Ionic and nano calcium to reduce cadmium and arsenic toxicity in plants: Review of mechanisms and potentials.

Contamination of agricultural soils with heavy metal(loid)s like arsenic (As) and cadmium (Cd) is an ever increasing concern for crop production, quality, and global food security. Numerous in-situ and ex-situ remediation approaches have been developed to reduce As and Cd contamination in soils. However, field-scale applications of conventional remediation techniques are limited due to the associated environmental risks, low efficacy, and large capital investments. Recently, calcium (Ca) and Ca-based nano-formulations have emerged as promising solutions with the large potential to mitigate As and Cd toxicity in soil for plants. This review provides comprehensive insights into the phytotoxic effects of As and Cd stress/toxicity and discusses the applications of Ca-based ionic and nano-agrochemicals to alleviate As and Cd toxicity in important crops such as rice, wheat, maize, and barley. Further, various molecular and physiological mechanisms induced by ionic and nano Ca to mitigate As and Cd stress/toxicity in plants are discussed. This review also critically analyzes the efficiency of these emerging Ca-based approaches, both ionic and nano-formulations, in mitigating As and Cd toxicity in comparison to conventional remediation techniques. Additionally, future perspectives and ecological concerns of the remediation approaches encompassing ionic and nano Ca have been discussed. Overall, the review provides an updated and in-depth knowledge for developing sustainable and effective strategies to address the challenges posed by As and Cd contamination in agricultural crops.

Impact of Plant Community Diversity on Greenhouse Gas Emissions in Riparian Zones.

Plant community succession can impact greenhouse gas (GHG) emissions from the soil by altering the soil carbon and nitrogen cycles. However, the effects of community landscape diversity on soil GHG emissions have rarely been fully understood. Therefore, this study investigated how plant landscape diversity, structure type, and species composition, affect soil GHG emissions in a riparian zone. Soil GHG emissions were assessed by measuring the air samples collected from four study sites, which have different plant community structure types and species compositions (natural sites with complex plants, landscaped sites with fruit trees and grasses, untended sites with ruderals, and farmland sites), using the static chamber method. Significant differences were observed in soil carbon dioxide (CO2; p < 0.001), nitrous oxide (N2O; p < 0.001), and methane (CH4; p = 0.005) emissions. The untended site with ruderals exhibited the highest CO2 emissions, while N2O emissions increased as plant community diversity decreased. All sites acted as sinks for CH4 emissions, with decreased CH4 uptake efficiency in more diverse plant communities. The Mantel test and variance partitioning analysis revealed soil microbial biomass as an indirect influencer of GHG emissions. This study could help predict soil GHG emissions and their global warming potential under future changes in the island riparian zones.

Co-application of Parthenium biochar and urea effectively mitigate cadmium toxicity during wheat growth.

Environmental contamination by cadmium (Cd), a highly toxic heavy metal, poses significant health risks to plants and humans. Biochar has been effectively used to promote plant growth and productivity under Cd stress. This study presents an innovative application of biochar derived from the invasive weed Parthenium hysterophorus to promote plant growth and productivity under Cd stress. Our study includes detailed soil and plant analyses, providing a holistic perspective on how biochar and urea amendments influence soil properties, nutrient availability, and plant physiological responses. To address these, we established seven treatments: the control, Cd alone (5 mg kg-1), biochar alone (5 %), urea alone (3 g kg-1), biochar with Cd, urea with Cd, and a combination of biochar and urea with Cd. Cd stress alone significantly reduced plant growth indicators such as shoot and root length, fresh and dry biomass, chlorophyll content, and grain yield. However, the supplementation of biochar, urea, or their combination significantly increased shoot length (by 48%, 34%, and 65%), root length (by 73%, 46%, and 70%), and fresh shoot biomass (by 4%, 31%, and 4%), respectively. This improvement is attributed to enhanced soil properties and improved nutrient absorption. The biochar-urea combination also enhanced Cd tolerance by improving total chlorophyll content by 14 %, 13 %, and 16 % compared to the control, respectively. Similaly, these treatments significantly (p < 0.05) boosted the activity of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase by 51 %, 30 %, and 51 %, respectively, thereby mitigating oxidative stress as a defensive mechanism. The Cd tolerance was improved by biochar, urea, and their combinations, which reduced Cd content in the shoots (by 60.5 %, 38.9 %, and 51.3 %), roots (by 47.5 %, 23.9 %, and 57.6 %), and grains (by 58.1 %, 30.2 %, and 38.3 %) relative to Cd stress alone, respectively. The synergistic effects of biochar and urea are achieved through improved soil properties, nutrient availability, activating antioxidant defense mechanisms, and minimizing the accumulation of metal ions in plant tissues, thereby enhancing plant defenses against Cd stress. Conclusively, converting invasive Parthenium weed into biochar and combining it with urea offers an environmentally friendly solution to manage its spreading while effectively mitigating Cd stress in crops.

Does Bidens pilosa L. Affect Carbon and Nitrogen Contents, Enzymatic Activities, and Bacterial Communities in Soil Treated with Different Forms of Nitrogen Deposition?

The deposition of nitrogen in soil may be influenced by the presence of different nitrogen components, which may affect the accessibility of soil nitrogen and invasive plant-soil microbe interactions. This, in turn, may alter the success of invasive plants. This study aimed to clarify the influences of the invasive plant Bidens pilosa L. on the physicochemical properties, carbon and nitrogen contents, enzymatic activities, and bacterial communities in soil in comparison to the native plant Pterocypsela laciniata (Houtt.) Shih treated with simulated nitrogen deposition at 5 g nitrogen m-2 yr-1 in four forms (nitrate, ammonium, urea, and mixed nitrogen). Monocultural B. pilosa resulted in a notable increase in soil pH but a substantial decrease in the moisture, electrical conductivity, ammonium content, and the activities of polyphenol oxidase, ß-xylosidase, FDA hydrolase, and sucrase in soil in comparison to the control. Co-cultivating B. pilosa and P. laciniata resulted in a notable increase in total soil organic carbon content in comparison to the control. Monocultural B. pilosa resulted in a notable decrease in soil bacterial alpha diversity in comparison to monocultural P. laciniata. Soil FDA hydrolase activity and soil bacterial alpha diversity, especially the indices of Shannon's diversity, Simpson's dominance, and Pielou's evenness, exhibited a notable decline under co-cultivated B. pilosa and P. laciniata treated with nitrate in comparison to those treated with ammonium, urea, and mixed nitrogen.

Exposure to toxic cadmium concentration induce physiological and molecular mechanisms alleviating herbivory infestation in Wedelia.

Cadmium (Cd) toxicity induces significant disruptions in growth and development, plants have developed strategies to alleviate metal toxicity promoting establishment even during herbivores infestation. The study demonstrates that W. trilobata maintains growth and development under the combined stress of Cd exposure and herbivore invasion by Spodoptera litura, in contrast to W. chinensis. Cd toxicity markedly reduce shoot elongation and total fresh biomass, and a significant decrease in the dry weight of the shoot biomass and leaf count by 19%, 18%, 16%, and 19% in W. trilobata compared to controls. An even more pronounced decrease of 35%, 43%, 45% and 43% was found in W. chinensis. Compared to W. chinensis, W. trilobata showed a higher increase in phytohormone production including abscisic acid (ABA), gibberellic acid (GA3), indole-3-acetic acid (IAA) and methyl jasmonic acid (JA-me) under both Cd and herbivory stress as compared with respective controls. In addition, leaf ultra-structure also showed the highest damage to cell membranous structures by Cd-toxicity in W. chinensis. Furthermore, RNA-seq analysis revealed numerous genes viz., EMSY, MCCA, TIRI, BED-type, ABA, JAZ, CAB-6, CPSI, LHCII, CAX, HNM, ABC-Cd-trans and GBLP being differentially expressed between Cd-stress and herbivory groups in both W. trilobata and W. chinensis, with a particular emphasis on genes associated with metal transport and carbohydrate metabolism. Analyses employing the Gene Ontology (GO) system, the Clusters of Orthologous Groups (COG) categorization, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, highlight the functional and evolutionary relationships among the genes of the Phenylpropanoid and Flavonoid biosynthesis pathways and brassinosterod metabolism, associated with plant growth and development under Cd-toxicity and herbivory. W. trilobata opposite of W. chinensis, significantly improve plant growth and mitigates Cd toxicity through modulation of metabolic processes, and regulation of responsible genes, to sustain its growth under Cd and herbivory stress, which can be used in stress improvement in plants for sustainable ecosystem biodiversity and food security.

Cadmium induced defense enhance the invasive potential of Wedelia trilobata under herbivore infestation.

Cadmium (Cd) pollution is on the rise due to rapid urbanization, which emphasize the potential adverse effects on plant biodiversity and human health. Wedelia as a dominant invasive species, is tested for its tolerance to Cd-toxicity and herbivore infestation. We investigate defense mechanism system of invasive Wedelia trilobata and its native congener Wedelia chinensis against the Cd-pollution and Spodoptera litura infestation. We found that Cd-toxicity significantly increase hydrogen peroxide (H2O2), Malondialdehyde (MDA) and hydroxyl ions (O2•) in W. chinensis 20.61%, 4.78% and 15.68% in leave and 27.44%, 25.52% and 30.88% in root, respectively. The photosynthetic pigments (Chla, Chla and Caro) and chlorophyll florescence (Fo and Fv/Fm) declined by (60.23%, 58.48% and 51.96%), and (73.29% and 55.75%) respectively in W. chinensis and (44.76%, 44.24% and 44.30%), and (54.66% and 45.36%) in W. trilobata under Cd treatment and S. litura. Invasive W. trilobata had higher enzymatic antioxidant SOD 126.9/71.64%, POD 97.24/94.92%, CAT 53.99/25.62% and APX 82.79/50.19%, and nonenzymatic antioxidant ASA 10.47/16.87%, DHA 15.07/27.88%, GSH 15.91/10.03% and GSSG 13.56/17.93% activity in leaf/root, respectively. Overall, W. trilobata accumulate higher Cd content 55.41%, 50.61% and 13.95% in root, shoot and leaf tissues respectively, than its native congener W. chinensis. While, nutrient profile of W. chinensis reveals less uptake of Fe, Cu and Zn than W. trilobata. W. trilobata showed efficient alleviation of oxidative damage through upregulating the genes related to key defense such as SOD, POD, CAT, APX, GR, PROL, FLV, ABA and JAZ, and metal transporter in leaves, shoot and root tissues, respectively. Conclusively, W. trilobata efficiently employed Cd-triggered defense for successful invasion, even under S. litura infestation, in Cd-contaminated soil.

Microplastics and cadmium affect invasion success by altering complementarity and selection effects in native community.

The diversity-invasibility hypothesis predicts that native plant communities with high biodiversity should be more resistant to invasion than low biodiversity communities. However, observational studies have found that there is often a positive relationship between native community diversity and invasibility. Pollutants were not tested for their potential to cause this positive relationship. Here, we established native communities with three levels of diversity (1, 2 and 4 species) and introduced an invasive plant [Symphyotrichum subulatum (Michx.) G. L. Nesom] to test the effects of different pollutant treatments (i.e., unpolluted control, microplastics (MPs) alone, cadmium (Cd) alone, and their combination) on the relationship between native community diversity and community invasibility. Our results indicate that different MPs and Cd treatments altered the invasibility of native communities, but this effect may depend on the type of pollutant. MPs single treatment reduced invasion success, and the degree of reduction increased with increasing native community diversity (Diversity 2: - 14.1 %; Diversity 4: - 63.1 %). Cd single treatment increased the aboveground biomass of invasive plants (+ 40.2 %) and invasion success. The presence of MPs inhibited the contribution of Cd to invasion success. Furthermore, we found that the complementarity and selection effects of the native community were negatively correlated with invasion success, and their relative contributions to invasion success also depended on the pollutant type. We found new evidence of how pollutants affect the relationship between native community diversity and habitat invasibility, which provides new perspectives for understanding and managing biological invasions in the context of environmental pollution. This may contribute to promoting the conservation of biodiversity, especially in ecologically sensitive and polluted areas.

Clonal integration can promote the growth and spread of Alternanthera philoxeroides in cadmium-contaminated environments.

Clonal plants are able to support the growth of their ramets in stressful environments via clonal integration between the ramets. However, it remains unclear whether the developmental status of stressed ramets affects the role of clonal integration. Here, we explored the effects of clonal integration at both the ramet level and the whole clonal fragment level when the apical ramets (younger) and basal ramets (older) were subjected to different concentrations of cadmium contamination. We grew pairs of ramets of Alternanthera philoxeroides, which were connected or disconnected by stolon between them. The apical and basal ramets were either uncontaminated or individually subjected to Cd contamination at concentrations of 5 mg kg-1 and 50 mg kg-1, respectively. Our results showed that clonal integration significantly promoted the growth of apical ramets subjected to Cd contamination. More importantly, under high Cd treatment, clonal integration also had a significant positive effect on the fitness of the whole clonal fragments. However, clonal integration did not affect plant growth when basal ramets were subjected to Cd contamination. Our study reveals the influence of the developmental status of stressed ramets on the role of clonal integration in heterogeneous heavy metal stress environments, suggesting that clonal integration may facilitate the spread of A. philoxeroides in Cd-contaminated habitats.

Effects of copper oxide nanoparticles on reproductive system of zebrafish.

Copper oxide nanoparticles (CuO NPs) were regarded as the versatile materials in daily life and the in-depth evaluation of their biological effects is of great concern. Herein the female and male zebrafishes were chosen as the model animals to analyze the reproductive toxicity caused by CuO NPs at low concentration (10, 50 and 100 µg/L) After 20-days exposure, the structure of zebrafish ovary and testis were impaired. Moreover, the contents of 17ß-estradiol (E2) in both females and males were increased, while the contents of testosterone (T) were decreased, indicating the imbalanced sex hormones caused by CuO NPs. The expression of genes along the hypothalamic pituitary-gonad (HPG) axis, were examined with quantitative real-time PCR to further evaluate the toxic mechanisms. Meanwhile, the levels of erα/er2ß and cyp19a in female zebrafishes and erα/er2ß, lhr, hmgra/hmgrb, 3ßhsd and 17ßhsd in male zebrafishes were obviously up-regulated. While, the level of αr was obviously down-regulated in female and male zebrafishes. Thus, the obtained data uncovered that long-term exposure of CuO NPs with low dose could trigger the endocrine disorder, resulting in the disturbance of E2 and T level, inhibition of gonad development, and alteration of HPG axis genes. In brief, this study enriched the toxicological data of NPs on aquatic vertebrates and provided the theoretical support for assessing the environmental safety of NPs.

Phenolic root exudates enhance Avicennia marina tolerance to cadmium under the mediation of functional bacteria in mangrove sediments.

This study was carried out to demonstrate the mechanism of phenolic root exudates affecting microbial-mediated cadmium (Cd) speciation transformation thus enhancing the Avicennia marina tolerance to Cd. A rhizo-box experiment was conducted including eight treatments with four Cd levels (0, 1, 2, and 4 mg Cd kg-1) and two phenol levels (0, 15 mg kg-1). The results showed that the addition of phenols increased the pH, reduced the number of iron-reducing bacteria (IRB) and sulfur-oxidizing bacteria (SOB) in the rhizosphere sediments, meanwhile promoted the transformation of Cd to low activity speciation. Furthermore, the sulfate accumulation and synthesis of flavonoid phenols in plants were also enhanced. The results indicated that phenolic root exudates inhibit functional bacteria-mediated Fe and S cycles and promote the immobilization of Cd in the sediments. In conclusion, the mitigation of Cd phytotoxicity induced by phenolic root exudates enhanced the Cd tolerance of A. marina.

The Effect of the Spargers Design on the Wastewater Treatment of Gas-Liquid Dispersion Process in a Stirred Tank.

The hydrodynamic and power characteristics of curved Rushton impeller in an air-wastewater system were investigated using the CFD-PBM method. Studies were conducted primarily in a mixing vessel of diameter 0.39 m. The inference of operating conditions, sparger distribution, and numbers on bulk flow patterns, gas-filled cavity formation, and power consumption have been investigated in detail. It found that the gassed power consumption is closely related to cavity shape and flow patterns. In particular, the development of large cavities causes a significant reduction in power drawn, impeller pumping capacity, and gas dispersion capability. The sparger distribution and location have a strong influence on relative power drawn, power required to disperse gas, and stability of operation. Of the sparger configurations studied, the use of three sparger distributions is suggested, since relative power drawn, gas dispersion capability, and flow patterns in dispersing gas are all enhanced.

Butyl Benzyl Phthalate in Urban Sewage by Magnetic-Based Immunoassay: Environmental Levels and Risk Assessment.

A magnetic-based immunoassay (MBI) combined with biotin-streptavidin amplification was proposed for butyl benzyl phthalate (BBP) investigation and risk assessment. The values of LOD (limit of detection, IC10) and IC50 were 0.57 ng/mL and 119.61 ng/mL, with a detection range of 0.57-24,977.71 ng/mL for MBI. The specificity, accuracy and precision are well demonstrated. A total of 36 environmental water samples of urban sewage from Zhenjiang, China, were collected and assessed for BBP contamination. The results show that BBP-positive levels ranged from 2.47 to 89.21 ng/mL, with a positive rate of 77.8%. The health effects of BBP in the urban sewage were within a controllable range, and the ambient severity for health (ASI) was below 1.49. The highest value of AS for ecology (ASII) was 7.43, which indicates a potential harm to ecology. The entropy value of risk quotient was below 100, the highest being 59.47, which poses a low risk to the environment and ecology, indicating that there is a need to strengthen BBP controls. The non-carcinogenic risk of BBP exposure from drinking water was higher for females than that for males, and the non-carcinogenic risk from drinking-water and bathing pathways was negligible. This study could provide an alternative method for detecting BBP and essential information for controlling BBP contamination.

Increased fluctuation of sulfur alleviates cadmium toxicity and exacerbates the expansion of Spartina alterniflora in coastal wetlands.

Evidence suggests that the invasion of Spartina alterniflora (S. alterniflora) poses potentially serious risks to the stability of coastal wetlands, an ecosystem that is extremely vulnerable to both biological and non-biological threats. However, the effects and mechanisms of sulfur (S) in mediating the growth and expansion of S. alterniflora are poorly understood, particularly when sediments are contaminated with cadmium (Cd). A 6-month greenhouse study was conducted to evaluate the mediating effect of S on Cd tolerance and growth of S. alterniflora. Treatments consisted of a factorial combination of three S rates (applied as Na2SO4; 0, 500, 1000 mg kg-1 dry weight (DW), as S0, S500, and S1000) and four Cd rates (applied as CdCl2; 0, 1, 2, 4 mg kg-1 DW, as Cd0, Cd1, Cd2, and Cd4). Results showed that although the exogenous S supply obviously increased Cd accumulation in roots (up to 71.22 ± 6.43 mg kg-1 DW) due to the decrease of Fe concentration in iron plaque (down to 4.02 ± 1.18 mg g-1 DW), biomass reduction and oxidative stress in plant tissues were significantly alleviated. The addition of S significantly up-regulated the concentration of compounds related to Cd tolerance, including proline and glutathione. Therefore, the translocation of Cd was restricted, and plant growth was not impacted. The present study demonstrated that the exogenous sulfur supply could promote the growth of S. alterniflora and enhance its tolerance to Cd. Therefore, under the effects of S. alterniflora, the increased fluctuations of S pool caused by the release and deposition of S might further exacerbate S. alterniflora expansion in Cd contaminated coastal wetlands.

Cadmium hyperaccumulation as an inexpensive metal armor against disease in Crofton weed.

Invasive plants readily invade metal-contaminated areas. The hyperaccumulation of toxic heavy metals is not an uncommon feature among plant species. Although several hypotheses were proposed to explain this phenomenon, it is currently unclear how hyperaccumulation may benefit plants. The invasive Crofton weed (Ageratina adenophora) is a known hyperaccumulator of chromium and lead. We previously found that the species can also hyperaccumulate cadmium. The role of phytoaccumulation in defense to pathogen attack is unclear. We inoculated A. adenophora plants with a common generalist pathogen (Rhizoctonia solani) to test its resistance under cadmium treatment. We found evidence that cadmium hyperaccumulation reduced pathogen infection in A. adenophora. Our findings indicate elemental defense is highly cost efficient for hyperaccumulators inhabiting metal-contaminated sites, where plants were only modestly affected by cadmium. The reduction in pathogen damage conferred by cadmium was relatively high, particularly under lower cadmium levels. However, the benefits at higher levels may be capped. Elemental defense may be a key mechanism for plant invasion into polluted sites, especially in regions with widespread industrial activity. Our study highlights the importance of testing different metal concentrations when testing plant resistance and the importance of considering enemy attack when selecting plants for phytoremediation.

Cadmium influences the litter decomposition of Solidago canadensis L. and soil N-fixing bacterial communities.

It is important to illuminate the effects of litter decomposition of invasive alien species on soil N-fixing bacterial communities (SoNiBa), especially under heavy metal pollution to better outline the mechanisms for invasion success of invasive alien species. This study attempts to identify the effects of litter decomposition of Solidago canadensis L. on SoNiBa under cadmium (Cd) pollution with different concentrations (i.e., low concentration, 7.5 mg/kg soil; high concentration, 15 mg/kg soil) via a polyethylene litterbags-experiment. Electrical conductivity and total N of soil were the most important environmental factors for determining the variations of SoNiBa composition. S. canadensis did not significantly affect the alpha diversity of SoNiBa but significantly affect the beta diversity of SoNiBa and SoNiBa composition. Thus, SoNiBa composition, rather than alpha diversity of SoNiBa, was the most important determinant of the invasion success of S. canadensis. Cd with 15 mg/kg soil did not address distinct effects on alpha diversity of SoNiBa, but Cd with 7.5 mg/kg soil noticeably raised the number of species and species richness of SoNiBa mainly due to the hormonal effects. The combined S. canadensis and Cd with 15 mg/kg soil obviously decreased cumulative mass losses and the rate of litter decomposition (k) of S. canadensis, but the combined S. canadensis and Cd with 7.5 mg/kg soil evidently accelerated cumulative mass losses and k of S. canadensis. Thus, Cd with 7.5 mg/kg soil can accelerate litter decomposition of S. canadensis, but Cd with 15 mg/kg soil can decline litter decomposition of S. canadensis.

Analysis of anatomical changes and cadmium distribution in Aegiceras corniculatum (L.) Blanco roots under cadmium stress.

Heavy metal stress changes the morphological and anatomical structure of plant organs. In this study, we determined the anatomical changes and Cd distribution in the roots of Aegiceras corniculatum (L.) Blanco (Black mangrove) under Cd stress. The results showed that Cd levels in A. corniculatum root tissues decreased in the following order: endodermis > pith > xylem > epidermis and exodermis > phloem > cortex. The endodermis secondary casparian strip replaces exodermis casparian strip and plays a role in the "retardation mechanism", which sort of compensates for the missing exodermis retardation effect. The xylem and pith both show high affinity for Cd and contain enriched Cd. This creates a low-Cd environment for phloem and protects the nutrient transport function of the vasculature against Cd toxicity. The present study provides new evidences suggesting that Cd regional enrichment and anatomical structure changes are an adaptive strategy of mangrove plants to HM tolerance.

Sensitive and selective determination of butyl benzyl phthalate from environmental samples using an enzyme immunoassay.

Increased awareness of phthalic acid esters (PAEs) toxicity has given rise to a dramatic increase in concern about the determination of these contaminations in the environment. In this paper, a sensitive, selective and rapid enzyme immunoassay of ELISA based on polyclonal antibody for detecting butyl benzyl phthalate (BBP) was developed and applied in the environmental water and soil samples. The hapten of BBP was synthesized, then applied to prepare artificial antigen and produce polyclonal antibody capable of specific recognizing BBP. From the optimal standard curve of ELISA for BBP, the values of LOD (limit of detection, IC10) and IC50 were 2.5 and 79.4 ng/mL, respectively. The ELISA showed high specificity, with the cross-reactivity toward BBP analogs < 9.6%. The satisfactory accuracy and precision were demonstrated by the recoveries of 76-116% and coefficient of variations (CVs) of 4.7-13.7%. Furthermore, BBP contamination was investigated at 3.1-25.2 ng/mL in real water samples and 4.2-76.4 ng/g in real soil samples (with the detection rate of 55% in 20 samples) by the developed ELISA, which also had shown a good correlation with that the results obtained by HPLC. All of this indicated that the developed enzyme immunoassay could be applied for sensitive and selective determination of BBP contamination in the environmental samples. Furthermore, the strategy of BBP hapten synthesis and an alternative method of BBP determination could be provided.

Distribution correlations of cadmium to calcium, phosphorus, sodium and chloridion in mangrove Aegiceras corniculatum root tissues.

Nutriment distributions might influence Cd distribution and Cd tolerance in mangrove plant roots. To demonstrate this, Aegiceras corniculatum was stressed by Cd, and the distributions of Cd, Ca, P, Na and Cl in plant roots were detected with the aid of SEM-EDX. It was found that endodermis, pith and xylem were the predominant tissues for retardation and regional enrichment of Cd. Na and Cl distributions suggest a critical role of salt resistance tissues on Cd tolerance in roots. P participated in Cd retardation and regional enrichment of endodermis and xylem. P, Na, Cl and Ca distribution had a high correlation to that of Cd in roots. The synergetic accumulation between Ca and Cd could be a crucial mechanism for Cd tolerance in A. corniculatum roots. In conclusion, the research of Cd and nutriment distributions in A. corniculatum roots deepens the understanding on Cd tolerance in mangrove plants.

The mutual restraint effect between the expansion of Alternanthera philoxeroides (Mart.) Griseb and cadmium mobility in aquatic environment.

Alternanthera philoxeroides (Mart.) Griseb is one of the most malignant weeds in its invision habitats. While in the cadmium-contaminated aquatic environment, does A. philoxeroides possess good tolerance and adaptability? To demonstrate the effects of cadmium on A. philoxeroides in the polluted water bodies, a hydroponic stress experiment was conducted over a gradient of Cd concentrations (0, 2.5 and 5mg/l) in triplicate. The seedlings were cultured in a greenhouse and harvested on days 0, 10, 20, 30 and 40, respectively. The results showed the effects of mutual restraint between Cd and A. philoxeroides. The A. philoxeroides seedlings were enriched with large amounts of Cd, and the toxicity of Cd inhibited the rapid growth of A. philoxeroides and induced the rapid degradation of chlorophylls in its tissues. Furthermore, the use of iron plaque effectively immobilized Cd of 1123-2883mg/kg·DW on the root surface, thus it decreased the transferability of Cd in the aquatic environment. Due to its extensive adaptability, good Cd tolerance and the immobilization of Cd predominantly in the roots (the highest Cd concentration enriched was 7588.65±628.90mg/kg·DW in roots). A. philoxeroides effectively restrained the translocation of Cd and partitioned Cd in the roots within water bodies. CAPSULE: The antagonistic effect exists between the invasion of A. philoxeroides and cadmium mobility in aquatic environments.

Time-resolved immunoassay based on magnetic particles for the detection of diethyl phthalate in environmental water samples.

Diethyl phthalate (DEP) is an extensively used phthalic acid diester (PAEs) with estrogenic activity and the potential for carcinogenic and teratogenic effects. To monitor trace DEP in environmental waters, a sensitive direct competitive time-resolved fluoroimmunoassay based on magnetic particles (MPs) as solid support was established. For the assay system, the anti-DEP antibody was oriented on the surface of the MPs using goat anti-rabbit antibody as linkers, and DEP-OVA was labeled using Eu3+. Several physicochemical factors that potentially influence the assay performance of the proposed method were investigated in detail, including concentration of MPs, dilution of DEP-OVA-Eu3+ and incubation time. Under the optimized conditions, the method showed: (i) low limit of detection (LOD) of 5.92ng/L; (ii) satisfactory accuracy (recoveries, 91.97-134.54%) with good reproducibility (inter-CV, 4.17-9.17%; intra-CV, 7.41-14.72%). All of which indicated that the newly established method had much higher efficiency and great potential for use in environmental water analysis for DEP. In addition, the proposed immunoassay was applied for investigation of DEP in aquatic environments at Zhenjiang City. Our results showed that DEP was detected at the concentration of 2.98-65.18ng/mL in river samples and 46.95-306.19ng/mL in wastewater treatment plants (WWTPs), which showed rather high concentrations compared with reported data. Our study provides background data important for risk assessment and contamination control of DEP in the aquatic environment of this area.