Weathering and accumulation of trace elements in the soils of the Porali Plain, Balochistan: repercussions in agriculture

This study is thefirst attempt to assess the nature of the soil,especially on the western side of the Porali Plain in Balochistan;a new emerging agriculture hub,using weathering and pollution indices supplemented by multi-variate analysis based on geochemical data.The outcomes of this study are expected to help farmers in soil manage-ment and selecting suitable crops for the region.Twenty-five soil samples were collected,mainly from the arable land of the Porali Plain.After drying and coning-quarter-ing,soil samples were analyzed for major and trace ele-ments using the XRF technique;sieving and hydrometric methods were employed for granulometric analysis.Esti-mated data were analyzed using Excel,SPSS,and Surfer software to calculate various indices,correlation matrix,and spatial distribution.The granulometric analysis showed that 76%of the samples belonged to loam types of soil,12%to sand type,and 8%to silt type.Weathering indices:CIA,CIW,PIA,PWI,WIP,CIX,and ICV were calculated to infer the level of alteration.These indices reflect mod-erate to intense weathering;supported by K_(2)O/AI_(2)O_(3),Rb/K_(2)O,Rb/Ti,and Rb/Sr ratios.Assessment of the geo-ac-cumulation and Nemerow Pollution indices pinpoint rela-tively high concentrations of Pb,Ni,and Cr concentration in the soils.The correlation matrix and Principal Compo-nent Analysis show that the soil in this study area is mainly derived from the weathering of igneous rocks of Bela Ophiolite(Cretaceous age)and Jurassic sedimentary rocks of Mor Range having SEDEX/MVT type mineralization.Weathering may result in the undesirable accumulation of certain trace elements which adversely affects crops.

Potential Groundwater Pollution Risks by Heavy Metals from Agricultural Soil in Songon Area(Abidjan,Cote d’Ivoire)

The soil samples were collected taking into account the land use in Songon area. The hydraulic conductivity (K) of soils was characterized in-situ when specific yield (Sy), pHw and concentrations of Cooper, Iron, Zinc, Cadmium, Chromium and Lead were measured in the laboratory. Pollution load indices (PLI) were calculated to evaluate the soil contamination levels. The soils were neutral and alkaline (6.7≤ pH ≤ 9.20), permeable (1.9 í 10-5?m·s-1?≤ K ≤ 8.2 í 10-4?m·s-1), with a high specific yield (13.33% ≤ Sy ≤ 33.33%) which can favor the pollutants transfer. The heavy metals (Fe, Cu, Zn, Cd, Cr and Pb) have very high concentrations in soils. The integrated pollution indices (PLI) indicate that almost 70% of Songon soils are moderately contaminated by the investigated heavy metals, with windows presenting high indices of pollution related to the intensive use of fertilizers and pesticides. The establishment of new boreholes in the Songon area should consider these heavy metals, so as to avoid the risk of groundwater pollution due to the physical properties of soils.

Diagnosis of Lead Pollution of Surface Waters of a River: Case of the Djiri River in the Republic of Congo

This research work focuses on the physico-chemical analysis of surface water from the Djiri River with the aim of preventing the population against possible water pollution. The analysis of samples taken from the Djiri river revealed the presence of lead in these waters at levels exceeding the WHO guideline values: an average annual pollution (0.93 mg/l) which is visibly higher than the value. WHO guide (0.01 mg/l) in situ data from the Djiri River revealed a significant drop in flow between the 2016 period characterized by a divergence index of 0.82344, thus highlighting a hydrological situation for which national hydrological stakeholders will absolutely have to implement measures, remedial measures or mechanisms to protect this river against possible disappearance by elimination of lead in the water.

Potential risk of soil irrigation with treated wastewater over 40 years:a field experiment under semi-arid conditions in northeastern Tunisia

In Tunisia,water scarcity is only adding pressure on water demand in agriculture.In the context of sustainable development goals,Tunisia has been reusing treated wastewater(TWW)as a renewable and inexpensive source for soil fertigation and groundwater(GW)recharge.However,major risks can be expected when the irrigation water is of poor quality.This study aims for evaluating the potential risk of TWW and GW irrigation on soil parameters.Accordingly,we evaluated the suitability of water quality through the analysis of major and minor cations and anions,metallic trace elements(MTEs),and the sodium hazard by using the sodium adsorption ratio(SAR)and the soluble sodium percentage(SSP).The risk of soil sodicity was further assessed by SAR and the exchangeable sodium percentage(ESP).The degree of soil pollution caused by MTEs accumulation was evaluated using geoaccumulation index(Igeo)and pollution load index(PLI).Soil maps were generated using inverse spline interpolation in ArcGIS software.The results show that both water samples(i.e.,TWW and GW)are suitable for soil irrigation in terms of salinity(electrical conductivity<7000μS/cm)and sodicity(SAR<10.00;SSP<60.00%).However,the contents of PO_(4)^(3-),Cu^(2+),and Cd^(2+)exceed the maximum threshold values set by the national and other standards.Concerning the soil samples,the average levels of SAR and ESP are within the standards(SAR<13.00;ESP<15.00%).On the other hand,PLI results reveal moderate pollution in the plot irrigated with TWW and no to moderate pollution in the plot irrigated with GW.Igeo results indicate that Cu^(2+)is the metallic trace element(MTE)with the highest risk of soil pollution in both plots(Igeo>5.00),followed by Ni^(2+)and Pb^(2+).Nevertheless,Cd^(2+)presents the lowest risk of soil pollution(Igeo<0.00).Statistical data indicates that Ca^(2+),Na+,Ni^(2+),and Pb^(2+)are highly distributed in both plots(coefficient of variation>50.0%).This study shows that the use of imagery tools,such as ArcGIS,can provide important information for evaluating the current status of soil fertility or pollution and for better managing soil irrigation with TWW.

Geochemistry of Potentially Toxic Elements in Soil and Sediments of a Tanzanian Small-Scale Gold Mining Area

Small-scale gold mining is linked to significant environmental pollution by potentially toxic elements (PTEs). However, research on the pollution caused by such mining activities remains insufficient especially in developing countries. In the present study, a systematic investigation assessed the pollution and level of ecological risk of PTEs in soil and stream sediments in an active small scale gold mining area of Isanga, in Nzega, Tanzania. Samples amounting to 16 soil and 20 sediment were gathered from the study area and analyzed for five PTEs concentrations (As, Cd, Cr, Hg and Pb) using the AAS method. The contamination level and ecological risk were assessed using several pollution indices. The results suggest that the assessed environmental systems of the Isanga mining area and its vicinities are lowly contaminated by PTEs and have a low potential to pose ecological risks. Hg and Cd with mean concentrations of 0.09 mg/kg and 0.26 mg/kg respectively were found to be the most enriched PTEs in soil, compared to their average continental crust concentrations (0.056 mg/kg and 0.102 mg/kg respectively). The levels of the evaluated PTEs in the study area are susceptible to increase over time if proactive steps are not taken to control mining and waste disposal activities.

Assessment of Bacteria, Morphological Characteristics, and Elemental Composition of Dust Fallout

Dust fallout can have diverse impacts ranging from major health problems to environmental concerns. It can harbour disease-causing microorganisms and toxic heavy metals, and it is therefore critical to establish the microbial and the mineral compositions of the dust fallout in a particular site and elucidate the possible related health implications for humans and the entire environment. In this study, dust fallout samples were collected from Arandis, a town in the Erongo region (Namibia), using the American Society for Testing and Materials standard method (ASTM D1739) for collection and analysis of dust fallout (settleable particulate matter). The identification of present viable bacteria was done through culturing and isolation techniques and the morphological characteristics, and the elemental composition of the dust fallout were determined using the Stereomicroscope and the X-ray fluorescence, respectively. The results showed that the most dominant bacteria contained in the fallout dust were the Bacillus species. The morphological characterisation revealed that the present particles were mixed black, brownish, greenish, and crystal particles with irregular, cubical, flocks and flake shapes. The elemental investigations indicated that the dust fallout contained Hg, As, Fe, Ni, Cr, Mn, Al and Pb occurring in varying concentrations and the status of pollution of the dust fallout ranged from low to severe concerning the inconsistent heavy metal indices that are the contamination factor, pollution load index and the enrichment factor.

Characterization of Urban Soil with SEM-EDX

The coal is largely used for generation of energy in the India, and their huge exploitations cause contamination of the soil. In the present work, the inorganic contamination of surface soil in the coal basin of the country, Korba is described. The concentration of elements i.e. C, O, S, Cl, Na, Mg, Al, Si, P, K, Ca, Ti, Fe, Mn and Ni in the surface soils (n = 30) was analysed by technique i.e. scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), ranged from 6.6% - 36.4%, 37.8% - 54.3%, 0.07% - 0.39%, 0.03% - 0.25%, 0.10% - 0.39%, 0.12% - 0.49%, 3.7% - 10.3%, 12.2% - 24.4%, 0.11% - 0.60%, 0.68% - 3.22%, 0.8% - 2.7%, 0.25% - 0.61%, 2.3% - 6.4%, 0.08% - 0.22% and 0.04% - 0.16% with mean value (p = 0.05) of 18.8% ± 2.7%, 49.0% ± 1.5%, 0.18% ± 0.03%, 0.11% ± 0.02%, 0.23% ± 0.03%, 0.32% ± 0.03%, 6.1% ± 0.5%, 16.9% ± 0.9%, 0.27% ± 0.04%, 1.6% ± 0.2%, 1.5% ± 0.2%, 0.41% ± 0.03%, 4.3% ± 0.4%, 0.14% ± 0.02% and 0.08% ± 0.01%, respectively. The surface soil morphology, concentration variation of elements, pollution indices and contaminant sources in the soil are discussed.

Polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls in surface soil from the Tibetan Plateau

Concentrations of Polychlorinated dibenzo-p-dioxins and dibenzofurans（PCDD/Fs） and polychlorinated biphenyls（PCBs） in soil samples from Tibetan Plateau were determined. The average concentration of total 2,3,7,8-PCDD/Fs was（2.30 ± 1.02） pg/g, and World Health Organization Toxicity Equivalency（WHO-TEQ） average concentration was（0.013 ± 0.010）pg WHO-TEQ/g. The average concentration of ∑PCBs（7 indicator PCB and 12 dioxin like-PCB congeners） was（16.2 ± 9.25） pg/g, and WHO-TEQ average concentration was 0.043 ±0.049 pg WHO-TEQ/g. Comparing to previous studies in similar environmental conditions,PCDD/Fs and PCBs in this study showed a relatively lower concentration. The altitude dependences of PCDD/Fs and PCBs were also studied. Total organic carbon（TOC） normalized concentrations presented a quadratic relation with the altitudes, and an inflection could be found on the parabola of the total concentrations and some congeners of high concentration.The concentrations decreased with altitudes below about 4500 m above sea level（a.s.l.）, while they increased with altitudes above it. These phenomena indicate that cold condensation of PCDD/Fs and PCBs would happen above 4500 m a.s.l, on the Tibetan Plateau.