Direct Electrodeposition of Carbon Dots Modifying Bismuth Film Electrode for Sensitive Detection of Cd2+ and Pb2+

A sensitive, selective, and stable sensor for the simultaneous determination of Cd2+ and Pb2+ in aqueous solution has been developed based on the carbon dots (CDs) and Nafion-modified bismuth film glassy carbon electrode (GCE). High graphitized CDs prepared by the sulfuric acid-assisted hydrothermal synthesis were directly electrodeposited on the GCE surface by cyclic voltammetry. Compared with the conventional bismuth film electrodes, CDs greatly improved the electrochemical activity of the bismuth film electrode for the detection of Cd2+ and Pb2+. After decorating CDs, the surface impedance of the GCE was decreased from 10.9 kΩ to 4.84 kΩ. Meanwhile, the corresponding response currents of the Bi/GCE were increased over 7.4 and 2.4 times for Cd2+ and Pb2+ with a wide linear range of 0.05-0.50 mg/L, respectively. High sensitivity was obtained with the detection limits of 3.1 μg L-1 (Cd2+) and 2.3 μg L-1 (Pb2+). Moreover, good stability was obtained for the simultaneous determination of Cd2+ and Pb2+ in the practical underground water with the relative standard deviations less than 10%. The results indicated that the CDs-modified bismuth film electrode could potentially be applied to detect the heavy metal ion concentrations in practical environment.

Development and Analysis of Long-Term Measurement Systems for Groundwater Level Using Electric Capacity

In soil dams and embankments made of soil, deterioration and stress release owing to internal and external influences occur, and the instability of the body increases as the shear strength decreases. In particular, understanding the location and flow of underground water is very important for securing the long-term stability of waterfront structures in contact with water. However, the physical limitations of measuring equipment cause many difficulties in understanding the existence and location of groundwater over a long period of time. In this study, measuring equipment using electric capacity was developed for the long-term measurement of groundwater, and contactless measuring sensors were manufactured to eliminate the possibility of corrosion by water. In addition, the precision of the measurement data was improved by applying waterproof and water-repellent coatings to the measurement sensor. Laboratory tests conducted using the developed equipment demonstrate the high precision of the measurement data according to the groundwater level change and enhanced durability of the sensor, which facilitate long-term measurements in the field.

A Systematic Visualization Review of Green Environment and Public Health for 2003-2019 Based on The Co-Citation Bibliometric Analysis Theory

Currently, the world is facing challenges of environmental pollution and public health owing to increasing urbanization. Therefore, many researchers from developed and developing countries are considering environmental pollution and public health to be the most important topics for sustainable development alongside a healthy and green environment. Although in the literature many researchers have investigated a pictorial view of green environment by defining the urban green space and blue space effects on public health, the green environments and public health research trend remains unclear. Thus, this study aimed to contribute to the literature by visualizing the bibliometric for green environments and public health, and to identify the missing research pathway. Data for this study was collected from the Web of Science from 2003-2019 in order to facilitate a visualization and bibliometric analysis carried out by CiteSpace. The visualization results reveal the most influential studies, institutions, authors, countries, keywords, and category cloud in the green environments and public health research field. Furthermore, this study suggests that researchers need to pay attention to how the genome changes due to climate change, as well as environmental pollution and its effect on human health. Mental health and research related to green environment and social health is also missing. In addition, there is also a missing link regarding green environment, underground water and public health. Additionally, this study could help authors and publishers make decisions concerning research on green environments and public health and planning for future perspectives to contribute to both academic development and applied methodology.

Study of migration of radioactive elements in clay layers during the burial of radioactive waste

In 2015, Kazakhstan and the International Atomic Energy Agency (IAEA) signed an agreement to host a low-enriched uranium bank in Ust-Kamenogorsk. In 2019, several batches of enriched uranium were delivered to Kazakhstan and the bank began operations at the Ulba Metallurgical Plant. When transporting and disposing of radioactive elements, there is a need to reduce this possibility by limiting the transfer of uranium from underground storage to underground water. Therefore, in this article, a study was conducted on the migration of radioactive elements in clay layers during the disposal of radioactive uranium waste. There are now many underground repositories (for some types of radioactive waste). These systems are based on different underground container structures for different geological formations. For underground repositories located in geological environments where enriched uranium can migrate, other system components must reduce this possibility by preventing or limiting uranium mobility. This work investigates the process of convective transport of radioactive elements, in a moist soil layer through the installation of an additional natural clay barrier layer, the migration of radioactive elements during safe disposal, the effect of diffusion and convection through the solid waste layer.

A Study on the Impact of Unconventional (and Conventional) Drilling on Housing Prices in Central Oklahoma

Shale energy development activity may benefit some aspects of a regional economy (such as increased jobs or tax revenue); however, there may also be negative impacts to the local environment, such as noise and underground water contamination. We study the impact of unconventional drilling activity on housing price in an area of the country with a long history of crude oil production. A prospective home buyer may want to avoid a place near sites that have been drilled using unconventional drill technologies such as horizontal fracturing. Adopting a hedonic price model, we estimate the impact of distance to and density of unconventional drilling on housing prices in two central counties in Oklahoma during the period 2001–2016. We also apply a semiparametric approach to deal with the possibility that the relationship between an environmental pollutant source and housing price is nonlinear. The empirical results are consistent in terms of physical housing characteristics and locational aspects in all cases, with drilling activity having only a minimal effect in benchmark models. Further, the semiparametric estimation results support the findings that drilling activity has only limited impacts on local housing prices.

Experimental studies of iron transformations kinetics and autocatalysis during its physicochemical removal from underground water

The mathematical model of physicochemical iron removal from groundwater was developed. It consists of three interrelated compartments. The results of the experimental research provide information in support of the first two compartments of the mathematical model. The dependencies for the concentrations of the adsorbed ferrous iron and deposited hydroxide concentrations are obtained as a result of the exact solution of the system of the mass transfer equations for two forms of iron in relation to the inlet surface of the bed. An analysis of the experimental data of the dynamics of the deposit accumulation in a small bed sample was made, using a special application that allowed to select the values of the kinetic coefficients and other model parameters based on these dependencies. We evaluated the autocatalytic effect on the dynamics of iron ferrous and ferric forms. The verification of the mathematical model was carried out involving the experimental data obtained under laboratory and industrial conditions.

Legal and water management policy during climate warming in Poland

The article discusses some of the effects of global warming on rivers, lakes and underground water in Poland. It documents serious difficulties in river shipping and energy, as well as the exposing of areas previously occupied by lakes as a result water levels lowering. It is pointed out that the rapid increase in intensive irrigation of agricultural areas is causing excessive exploitation of underground water. The analysis takes into account the relevant data. The presentation of the effects of global warming is expanded upon with the legal provisions applicable in these situations. In the absence of climate change law, these are general regulations that face a number of difficulties in application. The detailing of areas of law and hydrology leads to the conclusion that Poland lacks a coherent policy on climate warming.