Application of geochemical techniques for prospecting unconventional phosphate sources: A case study of the lake sediments in Eppawala area Sri Lanka

Dushyantha, Nimila; Hemalal, Pva; Jayawardena, Chulantha; Ratnayake, Amila Sandaruwan; Ratnayake, Nalin Prasanna

doi:10.1016/j.gexplo.2019.02.010

Cited by 15 publications

(12 citation statements)

References 49 publications

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“…The EPD is the only phosphate mine in Sri Lanka with an annual production of 50,000 tonnes of rock phosphate fertilizers (Dushyantha et al, 2019;2020). It lies in the Eppawala area of the North-Central province, which belongs to the Wanni Complex (Figure 1) of Sri Lanka.…”

Section: Study Areamentioning

confidence: 99%

“…Based on the location of the EPD, the present study area is divided into upstream (Ihalahalmilla and Koon lakes) and downstream (Kiralogama lake) regions (Figure 1b) (Dushyantha et al, 2017;. The lakes are located in the dry climatic zone of Sri Lanka, and thus water levels of the lakes are raised dramatically during the rainy season, particularly in the north-eastern monsoon (December to February).…”

Section: Study Areamentioning

confidence: 99%

“…Figure 1: (a) The simplified geological map of Sri Lanka with major lithotectonic complexes (after Cooray, 1984); (b) the study area illustrating Ihalahalmilla, Koon, and Kiralogama lakes along with the Eppawala phosphate deposit (EPD) (Dushyantha et al, 2019).…”

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confidence: 99%

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Risk assessment of heavy metals in the freshwater lake sediments around Eppawala phosphate deposit, Sri Lanka

Batapola,

Dushyantha,

Ratnayake

et al. 2024

J. Natn. Sci. Foundation Sri Lanka

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The Eppawala area in Sri Lanka has an agricultural-based economy. As a result, the recent agricultural intensification could increase the risk of heavy metal contamination in lakes in the area as the main water canal in the area, i.e., Jaya Ganga, flows across these lakes. Therefore, this study focuses on the risk assessment of heavy metals in the freshwater lake sediments in the Eppawala area and the identification of potential sources for heavy metal contamination in the lakes. Nine heavy metals (Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were investigated in surface sediments (n = 22) of the upstream and downstream lakes of the Eppawala Phosphate Deposit (EPD). The average heavy metal concentrations in the upstream lake sediments were higher than those downstream. Eppawala lake sediments were heavily polluted by As along with moderate to high Cr pollution. However, only As and Cd indicated considerable to moderate ecological risk levels to the local environment. The downstream lake sediments showed lower heavy metal contents compared to those upstream and had negative correlations between heavy metals and P2O5 contents. This reveals that the EPD does not contribute to the heavy metal contamination in the Eppawala lake sediments. However, the statistical analysis showed that heavy metals were mostly derived from similar pollution sources. Agrochemicals used in paddy cultivation in the vicinity might be a potential source of heavy metals. This study highlights the importance of implementing remediation to control the heavy metal pollution prevailing in the Eppawala lakes.

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

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Risk assessment of heavy metals in the freshwater lake sediments around Eppawala phosphate deposit, Sri Lanka

Batapola,

Dushyantha,

Ratnayake

et al. 2024

J. Natn. Sci. Foundation Sri Lanka

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“…Kalu Ganga River has the second largest river basin in Sri Lanka, with a 2766 km 2 drainage area originating from the central hills [21,22]. Since Sri Lanka is a tropical country, a high yield of sediments is evident due to the extreme weathering conditions [23][24][25]. In this context, after the weathering and decomposition of the gem-bearing source rocks in the catchment area, the Kalu Ganga River transports these sediments and redeposits them as alluvial layers, especially in old river channels and flood plains where the gemstones are found [14].…”

Section: Study Areamentioning

confidence: 99%

Recovery Potential of Rare Earth Elements (REEs) from the Gem Mining Waste of Sri Lanka: A Case Study for Mine Waste Management

et al. 2022

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Sri Lanka is one of the wealthiest countries in terms of gems. Therefore, gem mining is extensively carried out in many areas of Sri Lanka, including districts such as Ratnapura, Monaragala, Matale, and Kalutara. During the mining process, only valuable gemstones are collected, and the remaining gravel fraction with many heavy minerals is discarded. Therefore, the gem mining industry produces a large amount of waste that is mainly used only for backfilling. To sustainably manage this waste stream, gem mining waste collected from a gem pit at Wagawatta in the Kalutara district in Sri Lanka was investigated for value recovery, specifically for rare-earth elements (REEs). The gem-bearing alluvial layer contained 0.3% rare-earth oxide (REO) that could easily be upgraded up to 2.8% (LREEs = 94%) with wet sieving and subsequent density separation via a shaking table. Therefore, the concentrates of gem mine tailings with REE-bearing minerals have the potential to be a secondary source for LREEs. The organic-rich clay layer underlying the gem-bearing alluvial layer contained 0.6% REO with 49% HREEs, including Gd, Dy, Er, Yb, and especially Y enrichments. Detailed explorations are thus necessary to assess the REE potential in Sri Lanka’s gem mining waste, and value recovery flowsheets should be subsequently developed to economically extract REEs. In addition, the presence of high U concentrations (800 mg/kg) in the concentrated samples could be alarming when considering the health and safety of the people engaged in gem mining. This aspect also requires detailed research studies.

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“…Substantial deposits of cheaper and low grade Rock Phosphate (RP) are locally available in many countries of the world (Van straaten, 2002). Sri Lanka consists of two significant phosphate deposits in Eppawala and Ridigama (Dushyantha et al, 2017). Conventionally, RP is chemically processed by reacting with sulfuric or phosphoric acid although which involved with high cost and environmental pollution (Van Straaten, 2002).…”

Section: Introductionmentioning

confidence: 99%

Isolation of a potential rock phosphate solubilizing Aspergillus sp. towards development of biofertilizer

Kumari,

Senaratne,

Wijesinghe

2024

Ceylon J. Sci.

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Phosphorus (P) is one of the key bio elements that limits agricultural production. Although Sri Lanka is endowed with rock phosphate deposits, practical means to utilize this resource are limited. Phosphate-solubilizing fungi (PSF) play an important role in enhancing the bioavailability of soil phosphorus to plants. In this study, fungi from eight soil samples in Kaikawala, Sri Lanka, were isolated using spread plate method and analyzed for its phosphate solubility capacity. One fungal isolate with significant halo zones on Pikovskaya’s agar (PVK) plates, containing 0.5% tricalcium phosphate, was identified. After purification, the isolate was transferred to three media setups: PVK with 0.5% apatite (ERP) as the phosphate source, PVK with 0.5% tricalcium phosphate as a positive control, and PVK without P source as a negative control and analyzed for the solubilization index (SI). DNA sequences of the internal transcribed spacers with 5.8S region of ribosomal DNA (ITS1-5.8S-ITS2) was analyzed with universal primer pair ITS4-F/ITS5-R to determine the identity of the species. Fungal isolate PSF01 showed a phosphate solubilizing activity on both PVK media, ERP (1.07 ± 0.03 cm SI) and tricalcium phosphate (1.07 ± 0.01 cm), with similar effects (p > 0.05). However, the SI in the negative control was 1.00 ± 0.00 cm without halo zone (p < 0.05). The fungal strain is fast growing with initially white but quickly changing to black colonies after producing conidial spores on potato dextrose agar with distinctive conidial heads and pale-yellow lower surface characterized as Aspergillus. Sanger DNA sequencing identified the fungus as Aspergillus niger (99%) and a phylogenetic tree was constructed using MEGA11 software using reference data obtained from NCBI GenBank data to identify the isolated PSF01. Consequently, our preliminary studies demonstrate the importance of examining more soil samples to identify PSF for sustainable agricultural applications in the future.

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Application of geochemical techniques for prospecting unconventional phosphate sources: A case study of the lake sediments in Eppawala area Sri Lanka

Cited by 15 publications

References 49 publications

Risk assessment of heavy metals in the freshwater lake sediments around Eppawala phosphate deposit, Sri Lanka

Risk assessment of heavy metals in the freshwater lake sediments around Eppawala phosphate deposit, Sri Lanka

Recovery Potential of Rare Earth Elements (REEs) from the Gem Mining Waste of Sri Lanka: A Case Study for Mine Waste Management

Isolation of a potential rock phosphate solubilizing Aspergillus sp. towards development of biofertilizer

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