Holistic risk assessment of surface water contamination due to Pb-210 in oil produced water from the Bakken Shale

Research progress of the POP fugacity model: a bibliometrics-based analysis

With the emergence of environmental issues regarding persistent organic pollutants (POPs), fugacity models have been widely used in the concentration prediction and exposure assessment of POPs. Based on 778 relevant research articles published between 1979 and 2020 in the Web of Science Core Collection (WOSCC), the current research progress of the fugacity model on predicting the fate and transportation of POPs in the environment was analyzed by CiteSpace software. The results showed that the research subject has low interdisciplinarity, mainly involving environmental science and environmental engineering. The USA was the most paper-published country, followed by Canada and China. The publications of the Chinese Academy of Sciences, Lancaster University, and Environment Canada were leading. Collaboration between institutions was inactive and low intensity. Keyword co-occurrence analysis showed that polychlorinated biphenyls, organochlorine pesticides, and polycyclic aromatic hydrocarbons were the most concerning compounds, while air, water, soil, and sediment were the most concerning environmental media. Through co-citation cluster analysis, in addition to the in-depth exploration of traditional POPs, research on emerging POPs such as cyclic volatile methyl siloxane and dechlorane plus were new research frontiers. The distribution and transfer of POPs in the soil-air environment have attracted the most attention, and the regional grid model based on fugacity has been gradually improved and developed. The co-citation high-burst detection showed that the research hotspots gradually shifted from pollutant persistence and long-range transport potential to pollutant distribution rules among the different environmental media and the long-distance transmission simulation.

Societal aspects of NORM: An overlooked research field

While technical aspects of exposures to the naturally occurring radioactive material (NORM) are well explored, social science research on NORM is scarce, poorly indexed and dispersed across peer-reviewed literature, as well as various academic disciplines. Through an exploratory review of grey literature and a systematic review of scientific peer-reviewed articles published until December 2020, this paper addresses the following questions: (a) What are the societal challenges related to NORM? (b) What type of scientific research is being conducted on the societal aspects of NORM and (c) To what extent do the findings answer the identified challenges? Unfortunately, results of this study demonstrate a research gap related to the social, economic and cultural aspects of NORM management. Although the few existing studies offer some insights, for instance in relation to risk perception and risk communication, most of the societal challenges identified have not been addressed yet. This demonstrates the strong need for evidence based social science studies in order to improve the management of NORM.

Accumulation rates of natural radionuclides (40K, 210Pb, 226Ra, 238U, and 232Th) in topsoils due to long-term cultivations of water spinach (Ipomoea Aquatica Forssk.) and rice (Oryza Sativa L.) based on model assessments: A case study in Dong Nai province, Vietnam

In topsoils, the activity concentrations of natural radionuclides (hereafter NRs) increase due to the addition of NRs from fertilizers, irrigation water, and air dust pollution. On the other hand, various physical-chemical and environmental processes such as radioactive decay, volatilization, leaching, erosion, and plant uptake were responsible for the decrease of the activity concentrations of NRs in the topsoils. In this study, behaviours of ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²³⁸U, and ²³²Th in topsoils were modelled by the CEMC soil model and the HYDRUS-1D model. An exponential equation was proposed for estimating the accumulation rates of these radionuclides in the topsoils. Long-term accumulation of radionuclides was assessed for water spinach (Ipomoea Aquatica Forssk.) soil (hereafter VES) and rice (Oryza sativa L.) soil (hereafter RIS). We found that the current agricultural practices caused the increase of ⁴⁰K activity concentration in the water spinach soil, and ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, and ²³²Th activity concentrations in the rice soil. The accumulation rates of radionuclides were in the order ²³⁸U < ²³²Th < ²²⁶Ra < ²¹⁰Pb < ⁴⁰K. 25 years of cultivation with water spinach can increase/decrease + (165 ± 6) Bq of ⁴⁰K, - (8.2 ± 0.7) Bq of ²¹⁰Pb, - (4.3 ± 0.2) Bq of ²²⁶Ra, - (7 0.3 ± 0.3) Bq of ²³⁸U, and - (1.8 ± 0.1) Bq of ²³²Th in 1 kg soil. For rice cultivation, these values are + (1004 ± 39), + (3.3 ± 0.2), + (3.0 ± 0.2), - (5.1 ± 0.3), (2.2 ± 0.1) Bq kg^-1 for ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²³⁸U, and ²³²Th, respectively.

Levels of 226Ra in groundwater samples collected in Phu Yen province, Vietnam associated with health risks to local population and impacts on the maize (Zea mays L.) soil

Groundwater is a major source of drinking water and agricultural water in some regions of the world. However, it contains a high level of 226Ra that is potentially hazardous to human health and the environment. Normally, the activity concentration of 226Ra in groundwater is determined to assess the quality of groundwater that can be used as drinking water. There are few studies on the accumulation of 226Ra in the agricultural soil due to irrigation with groundwater. In this study, levels of 226Ra were determined on over 60 groundwater samples collected from the public water supply wells in Phu Yen province, Vietnam. Besides assessment of the health risks to population due to drinking groundwater samples, the impact of groundwater irrigation to the maize field in the study area was studied. For this purpose, two chemical fate models were applied and the comparison of their results was performed. Based on the model assessments, we predicted that the present agricultural practices increased the 226Ra activity concentration in the maize soil, and the level of 226Ra activity concentration in the topsoil can exceed the recommended level at 11.4 years of the present agricultural practices on the maize soil.

Risk grade assessment of sudden water pollution based on analytic hierarchy process and fuzzy comprehensive evaluation

Sudden water pollution is a global environmental issue. On a large spatial scale, any pollution source may cause water pollution incidents. Dividing a large watershed into several units and giving each unit a different level would be favorable for managing sudden water pollution incidents. To scientifically divide an area into units and determine their risk grade of sudden water pollution, data of pollution sources were collected, and an area was divided into risk assessment units of sudden water pollution. The risk grade assessment was conducted following the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation method. The technology combined with the AHP and fuzzy comprehensive evaluation (F-AHP) can generate the hydrology, pollution source, natural geography, and socioeconomic characteristics of each unit and provide a risk grade evaluation. A risk grade assessment was conducted using the Yongding River as a case study. The results show that the areas with high sudden water pollution risk were mainly distributed in Shanxi Datong and Hebei Zhangjiakou. Sufficient control of pollution sources in production processes and the establishment of necessary measures to strengthen inspections should reduce the risk of sudden water pollution.

Modelling the mitigation speeds of 137Cs, 90Sr and 131I in the topsoils and assessment of the radiological hazards

Fate modelling of artificial radionuclides (ARs) in top soils are necessary to assess the radiological effects to population. Among ARs, ¹³⁷Cs, ⁹⁰Sr and ¹³¹I are very important since the large abundances in the environment. In this study, the fates of ¹³⁷Cs, ⁹⁰Sr and ¹³¹I in the surface soil layers were simulated by the soil model which was developed by the Canadian Centre for Environmental Modelling and Chemistry (CEMC). The scenario that ¹³⁷Cs, ⁹⁰Sr and ¹³¹I contaminated in topsoil in the exclusion of Fukushima Daiichi nuclear power plant (NPP) accident was evaluated. The results show the expected time for the minimum hazardous level of exposure. It is 115.5 days after the exposure, when the total effective dose is 1 mSv y^-1 in which 0.46 mSv y^-1 from ingestion and 0.54 mSv y^-1 from gamma exposure. Hazard levels due to exposure progresses are varied in order gamma exposure (82.14%) > ingestion (17.47%) > inhalation (0.39%). The hazard levels from radionuclides are varied in order ¹³⁷Cs (63.34%) > ¹³¹I (33.48%) > ⁹⁰Sr (3.18%).

Improved waste-sourced biocomposite for simultaneous removal of crude oil and heavy metals from synthetic and real oilfield-produced water

Oil- and gas-produced water (PW) which contains various pollutants is an enormous threat to the environment. In this study, a novel low-cost bio-adsorbent was prepared from shrimp shell and acid-activated montmorillonite. The results of FT-IR spectroscopy, energy dispersive X-ray (EDX) analysis, and SEM-EDX technique indicated that the chitosan-activated montmorillonite (CTS-A-MMT) was prepared successfully. The synthesized CTS-A-MMT was applied to remove simultaneously five cationic and anionic metal species and crude oil from synthetic and real oilfield PW. The adsorption data indicated that crude oil and all studied metals (except As) were adsorbed to CTS-A-MMT in a monolayer model (best fitted by Langmuir model), while As adsorption fits well with Freundlich model. Kinetic models' evaluation demonstrated that the adsorption kinetics of metals on CTS-A-MMT are initially controlled by the chemical reaction (film diffusion) followed by intra-particle diffusion. Application of the prepared CTS-A-MMT in real oilfield PW indicated removal efficiency of 65 to 93% for metals and 87% for crude oil in simultaneous removal experiments. Presence of additional ions in PW decreased the removal of studied metals and crude oil considerably; however, the concentration of the investigated pollutants in treated PW is less than the ocean discharge criteria. It is concluded that the prepared CTS-A-MMT composite is a low-cost and effective adsorbent for treating wastewater contaminated with crude oil and heavy metals (i.e., PW).