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China is not only a main source area of Asian dust but also a significantly affected area of dust deposition in the world. However, the influence range of Asian dust deposition and its influence on soil provenance remains unclear, particularly in subtropical regions. This study identified the substantial effect of Asian dust on soils and quantified its contribution to subtropical soils of China. Three soil profiles derived from basalt in subtropical area (Shaoxing, Zhejiang, China) were selected and sampled. The pH, bulk density, and cation exchange capacity (CEC) of soils were determined. The Neodymium (Nd) and Thorium (Th) concentrations and Nd isotope of soils were determined. We used the Nd elemental and isotopic geochemistry to assess the deposition of Asian dust in soil profiles (up to 1 m depth). The upper soil layers have negative $${\varepsilon }_{Nd}(0)$$ values, which were close to those of Asian dust $${\varepsilon }_{Nd}\left(0\right)=-3.30)$$ , indicating the input of Asian dust to soils. Further, the high dust-derived Nd proportion in the soils $${(f}_{dust}^{Nd}=43\%)$$ also suggested a great contribution of Asian dust on soils. A comparison of Nd in the soils from subtropics (Zhejiang province, Southeast China) and tropics (Hainan province, China’s southernmost point) indicated that both regions were influenced by Asian dust but at different degrees. Asian dust has been identified as a vital source of Nd in subtropical soils of China. The high mass fraction of dust-derived Nd in the soil profiles indicated the important role of dust input in soil genesis. The results also suggest that Nd isotopes are powerful fingerprints in tracing the origin of soil materials.

Different amendments have diverse adsorption capacity for heavy metals. The objectives of this study were to evaluate adsorption efficiency of different kinds of amendments for heavy metals and to provide theoretical guidance for alleviation of heavy metals. The indoor oscillating experiments were carried out to investigate the adsorption efficiency of five amendments (i.e., lime, illite ilerite, ground phosphate rock, chitin, and corn straw charcoal) for adsorption capacity of heavy metals (i.e., Zn, Pb, and Cd). The adsorption efficiency of lime for Zn and Cd was 99.64% and 99.99% followed by chitin with adsorption efficiency of 74.94% and 81.63% respectively. The adsorption efficiency of amendments for Pb, Zn, and Cd was increased gradually with adsorption time. The adsorption efficiency has gradually reached a stable stage after certain time. In addition to adsorption of Pb by corn straw charcoal, the other four materials (i.e., lime, illite ilerite, ground phosphate rock, and chitin) have reached equilibrium when pH value was 3. The adsorption efficiency of lime (1%) for Zn was highest (99.98%). The adsorption efficiency of other materials for Pb was enhanced with increase in dosage except for chitin; however, the unit adsorption capacity was not decreased. It is concluded that adsorption efficiency of lime and chitin for heavy metals such as Zn, Pb, and Cd was more than illite ilerite, ground phosphate rock, and corn straw charcoal, which can be considered as an active sorption materials.

Biochar is an important material for remediation of contaminated soils, however, different biochars have variable effects on bioavailability of heavy metals. This experiment revealed that peanut shell biochar (PSB) has highest reduction of 78% concentration of Pb in plant roots. The maize straw biochar (MSB) has significantly decreased Zn and Cd concentration (mg/kg dry weight) in Chinese cabbage than other treatments of biochars. The plants of Chinese cabbage have exhibited an efficient transport capability for Zn and Cd. The biochars have reduced exchangeable form of Cd/Zn, enhanced residual heavy metals, and consequently diminished accumulation of heavy metals in plants. The straw block biochar (SBB), PSB and MSB have efficiently relieved the stresses of heavy metals in plants.

Fertilization changes the soil organic carbon (SOC) composition, affecting the carbon cycle of paddy soil. Understanding the mechanisms of physical fraction and chemical composition of SOC responding to fertilization can help regulate the nutrient release and carbon sequestration. However, it is unclear whether these changes in SOC composition to fertilization are consistent and how these are regulated by biotic and abiotic properties. Therefore, a positioning experiment in a rice field was conducted with a total of nine treatments. Chemical fertilizers (0, 337.5, and 675 kg ha

Nitrogen (N) fertilization is known to have a substantial effect on heavy metal uptake in plants. However, the impact of N fertilization on plant growth and heavy metal uptake of hyperaccumulator plants remains unclear. This study examined the effect of N fertilization on growth and uptake of zinc (Zn) and cadmium (Cd) in Zn/Cd-hyperaccumulating plants species, Sedum alfredii (S. alfredii) Hance (Crassulaceae). Plants of S. alfredii were grown for 60 days in nutrient solution with 100 μmol Cd L−1 and 0–10 mmol N L−1, and in a Cd-contaminated soil receiving N fertilizer and composted pig manure amendment. Biomass production, nutrient uptake, and concentrations and accumulation of Zn and Cd in plant parts were measured. In the hydroponic experiment, both low ( 5 mmol L−1) N supply decreased the growth and Zn and Cd accumulation in the whole plants. The 2.5 mmol N L−1 is an optimal N dosage for shoot biomass production and Zn accumulation in shoots, while the 1.0 mmol N L−1 is an optimal N dosage for Cd accumulation in shoots, which was 68.1% higher than the control. The N doses of 1 to 2.5 mmol L−1 N represented optimal conditions for Zn and Cd accumulation in the shoots of S. alfredii seedlings. In the soil pot experiment, shoot dry weight decreased with increasing N fertilization rate, while composted pig manure decreased biomass production. Both Zn and Cd accumulation in the shoots of S. alfredii decreased along with the addition of higher N fertilization rate. However, the composted pig manure amendment increased the accumulation of Zn, but not Cd in the shoots. The application of N at appropriate amount enhanced the phytoremediation efficiency by S. alfredii in Zn/Cd-polluted fields, but the effectiveness of phytoextraction technology needs to be validated in the field trials.

Improving soil quality, reducing waste, and mitigating climate change require an understanding of the balance between soil organic carbon (SOC) accumulation and depletion after the application of different quantities of fungal residue and chemical fertilizers. We evaluated the mineralized carbon (MC) content and mineralization rate (MR) after nine applications of chemical fertilizers (C) and fungal residue (F) in paddy fields, at rates of 0, 50, and 100%. A double exponential model was used to calculate the potential rates of MC and SOC turnover. The combined application of fungal residue and chemical fertilizers led to significantly higher MC and MR, by 24.97-100.05 and 24.36-98.07%, respectively, during 57 days of incubation than that of the control. The MC and MR values were highest with the C

Intercropping is a promising technique for remediation of soils contaminated with heavy metals. Organic acids can increase the availability of heavy metals in soil. Our aim was to assess the effect of oxalic acid as an activator for hyperaccumulator–landscape plant intercropping to efficiently restore contaminated soil with low cost. The hyperaccumulator plant (Sedum plumbizincicola) was intercropped with selected landscape plants: Oxalis corniculate (ground cover plant), Calendula officinalis (grass flower plant), and Buxus sinica (shrub). The effects of 11 mmol kg−1 oxalic acid treatment on growth and Cd accumulation capacity of Sedum plumbizincicola–landscape plants intercropping systems were evaluated in a 76-day pot experiment. Oxalic acid has increased the availability of Cd in soil. The biomass of Sedum, Oxalis, and Buxus plants was higher in treatment of oxalic acid than without oxalic acid. The biomass, chlorophyll, and catalase contents of Calendula were lower in treatment of oxalic acid than without oxalic acid, which indicated severe stress caused by enhanced availability of Cd. The malondialdehyde contents of Calendula and Buxus were higher in treatment of oxalic acid, which indicates that higher Cd availability has resulted damage of membrane. The free proline contents of Calendula and Buxus were higher in treatment of oxalic acid. The Cd content of Sedum plants was higher in treatment of oxalic acid than lower Cd in landscape plants with no application of oxalic acid. It is concluded that oxalic acid has a positive effect on remediation efficiency of Sedum plumbizincicola-Oxalis and Sedum plumbizincicola-Buxus intercropping systems. Oxalic acid has enhanced remediation efficiency of hyperaccumulator-landscape plants intercropping which has offered a new, useful and practical technique for remediation of urban soils with low-level Cd contamination.

Pot experiment was conducted to investigate the effects of wood biochar (5%), bamboo biochar (5%), rice straw biochar (5%) and Chinese walnut shell biochar (5%) on growth, accumulation of heavy metals in moso bamboo, soil physical properties, and solubility of heavy metals in soil. The results revealed that dry weight of moso bamboo was significantly increased in treatments of wood biochar (5%), rice straw biochar (5%) and Chinese walnut shell biochar (5%) except bamboo biochar (5%). Application of straw biochar (5%) was most effective in enhancing plants biomass, with increase of 157%, 113% and 111% in leaves, roots and stems of moso bamboo. All treatments of biochar have significantly improved soil electrical conductivity with maximum increase of 360% compared to CK. In case of heavy metals accumulation, application of 5% bamboo biochar, straw biochar and Chinese walnut shell biochar has reduced Cu uptake in roots by 15%, 35% and 26%, respectively. The biochars have significantly reduced solubility of soil heavy metals with maximum reduction of 58.91 mg kg−1 and 10.59 mg kg−1 of Cu and Pb with application of rice straw biochar. It is concluded that dry weight of moso bamboo was significantly enhanced by all treatments of biochar except bamboo biochar.

Environmental pollution caused by electrical waste (E-waste) dismantling has attracted much attention from environmental researchers in China and worldwide. A total of 90 topsoil samples, 10 soil profile samples and 14 groundwater samples, were collected from a typical E-waste dismantling area in southeastern China. The spatial and vertical variations of potentially hazardous metals (PHM) in paddy soils and their potentially ecological risks were studied. The results showed that the mean total concentrations of five PHM (Cd, Cu, Pb, Zn and Ni) in paddy soils were 0.38, 35.13, 35.40, 121.38 and 28.13 mg kg−1, respectively. The total Cd, and Pb concentrations in paddy soils had strong variability coefficients of 121.05% and 109.38%, respectively. Compared with the background values in Zhejiang province, the PHM were enriched in paddy soils. Part of the study area was seriously contaminated by these metals. The soil was contaminated with Cd, with high Pi Ave value (>1). The shallow groundwater was also contaminated by Cd in the E-waste dismantling area. Results of vertical variations of PHM in soils revealed significant accumulation of PHM in the topsoil (0–20 cm, 20–40 cm). Soil pH and organic matter (SOM) was significantly correlated with most of the total PHM in soils. Kriging interpolation and Moran's I were used to identify the contaminated hotspots of these PHM. It was found that high soil Cd, Cu, Ni, Zn were located in Da Xi and Zhe Guo towns, which was attributed to E-waste dismantling and other anthropogenic activities. Soil Ni was mainly influenced by the parent material. The PHM in soils may pose a potential threat to local ecosystem and human health.

With the rapid economic expansion, environmental degradation has become increasingly sever during the past three decades. Soil pollutions associated with toxic organic compounds and heavy metals have been identified in China. The accumulation of heavy metals in soils and its impact on food safety is of increasing concern. It has been reported that more than 20 million ha of land have been contaminated with heavy metals that can result in the potential health risks to human beings and soil ecosystems. This can potentially jeopardize the food security in China. Accumulation of heavy metals in suburb and rural soils is closely related to many anthropogenic activities, such as application of fertilizers and pesticides, irrigation of wastewater, discharge of mining, improper disposal of metal containing wastes, land application of animal manures, sewage sludge and coal combustion residues. Arable crops and vegetables in suburb and rural can take up heavy metals from contaminated soils, which is one of the main pathways of introducing heavy metals to human food chain. Events related to soil and vegetable contamination, food safety and human health risks, e.g., rice and vegetables with elevated concentrations of cadmium, are often reported in the media in recent years. The Chinese government has recently developed a number of new policies for prevention of soils from further soil contamination, and remediation of contaminated soils. This presentation will provide a comprehensive review on heavy metal pollution in soils and its impacts on food security in China, and also summarize some new technologies for remediation of soils contaminated with heavy metals.

Combining biochar with irrigation management to alter the microbial community is a sustainable method for remediating soils contaminated by heavy metals. However, studies on how these treatments promote Cr(VI) reduction are limited, and the corresponding microbial mechanisms are unclear. Therefore, we conducted a pot experiment to explore the responses of soil microbial communities to combined biochar amendment and irrigation management strategies and their involvement in Cr transformation in paddy soils. Six treatments were established using varying concentrations of biochar (0, 1, and 2% [w/w]) combined with two irrigation management strategies (continuous flooding [CF] and dry-wet alternation [DWA]). The results showed that the combined biochar addition and irrigation management strategy significantly altered soil pH, redox potential, organic matter content, and Fe(II) and sulfide concentrations. In addition, the Cr(VI) concentration under CF irrigation management was conspicuously lower (48.2-54.4%) than that under DWA irrigation management. Biochar amendment also resulted in a substantial reduction (8.8-27.4%) in Cr(VI) concentration. Moreover, the changes in soil physicochemical properties remarkably affected the soil microbial community. The microbial diversity and abundance significantly increased with biochar amendment. Furthermore, the combined biochar amendment and CF strategy stimulated the growth of Geobacter- and Anaeromyxobacter-related Fe(III)-reducing bacteria, Gallionella-related Fe(II)-oxidizing bacteria, and Desulfovibro- and Clostridium-related sulfate-reducing bacteria, which simultaneously facilitated the generation of Fe(II) and sulfide, thereby enhancing Cr(VI) reduction. Consequently, our results suggest that the effectively increased abundance of Fe-reducing/oxidizing bacteria and sulfate-reducing bacteria via combined CF irrigation management and biochar addition may be a key factor in reducing Cr(VI) in paddy soil. The keystone genera responsible for Cr(VI) reduction were Geobacter, Anaeromyxobacter, Gallionella, Desulfovibro, and Clostridium. This study provides novel insights into the coupling mechanism of the Fe/S/Cr transformation mediated by Fe-reducing/oxidizing bacteria and sulfate-reducing bacteria.

Wheat is the second most important food crop worldwide, which is prone to accumulate cadmium (Cd). Accumulation of Cd in wheat grains depends not only on wheat genotype, but also largely on the availability of soil Cd and its internal distribution. In this study, several experiments were used to achieve low-grain Cd content: a field trial for wheat genotype screening, a soil incubation experiment to test passivation effect of bamboo biochar on soil Cd, and a soil pot experiment to examine bamboo biochar effect on wheat grain accumulation. The results showed that of the 243 wheat cultivars tested, the variation range of grain Cd content was 0.365–1.243 mg/kg, in a field with soil Cd of 3 mg/kg. The application of bamboo biochar reduced soil Cd availability, among which 5.0% bamboo biochar treatment had the greatest effect. The content of available Cd in soil treated with 5.0% bamboo biochar decreased by 0.32 mg/kg compared with the control in a 120-day incubation experiment. Effect of bamboo biochar (0, 0.1%, 1.0%, and 5.0%) on reducing grain Cd content in two wheat genotypes (Mianyou-1 and 1279–9) was investigated. The application of bamboo biochar decreased Cd uptake by plants, while distribution of Cd in different wheat plant parts was more controlled by the plant genetic characteristics. Compared with the control, Cd content in roots, straw, and grains was decreased by 34.06% (P

The contamination of soil with heavy metals is a severe problem due to adverse impact of heavy metals on environmental safety and human health. It is essential to remediate soil contaminated with heavy metals. This study has evaluated the effects of pine biochar, kaolin, and triple super phosphate (TSP) on multiple heavy metals (Ni, Zn, Cu, and Cd) in contaminated soil and accumulation of heavy metals in plants. The amendments can reduce availability of heavy metals in soil by increasing pH, adsorption, complexation, or co-precipitation. Different amendments have variable effects on accumulation of heavy metals in plants and in soil due to its diverse mechanism of stability. The results showed that application of triple super phosphate (TSP) has significant reduced soil Cd exchangeable (EXC) fraction from 58.59 to 21.30%. Bound to carbonates (CAR) fraction decreased from 9.84 to 5.11%, and bound to Fe-Mn oxides (OX) fraction increased from 29.61 to 69.86%. The triple super phosphate (TSP) has the ability to stabilize Cu and especially Cd. However, triple super phosphate (TSP) has enhanced ecological risk of Zn and Ni. Application of pine biochar has significantly enhanced soil pH. The kaolin has significantly reduced EXC fraction of Cd and increased OX fraction of Cu. The amendments and heavy metals have not caused significant effect on SPAD value of Buxus microphylla Siebold & Zucc (B. microphylla). The triple super phosphate (TSP) has significant decreased biomass of B. microphylla and bamboo-williow (Salix sp.) by 24.91 and 57.43%, respectively. Pine biochar and kaolin have increased the accumulation of Zn and Cd in plants. It is concluded that triple super phosphate (TSP) was effective in remediation of Cd and kaolin was effective in remediation of Cd and Cu. Pine biochar was effective in remediation of Cd, Cu, and Zn.

The field trial was conducted to investigate remediation effects of two alkaline fertilizers and three water management techniques on Cd contaminated paddy soil. The results revealed downward trend of soil pH and EC during growth period of rice. The treatment of organic fertilizer has indicated high pH and organic matter than treatment of calcium magnesium phosphate fertilizer. The integrated effect of organic fertilizer and continuous flooding (COF) has significantly (p 0.05) reduced soil Eh to -180 mv at booting stage. The exchangeable Cd of soil decreased with growth of rice in all treatments. The continuous flooding has showed lowest content of soil exchangeable Cd at every stage of rice growth than other treatments. The organic fertilizer, calcium magnesium and phosphorus have promoted growth of rice. The treatments of continuous flooding were most effective in reducing Cd content in rice grain by 12.6-51.9%. The treatments of continuous flooding have lowest TF

The antioxidation system and accumulation ability of Moso bamboo (Phyllostachys pubescens), which is a valuable remediation material with large biomass and rapid growth rate were studied in hydroponics and pot experiments. In hydroponics experiment, TBARS concentrations and SOD activities decreased with increase of Pb treatments. The activities of POD boost up with elevated Pb treatments, and reached peak level with application of 400μM Pb. Proline concentrations reduced with application of 20μM Pb and then enhanced consistently with application of 100 and 400μM Pb. The biomass of Moso bamboo improved with increase of Pb treatments upto 400mgkg-1, and then decreased with application of each additional increment of Pb in pot experiment. Application of 800mgkg-1 Pb showed significant increase of photosynthetic pigments, however, non significant variation was observed for other treatments. The Pb concentration in roots, stems and leaves attained 523mgkg-1, 303mgkg-1 and 222mgkg-1 respectively with application of 1600mgkg-1 Pb compared with control. Analysis of TEM-EDX revealed that Pb in cell was mostly concentrated in cytoplasm then in cell wall and followed by vacuole. It is concluded that Moso bamboo may be potential remediation species for phytoremediation in low Pb contaminated soils.

The potentially toxic trace elements (PTEs) transfer characteristics in the soil-rice system plays an important role in soil quality management, and it can be used to guide the safe rice production. We collected soil and rice samples from three typical rice production areas (Nanxun, Shengzhou, Wenling in northern, central, and southern parts of Zhejiang Province, China). The controlling factors of PTEs&prime, transfer were studied for Hybrid rice and Japonica rice. The results indicated that the pH, organic matter (OM), and electrical conductivity (EC) values of Shengzhou were all lower than that of the other two production areas (Nanxun and Wenling). The concentrations of PTEs in the soils of Wenling were significantly higher than that in the other two areas, while the concentrations of PTEs in the rice of Shengzhou were significantly higher than that of Wenling and Nanxun (p &lt, 0.05). The enrichment index (EI) of PTEs were also different in the three production areas. The EIs of Cd and Zn were higher than that of Cu and Ni in the three production areas, and the EIs in Shengzhou were significantly higher than that of other two areas (p &lt, 0.05). The soil physico-chemical properties and PTEs&rsquo, fractions both played important roles in PTEs transfer in the soil-rice system. The log-linear model of EI for PTEs can predict the availability of PTEs in the soil-rice system under practical production areas. The accuracy of the model prediction of EI for Japonica rice was better than that for the Hybrid rice. The prediction model of Ni was better than that of other PTEs for both rices.

The biochars are efficient adsorbent of heavy metals. However, the type of biochar species determines the effectiveness of biochars for immobilization of heavy metals. In this experiment, we mixed different biochars in variable mass ratios and evaluated their effects on plant growth and bioavailability of heavy metals. The results revealed that amendment of single and mixed biochars has increased pH, EC, available P and K of soil. The straw block biochar with maize straw biochar at a mass ratio of 1:2 (SDM) has significantly decreased Pb and Cu concentration in soil. The straw block biochar with maize straw biochar at a mass ratio of 2:1 (DSM) has highly increased the dry biomass of Chinese cabbage than single biochar or control, whereas plant physiological properties were mostly not affected. It is concluded that peanut shell biochar with maize straw biochar at a mass ratio of 2:1 (DPS) and DSM have significantly decreased Pb, Zn and Cu concentration in plants. The single peanut shell biochar has significantly decreased the plant Cd concentration. The ability of transport of heavy metals in Chinese cabbage was in the sequence of Cd > Zn > Cu > Pb. The mixing of different biochars has decreased the concentration of heavy metals in plants more effectively than single biochar.

Urban soils are strongly related to human health. In this study, Lin&rsquo, an city was chosen as a typical small-scale city with which to study the spatial variation of potentially hazardous metals (PHMs) in urban soils and their potential ecological risks using multivariate analysis, geostatistics and GIS techniques. A total of 62 soil samples were collected from the study area. The results showed that the average concentrations of total soil Mn, Cu, Zn, Pb, Cr, Cd were 439.42, 42.23, 196.80, 62.55, 63.65, 0.22 mg&middot, kg&minus, 1, respectively. Compared with the background values and the environmental quality standards, these PHMs were accumulated in urban soils to some extent. The single potential ecological risk indices of PHMs indicated that Pb and Cd had relatively high ecological risks. The pH and most of the PHMs had significant correlations (p &lt, 0.05). The principle components analysis (PCA) showed that Pb, Zn and Cu had similar pollution sources related to the vehicles&rsquo, exhaust emission, Mn and Cr were mainly from the parent materials, while Cd was from the emission of industrial manufactories. The spatial structures and distributions of PHMs and their corresponding available fractions had strong/moderate spatial autocorrelation, which were influenced by human activities.

Application of activating agents can significantly improve efficiency of plants for remediation of soils contaminated by heavy metals, however, damage to soil and plants limits application of traditional activating agents. The aim of our experiments is to select an efficient,green and low-cost activating agent to improve efficiency of plant extraction technology. In this study, contaminated soil was remediated by Sedum alfredii. The effects of two plant extracts (i.e., Oxalis corniculata,OX and Medicago sativaextract, ME) in addition to citric acid (CA) were studied in oscillatory activation experiment and pot experiment. The oscillation activation experiment revealed that extraction quantity of heavy metals in the soil was enhanced significantly with concentration of plant extract. The extraction quantity of Zn from 100% OX extract and ME extract were significantly higher than 10 mmol/L CA (54.04% and 33.09%, respectively). The 10 mmol/L CA has best extraction efficiency for Cd, up to 41.36 µg/kg, which is significantly higher than CK (control) (p

The intensive human activities are the major cause of heavy metals pollution in suburban farmland, which poses threats to soil environment and safety of agricultural products. The combination of spatial analysis (SA), principal component analysis (PCA), input fluxes analysis (IFA) and UNMIX model have precisely analyzed the sources and relative contribution of heavy metals from each source. The results revealed that average contents of Cr, Ni, Cu, Zn, Pb and Cd were 37.82, 13.65, 17.93, 93.78, 48.84 and 0.24 mg kg−1, respectively. The spatial distribution indicated that parent materials, industrial activities and traffic emissions had significant effects on contents of heavy metals in topsoil. According to UNMIX model, the contribution rates of soil parent material, industrial/ traffic emissions, and agricultural activities to heavy metals in soil were 49.15%, 35.00% and 15.85% respectively. Which indicated largest contribution of natural sources, but input of human activities including industry, transportation and agriculture could not be ignored. The input fluxes analysis (IFA) reveals that atmospheric deposition was main source of heavy metals in soil, followed by fertilizer and irrigation. This study has presented reliable methods for analysis of sources of heavy metals in suburban farmland soil. The combination of UNMIX and IFA can accurately identify and quantify pollution sources.

Moso bamboo (Phyllostachys pubescens (Pradelle) Mazel ex J.Houz.) is recognized as a potential phytoremediation plant due to its huge biomass and high tolerance to environmental stresses. The objectives of this study were to investigate mechanism related to cadmium (Cd) tolerance and to evaluate Cd accumulation capacity of moso bamboo. The results of the pot experiment showed that Cd accumulation by bamboo increased with increasing the Cd levels in soil and the values in stem ranged from 28.51 to 132.13 mg kg(-1). Meanwhile chlorophyll in leaves and total biomass showed a decreasing trend. The bioaccumulation factors (BAF) for roots and stem in all the treatments were more than 1.0 and the translocation factor (TF) ranged from 0.70 to 1.06. In hydroponics experiment, the concentrations of malondialdehyde (MDA) in the leaves were significantly increased in Cd treated plants as compared with control. The activities of superoxide dismutase (SOD) and peroxidase (POD) were enhanced at initial stage and then decreased consistently with the increase of Cd addition. The proline concentrations were also increased due to the presence of Cd, particularly at 25 μM Cd treatment. According to TEM-EDX analysis, the cytoplasm was the main site for accumulation of Cd in moso bamboo. On the basis of overall results, it is suggested that moso bamboo could be successfully used for the remediation of low Cd (no more than 5 mg kg(-1)) contaminated soils.

Chinese hickory (Carya cathayensis Sarg.) is a famous woody nut in China. Currently, there is an increasing concern related to the soil heavy metal pollution in Chinese hickory plantations. In this study, a total of 188 soil samples were collected from Lin’an city, a typical Chinese hickory production area. The results showed that the average background concentrations of Cd, Cu, Zn, Pb, Ni and Cr in soils were 0.37, 40.76, 87.61, 30.10, 28.33 and 56.57 mg kg−1, respectively. The Cd and Pb concentrations in Chinese hickory plantation soils had strong variability coefficients of 186.49% and 95.42%, respectively. Compared with the background values in Zhejiang province, the heavy metals were enriched in the plantation soils. The accumulation ratio followed the order of Cu > Cd > Pb > Ni > Zn > Cr. Part of the study area was seriously contaminated by Cd and Cu, as 31.38% of soil Cd and Cu samples exceeded the second grade standardized value of Environmental Quality Standards of Soils (EQSS). The soils in our study area generally reached a moderate ecological risk, as its average RI value reached 103. Moran’s I and Kriging interpolation results revealed that all the studied heavy metals in soils had clear spatial distribution patterns. The high values of soil heavy metals (except Pb) were mainly distributed in the localities closest to the mine area. The apportionment of heavy metal pollution sources showed that the Cu, Ni and Cr in soils were mainly related to mining activities, Pb was closely related to fertilizer application, Cd and Zn were related to both. The heavy metals in soils may pose a potential threat to local ecosystem and human health. Our results implied that soil heavy metals should be tested, and risk-based management should be performed in the economic plantations in China. These maps could provide useful information for forestry and environmental management.

Biochar is a carbon-rich solid material derived from the pyrolysis of agricultural and forest residual biomass. Previous studies have shown that biochar is suitable as an adsorbent for soil contaminants such as heavy metals and consequently re- duces their bioavailability. However, the long-term effect of dif- ferent biochars on metal extractability or soil health has not been assessed. Therefore, a 1-year incubation experiment was carried out to investigate the effect of biochar produced from bamboo and rice straw (at temperatures ≥500 °C) on the heavy metal (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) extract- ability and enzyme activity (urease, catalase, and acid phospha- tase) in a contaminated sandy loam paddy soil. Three rates (0, 1, and 5 %) and two mesh sizes (

A hydroponics experiment was aimed at identifying the lead (Pb) tolerance and phytoremediation potential of Moso bamboo (Phyllostachys pubescens) seedlings grown under different Pb treatments. Experimental results indicated that at the highest Pb concentration (400 μmol/L), the growth of bamboo seedlings was inhibited and Pb concentrations in leaves, stems, and roots reached the maximum of 148.8, 482.2, and 4282.8 mg/kg, respectively. Scanning electron microscopy revealed that the excessive Pb caused decreased stomatal opening, formation of abundant inclusions in roots, and just a few inclusions in stems. The ultrastructural analysis using transmission electron microscopy revealed that the addition of excessive Pb caused abnormally shaped chloroplasts, disappearance of endoplasmic reticulum, shrinkage of nucleus and nucleolus, and loss of thylakoid membranes. Although ultrastructural analysis revealed some internal damage, even the plants exposed to 400 μmol/L Pb survived and no visual Pb toxicity symptoms such as necrosis and chlorosis were observed in these plants. Even at the highest Pb treatment, no significant difference was observed for the dry weight of stem compared with controls. It is suggested that use of Moso bamboo as an experimental material provides a new perspective for remediation of heavy metal contaminated soil owing to its high metal tolerance and greater biomass.

The effects of zinc (Zn) on seed germination and growth of Moso bamboo (Phyllostachys pubescens) were investigated. Under zinc stress, the seed germination rate did not show significant difference from that of the control. Hydroponics experiments indicated that Moso bamboo had a strong ability to accumulate Zn in the shoot and it reached its maximum value in the shoot at 100 μM Zn. The root Zn concentration ranged from 2,329.29 to 8,642.51 mg kg(-1), with the root Zn concentration at 10 μM Zn being 58.23 times that of the control. The root morphology parameters slightly increased at the lower Zn treatments, while growth restriction was evident at higher Zn treatments. Root ultrastructural studies revealed that the cell structure, root tips, and organelles were significantly changed under Zn stress as compared to those of the control. Some abnormalities were evident in the cell walls, vacuoles, mitochondria, plasmalemma, tonoplast, and xylem parenchyma of root cells. While Moso bamboo seems a suitable candidate for phytoremediation, its metal remediation ability should be further explored in future investigations.

Copper (Cu) is one of the essential elements for plant growth, while excessive Cu in soils has potential environmental risks. There is little information on spatial variation of Cu in practical paddy fields. This is now important for appropriate agricultural management. The spatial patterns of Cu, its fractions in soils, and its concentrations in rice were investigated in a typical rice production region-Wenling of southeastern China. A total of 96 pairs of rice grain and soil samples (0-15 cm) were collected. The total concentration of Cu and its fractions were very variable, with large skewness, kurtosis, and coefficient of variation (CV) values. Compared to the guideline value (50 mg kg(-1)), Cu pollution in paddy fields was observed in the study area. All the measured Cu concentrations in rice were lower than 10 mg kg(-1), suggesting that they remained at a safe level. Spatial analyses including Moran's I index and geostatistics results indicated that high-high spatial patterns for both Cu in soils and rice were found in the northwest part, which was mainly related to industrial and E-waste dismantling activities. The low-low spatial patterns of Cu in the soil-rice system were located in the south part of study area. The cross-correlogram results indicated that Cu concentration in rice was significantly spatially correlated with total Cu in soils, its fractions, and soil organic matter (SOM), but significantly negatively correlated with pH and electrical conductivity (EC). Most of the selected variables had a clear spatial correlation range with Cu in rice. The ranges of significant spatial correlation (p 0.05) could be obtained and further used for dividing agricultural management zones.

Moso bamboo (Phyllostachys pubescens) has great potential as phytoremediation material in soil contaminated by heavy metals. A hydroponics experiment was conducted to determine organic acid compounds of root exudates of lead- (Pb), zinc- (Zn), copper- (Cu), and cadmium (Cd)-tolerant of Moso bamboo. Plants were grown in nutrients solution which included Pb, Zn, Cu, and Cd applied as Pb(NO3)2 (200 μM), ZnSO4·7H2O (100 μM), CuSO4·5H2O (25 μM), and CdCl2 (10 μM), respectively. Oxalic acid and malic acid were detected in all treatments. Lactic acid was observed in Cu, Cd, and control treatments. The oxalic was the main organic acid exudated by Moso bamboo. In the sand culture experiment, the Moso bamboo significantly activated carbonate heavy metals under activation of roots. The concentration of water-soluble metals (except Pb) in sand were significantly increased as compared with control. Organic acids (1 mM mixed) were used due to its effect on the soil adsorption of heavy metals. After adding mixed organic acids, the Cu and Zn sorption capacity in soils was decreased markedly compared with enhanced Pb and Cd sorption capacity in soils. The sorption was analyzed using Langmuir and Freundlich equations with R 2 values that ranged from 0.956 to 0.999 and 0.919 to 0.997, respectively.

Moso bamboo (Phyllostachys pubescens) has an extremely fast growth rate, however little information is available on the dynamics of carbon accumulation during the fast growth period. Bamboo trunk were sampled at three different stages (1: shoot emergence to first shell detachment; 2: first shell detachment to branch emergence; 3: branch emergence to detachment of all shells) and divided into three parts (upper, middle and lower). The average shoot elongation rate and biomass accumulation rate were 17 cm/d and 96 g/d, respectively. The carbon content increased progressively at the growth stage, and the fixed carbon was partitioned into cell wall hemicellulose and cellulose to meet the demand of rapid cell elongation. Different rates of N, P, K, Ca, and Mg content were found among different parts. These results indicated that the fast growth of the bamboo trunk is related to the extraordinary ability of bamboo to assimilate carbon, but not consistently related to mineral nutrients absorption.

Moso bamboo is recognized as phytoremediation plant due to production of huge biomass and high tolerance in stressed environment. Hydroponics and pot experiments were conducted to investigate mechanism of copper tolerance and to evaluate copper accumulation capacity of Moso bamboo. In hydroponics experiment there was non significant variation in MDA contents of leaves compared with control. SOD and POD initially indicated enhancing trend with application of 5 μM Cu and then decreased consistently with application of 25 and 100 μM Cu. Application of each additional increment of copper have constantly enhanced proline contents while maximum increase of proline was observed with application of 100 μM copper. In pot experiment chlorophyll and biomass initially showed increasing tendency and decreased gradually with application of each additional increment of Cu. Normal growth of Moso bamboo was observed with application of 100 mg kg−1 copper. However, additional application of 300 or 600 mg kg−1 copper had significantly inhibited growth of Moso bamboo. The concentration of Cu in Moso bamboo has attained the levels of 340, 60, 23 mg kg−1 in roots, stems and leaves respectively. The vacuoles were the main organs which accumulated copper and reduced toxicity of copper as studied by TEM-DEX technology.

A hydroponic culture experiment was conducted to study the effect of copper toxicity on root morphology, ultrastructure, and copper accumulation in Moso bamboo (Phyllostachys pubescens). Root ultrastructure of Moso bamboo was studied by transmission electron microscopy and scanning electron microscopy. Application of 200 μM Cu resulted in an accumulation of 810 mg kg-1 dry weight and 91 mg kg-1 dry weight Cu in roots and shoots, respectively. The majority of the plants did not survive the application of 400 μM Cu. Biomass production declined consistently with application of each additional increment of Cu. Root growth was more severely inhibited than shoot growth. Cu adversely affected the root morphology of the plants, however, root surface area and number of root tips increased slightly at low levels of Cu. Root cell ultrastructure and organelles changed significantly under Cu stress, in particular, cell walls, mitochondria, and xylem parenchyma were affected.