2 mg l−1 of HA reduced Zn accumulation at 1 mg l−1 level (from 2,167 to 803 mg kg−1). Cd uptake by plant tissue, toxicity symptoms and accumulation at 0.25 and 0.5 mg l−1, were reduced (from 515 to 154 mg kg−1 and from 816 to 305 mg kg−1, respectively) by addition of 2 mg l−1 of HA. Cd uptake reached a maximum on day 9 of treatment, while that of Zn was observed on day 15. Long-term accumulation study revealed that HA reduced toxicity and accumulation of heavy metals.