Effect of humic acids on the toxicity of pollutants to Chlamydomonas reinhardtii: Investigation by a microscale algal growth inhibition test.

Dissolved humic substances (DHSs) are the major components of organic matter in the aquatic environment. DHSs are well known to considerably affect the speciation, solubility, and toxicity of a wide variety of pollutants in the aquatic environment. In this study, the effects of the toxicity of heavy metals and hydrophobic organic pollutants (HOPs) on Chlamydomonas reinhardtii in the presence of humic acid (HA) were examined by a microscale algal growth inhibition (μ-AGI) test based on spectrophotometric detection.

Elucidating molecular level impact of peat fire on soil organic matter by laser desorption ionization Fourier transform ion cyclotron resonance mass spectrometry.

In this work, laser desorption ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (LDI-FTICRMS) was used to investigate the molecular composition of a peat fire and laboratory heated soil organic matter (SOM). SOM isolated from soils obtained from unburned and burned sites at Central Kalimantan, Indonesia, were analyzed with LDI-FTICRMS. About 7500 peaks were found and assigned with molecular formulas for each mass spectrum.

Effects of peat fires on the characteristics of humic acid extracted from peat soil in Central Kalimantan, Indonesia.

When peat forest fires happen, it leads to burn soil and also humic acids as a dominant organic matter contained in peat soil as well as the forest. The structure and properties of humic acids vary depending on their origin and environment, therefore the transformation of humic acid is also diverse. The impacts of the peat fires on peat soil from Central Kalimantan, Indonesia were investigated through the characterization of humic acids, extracted from soil in burnt and unburnt sites.

Mechanism of the toxicity induced by natural humic acid on human vascular endothelial cells.

Humic acid (HA), a group of high-molecular weight organic compounds characterized by an ability to bind heavy metals, is normally found in natural water. Although the impairment of vascular endothelial cells in the presence of humic substances has been reported to be involved in some diseases, the mechanisms responsible for this involvement remain unclear. In this study, we examined the cytotoxicity of HA obtained from peatland in Central Kalimantan, Indonesia, to human vascular endothelial cells, as well as the mechanisms behind these effects.

Metal concentrations of river water and sediments in West Java, Indonesia.

To determine the water environment and pollutants in West Java, the contents of metals and general water quality of the Ciliwung River in the Jakarta area were measured. High Escherichia coli number (116-149/mL) was detected downstream in the Ciliwung River. In addition to evaluate mercury pollution caused by gold mining, mercury contents of water and sediment samples from the Cikaniki River, and from paddy samples were determined.

Comparison of general water quality of rivers in Indonesia and Japan.

In Java and Kalimantan in Indonesia, river water plays important roles in human life; for example, for transportation, and economic activities of the inhabitants. However, industrial, agricultural and domestic water is discarded into rivers directly in many developing countries, including Indonesia, since drainage systems have not been completely constructed. In this study, to evaluate the water quality and to compare those levels of environmental contaminants in developing and developed countries, water quality and contents of endocrine disrupters were measured in a total of 64 water samples (Indonesia; 28 samples and Japan; 36 samples) from 53 sites.