Paramsothy Jeyakumar

Bioavailability of copper and zinc to poplar and microorganisms in a biosolids-amended soil

The effects of high concentrations of copper (Cu) and zinc (Zn) in a soil treated with biosolids previously spiked with these metals on poplar (Populus deltoides × yunnanensis) were investigated in a pot trial. The total soil metal concentrations in the treatments were 12, 46, 137, and 226 mg Cu/kg and 25, 141, 433, and 686 mg Zn/kg. Copper accumulation was lower in poplar leaves than Zn and the maximum bioconcentration factor was 0.8 for Cu and 10 for Zn. Copper was not found to be toxic to plants at any level of application or to mycorrhiza up to 137 mg/kg, but it was found to be toxic to soil microorganisms at all levels of Cu addition. Copper application increased mycorrhiza colonisation up to 137 mg Cu/kg and root dry matter at 226 mg Cu/kg, but had no effect on leaf dry matter. Increasing Zn rate decreased all plant and soil parameters. Lower percentages of Cu in the soil exchangeable fraction, and a lower Cu2+ concentrations in soil solution relative to Zn indicated lower bioavailability of Cu. Dehydrogenase activity was reduced by 50% at total solution-phase Cu and Zn concentrations of 0.1 and 27 mg/L, respectively, and solid-phase exchangeable Cu and Zn concentrations of 5 and 169 mg/kg, respectively.

Copper and zinc spiking of biosolids: effect of incubation period on metal fractionation and speciation and microbial activity

Environmental context. Global sewage sludge (biosolids) production is increasing as a result of rapidly growing human population and ensuing industrial activities. Disposal of this waste is becoming a serious environmental issue because the high levels of heavy metals in biosolids can upset soil microbial activity and nutrient balance when the waste is added to forest or agricultural lands. In the present study, a biosolid matrix was spiked with copper and zinc as a model for an environmental scenario. The findings of the present study are applicable to environmental regulations that seek to protect agriculture land, human and animal health, and soil and drinking water quality, in scenarios where biosolids are applied to soil. Abstract. Biosolids were amended separately with three levels of copper and zinc sulfate, and anaerobically incubated for 117 days. Copper in the unamended-biosolids solid phase was mainly found in the organic and residual fractions (85–95%). Copper addition decreased the percentage of Cu in these fractions and increased the percentage of Cu in the oxide and specifically adsorbed fractions. Zinc in the solid phase was mainly associated with the oxide (35–65%), specifically adsorbed (25–30%), and the exchangeable fractions (10–40%). Relatively, all Cu in the solution phase was complexed with organic matter; Zn was present mainly as Zn2+ and as an electrically neutral ion pair, ZnSO40. Metals were almost completely incorporated into the biosolids matrix by Day 55. Dehydrogenase activity was reduced by 50% (EC50, effective concentration for 50% activity reduction) at the total solution-phase Cu and Zn concentrations of 0.1 and 20 mg L–1, respectively, and solid-phase exchangeable Cu and Zn concentrations of 410 and 670 mg kg–1, respectively.

Tsunami impacts and rehabilitation of groundwater supply: lessons learned from eastern Sri Lanka

Huge devastation and human tragedy followed the December 26, 2004 tsunami in the Indian Ocean. The death toll from the earthquake, the tsunamis and the resultant floods totals to over 180,000 people in fourteen countries with tens of thousands reported missing, and over one million left homeless. After Indonesia, Sri Lanka was the second-hardest hit, with an estimated death toll of 35,000 people. Of immediate concern after the catastrophic event was the destruction of the traditional water supply system in the rural and semi-urban areas of the coastal belt, which for 80% of the population was based on groundwater, mostly drawn from private shallow open wells (Leclerc et al., 2008). Practically all wells within the reach of the flooding waves (up to a couple of kilometers inland) were inundated and filled with saltwater and contaminated with solid matter (sediment and waste), pathogens and other unknown chemicals, leaving the water unfit for drinking (Fig. 1a). Figure 1b shows the devastation of the 2004 Tsunami in a representative coastal town on the eastern coast of Sri Lanka. The density of wells in these areas is high, with practically each household having its own well (Fig. 2). (2008) found a well density up to 600 per km2. The local villagers reported that the water level reached close to the top of the coconut palm trees shown in the figure (approximately 5 m). Over one thousand lives were lost at this particular site. (2005) and (2005) estimated that the tsunami waves contaminated more than 50,000 wells in coastal Sri Lanka. This initial figure is highly underestimated, however, as the present research found, based on well statistics and flooding patterns, that approximately 18,000 wells were affected in an area representing only 3% of the affected coast line in Sri Lanka (Villholth et al., 2009). This suggests that the total number of affected wells is more in the range of half a million. The total number of people, mostly living in poor coastal rural areas, affected by the disruption of their water supply from wells could be in the range of 2.5 million. Approximately 75% of the coastline of Sri Lanka was impacted by the tsunami. Open image in new window Fig. 1 Tsunami impact on open well and the general devastation of the coastal area in east Sri Lanka (Courtesy a: Scott Tylor and Jayantha Obeysekera Open image in new window Fig. 2 Tsunami-impact site on the east coast of Sri Lanka (Courtesy: Scott Tylor and Jayantha Obeyseckera).

Correction to: Effect of simulated acid rain on fluorine mobility and the bacterial community of phosphogypsum

After publication of this study (Wang et al. 2018), we noticed a major mistake in the Fig. 7 that the Fig. 7a and the Fig. 7b were published with a same picture. The correct Fig. 7 was labeled here. We sincerely regret for the error, and sorry for the inconveniences!