Mn Values Research Articles

Occurrence of toxic elements in river areas along drains and groundwater resources: source of contamination and associated health risk.

The objective of the current research was to examine the water quality of the River Ravi and the River Sutlej, with a specific focus on potentially toxic elements (PTEs). Additionally, we sought to monitor the sources of pollution in these rivers by gathering samples from the primary drains that carry industrial and municipal waste into these water bodies. Furthermore, we aimed to evaluate the impact of PTEs in surface water on groundwater quality by collecting groundwater samples from nearby populated areas. A total of 30 samples were collected from these three sources: rivers (6 samples), drains (9 samples), and groundwater (15 samples). The analysis revealed that the levels of PTEs in the samples from these three resources having a mean value: arsenic (As) 23.5µg/L, zinc (Zn) 2.35mg/L, manganese (Mn) 0.51mg/L, lead (Pb) 6.63µg/L, and chromium (Cr) 10.9µg/L, exceeded the recommended values set by the World Health Organization (WHO). Furthermore, PTEs including (As 84%), (Zn 65%), (Mn 69%), (Pb 53%), (Cr 53%), and (Ni 27%), samples were beyond the recommended values of WHO. The results of the Principal Component Analysis indicated that surface water and groundwater exhibited total variability of 83.87% and 85.97%, respectively. This indicates that the aquifers in the study area have been contaminated due to both natural geogenic factors and anthropogenic sources. These sources include the discharge of industrial effluents, wastewater from municipal sources, mining activities, agricultural practices, weathering of rocks, and interactions between rocks and water. Spatial distribution maps clearly illustrated the widespread mobilization of PTEs throughout the study area. Furthermore, a health risk assessment was conducted to evaluate the potential adverse health effects of PTEs through the ingestion of drinking groundwater by both children and adults. Health risk assessment result show the mean carcinogenic values for As, Cr, Pb and Ni in children are calculated to be (1.88E-04), (2.61E-04), (2.16E-02), and (5.74E-05), respectively. Similarly, the mean carcinogenic values for the above mentioned PTEs in adults were recorded to be (2.39E-05), (3.32E-05), (1.19E-03), and (7.29E-06) respectively. The total hazard index values for As, Zn, Cr, Pb, Mn, Cu, and Ni in children were observed to be (9.07E + 00), (9.95E-07), (4.59E-04), (5.75E-04), (4.72E-05), (2.78E-03), and (5.27E-05) respectively. The analysis revealed that As has an adverse effect on the population of the study area as compared to other PTEs investigated in this study.

Formation conditions of Jixian System cherts in the Qishan area, Ordos Basin: Implications for marine redox conditions and paleoecology

Abundant chert bands and nodules are discovered throughout the Mesoproterozoic Jixian System in the Ordos Basin. These cherts faithfully record the Jixian period oceanic conditions and paleoecology. However, the diagenetic mechanism of the cherts remains unclear and controversial. To understand the origin of these cherts, we performed a multitracer study by combining field reconnaissance, petrological analyses, Si isotope analysis, and major and trace element analysis of chert samples from the Qishan section. The results show that Jixian cherts had a high Al/(Al + Fe + Mn) value (~0.48), showed a flat distribution of rare earth elements in seawater, and most of the Fe/Ti values are <20. A weak negative Ce anomaly (~0.97) indicates the contribution of REY to weakly oxygenated seawater. The high isotopic composition of silicon (δ30Si = 0.74 ‰-1.35 ‰) and the average Siex value of 37.52 indicate that there is a source of biological silica, and the relationship between Eu/Eu* and Y/Ho and δ30Si shows that the hydrothermal and volcanic influences were less and correlated with seawater. The chert bands were closely related to biological activities. The chert nodules were influenced by hydrothermal activity. Secondary cherts were related to diagenesis, but the nature of siliceous fluids remains unchanged, still characterized by biogenic activity origins. The sea oxygen concentration in the Jixian period had increased, with periodic variations in the intensity of biological activities affecting the pH of the water body, or biological photosynthesis binding SiO2 colloid in water, affecting chert sediments, leading to frequent interlayering between dolomite and chert bands. Episodic hydrothermal fluids and late-stage diagenetic processes jointly influenced the formation of cherts. This study bears significant significance in enhancing our understanding of the sedimentary environment and the origin of cherts during the Jixian period in the Ordos Basin.

Solvent Fractionation of Technical Lignin Materials with Industrially Relevant Solvents

Lignin fractionation aims at dividing the original lignin material into more uniform fractions that have the qualities desired for further processing of the material. Solvent fractionation is a versatile method that produces a soluble and an insoluble fraction with varying compositions, including molecular weight distribution, polydispersity (PDI), and phenolic hydroxyl (OHph) content. These properties are key factors in the further downstream applicability of lignin. Kraft, organosolv, and hydrolysis lignins were fractionated using multiple solvents and their water solutions with a single-stage fractionation protocol. The produced fractions were analyzed for their molecular size distribution and OHph content. Soluble fractions were discovered with desirable qualities, including a narrow size distribution (lowest PDI 1.4) and accumulation of OHph groups (up to 3.05 mmolOH/glignin). Three fractionation solvents, i.e., pure isopropanol, pure ethanol, and 30% γ-valerolactone, were found to produce solvent-specific soluble fractions that had relatively identical characteristic Mw, Mn, and PDI values regardless of the initial lignin material. This is crucially important new data that is beneficial for robust lignin applicability at industrial scale. Other important observations were made regarding water-alcohol solutions, as the increase in initial solid content resulted in changes in the composition of the fractions produced. Further applicability of the obtained fractions is examined in this paper. Patterns as well as differences between the three lignin materials were observed in their dissolution and the resulting compositions of the soluble fractions. This wide comparable dataset of industrially relevant solvents and lignin materials provides significant insight into the possibilities of lignin downstream processing.

Speciation, mobility, and risks of heavy metals in sediment and water of a freshwater Lake in Fujian Province, China

ABSTRACT This study investigated the level of dissolved heavy metals in the water of Longhu Lake and focused on the speciation, mobility, and risks of heavy metals (Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb) in sediment. The levels of heavy metals in the water were found to be below the thresholds set by the Chinese safe drinking water standard. The highest average percentages of Cr, Ni, Zn, and As were bound with residual fractions, while Pb and Cu were bound with reducible fractions. Additionally, the highest percentage of Cd and Mn was bound to the acid-soluble fraction in the sediment. These findings suggest that Cd, Mn, Pb, and Cu likely originated from anthropogenic sources in the lake. There was a strong correlation between total organic carbon (TOC) and metal fractions in the sediment, indicating that TOC may play a role in transporting heavy metal fractions. Risk assessment code values for Cd and Mn indicated higher risks and mobility, while Ni, Cu, and Zn showed medium risks and mobility for aquatic biota. To mitigate heavy metal contamination, it is recommended to improve monitoring and regulation of urban runoff and inlet areas.

Source apportionment and health risk assessment of PM10 bound carbonaceous and elemental species in the central Himalayas

In this extensive investigation, the sources and health risk assessment of carbonaceous aerosols, as well as the elemental compositions (Ca, Al, Fe, S, K, Mg, Pd, B, Mo, Zn, Ag, Nb, Ga, Cl, Ti, Zr, Na, Cr, Cu, Mn, Cs, P, Y, Sb, Ni, Sn, F, Sr, Br, Pm, U, Pb, Th, Br, Rb, and V) of PM10, were conducted throughout January-December 2021 in Nainital, a central Himalayan region of India. The average annual mass concentration of PM10 was determined to be 64±6 µg m-3. Carbonaceous aerosols (CAs), comprising OC, EC, WSOC, and SOC, exhibited annual averages of 9.3±0.8 µg m-3, 4.9±0.5 µg m-3, 1.5±0.2 µg m-3, 2.7±0.2 µg m-3, and 2.97±0.45 µg m-3, respectively. The elemental composition featured major contributors such as Ca, Al, Fe, S, and K, alongside trace levels of various elements (Mg, Pd, B, Mo, Zn, Ag, Nb, Ga, Cl, Ti, Zr, Na, and Cr). Positive Matrix Factorization (PMF) identified six primary contributors to PM10, each with varying percentage contributions: crustal/soil/road dust, soil re-suspension, combustion, vehicular emissions, industrial emissions, and biomass burning. The health risk assessment revealed elevated Hazard Quotient (HQ) values for Cr and Mn in children, indicating a non-carcinogenic health risk. Adults exposed to high Cr levels may face potential carcinogenic risks, while elements like Al, Pb, Cu, Zn, and Ni pose no health hazards, aligning with USEPA guidelines.

An investigation of novel biodegradable flexible copolyester derived from bio-based isosorbide: Synthesis and characterization of poly(butylene-co-isosorbide sebacate)

A series of fully bio-based poly(butylene-co-isosorbide sebacate) (PBISe) copolyesters are synthesized from sebacic acid (Se), 1,4-butanediol (BDO), and isosorbide (IS) via a two-step melt polycondensation method. The synthesized PBISe copolyesters are characterized using various techniques, including 1H NMR spectroscopy; GPC; FT-IR spectroscopy; HR-XRD; DSC; TGA; transparency, tensile, and tear strength testing; and rheological property analysis. The Mw and Mn values of the PBISe copolyesters are 126,000–148,000 and 50,000–63,500, respectively. The introduction of the rigid, bulky, and asymmetric IS unit disrupts the regularity and mobility of the polymer chain, resulting in a nearly linear reduction of the melting temperature, enthalpy, and crystallinity, from 66 to 42 °C, 81 to 37 J/g, and 41.4 to 19.0%, respectively, with an increase in the IS content from 0 to 30 mol% relative to the total diol concentration. The reduction of crystallinity without the formation of new crystal planes with the poly(butylene sebacate (PBSe) copolyester containing 30 mol% IS resulted in improved transparency (73.8% transmittance at 600 nm). Additionally, the PBISe copolyesters exhibit Tonset and Tmax in excess of 405 °C and 425 °C, respectively, as well as shear-thinning and viscous melt-flow behaviors, making them suitable for melt processing. The tensile strength and elongation at break of the hot-pressed films of the IS-added PBISe copolyesters with ≤16% content are 31.6–36.3 MPa and 639.2–809.9%, respectively. The developed PBISe copolyesters have great potential as bio-based, biodegradable, and flexible materials for packaging and coating applications with low processing temperatures.

Effects of Bacillus amyloliquefaciens on volatile components and nutrient element contents of Mentha piperita L. grown under salt stress

Bacillus amyloliquefaciens (Ba) was applied to Mentha piperita L. (peppermint) seedlings grown at various salt levels (0, 50, 75, and 100 mM) for 42 days (six weeks). The study was conducted in a total of eight groups, with 24 seedlings per group. At the end of the study, the seedlings were analyzed for plant nutrient elements and volatile compound contents. The negative effect of salt was observed in almost all parameters. When all groups were evaluated for plant nutrient elements, Ba had a positive effect on Zn, Mn, Cu, and Na values compared to the control, but it did not show any effect on B, Fe, K, P, Mg, and Ca. In volatile compounds, limonene was detected as the major component in all groups. As a result of the evaluation based on limonene, the highest rate was found in the control, and the lowest rate was found in 100 mM NaCl. The salt-dependent inhibition between the groups with the highest and lowest limonene was 73%. While the negative effects of salt were observed in almost all parameters, the promoter effects of Ba were not as pronounced.

CHARACTERIZATION OF LIGNIN DISSOLVED DURING ALKALINE SODIUM BOROHYDRIDE AND HYDROGEN PEROXIDE PRETREATMENTS OF SUGAR MAPLE (ACER SACCHARUM)

Sugar maple (Acer saccharum) wood chips were pretreated with aqueous sodium hydroxide, sodium borohydride, and hydrogen peroxide pretreatments, and the characterization (i.e., amount, molar masses, and molar mass distributions) of the lignin dissolved during the pretreatments was performed. Of the applied pretreatments, especially borohydride pretreatments were efficient in dissolving lignin from this feedstock, as 20% to 28% of the dissolved organics were found to consist of dissolved lignin, contributing to 3.4% to 9.0% of the initial wood lignin. Corresponding values for 2.5% and 5.0% alkaline peroxide pretreatments were from 5.9% to 9.2% dissolved lignin of the total dissolved organics and from 1.1% to 3.2% of the initial wood lignin. Additionally, determined molar masses and molar mass distributions indicated that borohydride pretreatments generally led to the formation of smaller-molar-mass lignin fragments when compared to reference pretreatments and to pretreatments conducted with alkaline peroxide process, indicating more efficient lignin degradation caused by borohydride addition. For example, Mn and Mw values of the analyzed reference effluents were 54%-62% and 66%-71% higher when compared to the corresponding borohydride effluents, respectively.

High Molar Mass Polycarbonates as Closed-Loop Recyclable Thermoplastics.

Using carbon dioxide (CO2) to make recyclable thermoplastics could reduce greenhouse gas emissions associated with polymer manufacturing. CO2/cyclic epoxide ring-opening copolymerization (ROCOP) allows for >30 wt % of the polycarbonate to derive from CO2; so far, the field has largely focused on oligocarbonates. In contrast, efficient catalysts for high molar mass polycarbonates are underinvestigated, and the resulting thermoplastic structure-property relationships, processing, and recycling need to be elucidated. This work describes a new organometallic Mg(II)Co(II) catalyst that combines high productivity, low loading tolerance, and the highest polymerization control to yield polycarbonates with number average molecular weight (Mn) values from 4 to 130 kg mol-1, with narrow, monomodal distributions. It is used in the ROCOP of CO2 with bicyclic epoxides to produce a series of samples, each with Mn > 100 kg mol-1, of poly(cyclohexene carbonate) (PCHC), poly(vinyl-cyclohexene carbonate) (PvCHC), poly(ethyl-cyclohexene carbonate) (PeCHC, by hydrogenation of PvCHC), and poly(cyclopentene carbonate) (PCPC). All these materials are amorphous thermoplastics, with high glass transition temperatures (85 < Tg < 126 °C, by differential scanning calorimetry) and high thermal stability (Td > 260 °C). The cyclic ring substituents mediate the materials' chain entanglements, viscosity, and glass transition temperatures. Specifically, PCPC was found to have 10× lower entanglement molecular weight (Me)n and 100× lower zero-shear viscosity compared to those of PCHC, showing potential as a future thermoplastic. All these high molecular weight polymers are fully recyclable, either by reprocessing or by using the Mg(II)Co(II) catalyst for highly selective depolymerizations to epoxides and CO2. PCPC shows the fastest depolymerization rates, achieving an activity of 2500 h-1 and >99% selectivity for cyclopentene oxide and CO2.

Human biomonitoring of trace metals from different altitudinal settings of Pakistan.

Human biomonitoring of toxic trace elements is of critical importance for public health protection. The current study aims to assess the levels of selected trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) into paired human nail and hair samples (n = 180 each) from different altitudinal setting along the Indus River, and which were measured by using inductively coupled plasma mass spectrometry (ICP-MS). The human samples (hair and nail) were collected from four different ecological zones of Pakistan which include frozen mountain zone (FMZ), wet mountain zone (WMZ), riverine delta zone (RDZ), and low-lying southern areas (LLZ). Our results showed the following occurrence trends into studied hair samples: higher values (ppm) of Zn (281), Co (0.136), and Mn (5.65) at FMZ; Cr (1.37), Mn (7.83), and Ni (1.22) at WMZ; Co (0.15), Mn (11.89), and Ni (0.99) at RDZ; and Mn (8.99) and Ni (0.90) at LLZ. While in the case of nails, the levels (ppm) of Mn (9.91) at FMZ and Mn (9.38, 24.1, and 12.5), Cr (1.84, 3.87, and 2.33), and Ni (10.69, 8.89, and 12.6) at WMZ, RDZ and LLZ, respectively, showed higher concentration. In general, among the studied trace elements, Mn and Ni in hair/nail samples were consistently higher and exceeded the WHO threshold/published reference values in most of the studied samples (> 50-60%) throughout the Indus basin. Similarly, hair/nail Pb values were also higher in few cases (2-10%) at all studied zones and exceeded the WHO threshold/published reference values. Our area-wise comparisons of studied metals exhibited altitudinal trends for Cd, Cr, Zn, and Mn (p < 0.05), and surprisingly, the values were increasing from south to north (at higher altitudes) and indicative of geogenic sources of the studied toxic elements, except Mn, which was higher at lower floodplain areas. Estimated daily intake (EDI) values showed that food and drinking water had the highest contribution towards Zn, Cu, Mn, and Ni and accumulation at all studied zones. Whereas, dust also acts as the main exposure route for Mn, Co, Cr, and Cd followed by the food, and water.

Mediterranean Wildfires’ Effect on Soil Quality and Properties: A Case from Northern Euboea, Greece

Mediterranean Wildfires’ Effect on Soil Quality and Properties: A Case from Northern Euboea, Greece

Variability of micronutrients status along topographic positions and toxicity potential of soils under rice cultivation in Niger State, Nigeria

Micronutrients are important for good crop performance. There is limited quantitative data on the content and distribution of micronutrients in soils under rice cultivation in Niger state, particularly, on the soils of Baddeggi and Makusidi. To achieve this, soil samples were purposively collected along topographic positions (upper-slope, mid-slope, lower-slope and bottomlands) in the two areas. To assess the distribution of iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu), a total of sixty-four composite samples were collected at 0-15 and 15-30 cm depth and were determined by Atomic Absorption Spectrophotometry. The results revealed that the mean values of available Fe, Mn, Zn and Cu were 182.40, 41.90, 7.90 and 6.50 mg/kg for Baddeggi and 254.30, 275.13, 16.25 and 7.88 mg/kg for Makusidi respectively. The very high Fe and Mn in the study sites may lead to toxicity of these elements. The Cu and Zn were also relatively high, and their deficiencies are unlikely to occur in the study area.

Assessment of heavy metals in sediments and water accumulated by effects shipwrecks in Shatt Al-Arab River, southern Iraq

In this study, the total concentration of seven heavy metals (Cd, Cu, Fe, Pb, Mn, Ni, and Zn) in sediment and water was taken to determine how much the environment is impacted by rising levels of heavy metals that are not naturally occurring in five stations representing the large shipwrecks in Shatt Al-Arab River in Basra South Iraq by using atomic absorption. The heavy metals concentration in the five sediment stations is ordered as follows: Fe>Mn>Ni>Zn>Cu>Cd> Pb. While, the heavy metals concentration in the five water stations is ordered as follows: Fe>Ni>Mn>Cu>Pb>Zn>Cd. The current results of the study indicate that the concentrations of Cd, Fe, and Pb (slightly contaminated) metals in water are higher than the Iraqi standards (Iraqi standards for drinking water) and international standards (WHO, U.S. EPA, E.U.). An increase in heavy metal concentrations is attributed to the raw materials from which sunken ships are made near stations and these ships being exposed to military bombardment. The level of pollution in the sediment was assessed by employing the Geo accumulation index (I-geo), Contamination factor (CF), and Enrichment factor (EF). The calculated results of I-geo indicate that Cd can be considered to be moderate – strongly polluted except S5 considered strong to extremely polluted. However, Cu, Fe, Pb, Mn, Ni, and Zn showed almost unpolluted levels across all stations. The CF values indicate that this environment is very highly contaminated with Cd, while CF values for Cu, Fe, Pb, and Mn display low contamination. while CF values for Ni are moderate contamination except for S1 is low contamination. The pollution level for Zn is S1and S5 is low contamination and S2,3,4 is moderate contamination. The EF values refer to Cd at S5 indicating extremely severe enrichment and other stations refer to severe enrichment and minor enrichment for Fe, Mn, Ni, and Zn. Copper (Cu) has minor enrichment at S2 but no enrichment at the other stations. Conversely, Lead (Pb) shows no enrichment at any of the stations.

Determination of concentration of selected heavy metals in the organs of Guinea pigs reared at the University of Port Harcourt, Rivers State, Nigeria

Vegetation along major traffic roads are predisposed to heavy metals contamination due to wear and tear of vehicular components and emissions from vehicles. The concentration of ten heavy metals (Fe, Mn, Zn, Pb, Cu, Ni, Cr, Co Ag and Cd) in the leaves of four test plants (Panicum maximum Jacq.,Eleusine indica L., Xanthosoma mafafa Schott. and Amaranthus spinosus L.) growing along four busy roads (Aba road, Ikwerre road, East/West road and NTA road) in parts of Obio/Akpor Local Government Area and a control ( in Ozuguru in Ikwerre Ngwo) in Etche Local Government Area, both in Rivers State, Nigeria were investigated in the study area. Along each road, four sampling points were set up at 1 km apart. The test plants were collected randomly and were pooled together to form composite sample. The collected test plants at each sample location were put in different sterile cellophane bags, labelled and served as soilage to the experimental animals. Eighteen guinea pigs were used for this investigation. Three guinea pigs were picked out of the eighteen guinea pigs using randomized block design for a preliminary test. The remaining fifteen guinea pigs were fed with the test plants from the experimental and control sites for six weeks. The concentration of the ten heavy metals were determined using Atomic Absorption Spectrophotometry (ASS). The results revealed that Aba road had the highest mean concentration value of heavy metals in Cu, Zn, Co, Cr and Cd with values (28.75±1.34), (32.46±0.9), (5.14±0.11), (4.79±0.21) and (3.17±0.12) respectively. The highest mean concentration value for Mn and Pb were observed in East/West road with values (7.57±1.48) and (5.39±1.53) respectively, while the highest mean concentration value for Fe was observed in Ikwerre road (192.84±2.64). NTA road had the least values for all heavy metals tested while Ni and Ag were not detected in all livers and kidneys of the experimental animals. The results from this findings show the health implication of roadside grazing of ruminants.

Evaluation of essential and trace metals/metalloids distribution and probable human health risk implications from branded liquid and powder milks available in Dhaka City, Bangladesh.

The processed forms of milk, branded liquid, and power milk available in Dhaka city, the capital of Bangladesh, were investigated for essential and trace metal/metalloids regarding nutritional and human health risk aspects. For this, the potential nutritional contribution, estimated daily intake (EDI) and non-carcinogenic risk for six different life stages with male and female categories, as well as the carcinogenic risk for children and adults of both genders, were addressed. In total, 46 branded liquid and powder milk samples were considered for this analysis employing atomic absorption spectroscopy. The concentration of essential elements showed the trends of K > Ca > Na > Mg > Fe > Zn > Mn > Cu and K > Ca > Na > Mg > Fe > Cu > Mn > Zn for liquid and powder milk samples, respectively, but the potentially hazardous one showed the same trends (Cr > Pb > Hg > As > Cd) for both items. Except for Cr, Hg, and Fe, the elemental compositions of both milk categories differed considerably (< 0.05). Compared to the threshold values for milk samples (liquid and powder), Fe (19% and 27%), Mn (100% and 63%), Cu (0% and 23%), Zn (94% and 0%), Pb (25% and 13%), and Cr (0% and 3%) showed above the permissible limits. The nutrient input was the highest for Ca (27.2% and 18.7%), followed by Mg, K, and Na. The EDI of studied elements was within the daily permissible limit in both the milk category (except age group (≤ 3) and the female category). The non-carcinogenic risk assessment showed that the age groups ≤ 3 for liquid milk and ≤ 3 and 3 < X ≤ 14 with female categories for powder milk exceeded the threshold level (> 1) in the case of Cr, Cd, As, Zn, and Mn. The probable carcinogenic risks indicated an unacceptable risk level (< 1.00E-04) for the ingestion of Cr through powder milk samples for children in male and female categories. Finally, it believes that green cow farming practices and green milk processing technology, as well as continuous monitoring of toxic metals, can limit the ultimate risk worldwide.

Spatial distribution and health risk assessment of toxic metal(oid)s in soils of coal mining areas of the Salt Range, Punjab, Pakistan

Long-term coal mining operations have been linked to increases in HM concentrations in subterranean soils, which degrades soil quality. The clusters of coal mines and mine tailings considerably increase metal(loid)s concentrations in the surrounding soils and air of the Eastern (ESR), Central (CSR), and Trans-Indus Salt Range (TSR). The present study was conducted in this scenario to ascertain the occurrence and dispersion of toxic metals from mine tailings to different environmental components and their pollution load in soils and possible risk. The geochemical characterization of the soil, coal waste, and dust particulate matter revealed that waste samples are highly enriched in As, Cd, Pb, Fe, and Zn. In terms of soil quality standards, geo-accumulation index (Igeo), enrichment factor (EF), and contamination factor (CF), Fe, Mn, and Zn are extremely contaminated. However, As, Cd, Co, and Cr show moderate contamination. These harmful soil contaminants, primarily originate from coal-associated tailings. Further, the principal component analysis, multiple linear regression (PCA-MLR), and agglomerative hierarchical clustering (AHC) signify that mineralization and weathering of sulfide and carbonate minerals within the coal wastes and lithological units of the present study area cause the release of environmentally sensitive trace elements, which upon dispersion, leaching, and atmospheric deposition enters the air and soils of the present study area. We propose that higher HI index of Co (4), Fe (35), Mn (11), and Zn (13) values can be a significant human health concern.

Micronutrient Status and Distribution of Some Community Lands Earmarked for Agricultural Intensification in Bayelsa State for Food Security

Improved agricultural production requires balanced nutrients. In spite of Bayelsa State’s intention to increase its’ agricultural base, little or no information is available on the soils micronutrient status. This study evaluated the status and distribution of Fe, Mn, Zn and Cu in some communities earmarked for agricultural intensification. Sample collection was guided by horizon differentiation. Micronutrients distribution variation was evaluated using coefficient of variation. Iron concentration varied from 41-91 mg/kg in Elemebiri (ELM) soils with moderate %CV (16, 17 and 28 for ELM1, ELM2 and ELM3) and 34-92 mg/kg in Trofani (TFN) soils with moderate to high %CV (30, 20 and 33 for TFN1, TFN2 and TFN3), respectively. The Mn values varied from 1.3 – 4.25 mg/kg for Elemebiri soils and 0.34 – 3.8 mg/kg for Trofani soils. The %CV of Mn was high as ELM1, ELM2 and ELM3 recorded 36, 31 and 38 %CV and TFN1, TFN2 and TFN3 87, 56 and 63, respectively. Available Zn varied between 3.48 – 16.56 mg/kg and 0.87 – 18.56 mg/kg in the Elemebiri and Trofani soils, respectively. The %CV for Zn was 32, 26, and 53 for ELM1, ELM2 and ELM3 and 41, 24 and 56 for TFN1, TFN2 and TFN3, respectively. Copper concentration varied between 1.24 – 5.3 mg/kg for Elemebiri soils and 0.75 – 5.7 mg/kg for Trofani soils. The %CV for Cu was 28, 33 and 25 for ELM1, ELM2 and ELM3 and 36, 53 and 43 for TFN1, TFN2 and TFN3, respectively. Though micronutrient status of the soils looks promising, there is need for close monitoring.

Enhancement of nonlinear optical effects of pure and Mn-doped CsPbBr3 perovskite films by external voltage

CsPbBr3 and Mn:CsPbBr3 nanocrystal (NC) films were prepared on indium tin oxide (ITO) glass by a slow solvent evaporation method. The ITO layer was applied a voltage to enhance the nonlinear optical (NLO) properties of CsPbBr3 and Mn:CsPbBr3 nanocrystal (NC) films. When the voltage is zero, the Z-scan results show that the nonlinear absorption (NLA) coefficients β of CsPbBr3 and Mn:CsPbBr3 NC films are 1.60 × 103 cm/GW and 1.54 × 104 cm/GW, respectively. The nonlinear refraction (NLR) coefficients γ of CsPbBr3 and Mn:CsPbBr3 NC films are 2.07 × 10−5 cm2/W and 2.48 × 10−5 cm2/W, respectively. Subsequently, the voltages of 5.03–13.42 V were applied to the ITO layer. Finally, when the voltage is 13.42 V, the β values of CsPbBr3 (1.75 × 104 cm/GW) and Mn:CsPbBr3 (3.98 × 104 cm/GW) NC films are 10.9 and 2.6 times higher than those without the applied voltage, respectively. The γ values of CsPbBr3 and Mn:CsPbBr3 NC films are 3.73 × 10−5 cm2/W and 3.88 × 10−5 cm2/W, respectively. This research proposes an effective method to improve the third-order NLO performances of CsPbBr3 and Mn:CsPbBr3 NC films by applying voltage.

Upwelling-driven biogenic silica accumulation in the Yangtze Sea, South China during Late Ordovician to Early Silurian time: A possible link with the global climatic transitions

Silica accumulation in the Yangtze Sea during the Ordovician–Silurian (O–S) transition appears to have coincided with global climatic fluctuations, widespread upwelling, and volcanism. There is a need to further evaluate their respective contributions to silica deposition and potential relationships among these factors. The current study selected siliceous deposits in the Wufeng and Longmaxi Formations from four sections spanning the inner to outer Yangtze Sea, South China, to gain a deeper understanding of the climatic and oceanographic evolution associated with silica enrichment. Al/(Al + Fe + Mn) values, the presence of radiolarians, and Si isotope values of samples recovered from the investigated shale successions offer compelling evidence that the silica is largely of biogenic origin with some terrigenous contributions. Further, various productivity and redox proxies suggest that biogenic silica (BSi) accumulated under conditions of enhanced marine productivity and anoxic bottom water conditions. Hg/TOC and Zr/Al2O3 profiles suggest intermittent volcanism during the BSi deposition in the Yangtze Sea. However, the lack of correlation between BSi and Hg/TOC values indicates that volcanic iron fertilization was not responsible for BSi accumulation. Instead, most BSi-rich samples are dominated by low MnEF × CoEF values (<0.5), consistent with BSi deposited in modern upwelling settings. Hydrographic reconstruction based on Mo–U covariation indicates a more open water setting in the outer Yangtze Sea, while the coeval inner Yangtze Sea was relatively restricted. Therefore, upwelling events appear to have been more vigorous in the outer Yangtze Sea. Published and new Chemical Index of Alteration (CIA), BSi, and MnEF × CoEF data for the Wufeng and Longmaxi Formations across the inner to outer Yangtze Sea demonstrate that temporal and spatial variations of BSi were controlled by climate-driven upwelling. In particular, cool-water upwelling contemporaneous with Hirnantian glaciation may have been responsible for the establishment of the cool-water fauna of the shallow-water Guanyinqiao Bed and enhanced silica deposition in deeper water. Moreover, a moderate negative relationship between compiled CIA and BSi contents suggests that enhanced upwelling driving BSi accumulation appears to have been favored during cooling events. Integrated analysis of BSi deposits of the Laurentia and Baltica continental margins further suggests that BSi accumulation on continental margins during the O–S transition was primarily influenced by global cooling. Therefore, we suggest that wind patterns or/and thermohaline circulation, influenced by climate fluctuations, induced widespread cold water upwelling events during the O–S transition. Moreover, elevated BSi production diluted accumulating OM resulting in the observed parabolic relationship of BSi and TOC.

Groundwater Environment and Health Risk Assessment in an In Situ Oil Shale Mining Area

To clarify the risk posed to groundwater in oil shale in situ mining areas, we examine five leached pollutants: Fe, Mn, Cr, sulfate, and ammonia nitrogen. Potential groundwater contents of these five pollutants were evaluated using an improved Nemero comprehensive index method and a health risk assessment method. The results show that, compared with the Class III groundwater quality standard (GB/T 14848-2017) used in the People’s Republic of China, average values of Fe, Mn, and sulfate in leaching solution from Fuyu oil shale exceed the standard, while Cr and ammonia nitrogen do not exceed the standard, and the leaching solution is within Class V groundwater quality. The average values of Fe and Mn in the leaching solution from Fushun oil shale exceed the Class III standard, while Cr, sulfate, and ammonia nitrogen values from this oil shale do not exceed the standard, and the leaching solution is Class IV in terms of groundwater quality. The weighting value used in the Nemero assessment method for the heavy metal Cr is the largest as its potential to cause harm to groundwater quality is the largest. The weight value for sulfate is the smallest as the harm degree is the smallest. The chemical carcinogen Cr has the greatest potential impact on human health. The health risk caused by the chemical non-carcinogen Mn is greater than that caused by Fe and ammonia nitrogen. When high pyrolysis temperatures are used, Mn will be released into groundwater in large quantities. Therefore, supervision and control should be strengthened. The results presented here can provide a reference for the comprehensive evaluation of groundwater risks caused by in situ oil shale mining.