Soil Zn Concentrations Research Articles

Role of Different Cover Crops on DTPA-Extractable Micronutrients in an Apricot Orchard

This study was conducted to compare the effect of different cover crop treatments on DTPA-extractable micronutrients (Fe, Mn, Zn, Cu) and soil pH in an apricot orchard with clay texture located in Malatya province of Turkey. For this purpose, 5 different experimental groups (Vicia villosa Roth (VV), Vicia pannonica Crantz (VP), Vicia pannonica Crantz and Tritikale mixture (70% + 30%, respectively) (VPT), Phacelia tanacetifolia Benth (PT), Fagopyrum esculentum Moench (FE)) and 3 control groups (mechanically cultivated (MC), herbicide treatment (HC) and bare control plot (BC)) were used in the apricot orchards. The soils were sampled from 0–20 cm and 20-40 cm depths in each plot for soil analyses. According to the obtained results, while cover crop treatments reduced pH values of soils according to the bare control, the cover crops increased the Fe, Mn and Zn contents of soils in the 0-20 cm soil depth. The highest Ext-Fe, Mn and Zn contents were obtained in the VV (14.83mg kg-1, 8.42 mg kg-1, 1.03 mg kg-1, respectively) at the 0-20 cm soil depth. As compared to bare control, highest percent increases in Fe, Mn and Zn contents were determined in the VV 27.73%, 31.69% and 37.54%, respectively. The greatest significant negative correlations in the VV treatment were observed between pH and Fe (-0.985**), between pH and Mn (-0.945**) and between pH and Zn (-0.764*). The greatest significant negative correlations in the VP treatment were observed between pH and Fe (-0.948**), between pH and Mn (-0.928**) and between pH and Zn (-0.722*). It was concluded based on current findings that cover crops, especially Vicia villosa Roth and Vicia pannonica Crantz could be incorporated into cropping systems to improve micronutrients and to provide a sustainable soil management.

Soil Testate Amoebae and Diatoms as Bioindicators of an Old Heavy Metal Contaminated Floodplain in Japan.

Soil protists are rarely included in ecotoxicological investigations, despite their fundamental role in ecological processes. Moreover, testate amoebae and diatoms contribute considerably to silicon fluxes in soils. We investigated the effects of heavy metals on testate amoebae (species and individual densities) and diatoms (individual densities) in aged soils of a floodplain (Watarase retarding basin, Japan) taking soil samples from two unpolluted reference sites and two polluted sites. The total concentrations of Cu, Pb, and Zn in soil were higher at the polluted sites as compared with the reference sites. The available concentrations of Co, Cu, and Zn in CaCl2 extracts were higher at the polluted sites but available Pb was not detectable. Testate amoeba taxonomic richness was higher in the reference sites (45/38 taxa) than in the polluted sites (36/27 taxa). The reference sites had higher diatom and amoeba densities than the polluted sites. There was a significant negative correlation between total testate amoeba density and heavy metal concentration (available Co), while significant negative correlations were found between diatom density and Co, Cu, and Zn (available and total concentration). Densities of Cyclopyxis kahli cyclostoma, Centropyxis spp., and Trinema complanatum were negatively correlated to concentrations of available heavy metals. The observed decrease in individual numbers due to heavy metal pollution resulted in a considerable decline in protozoic (testate amoebae) and protophytic (pennate diatoms) silicon pools. Our data suggest that heavy metal pollution affects biogeochemical cycling in this system.

Risk assessment of heavy metal contamination of paddy soil and rice (Oryza sativa) from Abakaliki, Nigeria.

The study assessed the concentration and bioavailability of Pb, Cd, Zn, Cr and Fe metals in soil from rice fields in Abakaliki, Nigeria. The concentrations of these heavy metals in rice grains were also determined, with a view to assessing their human health risk on consumers. Heavy metal concentrations in soil and rice were determined using FAAS after digestion with 5:1 HNO3:HClO4 while Tessier's sequential extraction method was used to obtain the fractionated soil digests. The mean concentrations (μg/g) of the total heavy metal ranged from 1.036 ± 1.86 (Cd) to 6900.537 ± 734.82 (Fe) in soil while that of rice grains ranged from 0.024 ± 0.07 (Cd) to 101.446 ± 75.26 (Fe).The concentrations of Fe and Cd in most of the soil samples and Pb in rice grains exceeded some Nigerian and International standards. The heavy metal sequential extractions of soil samples showed that lead and zinc were less mobile in the soil and are bioavailable for plant uptake. The estimated daily intake of the metals was below the tolerable daily intake. The hazard quotient and the total hazard index were less than one showing that at present, there is no possible adverse health effect on rice consumers.

Distribution characteristics and health risk assessment of heavy metals and PAHs in the soils of green spaces in Shanghai, China.

The environmental sustainability of megacities is a global problem, and megacities are experiencing increasing pressure and challenges with regard to providing a suitable living environment for people. Urban green space plays a crucial role in protecting urban ecological environments and in maintaining the physical and mental health of residents. In this study, a total of 94 soil samples from green spaces in Shanghai, including park green spaces and road green spaces in the eight central urban districts, were collected, and the contents of heavy metals and polycyclic aromatic hydrocarbons (PAHs) were analyzed to determine the distribution characteristics and influencing factors and to assess the associated health risks. The accumulation of heavy metals was greater in park green space soils than in road green space soils, although the variation coefficient of the former was lower than that of the latter. Conversely, the accumulation of PAHs was lower in park green space soils than that in road green space soils, although the variation coefficient of the former was higher than that of the latter. In particular, Cu, Zn, Pb, Cd, As, and PAHs have accumulated in Shanghai green space soils. With increasing soil depth (0-2cm, 2-5cm, 5-10cm, and 10-30cm), the PAH content increased in the park green space soils but decreased in the road green space soils. According to the "Technical guidelines for risk assessment of contaminated sites (MEP of China 2014)," the overall health risk posed by green space soils in urban areas in Shanghai can be considered safe, except at individual sampling sites. The PAH, Cu, and Zn contents of park green space soils might be related to the application of organic materials and to traffic and industry emissions. However, the soil pollutants in road green spaces are predominantly related to traffic and industrial emissions. Therefore, the monitoring and management of soil environmental quality must be strengthened.

Trace elements in rice grain and agricultural soils: assessment of health risk of inhabitants near a former secondary lead smelter in Khulna, Bangladesh.

Ingestion of food grain grown in metal-contaminated soils may cause serious effects on human health. This study assessed the concentrations of Pb, As, Cd and Zn in agricultural soils and in rice grains near a former secondary lead smelter in Khulna, Bangladesh. It analyzed 29 samples of surface soil and rice grain collected around 500m of the smelter. Contamination factor (Cf), pollution load index and total hazard quotient (THQ) were calculated to determine ecological and human health risks. Cd was not detected in any of the samples. For the soil samples, medians of the concentrations of Pb, As and Zn were 109, 6.2 and 514mg/kg, respectively. For the rice grain samples, medians of the concentrations of Pb, As and Zn were 4, 1.4 and 25mg/kg fw, respectively. Medians of the concentrations of Pb and As in rice grain were higher compared to their maximum allowable limit (0.2mg/kg), which indicate potential health risks to inhabitants near the Pb smelter. The mean values of Cf for Pb, As, and Zn were, respectively, 11.6, 2.1 and 7.4. For Pb, around 41% of the samples had Cf > 6 indicating very strong contamination. THQ values for Pb and As were greater than 1.0, which evinces the health hazards of these trace elements. Measures should be taken to prevent trace elements exposure from Pb smelter in the study area.

Fertilizer management and soil type influence grain zinc and iron concentration under contrasting smallholder cropping systems in Zimbabwe

Micronutrient deficiencies remain prevalent in food systems of southern Africa, although advances in biofortification through crop breeding and agronomy provide opportunities to address these. We determined baseline soil availability of zinc (Zn) and iron (Fe) and the effects of soil type and farmer management on extractable soil Zn and Fe and subsequent concentration in cereal and legume grains under two contrasting agro-ecologies in Zimbabwe. Soil and crop surveys were conducted in Hwedza and Mutasa Districts of Zimbabwe in 2015–16 on 350 locations over different soil types. Fields with different levels of productivity (designated as “most” and “least” productive fields) were sampled using an inherited hierarchical randomized sampling design. Grain Zn and Fe concentration in maize (Zea mays), sorghum (Sorghum bicolor), finger millet (Eleusine coracana) and cowpea (Vigna unguiculata) were generally insufficient for adequate human nutrition. A Linear Mixed Effects (LME) model revealed that diethylene triamine penta-acetic acid- (DTPA) extractable soil Zn concentration and grain Zn concentration were affected primarily by field productivity level. DTPA-extractable soil Zn concentration was more than two-fold greater on the most productive fields (mean 0.8 mg kg−1) than on the least productive fields, with mean grain Zn concentration of 25.2 mg grain Zn kg−1 which was 13% greater than seen on the least productive fields. An interaction effect of field productivity level and total soil Zn concentration on DTPA-extractable soil Zn concentration suggests potential contribution of organic matter management to unlocking unavailable forms of soil Zn. DTPA-extractable soil Fe and grain Fe concentration were primarily affected by soil type and crop type, respectively. The LME modelling approach revealed additional soil geochemical covariates affected DTPA-extractable soil Zn and Fe concentration and grain Zn and Fe concentration within Districts. Future studies can therefore be powered to detect their roles at wider spatial scales for sustainable management of crop Zn and Fe nutrition.

The mycorrhizal pathway of zinc uptake contributes to zinc accumulation in barley and wheat grain

BackgroundIncreasing zinc (Zn) concentrations in crops is important for alleviation of human Zn deficiency. Arbuscular mycorrhizal fungi (AMF) contribute to plant Zn uptake, but their contribution to Zn in the edible portion of crops has not yet been investigated. This study aimed to quantify the mycorrhizal pathway of Zn uptake into grain of wheat and barley under varying soil Zn availabilities. Bread wheat (Triticum aestivum) and barley (Hordeum vulgare) were grown in pots with a hyphal compartment containing 65Zn. Plants were inoculated with Rhizophagus irregularis and grown at three soil Zn concentrations. Radioactive Zn in grain and straw was measured and the contribution of AMF to Zn uptake was calculated.ResultsThe mycorrhizal pathway of Zn uptake contributed up to 24.3% of total above-ground Zn in wheat, and up to 12.7% of that Zn in barley. The greatest contribution by the mycorrhizal pathway was observed in barley at the lowest Zn addition, and in wheat at the highest one. In addition, grain yield of bread wheat was increased by AMF.ConclusionsThese results suggest that AMF have a substantial role in uptake of Zn into cereals, and the proportional contribution by the MPU is dependent on plant species, as well as available soil Zn.

Application of ecogeochemical prediction model to safely exploit seleniferous soil

Seleniferous soil and crops have recently attracted attention worldwide. Cultivating seleniferous crops in the absence of heavy metals is greatly challenging. This study aimed to develop approaches for the safe exploitation of seleniferous soil. We collected 246 pairs of rice grain samples and their corresponding rhizosphere soil samples and 8542 topsoil samples from Binyang and Xingbin in Guangxi. The Cd, Cu, Hg, Pb, Zn, and Se contents of soil and rice grain samples were tested. Several soil properties, including CaO, Mn, Mo, and S contents; total organic carbon content; and pH were also measured. Soil and rice grain samples that were classified as seleniferous accounted for 85.77% and 88% of all samples, respectively. More than 30% of soil and rice grain samples were potentially polluted by Cd. The percentage of seleniferous rice grain samples increased as soil Se concentration increased. Notably, however, the percentage of Cd-polluted rice grain samples decreased with the increase in soil Cd concentration. Models for the prediction of BAFs of heavy metal and Se were accurately established on the basis of significant partial correlations between log10 (BAFs) and log10 (soil properties). Farmlands with seleniferous soil under preferential protection and with safely exploited seleniferous soil accounted for 82.61% of the total study area. Sites that require remediation or land-use changes accounted for only 14.7% of the total study area and were mainly distributed in the center of the study area.

Assessment of soil quality for vineyard fields: A case study in Menderes District of Izmir, Turkey

This study was carried out to determine the suitable classification of soil quality for vineyard fields of Akçaköy, Çatalca, Efemçukuru, Görece and Yeniköy villages in Menderes district of Izmir-Turkey. In vineyard fields, soil pH gave a positive relation with Ca and significant negative relations with P, Fe, Mn and Zn contents. Soil organic matter (OM) content had significant positive relations with EC, P, Fe, Mn and Zn and significant negative relations with bulk density and CaCO 3 content. Soil quality index values for the vineyard fields varied between 0.38 and 0.85 with a mean of 0.57. Only one of the 28 soil samples taken from different vineyard fields was found in very suitable (S 1 :1.00-0.75) class, 8 in suitable (S 2 :0.75-060), 12 in marginal suitable (S 3 :0.60-0.50) and 7 in non-suitable (N:<0.50) class according to the soil quality index (SQI). Restricting soil factors for vine growth in the fields classified in S 2 and S 3 classes generally became low pH, low organic matter (OM), P, Fe, Mn, Cu, Mg and K contents than that of suggested levels. In addition to restring factors in S 2 and S 3 classes, physical properties in soils classified in N class were lower than suggested levels. The SQI values showed significant positive relations with grape yield, soil OM, P, K, Fe, Cu, Mn, Zn contents and significant negative relations with soil pH, exch. Ca and CaCO 3 contents. The grape yields had also positive relations with soil OM, Fe, Mn, Zn contents and negative correlations with soil pH and CaCO 3 content. Soil quality in a vineyard field should be assessed to reach successful sustainable and precision agricultural practices for high crop production.

Evaluation of Efficacy of ZnO Nanoparticles as Remedial Zinc Nanofertilizer for Rice

Zinc (Zn) is an important element of nutritional significance to humans, animals, and plants. The impact of zinc oxide nanoparticles (ZnONPs) foliar spray at four different concentrations, viz. 0, 0.5, 1.0 and 5.0 g L−1 at 15-day interval on rice crop cv. PR-121 grown in Zn-deficient soil was assessed in a pot study for remediation of Zn deficiency and enhanced Zn fortification. The soil samples were analyzed for chemical properties, culturable microbial counts, dehydrogenase activity and plant vegetative characteristics, yield, and nutrient profile while the leaf samples were analyzed by scanning EM imaging and SEM-EDS techniques. The leaf surface after foliar spray showed the presence of ZnONPs on the leaf lamina near stomatal openings. The foliar application of ZnONPs (@ 5.0 g L−1) significantly improved the growth and yield parameters. However, root characteristics attained the highest values at 1.0 g L−1 ZnONPs application. The soil microbial counts and enzyme activities such as viable cell counts and dehydrogenase activity were observed to be the highest at 5.0 g L−1 ZnONPs treatment. Overall, ZnONPs treatments successfully reverted the Zn-deficiency symptoms besides enhancing the plant Zn contents, though the response was concentration dependent. These findings indicate that ZnONPs can be effectively used for remediation and Zn fortification in rice cultivated under low soil Zn concentrations.

Distribution characteristics of heavy metals in surface soils from the western area of Nansi Lake, China.

Surface soil samples collected from the western area of Nansi Lake, China, were analyzed for selected heavy metals including As, Cd, Pb, and Zn, to determine their spatial distributions and environmental effects. The average concentrations of As, Cd, Pb, and Zn in soil were 13.21mg/kg, 0.20mg/kg, 23.94mg/kg, and 79.95mg/kg, respectively. The concentration of As, Cd, and Zn was approximately 1.44-, 2.33-, and 1.25-fold higher than its background values in study area, respectively. Meanwhile, the concentrations of heavy metals progressively decreased from east to west within the study area, in a step-function distribution. The differences in the heavy metal distribution characteristics might be caused by the lake water irrigation and agricultural activities such as fertilizer and pesticide use. There were significant positive correlations between the values of OrgC, Al2O3, and Fe2O3 and concentrations of heavy metals. According to the Geo-accumulation index (Igeo) and the potential ecological risk index (PERI), Cd posed higher potential ecological risk in surface soil when compared with As, Pb, and Zn. These results could provide the scientific basis on which to evaluate the distribution of heavy metals under natural and anthropogenic influences in the surface soil near Nansi Lake, China.

Spatial variability and digital mapping of Zn content in soil and foliage of wheat producing area in district Jhelum-Pakistan

Spatial variability and digital mapping of Zn content in soil and foliage of wheat producing area in district Jhelum-Pakistan

Assessment of the effects of cassava mill effluent on the soil and its microbiota in Biase local government area of Cross river state, Nigeria

The effects of cassava mill effluent (CME) on the soil and soil micro-biota was investigated. Soil samples were collected from sites polluted with CME and also from an adjacent site not polluted with CME. Standard microbiological methods were used in the isolation, antibiotic susceptibility and enumerating the population of the microorganisms while the physico-chemical parameters of the soil were determined using standard chemical processes. The bacteria isolates were Bacillus sp., Pseudomonas sp., Enterobacter sp., Escherichia coli, Corynebacterium sp. and Proteus sp. and the fungal isolates were Aspergillus sp., Candida sp., Mucor sp., Penicillium sp., Saccharomyces sp. and Rhizopus sp. The mean aerobic bacterial count for the soil samples ranged from 7.1±0.11x105 cfu/g for the control soil to 8.0±0.19x105 cfu/g for the CME impacted soil. The mean heterotrophic fungal counts varied from 4.7±0.41x105 cfu/g for CME impacted soil to 4.2±0.57x105 cfu/g for the control soil. Susceptibility profile showed that Bacillus sp. from the CME impacted site had reduced susceptibility to levoflacin, amoxil, chloramphenicol, and Ciprofloxacin. Pseudomonas sp. from the same site had reduced susceptibility to streptomycin, ampicilin, tarivid, peflacin, augmentin and ciprofloxacin. Escherichia coli had reduced susceptibility to streptomycin, ampicilin, ciprorex and nalidixic acid. The heavy metals Cu, Zn, Ni, Co, and Fe content of the CME impacted soil increased greatly. Excessive application of CME had negative effects on the soil, hence the high concentration of heavy metals in CME dumpsites and high microbial presence. The study also showed that CME can induce the resistance potential of some soil microbes to antibiotics and seriously affect the physicochemical parameters of soil.

Distribution Characteristics and Pollution Assessment of Soil Heavy Metals under Different Land-Use Types in Xuzhou City, China

Xuzhou, as a mining city in China, has been experiencing 130 years of coal mining and processing. To explore the spatial distribution characteristics and pollution status of soil heavy metals (Cr, Cd, As, Hg, Zn, and Pb) under different land-use types, a total of 2697 topsoil samples were collected in all of the areas (except for water) of Xuzhou in 2016. Overall, the mean concentrations of Cr (70.266 mg/kg), Cd (0.141 mg/kg), As (10.375 mg/kg), Hg (0.036 mg/kg), Zn (64.788 mg/kg), and Pb (24.84 mg/kg) in Xuzhou soils were lower than the environmental quality standard for soils (GB15618-1995). However, the mean concentrations of Cr, Hg, and Pb exceeded their corresponding background values, with the mean concentration of Hg being almost three times its background value. For different land-use types, the highest mean concentration of Cr was concentrated in grassland soils. The mean concentrations of Cd, As, Zn, and Pb in mining area soils were higher than those in the other soils. The mean concentration of Hg was the highest in the built-up area soils. Based on the potential ecological risk assessment, the forestland, garden land, grassland, and others were at low and moderate risk levels, the farmland and mining area were at low, moderate, and high risk levels, and the built-up area was at various risk levels in Xuzhou. There was a significant positive correlation between Cr, Pb, and Hg concentrations and the corresponding organic carbon contents in the farmland, built-up area, garden land, forestland, and other soils ( p &lt; 0.01 ). A high degree of correlation was found between Cr and Hg concentrations, as well as organic carbon contents in grassland soils, with values of p &lt; 0.05 and p &lt; 0.01 , respectively. An obvious correlation could be seen between Hg concentrations and organic carbon contents in mining area soils ( p &lt; 0.01 ).

Geographically Weighted Regression Effects on Soil Zinc Content Hyperspectral Modeling by Applying the Fractional-Order Differential

With the development of remote sensing techniques and the increasing need for soil contamination monitoring, we estimated soil heavy metal zinc (Zn) content using hyperspectral imaging. Geographically weighted regression (GWR), an extension of the ordinary least squares (OLS) regression framework, was proposed. By estimating a set of parameters for any number of locations in a study area, GWR can probe the spatial heterogeneity in data relationships, whereas the regression parameters of an OLS model are global and aspatially-varied. The objectives of this study were: (1) To find the possible relationships between hyperspectral data and soil Zn content, and (2) to investigate the existence of their spatial heterogeneity. In this study, 67 soil samples collected from Pingtan Island, Fujian Province, China, were used to conduct laboratory hyperspectral modeling for soil Zn content estimation. Four transformations of square root, logarithm, reciprocal of logarithm, and reciprocal, as well as the fractional-order differential operations were applied to increase the amount of reflectance data in which the effective variables for modeling might be involved, and to enhance the spectral characteristics of soil Zn content. To find sensitive variables and to remove redundancy and multicollinearity in the spectra, a data sifting process was applied by selecting wavelengths with local maximum in the absolute values of the correlation coefficients with Zn content in one type of spectral data and by employing Variance Inflation Factors. Since a modeling sample size of 46 is insufficient to construct the appropriate OLS and GWR models, four methods are proposed using all 67 samples to choose explanatory variables. A random process to select 57 samples for modeling and 10 samples for validation was applied to assess model performance, in which the mean verification R2 (Rv2) was used as an indicator. The results show that GWR stepwise regression is the most effective method to select better variables. As the mean Rv2 converges toward the OLS value when the bandwidth of the GWR model increases, the four variables selected by the GWR stepwise regression were used to establish the representative OLS and GWR models. The representative OLS model has the best mean verification effect among all studied models, which had a mean Rv2 value that is 44.6% higher than the OLS model constructed using OLS stepwise regression.

Long-term organic matter application reduces cadmium but not zinc concentrations in wheat

Wheat is a staple food crop and a major source of both the essential micronutrient zinc (Zn) and the toxic heavy metal cadmium (Cd) for humans. Since Zn and Cd are chemically similar, increasing Zn concentrations in wheat grains (biofortification), while preventing Cd accumulation, is an agronomic challenge. We used two Swiss agricultural long-term field trials, the “Dynamic-Organic-Conventional System Comparison Trial” (DOK) and the “Zurich Organic Fertilization Experiment” (ZOFE), to investigate the impact of long-term organic, mineral and combined fertilizer inputs on total and phytoavailable concentrations of soil Zn and Cd and their accumulation in winter wheat (Triticum aestivum L.). “Diffusive gradients in thin films” (DGT) and diethylene-triamine-pentaacetic acid (DTPA) extraction were used as proxies for plant available soil metals. Compared to unfertilized controls, long-term organic fertilization with composted manure or green waste compost led to higher soil organic carbon, cation exchange capacity and pH, while DGT-available Zn and Cd concentrations were reduced. The DGT method was a strong predictor of shoot and grain Cd, but not Zn concentrations. Shoot and grain Zn concentrations correlated with DTPA-extractable and total soil Zn concentrations in the ZOFE, but not the DOK trial. Long-term compost fertilization led to lower accumulation of Cd in wheat grains, but did not affect grain Zn. Therefore, Zn/Cd ratios in the grains increased. High Zn and Cd inputs with organic fertilizers and high Cd inputs with phosphate fertilizers led to positive Zn and Cd mass balances when taking into account atmospheric deposition and fertilizer inputs. On the other hand, mineral fertilization led to the depletion of soil Zn due to higher yields and thus higher Zn exports than under organic management. The study supports the use of organic fertilizers for reducing Cd concentrations of wheat grains in the long-term, given that the quality of the fertilizers is guaranteed.

Assessment of soil pH and heavy metal concentrations in agricultural land impacted with Medical Waste Incinerator (MWI) Flue Ash (FA) in Abia State, Nigeria

This study focused on the effect of heavy metals being introduced into soils through medical waste incinerator flue ash by collecting soil samples at different depths and distances to determine soil pH, Cu, Zn, Cr, Cd, Pb and Mn contents using standard methods and multivariate tools for data summary. Mean soil pH values ranged: 5.2 – 6.2 &gt; 4.8 of control due to flue ash as a liming agent and farming practices respectively, with low pH that encourages mobility and absorption of heavy metals in ecosystems. Heavy metals in incinerator site(mgkg-1) ranged:2.00105 ± 0.00-2.09050 ±0.00; 4.0011±0.00-12.3250±0.00; 6.0405±0.01-8.0150±0.01; 4.0150±0.00-7.0805±0.07; 0.2100±0.01-1.0950±0.01; 0.00±0.00-0.001100±0.00; 0.0305±0.01-0.1150±0.00 for Cu, Zn , Mn, Cr, Cd and Pb respectively, with control 0.55 ± 0.01-1.25 ± 0.01;1.25 ± 0.01-1.45 ± 0.01; 13.15 ± 0.07-14.15 ± 0.07; 0.02 ± 0.01; 0.00 ± 0.01-0.03 ± 0.01; .54 ±0.01-.54 ± 0.01 for Cu, Zn , Mn, Cr, Cd and Pb respectively .Metals were in order of: Cd≤ Cu ≤Pb≤ Cr≤Mn≤ Zn(LSD0.05). Result revealed that Cr, Cd and Pb were below the limits for agricultural soil by FAO, and were higher at 50-100m and decrease farther from incinerator. Negative correlation exists between Cr and Zn; Zn and Cu due to farming practices, Mn, Cd recorded positive correlation due to incinerator flue ash. Factor 1 loaded Cu positively, Cr, Pb, Mn, and Zn negatively loaded. Factor 2, exception of Cr, Cd, Pb, and Mn loaded negatively due to flue gas and lithogenic respectively, C/PI indicated soil being slightly, moderately to severely contaminated respectively. I-geo indicated uncontaminated to moderately contaminated, showing that heavy metal contaminations of soils is minor.Keywords: Element, Incineration, Flue Smoke, Soil Acidity, multivariate analysis

Multigenerational exposure of populations of Oppia nitens to zinc under pulse and continuous exposure scenarios.

Current soil remediation guidelines for metals reflect single-generation laboratory studies, but in the field, organisms are exposed to metals for more than one generation. The present study assessed the multigenerational effect of zinc (Zn) on Oppia nitens under a pulse or continuous exposure scenario. Synchronized adult mites (parents) were exposed to 6 concentrations of Zn in a field soil. For the pulse exposure, juveniles of parent mites from 3 of the 6 concentrations (105, 158, 237, 335, 553, and 800 mg/kg) were kept in clean media and reared until the third generation. At every generation, the sensitivity of the mites to Zn was tested in a dose-response manner. For the continuous exposure, the mites produced from the parents were re-exposed to the same concentration as their parents. According to critical-level estimates like the median effect concentration, all populations of the F2 and F3 generation mites in the pulse exposure were less sensitive to Zn than the parents and were protected at 250 mg/kg of Zn (Canadian Council of Ministers of the Environment [2018] soil quality guideline). However, the mite generations of the continuous exposure remained as sensitive as the parent generation and were not protected by the Zn guideline level. The Zn niche width narrowed considerably for all continuously exposed mite populations, indicating that they were more sensitive than the parent. Our results show that Zn has a deleterious multigenerational effect on continuously exposed populations of mites. Environ Toxicol Chem 2019;38:896-904. © 2019 SETAC.

Grain Zn concentrations and yield of Zn-biofortified versus Zn-efficient rice genotypes under contrasting growth conditions

Higher grain Zn concentration in ‘biofortified’ rice genotypes, bred for high grain Zn concentration, should not be at the expense of reduced grain yield. This study examined the grain yield and grain Zn concentration of Zn-biofortified genotypes in field experiments in the Philippines. Zinc-biofortified genotypes (high grain Zn concentration in Zn-sufficient soil) were compared with efficient genotypes (tolerant of soil Zn deficiency), inefficient genotypes (sensitive to soil Zn deficiency) and check genotypes (popular local varieties) at four sites (Bay, Bohol, Bukidnon and IRRI) with differing types and degrees of Zn deficiency, over five cropping seasons (wet season 2012, 2014 and 2015 and dry season 2013 and 2015). A common experimental design and plot size were used with treatments (genotypes and Zn fertilization) arranged in a two-factorial randomized complete block design. The results showed that biofortified genotypes achieved both the Philippine grain yield target (4.0 t ha−1) and grain Zn biofortification target (30 mg kg−1 for brown rice) only when grown under Zn-sufficient conditions. In Zn-deficient soils, most Zn-biofortified and deficiency-tolerant genotypes reached the Zn concentration target but not the yield target, suggesting the need to correct the soil Zn-deficiency to prevent yield penalty. Further, results from IRRI showed that only Zn-fertilized plants were able to achieve the Zn biofortification target during the wet season; whereas during the dry season, when the soil was less chemically-reduced and therefore the soil Zn probably more plant-available, grain Zn levels were all above the threshold, with or without Zn fertilizer. This suggests that Zn fertilization may not be needed during the dry season in soils with sufficient potentially plant-available Zn.

ADECUABILIDAD Y COMPARACIÓN DE TÉCNICAS ESPECTROSCÓPICAS PARA EL ANÁLISIS DE MUESTRAS DE ORIGEN GEOLÓGICO

Four analytical methodologies for the determination of chemical species of environmental interest were optimized and adapted. By means of the flame atomic absorption spectroscopy technique (FAAS) it was possible to sequentially quantify Fe, Mn, Cu, Cr, Ni, Pb, and Zn concentrations in sediment, soil and rock samples. Through the formation of colorful complexes of iron species, obtained under specific and well-defined reaction conditions, and their subsequent quantification by visible spectroscopy with independent methodologies, it was possible to determine the total iron, Fe 2+ and Fe 3+ content in mine leachates. The methodologies described turned out to be precise and accurate, they are free of matrix interferences and are comparable with other validated methodologies. The linearity intervals in FAAS for the seven elements vary from 0.05 to 16 mg/L, with detection limits between 0.03 and 0.2 mg/L. With respect to the colorimetric determinations of total Fe, Fe 2+ and Fe 3+ in samples of sulfided mining leachates, linear ranges of concentration comprised between 0.05 and 17.5 mg/L were observed. The detection limits obtained were 0.05 mg/L for total Fe and Fe 2+ and 0.14 mg/L for Fe 3+ .