Heterogeneous (gas-solid) chemistry of atmospheric Cr: A case study of Astana, Kazakhstan

Hexavalent chromium (Cr(VI)) is a known carcinogen derived from both anthropogenic and natural sources. This work reports the size-segregated concentrations of total Cr(VI) in particulate matter (PM) in Astana, the capital of Kazakhstan, and provides new insights into the gas-solid reactions of atmospheric Cr. A study of total Cr(VI) in the particulate matter, via a microwave-assisted digestion technique, was conducted using a 5-stage Sioutas Cascade impactor that captures airborne particles in size ranges: >2.5 μm, 1.0-2.5 μm, 0.50-1.0 μm, 0.25-0.50 μm, and <0.25 μm. The total Cr(VI) concentration in the size fraction <0.25 μm was the highest with a maximum value of 9.7 ng/m3. This high concentration may pose a greater risk because smaller airborne particles can penetrate deeper into the lower respiratory tract of the lungs. Total suspended particles Cr(VI) exceeded the 8.0 ng/m3 Reference Concentration (RfC) by 22 times. The overall total Cr(VI) concentration in summer was significantly higher than in fall (p < 0.05), which could be due to factors, including higher temperatures, ozone, and NO2 concentrations in summer and a higher VOC concentration in fall. The results indicate that the interaction between Cr(III) and Cr(VI) through gas-solid reaction can control the speciation of atmospheric Cr.

The incidence and body site of skin cancers in the population groups of Astana, Kazakhstan

BACKGROUND AND AIMS

Data on cutaneous malignant melanoma (CMM), squamous cell carcinoma of the skin (SCC), and basal cell carcinoma (BCC) in populations consisting of multi-racial groups in the Commonwealth of Independent States are limited. Here, the main aim was to analyse the incidence and body site of these cancers in the population groups of Astana, Kazakhstan (2007-2016).

METHODS

Annual age standardised incidences and body sites of BCC, SCC, and CMM in Astana's population, divided into "Kazakhs and other Turkic/Asian" and "Russian and other European/Caucasian" groups, were calculated from histologically confirmed cases reported to Astana Oncology Centre.

RESULTS

During the period January 2007 to October 2016, 647 skin cancers were diagnosed. The age and sex standardised incidence of BCC, SCC, and CMM increased significantly between 2007 to 2011 and 2012 to 2016. Higher incidences occurred in the Russian and other European/Caucasian group compared with the Kazakh and other Turkic/Asian group for the 3 skin cancers. BCC was the most common type of skin tumour, followed by SCC, and then CMM, in both population groups and sexes. The head/neck was the commonest site for BCC and SCC in all groups. For CMM, the most frequent site was the trunk in the Russian group and the head/neck in the Kazakh group.

CONCLUSION

The incidence of skin tumours in Astana rose over the past 10 years. Differences in skin phototypes and sun exposure/ protection behaviours may account for the more frequent occurrence of skin tumours in the Russian population group compared with the Kazakh population group.

Comparison between landfill gas and waste incineration for power generation in Astana, Kazakhstan

The city of Astana, the capital of Kazakhstan, which has a population of 804,474, and has been experiencing rapid growth over the last 15 years, generates approximately 1.39 kg capita(-1) day(-1) of municipal solid waste (MSW). Nearly 700 tonnes of MSW are collected daily, of which 97% is disposed of at landfills. The newest landfill was built using modern technologies, including a landfill gas (LFG) collection system.The rapid growth of Astana demands more energy on its path to development, and the viability analysis of MSW to generate electricity is imperative. This paper presents a technical-economic pre-feasibility study comparing landfill including LFG utilization and waste incineration (WI) to produce electricity. The performance of LFG with a reciprocating engine and WI with steam turbine power technologies were compared through corresponding greenhouse gases (GHG) reduction, cost of energy production (CEP), benefit-cost ratio (BCR), net present value (NPV) and internal rate of return (IRR) from the analyses. Results demonstrate that in the city of Astana, WI has the potential to reduce more than 200,000 tonnes of GHG per year, while LFG could reduce slightly less than 40,000 tonnes. LFG offers a CEP 5.7% larger than WI, while the latter presents a BCR two times higher than LFG. WI technology analysis depicts a NPV exceeding 280% of the equity, while for LFG, the NPV is less than the equity, which indicates an expected remarkable financial return for the WI technology and a marginal and risky scenario for the LFG technology. Only existing landfill facilities with a LFG collection system in place may turn LFG into a viable project.