Maximum Concentrations Of Zn Research Articles

Distribution and accumulation of UV filters (UVFs) and conservation status of Posidonia oceanica seagrass meadows in a prominent Mediterranean coastal tourist hub

This study investigates the presence and impact of UV filters in Posidonia oceanica meadows in Formentera, a Mediterranean tourist hotspot. It highlights the distribution of inorganic (TiO2 and ZnO) and organic UV filters (UVFs) in different environmental matrices, their accumulation in seagrass tissues and their impact on the seagrass health.In the overlying and canopy waters of P. oceanica, Zn concentrations surpassed Ti, with three organic UVFs (benzophenone-3 [BP-3], avobenzone and homosalate [HMS]) consistently detected. Ti concentrations were generally higher than Zn in rhizosphere sediments, along with recurrent presence of octocrylene, HMS, 2-ethylhexyl methoxycinnamate (EHMC), and 4-methylbenzylidene camphor (4-MBC). Maximum Zn concentrations were found in canopy waters (3052.9 ng L−1). Both Ti and Zn were found in all P. oceanica tissues and leaf epiphytes across all study sites. Additional UVFs like octocrylene, avobenzone, and BP-8 were also detected in P. oceanica tissues and epiphytes. Elevated levels of octocrylene in leaf epiphytes (2112.1 ng g−1 dw) and avobenzone in leaves (364.2 ng g−1 dw) and leaf epiphytes (199.6 ng g−1 dw) were observed in the Port of La Savina, the island's main entry port. Octocrylene concentrations (up to 2575 ng g−1 dw) in rhizosphere sediments near sewage discharge points exceeded reported maxima, highlighting wastewater treatment plants as significant sources of organic UVFs. Correlational analyses suggested that the accumulation of octocrylene, avobenzone, and BP-3 negatively impacted P. oceanica's conservation status, affecting global density, density at 100 % cover, and leaf morphometry. Positive correlations were observed between leaf polyphenols (antioxidants) and concentrations of avobenzone, benzophenone-8 (BP-8), and BP-3, indicating potential oxidative stress induced by UVFs in P. oceanica.Our study underscores the pervasive presence of UV filters in P. oceanica habitats, with implications for seagrass health and conservation, especially in areas of high tourism and sewage discharge.

Nano-zinc oxide foliar application at the tuber initiation stage enhances the starch synthesis and zinc bioaccumulation in potato tubers

Crops cultivated on alkaline soils are normally deficient in micronutrients, therefore among others, zinc deficiency is a widespread problem in Pakistan. By using a novel approach, we have shown that agronomic biofortification of potato tubers can be achieved through application of nano-zinc oxide during the tuber initiation stage. Field experimentation was performed during the potato growing season (2021-2022) with five different concentrations of nano-zinc oxide (0, 25, 50, 100, and 250 mg L-1) applied to 55-d old plants at tuber initiation stage, and after 40 days of spray, potato tubers were harvested for the analysis of various biochemical and agronomic traits and changes in bioavailable concentration of Zn in potato tubers. An increase in growth and yield traits was recorded due to spray of 25 and 50 mg L-1 nano-zinc oxide. Starch fraction in tubers was increased in response to all nano-zinc oxide concentrations. Interestingly, over 50% increase in starch was recorded due to application of 25 mg L-1 nano-zinc oxide, while higher doses up to 250 mg L-1 increased tuber starch by ~34%. Soluble sugars increased progressively up to 250 mg L-1 reaching maximum values than the control. Above all, maximum concentration of Zn in potato tuber was recorded in response to 250 mg L-1 spray of nano-zinc oxide ranging up to 58.2 - 65.5 µg g-1 dry weight. Overall, exogenous application of nano-zinc oxide to potato plants can improve potato tuber quality by enhancing starch contents and contributing to translocation of Zn in potato tubers leading to agronomic biofortification.

Phenotypic variability of Aphantopus hyperantus and Coenonympha arcania (Lepidoptera: nymphalidae) in the vicinity of the Sredneuralsk copper smelter. 1. Metal content and wing length

We tested the hypotheses that near a copper smelter, marigolds Aphantopus hyperantus and Coenonympha arcania accumulate metals in higher concentrations compared to the background territory and that the accumulation of metals in the body of adults negatively correlates with wing length, but positively with fluctuating asymmetry of wing length. We measured the length of the forewing and individual concentrations of Zn, Cu, Pb and Cd in the body of adults captured at different distances from the Sredneuralsk copper smelter (Revda, Russia). The metal content reaches very high levels, with Zn concentrations higher than Cu and Pb concentrations by an order of magnitude, and Cd concentrations by two orders of magnitude. In both species, males accumulate metals significantly more than females. The maximum concentrations of Zn, Cu and Cd were found near the plant. Wing length either did not differ between sites or was higher near the plant. Only for females of one of the species (A. hyperantus) a statistically significant negative relationship was found between Cu concentrations and wing size. In both species, fluctuating wing size asymmetry did not differ between sites and was not affected by metal concentrations at the individual level.

Differential response of nano zinc sulphate with other conventional sources of Zn in mitigating salinity stress in rice grown on saline-sodic soil

Salinization causes the degradation of the soil and threatening the global food security but the application of essential micronutrients like zinc (Zn), improve the plant growth by stabilizing the plant cell and root development. Keeping in view the above-mentioned scenario, an experiment was conducted to compare the efficiency of conventional Zn fertilizers like zinc sulphate (ZnSO4), zinc ethylene diamine tetra acetic acid (Zn-EDTA) and advance nano Zn fertilizers such as zinc sulphate nanoparticles (ZnSO4NPs), and zinc oxide nanoparticles (ZnONPs) (applied at the rate of 5 and 10 mg/kg) in saline-sodic soil. Results revealed that the maximum plant height (67%), spike length (72%), root length (162%), number of tillers (71%), paddy weight (100%), shoot dry weight (158%), and root dry weight (119%) was found in ZnSO4NPs applied at the rate of 10 mg/kg (ZnSO4NPs-10) as compared to salt-affected control (SAC). Similarly, the plants physiological attributes like chlorophyll contents (91%), photosynthesis rate (113%), transpiration rate (106%), stomatal conductance (56%) and internal CO2 (11%) were increased by the application of ZnSO4NPs-10, as compared to SAC. The maximum Zn concentration in root (153%), shoot (205%) and paddy (167%) found in ZnSO4NPs-10, as compared to control. In the body of rice plants, other nutrients like phosphorus and potassium were also increased by the application of ZnSO4NPs-10 and soil chemical attributes such as sodium and sodium adsorption ratio were decreased. The current experiment concluded that the application of ZnSO4NPs at the rate of 10 mg/kg in salt-affected paddy soil increased the growth, physiology, up take of essential nutrients and yield of rice by balancing the cationic ratio under salt stress.

Zinc-Based Mineral (ZnSO4·7H2O) and Chelated (Zn-EDTA) Fertilizers improve the Productivity, Quality and Efficiency Indices of Field Pea (Pisum sativum L.) through Biofortification

BackgroundField pea (Pisum sativum L.) is an essential pulse crop which can offer highly nutritional food to human beings. But, the inadequate availability of nutrients such as Zn could pose a significant threat to public health. Thus, there is a need to improve the food quality parameters and nutrient levels of the crop using biofortification thus, making it beneficial for human consumption. MethodsThis study evaluated the influence of zinc (Zn) foliar application on food quality parameters, yield, Zn concentration and its uptake along with the economics of field pea cultivation. In the experiment, different concentrations of ZnSO4·7H2O and Zn-EDTA at the flowering and bud initiation stage were applied to the field pea. ResultsThe foliar application of ZnSO4·7H2O (1.0%) at the flowering and bud initiation stages (treatment T7) was highly efficient in increasing food quality parameters such as crude fibre, TSS, N, K and protein content with maximum values of 3.02, 20.5, 3.15, 3.41 and 14.97%, respectively. Also, the maximum yields of grain and straw in field pea for treatment T7 were 4840 kg ha−1 and 3275 kg ha−1, respectively. Similarly, the maximum Zn concentration in grain (54.8 mg kg−1) and straw (52.5 mg kg−1) of field pea was observed in treatment T7. Additionally, Zn uptake by grain (214 g ha−1) and straw (167 g ha−1) was the maximum for the treatment T7 involving ZnSO4·7H2O (1.0%). Whereas, grain Zn concentration and uptake decreased in the treatments involving the use of Zn-EDTA due to the formation of the complex resulting in the reduced availability of Zn to crop. ConclusionTherefore, the application of ZnSO4·7H2O (1.0%) at the flowering and bud initiation stage significantly improved the food quality parameters, grain and straw yield, concentration of Zn and uptake over control and could be used to alleviate the Zn deficiency in field pea.

Lead and Zinc Uptake and Toxicity in Maize and Their Management

Soil contamination with heavy metals is a global problem, and these metals can reach the food chain through uptake by plants, endangering human health. Among the metal pollutants in soils, zinc (Zn) and lead (Pb) are common co-pollutants from anthropogenic activities. Thus, we sought to define the accumulation of Zn and Pb in agricultural soils and maize. Concentrations of Pb in agricultural soil (in Namibia) could reach 3015 mg/Kg, whereas concentrations of Zn in soil (in China) could reach 1140 mg/Kg. In addition, the maximum concentrations of Zn and Pb were 27,870 and 2020 mg/Kg in maize roots and 4180 and 6320 mg/Kg in shoots, respectively. Recent studies have shown that soil properties (such as organic matter content, pH, cation exchange capacity (CEC), texture, and clay content) can play important roles in the bioavailability of Zn and Pb. We also investigated some of the genes and proteins involved in the uptake and transport of Zn and Pb by maize. Among several amendment methods to reduce the bioavailability of Zn and Pb in soils, the use of biochar, bioremediation, and the application of gypsum and lime have been widely reported as effective methods for reducing the accumulation of metals in soils and plants.

Optoelectronic properties of nanostructured Sb2Se3 films synthesized by electrodeposition method: Effect of Zn concentrations

In this research, the effect of different concentrations of Zn doping on antimony selenide (Sb2Se3) nanostructured films is investigated using electrodeposition method to study the properties of optoelectronics. XRD patterns confirmed the formation of polycrystalline orthorhombic Sb2Se3 films and FESEM images confirmed the formation of spherical particles at the nanoscale. Studying optical properties showed the band gap energy of less than 2.00 eV and investigating the electrical properties represented an increase in the density of electrical carriers in the films of Sb2Se3 with adding Zn concentrations. Photodetector parameters were calculated by photocurrent characterization and with alternating xenon light (on and off). It was found that sensitivity from 316.66 % to 4017.64 %, gain from 218.36 to 3924.30, responsivity from 0.0095 to 0.1708 mA/W, and specific detectivity from 1.02 × 10+9 to 1.54 × 10+9 Jones of the undoped sample reached its maximum possible value with increasing doping in the sample with maximum Zn concentration.

Bioaccumulation Factor (BAF) of heavy metals in green seaweed to assess the phytoremediation potential

Heavy metals are mostly discharged from several anthropogenic sources in the lower Gangetic delta. They are a matter of great concern due to their non-conservative nature. Heavy metals Zn, Cu, and Pb, were analyzed in the estuarine water and thallus body tissue of Enteromorpha compressa from 10 different stations in the lower Gangetic delta complex through three seasons. The levels of heavy metals varied as per the order Zn > Cu > Pb in both the aquatic phase and biological sample, irrespective of stations. The maximum concentration of Zn was observed in Kakdwip (Stn. IV) and both Cu and Pb in Nayachar Island (Stn. III). The minimum was observed in Bagmara (Stn. X) for all metals in the seaweed sample through all the seasons. The levels of all dissolved heavy metals were maximum in Nayachar Island (Stn. III) and lowest in Bagmara (Stn. IV). A distinct seasonal pattern is observed for all the selected metals with the highest value during monsoon, followed by postmonsoon and premonsoon. The Bioaccumulation Factors (BAF) computed for all the selected heavy metals exhibit the highest value for Pb, followed by Zn and Cu. The highest BAF observed for Pb is an issue of grave concern due to its toxic nature compared to Zn and Cu. ANOVA computed on the data sets of dissolved and bioaccumulated heavy metals and BAFs exhibit significant Spatio-temporal variation, suggesting the need for seasonal and station-wise monitoring, preferably in context to the BAF. The spatial variation in the level of heavy metals in the seaweed species Enteromorpha compressa is due to differences in activities and sources of pollution in these regions. The overall result suggests that seaweed may be a potential bio-purifier in the coastal area mainly exposed to many anthropogenic activities.

Can Potato Crop on Sandy Soil Be Safely Irrigated with Heavy Metal Polluted Water?

Heavy metal (HM) accumulation in soil and plants can occur when water contaminated with HMs is used as a source of irrigation (El-Salam Canal, Egypt). In this study, the effect of watering potato crop in sandy soil from a polluted water source under flood irrigation (FI), sprinkler irrigation (SI), and surface drip irrigation (DI) on the transport of the HMs copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn) in the root zone was experimentally investigated. HM concentrations in potato plant parts was also determined. The field experiments were conducted in a completely randomized block with three replicates for each irrigation method by using nine field lysimeters. Soil and plant samples were collected at the end of the growing season to determine their HM content. The results showed that regardless of irrigation method, irrigation with HM contaminated water raised HM concentrations in both soil and potato plants. DI produced the highest concentrations of most HMs (Cu, Mn, and Pb) in the upper soil layer (0–40 cm) and highest Cu, Pb, and Zn concentrations in plant tubers as well. Maximum Zn concentration in the upper soil layer and maximum Mn concentration in plant tubers occurred under SI. The maximum concentrations of Cu, Mn, Pb, and Zn in both the upper soil layer and plant tubers were 12.0, 140.0, 11.6 and 67.9 mg/kg and 6.3, 9.4, 2.3 and 23.9 mg/kg, respectively. However, FI produced the highest concentrations in the deep soil layer (40–60 cm) and the least concentration of HMs in plant tubers. These concentrations were 18.8, 203.8, 13.3 and 70 mg/kg and 4.0, 6.0, 0.6 and 17.1 mg/kg in soil and plant tubers for Cu, Mn, Pb, and Zn, respectively. The maximum concentrations of HMs in soil and potato plants were lower than the maximum permissible limits. Therefore, El-Salam Canal water appears not to be harmful in the short term. However, as shown in the results, HM accumulation depends on irrigation technique; thus, more studies are needed to determine harmful effects in the long term.

Hydrochemical characteristics and health risk assessment of groundwater in karst areas of southwest China: A case study of Bama, Guangxi

The southwest karst area is considered to have the most vulnerable groundwater environment in China. Groundwater quality is an important factor restricting sustainable economic development. In this study, traditional water chemistry method, water quality index (WQI), and hazard index (HI) were applied to comparatively analyze the hydrochemical characteristics of groundwater and the water quality in the exposed karst region (EKR) and buried karst region (BKR) in Bama, a typical karst area in southwest China. Generally, the main water type was Ca/Mg–HCO3. Due to the predominance of dissolution of carbonate rocks in EKR and silicate rocks in BKR, higher total dissolved solids (TDS), Ca and HCO3− concentrations, and lower H2SiO3 content were detected in groundwater in EKR compared with BKR. As affected by weathering of rocks such as lead-zinc ore, the maximum concentrations of Zn and Sr were 11.23 mg/L and 13.30 mg/L, showing that mineral water resources are widely distributed in Bama. The ion ratios and isotope abundances (δD and δ18O) in groundwater samples indicated stronger evaporation and rock-water interaction in EKR than BKR. Human activities exerted a more significant influence on the water quality in EKR compared to BKR. The mean WQI value also suggested that the groundwater quality was better in BKR (9.56) than EKR (12.17). Although 95.7% of the water samples in the study area were classified as excellent based on their WQI values, 4.3% of the water samples still had significant health risks (HI > 1) due to the high Sb, Zn, As, and Sr concentrations. It is recommended to reduce anthropogenic pollution in EKR and develop a plan for clean production of mineral water industry according to local conditions, which will help the sustainable development of the local economy.

Silicon and Zinc Improves Grain Yield and Nutrient Status in Rice When Supplied During the Different Growth Stages

Silicon (Si) and zinc (Zn) has been recognized as beneficial elements to improve rice (Oryza sativa L.) grain yield. The present study was aimed at investigating the effects of silicon and zinc foliar application at different growth stages on yield components, grain yield, and concentration of silicon and zinc in rice grain. The experiment design was a factorial two-factor randomized complete block design (RCBD) with three replications. Treatments included the fertilizers foliar application at 3 levels (Potassium silicate, Silicon nanoparticles, Zinc Oxide nanoparticles) and rice growth stages at 5 levels (T1: early tillering + middle tillering + late tillering + full heading stage; T2: middle tillering + late tillering + full heading stage; T3: late tillering + full heading stage; T4: late tillering; T5: full heading stage). The results indicated that the application of Si and Zn nanoparticles was superior to potassium silicate in terms of improving the yield components, yield and nutrients concentration in rice grain. Application of Si and Zn nanoparticles increased the grain yield by 7.4 and 4.5%, respectively, above the potassium silicate. Foliar application of nutrients in both T1 and T2 stages led to improved grain yield (7716 and 7700 kg.ha-1 , respectively). The highest Si concentration in grain was obtained by foliar application of nano-Si at the T1 and T2 stages (3.97 and 3.83%, respectively), while the maximum Zn concentration in grain was observed with the nano-Zn application at the T2 stage (21.67 mg.kg-1 ). In general, we suggest applying Si and Zn nanoparticles at the middle tillering + late tillering + full heading stages to improve the yield and rice grain fortifying.

Luminescence of ZnO nanocrystals in silica synthesized by dual (Zn, O) implantation and thermal annealing

Zinc blende ZnO nanocrystals (NCs) were synthesised in amorphous silica by high-fluence dual (Zn, O) ion implantation and subsequent thermal annealing in air. We observed the formation of core/shell nanoparticles at the depth of maximum Zn concentration as a result of an incomplete oxidation process. The silica matrix with ZnO NCs exhibits an intense white-greenish emission. Low-temperature photoluminescence spectroscopy revealed various radiative recombination mechanisms in the zinc blende ZnO NCs involving intrinsic defects that act as donors and acceptors.

Ecological state of the soil cover of coal deposits in the Republic of Tyva

The article deals with the ecological state of the soil cover of the currently actively developed coal deposits, which are located in the steppe zone of the Central Tuva Basin. Two of them – Kaa-Khem and Chadan – mining is carried out in an open way for more than 50 years, resulting in the formation of quarries and extensive waste rock dump fields. The third field – Mezhegey – has been producing by mine method since 2013. It was revealed that in the areas where open-pit mining is carried out, the maximum concentration of Zn, As, Ni in the eastern and south-eastern parts of the fields, soil contamination by Ni and As was also established. The presented materials can be used to manage the state of the environment and optimize the use of natural resources in the areas of activity of mining enterprises, which will help to reduce the anthropogenic impact on the ecosystems of the dry-steppe region.

Enhancement in Plant Growth and Zinc Biofortification of Chickpea (Cicer arietinum L.) by Bacillus altitudinis

Zinc-solubilizing bacteria (ZSB) are potential and ideal substitutes for Zn supplement. Currently, limited reports are available on the bacteria displaying capability to transform insoluble forms of zinc (Zn) to an available form. Therefore, attempts were made to identify and characterize Zn-solubilizing strains from chickpea rhizosphere for growth promotion and Zn biofortification. Sixty-one bacteria isolated from rhizosphere of chickpea from different parts of Indo-Gangetic plains (IGP) of India were screened for Zn-solubilizing capabilities by cultivating on BTG medium supplemented with ZnO, Zn3(PO4)2, and ZnCO3. Two potential ZSB (BT3 and CT8) were chosen based on their zinc solubilization index and zinc solubilization efficiency and later identified by 16S rRNA gene sequence analysis. In vitro assays were performed to determine their plant growth-promoting attributes. PCR assay was performed to confirm the presence of zinc uptake regulator (zur) gene in potential strains. Pot experiments were carried out to evaluate the effect of two potential ZSB (BT3 and CT8) on growth promotion and Zn biofortification in chickpea. Atomic absorption spectroscopy was employed to determine the Zn content in the plants. Out of twenty-four ZSB, only two strains (BT3 and CT8) were able to solubilize all the three Zn sources. Isolate, BT3 released maximum concentration of Zn from ZnCO3 (150.2 ± 1.1 mg l−1), while CT8 released maximum from ZnO (130.2 ± 1.2 mg l−1) and Zn3(PO4)2 (116.5 ± 1.2 mg l−1), respectively. The pH of medium was strongly acidic which ranged from 5.2 to 3.9, and the organic acid analysis revealed hexanoic acid, pentanoic acid, and mandelic acids as prime organic acids produced by isolates. The presence of zur genes indicated the involvement of zur-mediated molecular mechanisms in these strains. These isolates also showed plant growth-promoting traits such as production of indole acetic acid (IAA), ammonia, siderophores, and phosphate solubilization. The 16S rRNA sequence analysis revealed that both the isolates had close similarity with Bacillus altitudinis. Inoculation of isolates BT3 and CT8 improved the growth parameters of chickpea and increased the plant’s Zn uptake by 3.9–6.0%. B. altitudinis strains (BT3 and CT8) show excellent capabilities to solubilize insoluble Zn compounds like oxides, phosphates, and carbonates of Zn, making them valuable source for improving Zn uptake and growth of chickpea.

Synthesis, characterization and application of ZnO nanoparticles for improved growth and Zn biofortification in maize

ABSTRACT Zinc (Zn) deficiency is common on calcareous soils due to fixation with soil components and precipitation with other ions. ZnO nanoparticles (ZnO NPs) may serve a better source of Zn for improved growth and biofortification in maize grains. Pot and field experiments were conducted to evaluate the effect of ZnO nanoparticles in comparison with conventional Zn fertilizer (ZnSO4) on growth and grain Zn contents of maize. In both experiments, Zn application improved growth and physiological parameters of plants; however, maximum improvement was observed in treatments receiving ZnSO4 (soluble) or ZnO nanoparticles (insoluble source of Zn). Application of ZnO nanoparticles also improved Zn concentration in shoots as well as in grains in field experiment. In field experiment, Zn partitioning was also calculated and interestingly it is found that Zn concentration at maturity stages was reduced in stem and mature leaves. Maximum Zn concentration (~80 mg kg−1) was observed in young leaves at vegetative growth stage in treatments receiving ZnO nanoparticles. Foliar applied ZnO NPs showed maximum increase in grain Zn concentration (82%). It is concluded that ZnO NPs improved maize growth, yield and grain Zn contents. Being cheaper and efficient source, it can be used for Zn biofortification.

Assessment of Drain Water Used for Irrigation in the Delhi Region.

Background.Industries such as electroplating, mining and battery production are major sources of heavy metal-rich waste entering nearby water bodies. Irrigation with heavy metal contaminated water can deteriorate soil quality as well as agricultural produce and have further toxic effects on human health.Objectives.The objective of the present study was to estimate the concentration of hazardous heavy metals such as chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn) and lead (Pb), as well as physico-chemical variables (pH, electrical conductivity, total dissolved solids, chemical oxygen demand and dissolved oxygen) at sampling locations along the Najafgarh and Loha mandi drains in Delhi, National Capital Region, India.Methods.The present study evaluated the quality of wastewater from the Najafgarh and Loha mandi drains, which are used for irrigational purposes in the Delhi region. Drain water quality was monitored for a period of 2 years for physico-chemical variables (pH, chemical oxygen demand, electrical conductivity and dissolved oxygen) as well as heavy metal concentrations (Cr, Cu, Cd, Zn, Ni and Pb). The two-year monitoring period (July 2012–March 2014) was chosen to represent three seasons: pre-monsoon, monsoon, and post-monsoon.Results.Varied concentrations of multiple heavy metals were found due to the extensive discharge of untreated industrial effluents into the drain water. Punjabi Bagh of Najafgarh drain was the most contaminated sampling site with the maximum concentration of Zn (12.040 ± 0.361 mg L−1), followed by Cr (2.436 ± 0.073mg L−1) and Cu (2.617 ± 0.078 mg L−1).Conclusions.Consumption of heavy metal-contaminated agricultural products can cause deleterious human health effects, leading to further health problems. The presence of multi-heavy metal ions above the Food and Agriculture Organization of the United Nations (FAO) permissible limits indicated that drain water was not suitable for irrigational purposes, and adequate measures are required to remove the heavy metal load from drain water.Competing Interests.The authors declare no competing financial interests.

Assessment of trends and emission sources of heavy metals from the soil sediments near the Bohai Bay.

Anthropogenic emission sources (mainly vehicular and industrial emission) are one of the major emission sources of the heavy metals in aquatic ecosystems which have significant potential to perturb the marine geochemistry and ecosystem as well as human life also. In the present study, we tried to investigate the accumulation of heavy metals (Zn, Cr, Ni, Cu, Pb, Co, As, Cd, and Hg) at two sediment cores near the Bohai Bay in Southern Tianjin and reconstruct their historical trends over the last hundred years to understand the impacts of anthropogenic activities. The concentration of Zn and Cr is found maximum than the other studied heavy metals. Results suggest that in the mid-twentieth century, the maximum concentrations of Zn, Cr, Ni, Cu, and Pb are mainly because of the opening of Dagang Oilfield which emits a huge amount of heavy metals into the environment. Source apportionment analysis has been carried out using positive matrix factorization (PMF) model which suggests three major emission sectors of heavy metals, i.e., coal combustion, manufacturing, and smelting dust, having different contribution 32%, 40%, and 28% respectively to the total heavy metal burden. Industrial emissions are found to be the major sources of Cr, Ni, and Co while Pb is mainly originated from the coal combustion. The risk assessment analysis shows the value of mean effects range median (ERM) quotients ~ 0.17 for the two sediment cores which suggest nearly 21% toxicity of the studied metals indicating towards the policymakers for the mitigation of air pollution surrounding Tianjin.

Heavy metal bioavailability and accumulation in winter wheat (Triticum aestivum L.) irrigated with treated wastewater in calcareous soils

Irrigation with raw or diluted wastewater increases in many developing countries, but the increasing availability and use of wastewater generates challenges for public agencies charged with minimizing potential impacts on public health and the environment. In this study, the available (DTPA-extractable) concentration of Zn, Cu, Cd, Pb, and Ni in the surface soil was measured in five sites irrigated with treated wastewater as compared with a site irrigated with freshwater (control). The major sources of wastewater were municipal wastewater, household, commercial, and industrial effluents, which were treated to settle and remove solids prior its use for irrigation. In addition, the concentration of the above five heavy metals and their accumulation and mobilization characteristics were determined in the roots, shoots, and grains of winter wheat (Triticum aestivum L.) grown in treated wastewater-irrigated soils. Irrigation with treated wastewater resulted in a remarkable build-up of metal concentrations in the soil (averaged over five sites) in the order of Cd (178.2%) > Ni (105.1%) > Cu (66.4%) > Zn (66.0%) > Pb (40.9%) compared with control. However, only Cd concentration exceeded the permissible range. The concentration of heavy metals was significantly greater (P < 0.05) in wheat roots than in shoots and grains (root ≫ shoot > grain). The highest concentrations were found in the roots in the order of Cu > Zn > Pb > Cd > Ni. The maximum concentrations of Zn, Cu, Ni, Cd, and Pb in wheat grains were 3.20, 1.20, 0.52, 0.31, and 0.21 mg kg−1, respectively. The bioconcentration and translocation factors of wheat showed that heavy metals quantitatively accumulated in the roots and were poorly translocated to the grains. The potential health risks, calculated as hazard quotients (HQ), were less than unity for most heavy metals, indicating that local people are within the safe limit regarding non-carcinogenic risks. However, the HQ value of Cd exceeded 1 for both children and adults, indicating a high health hazard for the whole exposed population by this metal.

Foliar application of Zn can reduce Cd concentrations in rice (Oryza sativa L.) under field conditions.

Cadmium (Cd) pollution in rice and its transfer to food chain are cause of global concern. Application of zinc (Zn) can reduce Cd uptake by plants, as both these metals are generally antagonistic in soil-plant systems. In a field experiment on Cd-contaminated acid soil, we investigated the effectiveness of foliar application of Zn in minimizing Cd accumulation and its effect on the content of mineral nutrient elements in rice. The treatment was done at an early grain filling stag using 0.3 and 0.5% w/v ZnSO4·7H2O solution. The spray did not affect the grain yield of rice but decreased the Cd concentration in the root, straw, husk, and brown rice to some extent and increased the Zn concentration. Foliar application of 0.5% ZnSO4 resulted in maximum Zn concentration and minimum Cd concentration in brown rice. However, the concentrations of P, K, Ca, Mg, Cu, and Mn in brown rice were not affected. The correlation between Cd and Zn concentrations in brown rice, husk, and root was significantly negative, and that between Cd and Mn concentrations in brown rice was significantly positive. The inhibition of Cd uptake resulted in a decrease in its concentration in brown rice after the treatments. Thus, the foliar application of a suitable concentration of Zn at the early grain filling stage could effectively minimize the Cd concentration while enhancing the Zn concentration in brown rice on Cd-contaminated acid soil.

English

The essentiality of phosphorus (P) as a macronutrient and that of zinc (Zn) as micronutrient for plants has been established long ago but their interactive effects on economic yield of crops are still controversial particularly in calcareous saline-sodic soils. Therefore, a pot experiment was conducted to evaluate the P-Zn interaction effects on wheat in saline-sodic soil. The treatments comprised of four levels of P (0, 25, 50 and 75 mg kg(-1) soil) and three levels of Zn (0, 5 and 10 mg kg(-1) soil) arranged in completely randomized design each with three replications. The results showed that total number of tillers, plant height, straw dry weight and 1000-grain weight was significantly (P <= 0.05) higher in saline-sodic control closely followed by applied P at 75 mg kg(-1) soil + Zn at 5 mg kg(-1) soil (P75Zn5). While maximum Zn concentration in wheat straw and grains was observed in P75Zn5. The maximum ammonium-bicarbonate-diethylene-triamine-penta-acetic acid (AB-DTPA) extractable P and Zn in post-experiment soil was recorded with P at 75 mg kg(-1) soil + Zn at 10 mg kg(-1) soil (P75Zn10). Thus, application of P at 75 mg kg(-1) soil along with Zn 5 mg kg(-1) soil was the appropriate combination of P and Zn for substantial increase in growth and yield of wheat in saline-sodic soil.