Soil Zn Concentrations Research Articles

Tree species as a biomonitor of metal pollution in arid Mediterranean environments: case for arid southern Tunisia.

We investigated the accumulation of Zn, Cu, Pb, and Cd in the soil and the leaves and bark of five common tree species (Eucalyptus occidentalis Endl., Acacia salicina Lindl., Cupressus sempervirens L., Casuarina equisetifolia L., and Tamarix aphylla (L.) Karst.) in the city of Gabès Tunisia to elucidate their bioaccumulation potential and determine their usefulness as biomonitors of metallic pollution in arid urban areas. Our results indicated that the bark had higher mean concentrations of Pb and Cd than leaves. In contrast, the leaves had higher mean concentrations of Zn and Cu than bark. No hyperaccumulation was detected for any of the analyzed metals in any of the studied species. E. occidentalis and T. aphylla had the highest mean concentrations of the investigated metals in leaves and bark. Based on the calculated metal accumulation index (MAI) values, these two species accumulated more metals than other studied tree species. Likewise, the concentrations of Zn, Cu, Pb, and Cd in soil had significant positive correlations with that in leaves and bark. Accordingly, E. occidentalis could be used for biomonitoring in arid areas subjected to industrial and traffic pollution. T. aphylla would be a good alternative when native species are a priority.

Heavy metal contents, mobility and origin in agricultural topsoils of the Galápagos Islands

While the Galápagos Islands have been renowned for their unique flora and fauna since the time of Charles Darwin, the soils of the isolated island chain have been mostly overlooked and little information on their heavy metal contents is available. The aim of this study was therefore to examine the total heavy metal (Cd, Co, Cr, Cu, Ni, Pb, U, Zn) contents of soils from the agricultural areas on islands Isabela, Santa Cruz and San Cristóbal, and identify trends with duration of exposure to weathering processes. Additionally, the mobility of these elements was assessed using ammonium nitrate extraction. In general, levels of Cd, Co, Cr, Cu, Ni and Zn were high compared to other world locations, while Pb levels were low and U levels were similar. Ni, Co, Cr, and to a lesser extent Pb and U tended to accumulate with increasing weathering duration. Soil concentrations of Cd, Zn, Cu, and possibly Pb and U, may have been influenced by use of agrochemicals, particularly on Santa Cruz Island. Mobility of Cd displayed an increasing trend with soil age, while Ni mobility decreased. Many soils had total contents of Cd, Co, Cr, Cu, Ni and Zn above threshold values indicating possible ecological or health risks. Systematic examination of trace element contents in soils from pristine national park areas would further assist in the delineation of background levels and the development of soil quality standards to ensure crop quality, animal and human health on this unique island chain.

Assessment of heavy metal pollution in the agricultural soils, plants, and in the atmospheric particulate matter of a suburban industrial region in Dhaka, Bangladesh.

Unplanned industrialization and improper management of wastes and gases into open surfaces are affecting the agricultural lands causing heavy metal pollution. This study monitored a suburban industrial zone located beside the Dhaka Export Processing Zone (DEPZ) at the Dhaka district in Bangladesh. We studied the heavy metal (Fe, Mn, Cr, Cu, Ni, Co, Zn, Pb, and Cd) concentration in the agricultural soils, plants, and in the atmospheric particulate matter (PM). The soils were found moderately contaminated with Fe, Cu, Ni, Co, and Zn and less contamination with Mn, Cr, Pb, and Cd. The enrichment factor (EF) and pollution load index (PLI) concluded a moderate level of soil pollution in this region. Besides, the plant samples showed an excess level of Cr and a similar level of Cu, Ni, Co, Zn, Pb, and Cd compared with the levels of industrial polluted sites of Bangladesh. The atmospheric PM analysis showed the presence of Fe, Mn, Cu, Ni, Zn, and Pb metals. The EF showed the anthropogenic origin of Mn and Ni in the atmospheric PM. The statistical correlation (r < 0.0001) of soil and plant heavy metals showed the possibility of transfer of metals from soil to plant which will cause the increase of pollution intensity. Overall, this agricultural region became an intermediate pollution zone. This study will help the decision-maker become conscious of heavy metal pollution in the suburban regions to monitor agricultural lands from anthropogenic pollution.

Distribution and secondary enrichment of heavy metal elements in karstic soils with high geochemical background in Guangxi, China

Karst environments are globally significant, and the soils that develop on these landscapes often have unique geochemical features, including elevated–levels of metals. However, it has not been determined whether the enrichment of metals in soils is mainly controlled by parent rocks or secondary enrichment during weathering. In this paper, we studied the control of the accumulation of heavy metals in soils by parent materials and/or the process of soil formation. We examined the un–weathered carbonate and clastic bedrocks, as well as surface soils in a typical karst area in Guangxi of China. The spatial distribution of heavy metal (Cd, As, Cr, Cu, Hg, Ni, Pb, and Zn) concentrations in soils was mainly controlled by the geological background. Except for Cd, the concentrations of heavy metals in carbonate rocks were much lower than those in clastic rocks, whereas the soils derived from the carbonate rocks were highly enriched with heavy metals than those in clastic area. The enrichment of Cd in surface soils from the carbonate substrates was the result of the dual effect of secondary enrichment and parent rock inheritance, whereas the enrichment of other metals was mainly the result of secondary enrichment. During the weathering process of carbonate bedrock, great majority of the quantities of inherent heavy metals were leached, with only 2% of Cd being retained in situ. The high concentrations of soil Fe, Al, and Mn oxides, organic carbon and clay content (Al2O3/SiO2) were closely related to the enrichment of heavy metals in studied surface soils.

Accumulation of Potentially Toxic Elements in Viola L. (Sect. Melanium Ging.) from the Ultramafic and Non-ultramafic Soils of the Balkan Peninsula

The aim of the present study was to assess the metal concentrations in five species of the genus Viola L. (section Melanium) from 12 ultramafic outcrops and two non-ultramafic (prolluvium and dolomite) soils from Serbia and Bosnia and Herzegovina. The concentrations of P2O5, K2O, Ca, Mg, Fe, Mn, Zn, Cu, Cr, Co, Cd and Pb in soils and plant samples, as well as their shoot-to-root ratio, biological concentration and accumulation factors were determined. Five investigated Viola species growing on 14 different localities displayed considerable differences in concentration of potentially toxic elements in their roots and its accumulation in their shoots. Viola kopaonikensis and V. beckiana from ultramafic soils could be classified as strong Ni accumulators, since moderately high level of Ni was measured in their shoots (up to 266 mg kg−1 and 337 mg kg−1, respectively), while in V. tricolor high amount of the same element was accumulated in the roots (up to 395 mg kg−1). Population of V. beckiana from dolomitic site in Bosnia and Herzegovina accumulated high concentrations of Pb in the shoots (67.1 mg kg−1), as well as of Cd in both roots and shoots (81.1 mg kg−1 and 60.5 mg kg−1). The results also suggest that V. kopaonikensis populations from the ultramafic soils of Serbia emerge as Cr accumulators, which is quite rare trait within the genus Viola. It seems that species from Melanium section apply quite different strategies against toxic elements. Future studies should strive to explain what adaptive mechanisms are hidden behind it.

Soil chemical properties in forest patches across multiple spatiotemporal scales in mid-Atlantic U.S. metropolitan areas

Temperate deciduous forests in the United States are in the most densely populated states across the northern and mid-Atlantic east coast. Land development and associated human activities have resulted in small forests that are susceptible to various anthropogenic influences across multiple spatiotemporal scales. The objective of this study was to assess soil chemistry in forest patches of various sizes embedded within an urban development gradient. We established 36 forest sites along the U.S. east coast in northern Delaware and southeastern Pennsylvania, and assessed soil chemical properties across metro (city size), landscape (surrounding urban density), patch (forest patch size/shape, non-native plant invasion), and temporal (time since forest canopy closure) scales. At the metro and landscape scale, we found significantly greater soil Cu, Zn, and S concentrations in forest patches with greater surrounding urban density. At the forest patch scale, soil pH and Ca increased with greater abundance of non-native invasive plants within the forest, whereas soil organic matter decreased with plant invasion. However, increased soil pH and Ca with decreasing SOM may also be a result of land use legacies since we found younger forests had significantly more plant invasion. Forest patch size and shape were primarily related to urban density, where smaller forests with greater edge to interior ratios had greater soil Cu and Zn concentrations. These findings support the importance of considering forest patch structure (size and shape), site legacies, proximity to urban land uses, and duration of intact canopy in understanding patterns and processes in forest soils.

Strong phosphorus (P)-zinc (Zn) interactions in a calcareous soil-alfalfa system suggest that rational P fertilization should be considered for Zn biofortification on Zn-deficient soils and phytoremediation of Zn-contaminated soils

Zinc (Zn) and phosphorus (P) often interact negatively with each other in soil-plant systems. We investigated the effects of P-Zn interaction on Zn and P accumulation and partitioning in alfalfa. Plants were grown in a calcareous soil supplied with different rates of Zn (0, 200, and 800 mg kg−1) and P (0, 20, and 80 mg kg−1). Plant dry mass, Zn and P concentrations in shoots and roots, bulk soil and rhizosheath pH, rhizosheath carboxylates, and DTPA-extractable Zn concentration in the bulk soil were determined. Phosphorus-Zn interaction significantly affected DTPA-extractable Zn concentration, plant dry mass, accumulation of Zn and P, and partitioning of Zn in alfalfa, but did not affect rhizosheath pH or the amounts of rhizosheath carboxylates. Increasing P rate promoted plant growth at all soil Zn rates and might enhance the plants’ capacity to cope with excessive Zn; it resulted in a lower rhizosheath pH, which likely contributed to greater Zn and P uptake. Zinc deficiency enhanced exudation of citrate, malonate and malate, while the release of tartrate was related with P deficiency. There are strong P-Zn interactions in calcareous soil-plant system, such interactions significantly affect Zn bioavailability, plant growth, accumulation of Zn and P, and partitioning of Zn in alfalfa. Rational P fertilization should be considered for efficient Zn biofortification on Zn-deficient soils and phytoremediation of Zn-contaminated soils.

Lessons from 10 years of stakeholder adoption of a soil bioassay for assessing the risk of spinach Fusarium wilt

AbstractAlthough the maritime Pacific Northwest (PNW) is the only region of the United States suitable climatically for spinach seed production, the acidic soils are highly conducive to spinach Fusarium wilt caused by Fusarium oxysporum f. sp. spinaciae. A soil bioassay developed to quantify the risk of spinach Fusarium wilt in fields has been offered to seed growers annually since 2010. Soil sampled from growers' fields each winter was planted with highly susceptible, moderately susceptible, and partially resistant spinach inbred lines, and the plants rated weekly to calculate a Fusarium wilt severity index (FWSI) and the area under the disease progress curve (AUDPC). Results for 147 soils tested from 2010 to 2013 have been published. This study examined results for an additional 248 soils tested from 2014 to 2019 with the bioassay modified to include an option of agricultural limestone amendment to the soils tested. FWSI and AUDPC were affected significantly (p &lt; .001) by the main effects of soil and spinach inbred line, and the interaction of these factors. Correlation analyses showed a range in degree of association of FWSI and AUDPC with spinach seed crop rotation duration and soil properties, depending on the spinach inbred line (r = −.255 to –.267, n = 172 soils with characteristics suitable for correlation analyses). Stepwise regression models for 172 soils with relevant parameters for regression analyses identified spinach seed crop rotation interval, rate of agricultural limestone amendment, soil pH, and soil Fe, Mn, and Zn concentrations as most strongly associated with FWSI and AUDPC. However, the models accounted for ≤33.4% (R2) of the variability in Fusarium wilt risk. The soil bioassay remains a primary tool for spinach seed growers to select fields with low risk of Fusarium wilt.

Elemental analysis in surface soil and dust of roadside academic institutions in Dhaka city, Bangladesh and their impact on human health

The increasing industrial activities, number of vehicles on road and population in large cities causes the contamination of air in urban environment, and eventually affect human health. Therefore, the aim of this study was to collect soil and dust samples from twelve roadside academic institutions in Dhaka City, Bangladesh. One of the twelve sites is control site for this study. The elemental (Ca, Fe, K, Ti, Sr, Zn, Zr, Rb, Cr, Ni, Pb and Cu) concentration in soil and dust samples were analyzed by XRF technique. The metals concentration in dust and soil samples followed the following order: Fe > Ti > Sr > Zn > Zr > Rb > Pb > Cu, and Fe > Ti > Zr > Sr > Rb > Zn > Cu > Pb > As, respectively. As expected, the most elemental concentration at the control site, which was situated inside a village and ~ 1 km far away from the road, was lower compared with those in soil and dust samples. Average As concentration (16.52 mg/kg) in soil was observed to be three times higher than its background value. The concentration of Pb in the dust sample of a school at Sadarghat (136.04 mg/kg) was significantly higher than the other sites. We observed that the mean concentration for most of the metals had a higher concentration than the background values set by Chinese Environmental Protection Administration (CEPA), except for K and Zr. Soil samples were analyzed to determine the percentage of organic matter by dry combustion technique, and the average amount of organic matter in soil samples was 1.42%. Conversely, the contamination levels of heavy metals were assessed based on the geo-accumulation index ( I geo ), enrichment factor ( EF ) and contamination factor (CF). Subsequently non-carcinogenic health risk was determined using lifetime average daily dose ( LADD ). The non-carcinogenic health risk was found to be more prominent for children than that for adults. No significant carcinogenic health risk was found in the study area. • Concentration of Ca, Fe, K, Ti, Sr, Zn, As, Zr, Rb, Cr, Ni, Pb and Cu in soil and dust were determined by XRF • Average concentration for most of the metals have higher concentration than the background value. • Average arsenic concentration in soil was observed to be three times higher than its background value • Non-carcinogenic health risk was found to be more prominent for children than that for adults. • No significant carcinogenic health risk was found in the study area.

Agronomic Biofortification with Zinc and Iron for the Improvement of Wheat Phenology and Yield

| Both zinc (Zn) and iron (Fe) are involved in the biochemical and physiological processes of the wheat plant. Low Zn and Fe contents in soil and/or their low availabilities for plant uptake not only affect the final yield but also decrease their harvestable levels in the wheat grains. The research trials were conducted for two consecutive years (2016-17 and 2017-18) on the foliar supply of Zn and Fe to wheat at different growth stages in the Agronomy Research Farm, the University of Agriculture, Peshawar - Pakistan. Four Zn levels (0, 1, 2, and 3 kg ha-1) and four Fe levels (0, 2, 4, and 6 kg ha-1) at three growth stages (i.e. foliar application of full dosage at the tillering stage, full dosage at the booting stage and their respective half dosages at the tillering stage + half at the booting stage) along with one unsprayed check were used in the experiment. All the treatments’ combinations and a control {(4 x 4 x 3) +1} were laid out in a randomized complete block design having three replications. The plot size was 12 m2 accommodating ten rows. The recommended wheat cultivar ‘Pirsabaq 2013’ was sown by using 120 kg ha-1 seed rate. Nitrogen at the rate of 120 kg ha-1 was applied in two splits from urea. Similarly, 90 kg ha-1 phosphorus was applied from DAP at the time of sowing. Analysis of variance showed that sole foliar Zn application at 3 kg ha-1 significantly improved the flag leaf area (36.9 cm2) and leaf area tiller-1 (97.2 cm2). While more spike m-2 (248), maximum grains spike-1 (47.2), spike length (13.1 cm), and thousand grains weight (42.9 g) were observed with foliar application of 2 kg ha-1 Zn. Significantly maximum leaf area tiller-1 (96.4 m2), flag leaf area (36.2 cm2), spike m-2 (253), grains spike-1 (46.9), spike length (12.9 cm) and thousand grains weight (43 g) were found best with the application of 4 kg ha-1 Fe. In case of application stages, more leaf area per tiller (95.9 cm2) and flag leaf area (36 cm2) were observed with both the application of Zn and Fe when applied 100 % at tillering stage. Similarly, more spike-2 (250.9), maximum grain spike-1 (46.3), spike length (12.7 cm), and thousand grains weight (42.6 g) were noted with the split foliar application of both Zn and Fe. It can be concluded from the experiment that application of both foliar Zn and Fe enhanced the phenological development and yield component of wheat crop. Similarly, foliar application of full dosage at tillering stage also hastened the phenological parameters of wheat crop, therefore recommended for the wheat crop cultivation in the locality of Peshawar.

Comparing Trace Elements (As, Cu, Ni, Pb, and Zn) in Soils and Surface Waters among Montane, Upland Watersheds and Lowland, Urban Watersheds in New England, USA

Trace element biogeochemistry from soils to rivers is important for toxicity to aquatic ecosystems. The objective of this study was to determine whether trace element exports in contrasting watersheds are controlled by their abundance in soil, current land uses in the watershed, or geologic processes. Upland soils and river water samples were collected throughout the Deerfield watershed in southern Vermont and western Massachusetts and in the Quinebaug and Shetucket watersheds of eastern Connecticut. Soil concentrations were only an important predictor for dissolved Fe export, but no other trace element. Soil pH was not correlated with normalized dissolved exports of trace elements, but DOC was correlated with normalized dissolved Pb and Ni exports. The limited spatial and depth of soil sampling may have contributed to the poor correlation. Surprisingly, linear regressions and principal component analysis showed that human development was associated with higher soil trace metal concentrations but not significantly correlated with dissolved trace elements export. Instead, forest abundance was a strong predictor for lower Cu, Pb, and Zn soil concentrations and lower As, Fe, Ni and Pb dissolved exports across the watersheds. Dissolved exports of Al, K, and Si suggest that enhanced mineral dissolution in the montane watersheds was likely an important factor for matching or exceeding normalized pollutant trace element exports in more urbanized watersheds. Further studies are needed to evaluate subsurface/hyporheic controls as well as soil–surface water interface to quantify exchange and transport.

PENGARUH PUPUK ZA DAN KOMPOS TERHADAP KANDUNGAN Pb, Zn, Cu DAN N TANAH SERTA HASIL TANAMAN PADA SISTEM BUDIDAYA BAWANG MERAH DI TEPI DANAU BATUR, KINTAMANI, BANGLI

Vegetable cultivation is livelihoods for side Lake Batur communities, Kintamani, Bangli. Hilly natural conditions with a soil texture influenced by the eruption of Mount Batur, 900 m above sea level, and 900-3500 mm high rainfall, causing this region is very suitable for the cultivation of various vegetables, including shallot. One effort to meet the high demand for shallots is that efforts are made to improve cultivation techniques, including fertilizing to improve yields. In modern agriculture, the use of fertilizer is absolutely essential to trigger the level of crop production. The aims is to analyze the combination effect of using of inorganic fertilizer (ZA fertilizer) and organic fertilizer (compost fertilizer) on shallot vegetable cultivation systems on the content of pollutants, N nutrients and onion crop yields on the shores of Lake Batur, Kintamani District, Bangli Regency. The study using RBD with two factors where factor I: provision of organic fertilizer is leaf compost made aerobically (O), consisted of 3 levels, namely: O0 = 0*, O1 = 5* and O2 = 10*and factor II: the application of inorganic fertilizer namely ZA (S) fertilizer, consisted of 3 levels, namely: S0 = 0**, S1 = 50** and S2 = 100**, each repeated 3 times. The parameters observed were the growth and yield of shallots as well as the content of Pb, Zn, Cu and N nutrients in the soil. The nutrient content (N) in the soil, when using chemical fertilizer ZA and compost organic is not significantly different, as well as the results of onion plants, while the content of Pb, Zn and Cu on the use of chemical fertilizer ZA and organic compost, very real different. The highest soil Pb content in S2O1 treatment is 30.07***, the highest soil Zn content in the S2O1 treatment was 28.24***, and the highest soil Cu content in the S1O2 treatment is 17.22***.&#x0D; *= tons/ha&#x0D; **= kg/ha&#x0D; ***= mg/kg&#x0D; Keywords: compost; contents Pb; Zn; Cu of soil; shallot; ZA.

Status and associated human health risk of zinc accumulation in agricultural soils across China

Zinc (Zn) is not only an essential element for organisms, but it might also be an environmental pollutant. However, to date, there have not been any studies on Zn accumulation in Chinese agricultural soils at the national scale. In this study, soil Zn concentrations were obtained for soils from 277 sites with potential pollution (the “PP group”) and 1186 normal agricultural sites in China through a comprehensive literature search. Compared with the reported Zn contents of soils of other countries and regions in the world, the average concentration of Zn in soils in China (86.14 mg·kg−1) is relatively high. The total inventory of Zn in China’s agricultural soils was calculated to be 3.08 × 1010 tonnes. Zn contamination was serious in the PP group (e.g. 7076 mg·kg−1 in Yunnan province), and was primarily derived from anthropogenic activities including mining, smelting, and sewage irrigation. The accumulation of Zn in soils was influenced by different factors in different regions of China and varied with land-use pattern, with Zn concentrations in soils of different agriculture types decreasing in the following order: orchard > paddy field > vegetable land > wheat land. Zn pollution and associated risks in soils of regions in the PP group were more severe than those in normal agricultural soils. The hazard index (HI) values (for the PP group) for different human population groups varied as follows: children (2.40) > adult females (1.39) > adult males (1.23). The highest HI value obtained of 26.77 pertained to children. Overall, this study provides a comprehensive assessment of Zn accumulation in agricultural soils, and the results provide valuable information for the management and risk prevention of Zn contamination in China’s soils.

Effect of long-term fertilization of the permanent dry meadow on the zinc content in soil and meadow sward

The study took place between 2012 and 2014 in Falenty near Warsaw, Poland, as part of a long-term scientific experi-ment (first began in 1987) using the randomized block method. All blocks were irrigated until 2008. In 2009 each block was divided into two areas: irrigated and non-irrigated. The study involved four levels of inorganic nitrogen fertilizer and two levels of mixed inorganic and organic fertilizer in the form of fermented cattle urine. The soil in all experimental plots was characterized by low levels of zinc, ranging from 7.6 to 16.7 mg Zn∙kg–1 dry matter. Much lower Zn content in both soil layers of all irrigated plots was associated with increased yields on these plots, regardless of the level and form of ferti-lizer. The content of Zn in soil and sward in 2014 year was significantly lower compared in 2012. Inadequate levels of zinc for ruminant nutrition were observed in the sward from all plots (15.4–28.8 mg∙kg–1 dry matter). The higher content of zinc was found in sward harvested from the plot, which was not fertilized with phosphorus. The long-term inorganic and fer-mented urine fertilization resulted in very low zinc content in the soil and meadow sward.

Evaluation of the metal(loid)s phytoextraction potential of wild plants grown in three antimony mines in southern China

Wild plant species from three deserted antimony (Sb) mine areas in southern China were collected to measure eight metal(loid)s. Antimony, As (arsenic), Cd (cadmium), Cr (chromium), Cu (copper), Ni (nickel), Pb (lead), and Zn (zinc) concentrations in plants and soil were analyzed. The soils of the mining area was weakly alkaline and contained toxic levels of Sb, As, Pb, Cd, and Zn. Many plant species in the area (40 species and 19 families) have no clear signs of toxicity. The plants were divided into three categories (high, moderate, and low tendency to accumulate metals) based on their (ratio [RT], bioaccumulation factor [BCF], translocation factor [TF]) values. The plants with a high accumulation tendency exhibited the high potential to absorb Sb from contaminated soil; therefore, they can be used for the remediation or phytoremediation of Sb-contaminated soil.

Spatial Distribution, Contamination Assessment, and Sources of Heavy Metals in the Urban Green Space Soils of a City in North China

To study the condition of urban green space soils in the central parts of a city in North China, the spatial distribution, sources, and pollution levels of heavy metals (Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni) within green space soils in the central urban districts of the city were investigated. The results showed that the soil quality was high overall. The mean concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni were 0.172, 0.202, 9.02, 34.7, 57.0, 31.2, 85.7, and 26.3 mg·kg-1, respectively. The mean concentrations of Cd, Hg, Pb, and Zn in urban soils exceeded the background value of the Beijing-Tianjin-Tangshan region. All of the samples' heavy metal concentrations were lower than the risk screening values for soil contamination of development land in the national soil environment quality standards. With respect to the spatial distribution, the concentrations of As, Cr, and Ni were higher in the northwest of the study area, the concentrations of Cd and Zn were higher in the northeast, and the concentrations of Hg, Pb, and Cu were higher in the urban core area. As for the different land use types of the soils, the concentrations of Cd, Zn, and Ni were higher in the enterprise soils, while the concentrations of Hg, Pb, and Cu were higher in park and residential soils. Assessments of soil quality showed that 97.2% of soil samples' Nemerow integrated indices were less than 1, indicating that the soils were clean. Indices of potential ecological risk for all soil samples were less than 80, indicating that they posed a slight ecological risk. Multivariate statistical analysis (correlation and principle component analyses) showed that Cu, Pb, and Hg may originate from an anthropogenic source via the painting of ancient buildings and pesticides used to protect ancient trees. Chromium may originate from natural sources via geochemical activity and soil parent material; Cr, Zn, Ni, and As were derived from mixed sources through human and geochemical activities. The receptor model was used for identification and apportionment of pollution sources of elements over the standard. The contribution rates of sources were as follows:source 2(46.1%), source 3(33.1%), source 1(17.7%), and others (3.1%) for Cd, source 1(93.0%) for Cu, source 1(52.4%), source 3(24.2%), source 2(20.0%), and others (3.4%) for Zn, source 1(56.3%), source 2(37.8%), and source 3(5.8%) for Ni. Sources 1 and 3 were anthropogenic, while source 2 was natural.

Source apportionment of soil heavy metals using robust spatial receptor model with categorical land-use types and RGWR-corrected in-situ FPXRF data.

High-density samples are usually a prerequisite for obtaining high-precision source apportionment results in large-scale areas. In-situ field portable X-ray fluorescence spectrometry (FPXRF) is a fast and cheap way to increase the sample size of soil heavy metals (HMs). Moreover, categorical land-use types may be closely associated with source contributions. However, the above information has rarely been incorporated into the source apportionment. In this study, robust geographically weighted regression (RGWR) was first used to correct the spatially varying effect of the related soil factors (e.g., soil water and soil organic matter) on in-situ FPXRF in an urban-rural fringe of Wuhan City, China, and the correction accuracy of RGWR was compared with those of the traditionally non-spatial multiple linear regression (MLR) and basic GWR. Then, the effect of land-use types on HM concentrations was partitioned using analysis of variance (ANOVA). Last, based on the robust spatial receptor model (i.e., robust absolute principal component scores/RGWR [RAPCS/RGWR]), this study proposed RAPCS/RGWR with categorical land-use types and RGWR-corrected in-situ FPXRF data (RAPCS/RGWR_LU&FPXRF), and its performance was compared with those of RAPCS/RGWR with none or one kind of auxiliary data. Results showed that (i) the performances of the correction models for in-situ FPXRF data were in the order of RGWR>GWR>MLR, and the relative improvement of RGWR over MLR ranged from 52.6% to 70.71% for each HM; (ii) categorical land-use types significantly affected the concentrations of soil Zn, Cu, As, and Pb; (iii) the highest estimation accuracy for source contributions was obtained by RAPCS/RGWR_LU&FPXRF, and the lowest estimation accuracy was obtained by basic RAPCS/RGWR. It is concluded that land-use types and RGWR-corrected in-situ FPXRF data are closely associated with the source contribution, and RAPCS/RGWR_LU&FPXRF is a cost-effective source apportionment method for soil HMs in large-scale areas.

Comparison of Pollution Indicies in Assessing the Heavy Metal(loid)s Pollution of Arable Soils Adjacent to Industrial Complex in Gyenggi-do

Soils adjacent to the industrial complexes are known to be vulnerable to pollution with the diverse pollutant sources. This research assessed pollution level in the arable soils located nearby industrial complexes using different pollution indices. Both surface (0 - 15 cm) and subsurface (15 - 30 cm) soil samples were taken from 150 agricultural fields located nearby 15 industrial complexes. Total concentrations of As, Cd, Cu, Ni, Pb, Zn, and Hg in soils were determined after extracting with aqua regia and mostly were lower than the pollution threshold criteria for the agricultural soil designated by the Korean Soil Environment Conservation Act. The calculated PI values for As indicated the unpolluted status but those for all other metals were in the ranges of low to moderately polluted. The Igeo values for Cd and Zn indicated soils were in the unpolluted to moderately polluted ranges, but those for other metals were unpolluted. The Igeo evaluated the pollution level lower than PI due to the geochemical correction factor. The average PINemerow values for surface soil and subsurface soils were 1.26 and 0.73, respectively, indicating a higher pollution in surface soil than subsurface soil. Ranges of PINemerow values showed a wide spectrum of pollution level from clean to heavy pollution, depending on soil sampling sites. All pollution indices indicate that levels of pollution for Cd were higher than other metals. Also four pollution indices exhibited different levels of pollution, even though they are equally based on the total concentrations of heavy metals in soil. This discrepancy might be derived from the fact whether a pollution index considers the geochemical background level, an individual metal or overall metals. The results suggest that a suitable pollution index for the pollution assessment cannot be specified based on the total concentrations of metal in the arable soil. Pollution assessments of the arable soils using (A) single pollution index and (B) geoaccumulation index for each heavy metals, and (C) Nemerow pollution index for the integrated heavy metals in each industrial complex.

The potential of biochar to enhance concentration and utilization of selected macro and micro nutrients for chickpea (Cicer arietinum) grown in three contrasting soils

The balance in nutrient availability and retention after addition of biochar depends on the feedstock and application rates of the biochar in different soils. A pot experiment was conducted to assess the potential effect of biochar derived from poultry litter (PLB) and acacia (ACB) feedstocks on selected rhizospheric macro and micro-nutrients, shoot and root biomass, as well as nutrient uptake by chickpea grown in three different soil types. Treatments consisted of two biochar (PLB and ACB), four application rates of 0 (control), 0.5, 1 and 2% w/w, and three soil types [Fernwood (Arenosol); Pinedene (Gleyic Acrisol); Griffin (Helvic Acrisol)]. PLB application at 2% increased rhizospheric pH, CEC, and P, K, Ca, Mg, S, Zn concentrations in Pinedene and Griffin soils. Chickpea shoot and root biomass in the Pinedene and Griffin soils were highest at 0.5 and 1% PLB application and was attributed to increase in soil N and N uptake. Application of PLB and ACB at 1 and 2% showed a significant change in rhizospheric pH and available P in Fernwood soil resulting in a reduction of Fe concentration. The higher C:N ratio of the ACB probably resulted in immobilization of nutrients as evident from the low response in shoot and root biomass as well as shoot N uptake of chickpea in all soil types. The study confirmed that the effect of biochar on the availability of soil nutrients and plant growth is associated with the nature of the biochar feedstock, the rate of application and the soil characteristics.

Variation in Soil Microbial Population and Soil Enzymatic Activities Under Zincated Nanoclay Polymer Composites (ZNCPCs), Nano-ZnO and Zn Solubilizers in Rice Rhizosphere

Zinc deficiency is a major problem in production of rice crop, resulting in low grain Zn content. Use efficiency of conventional Zn sources (ZnSO4·7H2O) is very low. Therefore, technological interventions for increasing Zn use efficiency need to be explored. Nanoformulations of Zn, i.e. zincated nanoclay polymer composites (ZNCPCs), nano-ZnO (foliar application) and zinc solubilizer (Azospirillum brasilense), were compared with ZnSO4·7H2O (soil and foliar application) in rice (Oryza sativa var. Rajendra Mahsuri) rhizosphere at various phenological growth stages (maximum tillering, panicle initiation and harvesting). Effect of various Zn carriers on soil microbial population, enzymatic activities, DTPA-Zn content and Zn uptake was documented in pot experiment in Zn-deficient soil (DTPA-extractable Zn 0.48 mg kg−1). DTPA-extractable Zn content in soil at harvesting stage was found to be maximum in T6 (3.50 mg kg−1) followed by T4 (3.46 mg kg−1). Microbial population (bacteria, actinomycetes, fungi and zinc-solubilizing bacteria) was recorded to be highest in T4 (RDF + Azospirillum brasilense) followed by T6 (ZNCPC) at panicle initiation, maximum tillering and harvesting stages. Dehydrogenase activity was higher at maximum tillering stage in T6 (ZNCPC) followed by that in T4. Acid and alkaline phosphatase activities were found to be maximum at panicle initiation stage in T6 followed by T4 treatment. ZNCPC and zinc solubilizers stimulated soil microbial population consequently increasing the soil enzymatic activities and resulted in release of DTPA-extractable Zn in the rice rhizosphere. Maximum zinc uptake was recorded in treatment T6 (ZNCPC) Zn (303.42 mg kg−1). ZNCPC proved to be a promising fertilizer in increasing Zn use efficiency in rice rhizosphere. Findings of the present investigation need to be further evaluated in long-term field experiment to identify its cost/benefit ratio.