Environmental Engineering
M. Iqhrammullah; S. Saudah; M. Monalisa; F. Fahrurrozi; S.A. Akbar; S.S. Lubis
Abstract
BACKGROUND AND OBJECTIVES: The presence of heavy metals, specifically cadmium, in the environment poses significant threats to both ecological systems and human health. However, microalgae have shown potential in addressing this issue through their ability to absorb cadmium and produce valuable biomass, ...
Read More
BACKGROUND AND OBJECTIVES: The presence of heavy metals, specifically cadmium, in the environment poses significant threats to both ecological systems and human health. However, microalgae have shown potential in addressing this issue through their ability to absorb cadmium and produce valuable biomass, making them a promising solution for bioremediation. Among the various microalgae species, Chlorella vulgaris stands out as a suitable candidate due to its potential for biodiesel production and its capacity to effectively absorb cadmium. Therefore, the main objective of this study is to assess the toxicity of cadmium on Chlorella vulgaris cells using network meta-analysis as a methodology.METHODS: A comprehensive search was conducted on Scopus, Scilit, Google Scholar, and Web of Science to identify relevant studies published from 1 January 1990 to 16 January 2024. Only studies that reported the cell number of Chlorella vulgaris as a result of cadmium exposure were considered for inclusion. The collected data were then subjected to Bayesian frequentist network meta-analysis, utilizing standardized mean difference and a 95 percent confidence interval as measures of effect size. Additionally, a linear regression analysis was performed to examine the dose-dependent impact of cadmium toxicity.FINDINGS: Dose-dependent toxic effects of cadmium on Chlorella vulgaris were evident (R-square of more than 0.90), particularly at a concentration of 1 part per million, deemed as the maximum tolerable threshold. Prolonged exposure revealed a concentration-dependent reduction in cell viability, suggesting potential lifespan shortening. A comparison of growth stimulants, gibberellic acid and brassinolide (standard means differences of 1.7 and 3.8, respectively), in mitigating cadmium toxicity indicated the latter superior effectiveness in sustaining microalgal survivability. The presence of high nitrogen and low phosphorous levels was found to be significantly associated with a reduction in Chlorella vulgaris cells due to cadmium exposure.CONCLUSION: This research has provided conclusive proof of the harmful effects of cadmium on Chlorella vulgaris through the implementation of Bayesian frequentist network meta-analysis, offering valuable insights for environmental management practices. The findings reveal concentration-dependent effects of cadmium toxicity. The survivability of Chlorella vulgaris is determined by the compositions of macronutrients nitrogen and phosphorous. Comparative analyses highlight the superior protective effect of brassinolide over gibberellic acid in mitigating cadmium toxicity. Overall, the findings highlight the potential of Chlorella vulgaris in both bioremediation of heavy metals and biomass production.
D. Setyawan
Abstract
This study compares the energy intensity performance in Indonesia to other south-east Asia countries such as Vietnam, Thailand, Singapore, The Philippines and Malaysia for the period from 1971 to 2016. For this goal, this research employs a multiplicative Log Mean Divisia Index II method and Spatial-Temporal ...
Read More
This study compares the energy intensity performance in Indonesia to other south-east Asia countries such as Vietnam, Thailand, Singapore, The Philippines and Malaysia for the period from 1971 to 2016. For this goal, this research employs a multiplicative Log Mean Divisia Index II method and Spatial-Temporal Index Decomposition Analysis. The manufacturing sector and commercial sector played a key role in the regions economic structures that accounted for around 60% to 80% of the total economic output from 1971 to 2016. The contribution of the manufacturing sector increased quite significantly, from 8% in 1971 to a peak of around 31% in 2001, before it fell to 28% in 2016. On the other hand, the contribution of agriculture sector dropped from 49% in 1971 to approximately 17% in 2016. It is demonstrated in this research that the aggregate trend of the changes in energy intensity in these countries in the past forty-five years has been decreasing. For Indonesia, aggregate energy intensity rose steadily by an average of 3% per year from 1971 to 1999, more than doubling over this period, while from 1999 to 2001 energy intensity fell by 1% per annum on average, falling by 17% overall in 2016. Overall, in terms of structure and industry effects on aggregate energy intensity, all these countries showed a shift in industry value added to more energy-intensive industries which also offset by falling within-industry energy intensity. However, the analysis shows that both element of this trend was most pronounced in Indonesia.