Spatial Distribution Of Cd Research Articles

Mechanisms of N-doped microporous biochar decreased Cd transition in rhizosphere soils and its impact on soil bacterial community composition

Soil cadmium (Cd) contamination has garnered considerable attention. This study employed batch sorption experiments and rhizobox experiments to examine the impact of nitrogen-doped microporous biochar (NBB) on the temporal and spatial distribution of Cd in the rhizosphere of rice plants, with the aim of elucidating the underlying mechanisms. The results indicated that the adsorption of Cd(II) onto NBB was predominantly governed by chemical reactions. When applied to soil, the NBB significantly hindered the migration of Cd from the bulk soil to the rhizosphere. Additionally, the application of NBB decreased the redox potential (Eh) in the rhizosphere soil and increased the relative abundance of Anaeromyxobacteraceae, Geobacteraceae, Desulfurisporaceae, and Syntrophomonadaceae, which could facilitate the reduction of soil Cd availability. Furthermore, the NBB2 treatment encouraged the formation of iron plaque on the root surface, thereby limiting the uptake of Cd from the soil into the root system. Moreover, the N-doped microporous biochar treatment resulted in lower Cd levels in the stele of root, an effect that was associated with increased sulfur (S) content in the stele and epidermis, suggesting a potential role for S in Cd sequestration. Ultimately, the application of N-doped microporous biochar resulted in diminished Cd accumulation in the rice tissues.

Analysis of the Source Apportionment and Pathways of Heavy Metals in Soil in a Coal Mining Area Based on Machine Learning and an APCS-MLR Model

Long-term coal mining activities have led to severe heavy metal pollution in the soil environment of coal mining areas, posing significant threats to both ecological environments and human health. In this study, surface soil samples were collected from the overlying soil of coal gangue and the surrounding areas of the Panyi coal mine in Huainan. The concentrations of Cd, Zn, Cu, Ni, and Pb elements were determined. A self-organizing map (SOM) and an absolute principal component score multiple linear regression (APCS-MLR) receptor model were employed for the quantitative analysis of the soil’s heavy metal pollution sources and contributions. Additionally, this study focused on the analysis of the pathways of the relatively serious pollution of Cd. The results revealed that the average concentrations of heavy metals (Cd, Pb, Zn, Cu, Cr, and Ni) in the study area were 4.55, 0.59, 1.54, 0.69, 0.59, and 0.71 times the local soil background values, respectively. The concentrations of Cd and Zn exceeded the risk screening values at some sampling points, with exceedance rates of 44% and 8%, respectively, indicating a relatively serious Cd contamination. The sources of heavy metals in the soil in the study area were classified into four categories: mining activities, agricultural activities, weathering of natural matrices, and other unknown sources, with average contributions of 55.48 percent, 24.44 percent, 8.91 percent and 11.86 percent, respectively. Based on the spatial distribution of Cd, it was inferred that atmospheric deposition is one of the important pollution pathways of Cd in the study area. Cd profile distribution patterns and a surface water pollution survey showed that the farmland areas were affected by the irrigation water pathway to some extent. The vertical distribution of heavy metal content in the forest area showed a strong disorder, which was related to the absorption function of plant roots. The results of this study can help to improve the environmental management of heavy metal pollution so as to protect the ecological environment and human health.

Cadmium alters whole animal ionome and promotes the re-distribution of iron in intestinal cells of Caenorhabditis elegans.

The chronic exposure of humans to the toxic metal cadmium (Cd), either occupational or from food and air, causes various diseases, including neurodegenerative conditions, dysfunction of vital organs, and cancer. While the toxicology of Cd and its effect on the homeostasis of biologically relevant elements is increasingly recognized, the spatial distribution of Cd and other elements in Cd toxicity-caused diseases is still poorly understood. Here, we use Caenorhabditis elegans as a non-mammalian multicellular model system to determine the distribution of Cd at the tissue and cellular resolution and its effect on the internal levels and the distribution of biologically relevant elements. Using inductively coupled plasma-mass spectrophotometry (ICP-MS), we show that exposure of worms to Cd not only led to its internal accumulation but also significantly altered the C. elegans ionome. Specifically, Cd treatment was associated with increased levels of toxic elements such as arsenic (As) and rubidium (Rb) and a decreased accumulation of essential elements such as zinc (Zn), copper (Cu), manganese (Mn), calcium (Ca), cobalt (Co) and, depending on the Cd-concentration used in the assay, iron (Fe). We regarded these changes as an ionomic signature of Cd toxicity in C. elegans. We also show that supplementing nematode growth medium with Zn but not Cu, rescues Cd toxicity and that mutant worms lacking Zn transporters CDF-1 or SUR-7, or both are more sensitive to Cd toxicity. Finally, using synchrotron X-Ray fluorescence Microscopy (XRF), we showed that Cd significantly alters the spatial distribution of mineral elements. The effect of Cd on the distribution of Fe was particularly striking: while Fe was evenly distributed in intestinal cells of worms grown without Cd, in the presence of Cd, Fe, and Cd co-localized in punctum-like structures in the intestinal cells. Together, this study advances our understanding of the effect of Cd on the accumulation and distribution of biologically relevant elements. Considering that C. elegans possesses the principal tissues and cell types as humans, our data may have important implications for future therapeutic developments aiming to alleviate Cd-related pathologies in humans.

Risk Assessment and Source Analysis of Heavy Metal Pollution in Surface Sediments from Major River Systems in Maoming City, Guangdong Province

In order to understand the spatial distribution and sources of heavy metals in surface sediments of MaoMing city and to reasonably evaluate the ecological risk of heavy metals in sediments of the study area, the contents of heavy metals (As, Hg, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in surface sediments of eight rivers and three reservoirs were detected, and the risks of heavy metals were assessed using the geo-accumulation index (Igeo), potential ecological disk index (RI), and potential adverse biological impacts (ΣTUs). The sources of heavy metals were analyzed via correlation, principal component analysis (PCA), and positive matrix factorization (PMF). The results showed that the ω(Zn) (147.56 mg·kg-1) and ω(Hg) (0.20 mg·kg-1) were 3.72 and 2.25 times the background value, respectively, and the spatial distributions of Cd, Co, Cu, Mn, Ni, and Zn were in the order of northern>central>western>southeast. The geo-accumulation index results showed that Zn was at a moderate pollution level, 76.6% of the sampling sites of Hg were at a light-heavy pollution level, and other heavy metals were at a non-light pollution level. The results of potential ecological risk and potential adverse biological impacts indicated that the potential ecological risk index and toxicity effect of Gaozhou Reservoir were higher than those of other rivers, and Hg was the major contributor to heavy metal pollution. The three factors extracted from principal component analysis and positive matrix factorization represented natural sources, agricultural sources, and industrial sources, respectively. Therefore, in order to reduce the health hazards caused by heavy metals in sediments, a prevention and control system for the Hg element should be established.

Sublethal and lethal Cd toxicity in soybean roots specifically affects the metabolome, Cd binding to proteins and cellular distribution of Cd.

Soybean (Glycine max (L.) Merr.) plants were exposed to various Cd concentrations from background and low non-toxic (0.5-50nM) via sublethally toxic (< 550nM) to highly, ultimately lethally toxic (3µM) concentrations. Plants were cultivated hydroponically for 10 weeks until pod development stage of the control plants. The threshold and mechanism of sublethal Cd toxicity was investigated by metabolomics and metalloproteomics (HPLC-ICP-MS) measuring metal binding to proteins in the harvested roots. Spatial distribution of Cd was revealed by µXRF-CT. Specific binding of Cd to proteins already at 50nMCd revealed the likely high-affinity protein binding targets in roots, identified by protein purification from natural abundance. This revealed allantoinase, aquaporins, peroxidases and protein disulfide isomerase as the most likely high-affinity targets of Cd binding. Cd was deposited in cortex cell vacuoles at sublethal and bound to the cell walls of the outer cortex and the vascular bundle at lethal Cd. Cd binding to proteins likely inhibits them, and possibly induces detoxification mechanisms, as verified by metabolomics: allantoic acid and allantoate increased due to sublethal Cd toxicity. Changes of the Cd binding pattern indicated a detoxification strategy at lower Cd, but saturated binding sites at higher Cd concentrations.

Characteristics and influencing factors of metal distribution in different wetlands of the Liaohe Delta, Northeastern China

Metal distribution in different wetlands under the complex influence of natural and anthropogenic activities in the Liaohe Delta was analyzed to better protect and manage delta areas. Ninety-six soil samples were collected from six wetland types, and the levels, depth distributions, risk, and influencing factors of metals (i.e., As, Cd, Cr, Ni, Cu, Pb, Zn, Mn, Al, and Fe) were analyzed. The results showed that the concentrations of As, Cd, Cr, Ni, Zn, and Al in more than 70% of the soil samples were higher than the background value of Liaoning Province. The concentration of As decreased with distance from the estuary, while that of Cr was higher downstream of Liaohe. The spatial distributions of Cd, Ni, Cu, Pb, and Zn were similar. The concentrations of most metals in the topsoil were higher than those in the subsoil. According to the Nemerow pollution index, higher pollution was observed in the area far away from the Liaohe River and Bohai Sea for the topsoil layer, while for the subsoil layers, higher pollution was observed in the area near the Liaohe estuary. The correlation analysis showed that the wetland type was clearly correlated with Cd, Cu, Al, and S. The concentrations of Cd, Pb, Zn, C, N, P, and S and the electrical conductivity obviously decreased with soil depth, while the concentration of Mn was positively correlated with soil depth. Mn was negatively correlated with total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP), whereas Cd, Pb, and Zn showed positive correlation with TOC, TN, and total sulfur (TS). The general linear model indicated that wetland type had a significant effect on As, Cd, Ni, Cu, Pb, Zn, Al, and Fe (p&amp;lt; 0.01), while depth had a significant effect on Cd, Cr, and Pb (p&amp;lt; 0.01). The findings of this work will contribute to pollution control and ecosystem health conservation of the Liaohe Delta.

Spatial Distribution, Source Apportionment, and Ecological Risk Assessment of Soil Heavy Metals in Jianghugongmi Producing Area, Shandong Province

Taking the Jianghugongmi producing area as the research object, As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the soil of the study area were sampled and determined. The correlation of heavy metals was discussed using the multivariate statistical method, the spatial distribution interpolation analysis of heavy metals was carried out using ArcGIS 10.2, the quantitative source analysis of heavy metal pollution was carried out using the enrichment factor (EF) and PMF methods, and the potential ecological risk was evaluated. The results showed that the contents of the soil heavy metals As, Cd, Cu, Hg, Pb, and Zn were lower than the screening values specified in the standard for soil pollution risk control of agricultural land (GB 15618-2018), and the soil ecological environment risk was low; the maximum values of Cr and Ni exceeded the risk screening values, but the risk was low. The main distribution range of pH in the study area was 6.05-6.69, which was suitable for rice growth. The Mohe River indicated the spatial distribution of pH and heavy metals, which was closely related to the supergene geochemical characteristics of the elements. However, Hg and Cd showed different spatial distribution characteristics under human influence. Hg was distributed in the middle and high value distribution area along the west side of the river, and the spatial distribution of Cd was significantly different from north to south. The quantitative source analysis results based on the EF method and PMF showed that the main sources of heavy metals in the study area were agricultural sources, mixed sources, coal sources, and natural sources. The contribution rates of various sources accounted for 24.2%, 35.4%, 9.5%, and 30.9%, respectively. The medium strong ecological risk points of Hg in the study area were distributed along the west side of the Mohe River, whereas the moderate potential ecological risk points of Cd were concentrated in the cultivated land on both sides of the Mohe River, and the potential ecological risk index (Er) of the other elements was<40. Cd and Hg were the main potential ecological risk elements in the study area, whereas Cd was still the main potential pollution element in the cultivated land soil in the study area.

Spatial-Heterogeneity Analysis of the Heavy Metals Cd and Pb in Road Dust in the Main Urban Area of Harbin

To provide a scientific basis for pollution prevention and control of the urban environment, the current status of heavy-metal pollution in road dust in Harbin was studied. In total, 63 road dust samples in the main urban area of Harbin were collected, and the contents of Cd and Pb, two representative heavy metals, were detected. Using the Moran Index coupled with semi-variable function and geostatistical methods, the spatial correlation, variation structure, and distribution pattern were analyzed, and the estimated probability of the heavy metals exceeding the safety standard was determined. The study showed that: The mean concentrations of Cd and Pb were higher than the background values in Heilongjiang province, and both exhibited moderate variability, while the coefficient of variation of Cd was larger than that of Pb; Cd was weakly correlated in space and randomly distributed, Pb was moderately correlated in space and exhibited good spatial structure, and both were spatially aggregated. The optimal model for fitting the variance function showed that Cd was a spherical model, and Pb was an exponential model. The variation of Cd was mainly influenced by human factors, and the variation of Pb was influenced by both structural and random factors. The optimized interpolation results of the variance function had high accuracy, and the spatial distribution of Cd was elliptical, whereas the distribution of Pb was stripe-shaped, Cd was mainly influenced by traffic factors, such as industrial enterprise distribution and road painting, while Pb was influenced by natural factors such as river sediment or the study area belonging to a geologically high background area, in addition to the above factors. The estimated probabilities indicate a higher potential risk of Cd in the northeastern part of the study area.

Remediation of Cd-contaminated acid soil with shell powder-based nanocomposite

Soil acidification has negative effects on the sustainability of agricultural systems. In this present work, an acid soil amendment termed ASR was prepared with a nanocomposite consist of attapulgite (ATP), shell powder (SP), and red mud (RM), wherein ATP served as a nanocarrier. ASR could self-assembly to form a nanonetwork film around crop roots and hinder the input of H + and bivalent cadmium (Cd(II)) and the output of base cations (Ca 2+ and Mg 2+ and so on). Thus, ASR could effectively improve the pH of acid soil and meanwhile control the migration and spatial distribution of Cd(II), which reduced the bioavailable Cd(II) amount in the soil around crop roots. Note that pot experiment also indicated that ASR showed a positive effect on the growth of edible amaranths and significantly inhibited the uptake of Cd.

Effects of microbial organic fertilizer (MOF) application on cadmium uptake of rice in acidic paddy soil: Regulation of the iron oxides driven by the soil microorganisms

Rice often accumulates higher Cd from contaminated soils, thereby endangering human health. In this study, microbial organic fertilizer (MOF) was applied at the rate of 3, 4.5, and 7.5 t·MOF·ha−1, respectively, to passivate Cd in polluted soils. The goals of the field experiments were to understand how MOF reduces the uptake of Cd in rice by affecting the mobility and bioavailability of Cd in the rhizosphere soil. BCR sequential extraction analysis recorded that the addition of MOF decreased the content of available Cd and increased Cd residual fraction in soils. Compared with the control treatment, the application of 7.5 t·MOF·ha−1 significantly increased the yield of rice by 7.9% and decreased the Cd content in brown rice by 86.4%. The application of MOF strengthened the oxidation of iron by increasing the relative abundance of Fe-oxidizing bacteria (FeOB) Thiobacillus, and further increased the ratio of amorphous/dissociative iron oxides (Feo/Fed) and thickened the iron plaques on the root surface of rice. The spatial distribution of Cd and Fe on rice root indicated the key role of iron plaques in preventing Cd from entering rice. The structural equation model confirmed that MOF application regulated iron oxides by FeOB, dehydrogenase activity, and catalase activity, thereby reducing the Cd uptake of rice.

Is road-side fishpond water in Bangladesh safe for human use? An assessment using water quality indices

Pond water is used in everyday life by many people in Bangladesh, however, without sufficient and reliable information regarding water quality and pollution status. For this reason, geospatial analysis and mapping of water quality indices such as metal (MI), contamination (Cd), and physicochemical water quality index (WQI) were assessed to improve the understanding of potential pollution sources. Samples were collected from twenty randomly selected ponds situated in Jashore Sadar Upazila, Bangladesh. Nineteen (19) water quality parameters were measured, including pH, temperature, EC, TDS, total suspended solids (TSS), chloride, alkalinity, total hardness, salinity, Fe, Mn, Pb, Cr, Cd, Co, Zn, Ag, Ni, and Cu. The average concentration of Fe, Mn, Pb, Cd, and Ag was much higher than recommended standards. The WQI ranged from 1.59-5.27, Cd from -0.19-18.28, and MI from 7.81-26.28. The spatial distribution of MI indicates that the south-western and south-eastern region of the study area are stands out with a very high pollution pressure. The spatial distribution of Cd, follows the same trend as for MI. A multitude of different types of pollution sources contributes to the high pollution load such as, municipal wastewater, leachate from landfills, small industry wastewater and stormwater, and agricultural runoff. The studied pond water is highly polluted and not suitable for household use and fish consumption.

Cadmium, Chromium, and Cobalt in the Organs of Glyceria maxima and Bottom Sediments of the Pisa River and Its Tributaries (Poland).

The aim of the presented article was to determine whether human activity significantly influenced the enrichment of Cd, Co, and Cr, in river sediments and Glyceria maxima, in the basin of the Pisa River, an underdeveloped area in Poland. In this study, the content and spatial distribution of Cd, Cr, and Co in the organs underground and above ground, (sequentially: root, stem, leaf) of Glyceria maxima and bottom sediments of the Pisa River and its tributaries (Pisza Woda, Wincenta, Turośl and Skroda River) were analyzed. The Potentially toxic elements (PTEs) were determined by ASA method (Atomic Absorption Spectrometry). The results showed that the average PTEs contents in the river sediments occurred in the following descending order of Cd < Co < Cr. The highest values of the Igeo, CF coefficients, i.e., the greatest impact of anthropogenic activities on the water environment of the Pisa River and its tributaries, were found especially in the case of Cd. The research on the plant material has shown that the highest content of Cr and Co occurs in the roots, then in the stems, and the least in the leaves of Glyceria maxima. However, the amounts of Cd in the examined parts of Glyceria maxima had similar values. The content of Cd, Cr, and Co in the roots and above-ground parts exceeded the physiological values. Glyceria maxima can be used as a biological indicator material. Statistical analyzes showed the movement of PTEs in the sediment-root-stem-leaf system and identified the sources of PTEs, i.e., municipal wastewater treatment plants, the local food industry, and surface runoff.

Spatial Distribution Characteristics and Risk Assessment of Cadmium Pollution in Soil-crops system of an E-waste Dismantling Area

With the rapid development of electronic technology, soil heavy metal contamination caused by electronic waste dismantling activities has attracted the attention of many researchers. To investigate the contamination status and spatial distribution of Cd in soil-crop systems around an e-waste dismantling area, 171 pairs of soil and crop samples were collected for analysis. The concentrations of cadmium in root vegetable soil, leaf vegetable soil, solanaceous vegetable soil, and orchard soil were (1.292±0.647), (1.010±0.201), (0.921±0.125), and (0.861±0.135) mg·kg-1, respectively. The average values of cadmium in these four soil types were 10.0, 7.8, 7.1, and 6.3 times the background values of soil Cd in Zhejiang Province, respectively, and 4.31, 3.4, 3.07, and 2.72 times the risk screening values for soil contamination of agricultural land, clearly indicating cadmium accumulation in the soil. However, only a small percentage of crops contained cadmium levels that exceeded food safety limits. Moreover, different types of crops showed different capacities for cadmium enrichment and can be ranked accordingly: leaf vegetables > root vegetables > solanaceous vegetables > fruits. The single factor pollution index and the potential ecological risk assessment revealed severe Cd contamination in the study area, with a high potential ecological risk. Cadmium exposure posed a higher health risk for children than for adults. However, the single heavy metal cadmium pollution index does not indicate a threat to local residents at this time. Moran's I index and kriging interpolation results revealed that Cd has significant spatial autocorrelation, with high values mainly concentrating around the e-waste dismantling area, indicating a significant correlation with e-waste dismantling activities.

Spatial Distribution of Cd, Cu, Pb, and Ni in Dust, Plants, and Water along Jhang Road, Faisalabad

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Effect of Drag Coefficient Parameterizations on Air–Sea Coupled Simulations: A Case Study for Typhoons Haima and Nida in 2016

AbstractReasonable parameterization of air–sea momentum flux is important for the accuracy of ocean and atmosphere simulations, and in the numerical model, the parameterization of the air–sea momentum flux becomes a problem of parameterization of the sea surface wind stress drag coefficient (Cd). In this study, five kinds of typical Cd parameterization methods were assessed in the simulation of two typhoon cases, one of which was a supertyphoon and another was a common severe typhoon, based on an atmosphere–wave–ocean coupled model. Based on the two case studies, it was found that the typhoon path and minimum sea level pressure were not very sensitive to Cd parameterizations, though the spatial distribution of Cd and its variation with wind speed were all very different across the parameterization methods. However, Cd has a significant effect on the wind speed, and at high wind speed, the simulated maximum wind speed compared better with the observation in the experiment that adopted the Cd calculation method considering the effects of sea spray. Also, Cd plays an important role in the feedback processes between atmosphere and ocean during the typhoon process, through its effect on the air–sea heat and momentum flux, SST, ocean mixed layer depth, ocean currents, etc. The results of this study answered the question of how the Cd affects the atmosphere and ocean during the typhoon process, and to what extent they are affected, which can help to explain or even further improve the simulation results.

Characteristics of Cadmium Enrichment and Pollution Evaluation of a Soil-Crop System in a Typical Karst Area

In order to study the characteristics and factors influencing Cd accumulation in surface soils and crops in karst areas, and to provide a theoretical basis for safe land use, 360 surface soil samples, 7 deep soil samples, and 85 rice samples were collected from central Qianjiang District, Chongqing. The samples and 73 corn samples (corresponding to root-zone soil samples), were analysed to determine the content of Cd, TFe2 O3, Mn, organic matter (Corg), Se, and pH. Based on geostatistical analyses, the spatial distribution and Cd enrichment of the surface soils were determined and a safety evaluation for the soil and crops was carried out. The results showed that the spatial distribution of Cd in the surface soil was uneven, with the surface layer showing significant enrichment. This pattern was controlled by the soil parent material and human activities. The enrichment of surface layer was mainly affected by iron manganese oxides and organic matter (Corg). Soil Cd was mainly found at 'non-polluted' and 'lightly polluted' levels, although some areas present strong ecological risks. The main contaminated area occurs in association with Permian strata, demonstrating a geological control on soil Cd pollution. Slight-to-severe Cd pollution was identified in bulk crops; the recommended daily consumption limit for rice is 0.87 kg·d-1 and corn is 1.53 kg·d-1. The bioavailability of Cd is affected by soil pH and Se content. Under acidic conditions, Cd bioavailability is high, and crops in areas with high soil Se are safer. It is recommended that crops with low Cd accumulation are planted in the Permian outcrop area of Shuitian Township, or alternatively, soil pH should be adjusted to control the risk of Cd pollution and ensure safe land use. In addition, planting crops in areas with high soil Se content is preferable.

Distributional Characteristics and Source Identification of Cadmium in Soils of the Pearl River Delta, China.

The results of the Multi-Purpose Geochemical Survey in the Pearl River Delta (PRD) show that the pollution is serious. In this study, the influence of geological genesis, soil-forming process, and human activities on soil quality in PRD is analyzed, and the influence factors, genesis and spatial distributional characteristics of cadmium (Cd) in different soil depths are studied by inverse distance weighted (IDW) and hot spot analysis. The results show that the spatial distribution of Cd is significantly different in PRD and high-value is mainly concentrated in the central cities of Guangzhou-Foshan-Jiangmen-Zhongshan-Zhuhai. Moreover, hot spots with higher Cd content in deep are mainly along Beijiang, Dongjiang, and Pearl River Estuary (PRE). Overall, our findings suggest that the high background value areas formed by marine-land and fluvial sediments as well as intensive human activities that make PRD become an area under the dual restriction of geological genesis and human activities, pollution control cannot be ignored.

Health risk assessment of heavy metal pollution in a soil-rice system: a case study in the Jin-Qu Basin of China

A regional field survey of a total of 109 pairs of soil and rice samples was conducted to evaluate the health risks posed by heavy metals in the Jin-Qu Basin, China. The studied soils are characterized by acid (pH in mean level of 5.5), carbon rich (soil organic matter in mean of 33.6 g kg−1) and mainly contaminated by Cd (42.2% samples exceeded the standard value of 0.3 mg kg−1 (GB15618-2018)). The spatial distributions of Cd, Pb and Zn exhibited similar geographic trends. 34% and 30% of the rice samples containing Cd and Pb exceeded the threshold value of 0.2 mg kg−1 (GB2762-2017), respectively. The risk estimation of dietary intake had a target hazard quotient value of Cd of 0.918 and a hazard index value for rice consumption of 2.141. Totally, Cd and Pb were found to be the main components contributing to the potential health risks posed by non-carcinogenic effects for local inhabitants.

Detail investigation of toxicity, bioaccumulation, and translocation of Cd-based quantum dots and Cd salt in white mustard

In this study, a model crop plant white mustard (Sinapis alba L.) was treated with an aqueous dispersion of silica-coated CdTe quantum dots (CdTe/SiO2 QDs) in a 72-h short-term toxicity test. The toxicity was established via measurements of (i) the root length and (ii) the chlorophyll fluorescence. These results were compared to two other sources of cadmium, free Cd ions (CdCl2) and prime un-shell nanoparticles CdTe QDs. Tested compounds were applied in concentrations representing 20 and 200 μM Cd. The uptake and translocation of Cd were investigated using inductively coupled plasma optical emission spectrometry (ICP-OES) and the spatial Cd distribution was investigated in detail applying laser induced breakdown spectroscopy (LIBS). The LIBS maps with a lateral resolution of 100 μm were constructed for the whole plants, and maps with a lateral resolution of 25 μm (micro-LIBS arrangement) were used to analyse only the most interesting parts of plants with Cd presence (e.g. root tips or a part crossing the root into the above-ground part). Our results show that the bioaccumulation patterns and spatial distribution of Cd in CdTe/SiO2 QDs-treated plants differ from the plants of positive control and CdTe QDs. Fluorescence microscopy photographs revealed that CdTe/SiO2 became adsorbed onto the plant surface in comparison to CdTe QDs. Further, a physico-chemical characterization of QDs before and after the test exposure showed only minor changes in the nanoparticle diameters and no tendencies of QDs for agglomeration or aggregation during the exposure.

Spatial Distribution and Bio-accumulation of Cadmium and Lead in Soil, Rice and Vegetables in Typical Pollution Areas, China

The adverse effects of Cd and Pb on human health have been widely reported. While, there were several typical pollution areas in China which has not been investigated comprehensively and deeply. In this study, 475 soil and 472 plant samples from these pollution areas were analyzed for Cd and Pb with ICP-MS. Here, the pollution levels of different areas were analyzed and compared; the spatial distributions in soil, rice and cabbage samples were illustrated in map; and the relationships of Cd and Pb in soil and rice, soil and cabbage were also discussed. The results showed that Cd pollution still existed in some south, central-south and south-east zones except other three zones located in suburb of Tianjin, north-east and north China which might be explained by the higher background values, soil acidity, Karst landscape and metallurgy industry. Comparatively, the Pb concentrations showed lower over-standard rate. Moreover, the spatial distribution of Cd and Pb in rice and cabbage showed similar trends with those of soil samples. Particularly, the average Cd and Pb concentrations in lettuces were much higher than those in other plants. Cd and Pb concentrations in rice and cabbage showed low linear dependence with the concentrations in soil. The results in this study added basic environmental data and would be helpful to future soil remediation of these areas.