An evaluation of heavy metal pollution risk in tea cultivation soils of micro-catchments using various pollution indexes under humid environmental condition

Trace elements in tea in Ouargla, Algeria and health risk assessment

Tea is one of the most common drinks, consumed for its pleasant flavour and several medicinal values. The present study aimed to determine the levels of trace elements in tea products marketed in the Saharan region of Ouargla, Algeria and to evaluate the health risks associated with its regular consumption in adults and infants. To this aim, 78 tea samples were analysed by Inductively Coupled Plasma - Mass Spectrometry. Tea samples appeared to be contaminated by lead (0.73 ± 0.08 µg g-1) and aluminium (0.22 ± 0.02 µg g-1). Cadmium, arsenic, mercury, cobalt, manganese, nickel, chromium, zinc and copper were also detected. General linear model analysis indicated that black tea samples were the most contaminated. Tea samples packed in tea bags were the most contaminated with arsenic, aluminium and manganese. The hazard index was 0.28 and 1.33 for adults and for infants, respectively, indicating adverse non-carcinogenic effects in infants.

Evaluation of radioactive and heavy metal pollution in agricultural soil surrounding the lignite-fired thermal power plant using pollution indices

Soil pollution caused by heavy metals negatively affects the environment and human health. However, the assessment of the environmental and ecological risks caused by heavy metals in agricultural soils in developing countries is limited. This study was carried out to determine heavy metal pollution and its possible sources in the agricultural lands surrounding the lignite-fired Afşin-Elbistan thermal power plant (TPP). A total of 52 soil samples were collected from the agricultural soils surrounding the TPP, and seven different heavy metal (U, Th, Ni, Fe, Cu, Cr and Zn) analyzes were performed on these samples. Soil samples were taken according to the prevailing wind direction. Nickel had a higher geoaccumulation index (1.40) and enrichment factor (5.09) values than the other metals. In addition, U posed a "moderate potential ecological risk" in the study area. Pearson correlation and principal component analyses showed that U, Ni, and Cr were controlled by anthropogenic sources.

Evaluating heavy metal pollution risks and enzyme activity in soils with intensive hazelnut cultivation under humid ecological conditions

In order to promote sustainable agriculture and ensure food security, it has become more vital to identify the causes of soil pollution in agricultural areas. This study was carried out in order to determine the danger of heavy metal contamination in hazelnut production areas and to take the appropriate actions in accordance with the study's findings. In this context, the main objectives of this study were to (i) determine some physical, chemical, and biological properties and heavy metal concentrations of different soils in intensive hazelnut cultivation areas under humid ecological conditions; (ii) reveal the heavy metal pollution risks of these areas by their enrichment factor, contamination factor, geo-accumulation index, degree of contamination, pollution load index, and potential ecological risk index; (iii) analyze the quality of soils contaminated with heavy metals by their total enzyme activity index and the geometric mean of enzymatic activities; and (iv) explore the correlation between heavy metals and soil enzyme activity indices. According to our results, the average concentrations of heavy metals in the study area ranked as Fe > Mn > Zn > Cr > Ni > Cu > Co > Pb > Cd. Based on EF, the area was evaluated as between deficiency to low enrichment and moderate enrichment for all elements except for Cd. When the parameters used to assess the risk of heavy metal contamination were evaluated, it was determined that the risk of contamination of other elements in the study area, except Cd, was low. Finally, analyzing the heavy metals and soil enzyme activity indices shows that there is a negative correlation between Ni and GMea and TEI.

Health risk assessment of soil trace elements using the Sequential Gaussian Simulation approach

In this study, the performance of the Sequential Gaussian Simulation (SGS) approach was studied with the aim of accurately determining local health risk distributions associated with trace elements (V, Cr, Mn, Co, Ni, Cu, Zn, As, and Pb). This study plays a crucial role in determining the distribution of health risk levels, especially from heavy metals. In the SGS approach, health risk levels (non-carcinogenic and carcinogenic) were calculated for pixel sizes of 250 × 250 m². Results were compared to the conventional Ordinary Kriging (OK) method. The cross-validation performances of both methods were compared. Non-carcinogenic health risks calculated according to SGS and OK for children were, respectively, ρ_c: 0.57 and 0.23, RMSE: 0.45 and 0.57, and MAE: 0.33 and 0.43. In the case of adults, non-carcinogenic SGS and OK results were, respectively, ρ_c: 0.53 and 0.24, RMSE: 0.06 and 0.07, and MAE: 0.04 and 0.05 for adults. Carcinogenic health risk estimates obtained by SGS and OK were, respectively, ρ_c: 0.72 and 0.31, RMSE: 4.1 × 10^-5 and 5.8 × 10^-5, and MAE: 3.2 × 10^-5 and 4.3 × 10^-5 in the case of children, and in the case of adults the results were, respectively, ρ_c: 0.71 and 0.30, RMSE: 5 × 10^-6 and 4.3 × 10^-6, and MAE: 4 × 10^-6 and 5 × 10^-6. These results indicated that SGS offered a more accurate approach in determining health risk distributions.

Geographic information system-assisted site quality assessment for hazelnut cultivation using multi-criteria decision analysis in the Black Sea region, Turkey

Developing land suitability models for strategically critical agricultural products to expand sustainable agricultural policies and sensitive agriculture management has become a significant trend. This study aims to improve a unique land suitability model for hazelnut cultivation by applying the criteria set (7 main criteria, 35 sub-criteria) including qualitative and quantitative reasons, integrated fuzzy analytic hierarchy process, inverse distance weighting, multi-criteria decision analysis, geographic information system, and weighted linear combination approaches. The model developed in the present study was applied and tested in Ünye District of Ordu Province, where hazelnut production in the Eastern Black Sea region of Turkey is an important economic activity. While 71.17% of the study area is classified as very highly suitable, highly suitable, and moderately suitable, 28.83% of the study area has marginally suitable and unsuitable properties for hazelnut cultivation. Generally, it was determined that the coastal parts of the study area were the most suitable areas for hazelnut growing. The hazelnut land suitability model's two main criteria impacting the final score values are climatic and topographic conditions, respectively. Heavy metal pollution and physical, chemical, and fertility conditions related to soil properties followed these, respectively. The first ten sub-criteria with the highest weight value were determined as elevation, annual average temperature, annual average precipitation, aspect, annual average relative humidity, nickel (pollution), slope, annual average maximum temperature, lead (pollution), and soil depth, respectively. Existing hazelnut cultivation areas were used to test the model. Of the existing cultivation areas, 75.59% coincided with the very highly suitable, highly suitable, and moderately suitable classes presented in this study, while 17.15% were in marginally suitable and 7.26% in unsuitable classes. The study results reveal that the hazelnut land suitability model developed is suitable in mild climate conditions. Using this model as a general transition model will be beneficial to test it in areas containing similar climatic conditions and various soil properties. This study will create a rational background in ensuring the sustainable food production system and security, agricultural land use planning, strategic planning and management of the hazelnut plant, increasing agricultural productivity and income, and the ecosystem.

Occurrence, accumulation, and risk assessment of trace metals in tea (Camellia sinensis): A national reconnaissance

Accumulation of potentially toxic elements in soil and tea leaves is a particular concern for tea consumers worldwide. However, the contents of potentially toxic elements and their potential health and ecological risks in Chinese tea gardens have rarely been investigated on the national scale. In this study, we collected 225 paired soil and tea plant samples from 45 tea gardens in 15 provinces of China to survey the current risk of potentially toxic element accumulation in Chinese tea gardens. The results suggest that the average contents of most trace metals in rhizosphere soils meet the risk control standard for agricultural land in China. However, the mean contents of As, Cr, Cd, Zn, Cu, and Ni in rhizosphere soils were 1.94, 2.14, 1.23, 1.15, 1.18, and 1.19 times their corresponding background soil values in China. Cd had the highest geo-accumulation index, followed by As, Zn, Cr, Ni, Cu, Pb, and Mn in rhizosphere soils. Nearly 2.22% and 4.44% of soils were moderately to heavily contaminated with As and Cd, respectively. The risk index ranged from 18.0 to 292, with an average value of 90.0, indicating low to moderate ecological risk in Chinese tea gardens. This is the first national-scale reconnaissance of trace metals in tea across China. Our findings provide a useful reference for ensuring the quality and safety of tea production and mitigating the risk of toxic element accumulation in tea.