Impact of simulated acid rain on the growth of three species Brassica integrifolia,Brassica rapa,Brassica juncea in Hanoi,Vietnam

Environmental Science and Pollution Research - Over the past decade, the extent and magnitude of acid rain in Vietnam and other Asian countries have become more apparent. In this study, the effect...     

Impact of silver nanoparticles on natural marine biofilm bacteria

There has been a recent increase in the use of silver nanoparticles (Ag NPs) in a wide range of consumer products due to their highly effective antimicrobial properties. However, Ag NPs give cause for concern since their wide use makes them likely to be released into aquatic ecosystems and potentially affect natural bacterial communities. In this study marine biofilms were grown in situ in a coastal site (Singapore Harbour) and exposed in the laboratory for a further 24 h to 0-2000 μg L⁻¹ of well characterised Ag NPs. Increasing concentrations of Ag NPs caused a significant decrease in biofilm volume and biomass, and Ag uptake by biofilms per unit of volume was also dependent on concentration. Terminal fragment length polymorphisms and subsequent cluster and phylogenetic analysis showed the presence of major bacterial groups in biofilms irrespective of treatment with Ag NPs. This implies that even at the highest concentrations studied these taxonomic groups were not displaced. Nevertheless, biofilm succession was impeded on Ag NP treated biofilms, affecting the relative abundance of major bacterial groups in the biofilm community, with potential longer term effects on biofilm development and function.     

Effects of copper sulfate on growth and physiological responses of Limoniastrum monopetalum

A glasshouse study of the coastal shrub Limoniastrum monopetalum was carried out to evaluate its tolerance and capacity to accumulate copper. We investigate the effects of Cu from 0 to 60 mmol l^?1 on the growth, photosynthetic apparatus, and nutrient uptake of L. monopetalum, by measuring gas exchange, chlorophyll fluorescence parameters, photosynthetic pigments, and total copper, nitrogen, phosphorus, sulfur, calcium, and magnesium content in the plant tissues. Although L. monopetalum did not survive at 60 mmol l^?1 Cu, the species demonstrated a high tolerance to Cu-induced stress, since all plants survived external Cu concentrations of up to 35 mmol l^?1 and displayed similar growth in the Cu-enriched medium as in the control treatment of up to the external level of 15 mmol Cu l^?1 (1,000 mg Cu l^?1). The reduced growth registered in plants exposed to 35 mmol Cu l^?1 can be attributed to reduced photosynthetic carbon assimilation associated with the adverse effect of the metal on the photochemical apparatus and a reduction in the absorption of essential nutrients. Copper tolerance was associated with the capacity of the plant to accumulate the metal in its roots and effectively prevent its translocation to photosynthetic tissues. L. monopetalum has the characteristics of a Cu-excluder plant and could be used in the revegetation of Cu-contaminated soils.     

Synthesis of magnetic nanoparticles and their effects on growth and physiological parameters of Calotropis procera seedlings

Environmental Science and Pollution Research - The present study was carried out to elucidate effects of synthesized magnetic nanoparticles (MNPs) on morphological and physiological parameters and...     

Reaction of silver nanoparticles in the disinfection process

This study investigated the dissolution, aggregation, and reaction kinetics of silver nanoparticles (AgNPs) with the three types of water disinfectants (ultraviolet, sodium hypochlorite, and ozone) under the different conditions of pH, ionic strength, or humic acid (HA). The physicochemical changes of AgNPs were measured by using UV–Vis spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometer. The results showed that when AgNPs contacted the disinfectants, oxidative dissolution was the primary reaction. In addition, the reaction kinetics studies revealed that the reaction rate of AgNPs with disinfectants was significantly influenced by different disinfectants along with different pH and the presence of sodium nitrate and HA. Our research demonstrated the potential effect of disinfectants on AgNPs, which will improve our understanding of the fate of AgNPs in the disinfection processes in the water and wastewater treatment plant.     

Assessment of silver nanoparticle-induced physiological and molecular changes in Arabidopsis thaliana

In this study, the effect of silver nanoparticles and silver ions on Arabidopsis thaliana was investigated at physiological and molecular levels. The seedlings were grown in sublethal concentrations of silver nanoparticles and silver ions (0.2, 0.5, and 1 mg/L) in 1/4 Hoagland’s medium for 14 days under submerged hydroponic conditions. Significantly higher reduction in the total chlorophyll and increase in anthocyanin content were observed after exposure to 0.5 and 1 mg/L silver nanoparticles as compared to similar concentrations of silver ions. Lipid peroxidation increased significantly after exposure to 0.2, 0.5, and 1 mg/L of silver nanoparticles and 0.5 and 1 mg/L of silver ions. Qualitative analysis with dichloro-dihydro-fluorescein diacetate and rhodamine 123 fluorescence showed a dose-dependent increase in reactive oxygen species production and changes in mitochondrial membrane potential in the roots of seedlings exposed to different concentrations of silver nanoparticles. Real-time PCR analysis showed significant upregulation in the expression of sulfur assimilation, glutathione biosynthesis, glutathione S-transferase, and glutathione reductase genes upon exposure to silver nanoparticles as compared with silver ions. Overall, based on the physiological and molecular level responses, it was observed that exposure to silver nanoparticles exerted more toxic response than silver ions in A. thaliana.     

Antioxidative responses in relation to growth of mustard (Brassica juncea cv. Pusa Jaikisan) plants exposed to hexavalent chromium

Effect of hexavalent chromium (Cr6+) was seen on Brassica juncea cv. Pusa Jaikisan grown for 15 days in hydroponic culture supplemented with 0.2, 2 and 20 microM Cr. The inhibitory response of Cr6+ on growth of B. juncea was concentration and time dependent. The stimulation of plant growth, observed in response to exposure to 0.2 microM Cr6+, during initial 5 days was reversed on prolonged treatment and at higher Cr6+ concentrations (2 and 20 microM Cr6+). Despite reduction in growth, chlorophyll content increased substantially on 15 days exposure to 20 microM Cr6+. Significant increases in lipid peroxidation and tissue concentration of H2O2 occurred in plants exposed to 2 and 20 microM Cr6+. Effect of Cr6+ on antioxidative enzymes in roots and leaves was differential. SOD and CAT activities at lower levels of Cr6+ supply remained higher all through the treatment. While APX was very susceptible to excess Cr6+, GR and GST increased at elevated levels of Cr6+. The results suggested Cr6+ induced depression in plant growth of B. juncea to be a function of increased cellular accumulation of Cr despite increase in the activities of some of the antioxidative enzymes.     

Accumulation,speciation and localization of silver nanoparticles in the earthworm Eisenia fetida

Environmental Science and Pollution Research - The use of silver nanoparticles (AgNPs) in agriculture and many consumer products has led to a significant release of Ag in the environment. Although...     

Effects of scrubber by-product-stabilized dairy lagoon sludge on growth and physiological responses of sunflower (Helianthus annuus L.)

Brick manufacturing industries are challenged to comply with clean air mandates. Dry air scrubbers have been used to remove acid gases from the exhaust air from brick manufacturing plants. The use of dry air scrubbers results in the production of large quantities of an alkaline powder by-product. A greenhouse experiment was conducted to evaluate the potential of using dairy lagoon sludge stabilized with the scrubber by-product as a soil amendment. Lagoon sludge was stabilized with scrubber by-product at an application rate of 20 gl(-1). The sludge-scrubber by-product mixture was applied to a sandy loam soil to provide amendments ranging between 28 and 168 kg of plant available nitrogen (PAN)/ha for the growth of Helianthus annuus (sunflower). Use of the sludge-scrubber by-product mixture as a nitrogen fertilizer did not adversely affect sunflower seedling emergence; however, significantly higher (p<0.05) plant volume indices, leaf area, dry shoot and root masses, and seed yields were obtained for mature plants grown in sludge-treated soil relative to the control or fertilizer treatment. The sludge amendment did not severely impact gas exchange or chlorophyll a fluorescence of the plants and nutrient content of the sunflower tissues was generally within a sufficient range. The increased growth and yield of sunflower plants indicated the potential of the sludge-scrubber by-product mixture as a soil amendment in agricultural crop production.     

Evidence for the inhibitory effects of silver nanoparticles on the activities of soil exoenzymes

Silver nanoparticles (AgNPs) are well known to have antimicrobial ability, but very little is known about the effect of AgNPs on soil exoenzyme activities, which reflect the potential of a soil to support biochemical processes. This study provides evidence of the inhibitory effects of AgNPs on the activities of soil exoenzymes. Six exoenzymes related to nutrient cycles (urease, acid phosphatase, arylsulfatase, β-glucosidase) and the overall microbial activity (dehydrogenase, fluorescein diacetate hydrolase) were tested in soils treated with AgNPs (1, 10, 100 and 1000 μg g(-1)) and silver ion (0.035, 0.175, 0.525, 1 and 1.5 μg g(-1)). AgNPs were capable of inhibiting the activities of all the exoenzymes tested in this study. Especially, the urease and dehydrogenase activities were significantly related to the presence of AgNPs. The effects of silver ions dissolved from the AgNPs were not significant, indicating the adverse effects caused by AgNPs themselves. This study suggested that AgNPs negatively affect soil exoenzyme activities, with the urease activity especially sensitive to AgNPs.     

Alteration of shell nacre micromorphology in blue mussel Mytilus edulis after exposure to free-ionic silver and silver nanoparticles

This study describes the morphology of inner shell surface (ISS) of the blue mussel Mytilus edulis Linnaeus after short-term exposures to radiolabeled silver in free-ionic (^110mAg⁺) and engineered nanoparticulate (^110mAgNPs, <40 nm) phases. Radiolabeled silver in starting solutions was used in a similar low concentration (∼15 Bq mL⁻¹) for both treatments. After exposure experiments radiolabeled silver was leached from the ISS using HCl. It concentration for shells from both treatments was ∼0.5 Bq mL⁻¹. Whole ISS of young individuals and prismatic layer of adults showed no evidence of any major alteration process after silver uptake. However, the nacre portion of adult mussels exposed to both treatments revealed distinct doughnut shape structures (DSS) formed by calcium carbonate micrograins that covered the surface of aragonite tablets. Scanning electron microscope (SEM) imaging revealed the existence of only minor differences in DSS morphology between mussels exposed to Ag⁺ and AgNPs. From literature survey, DSS were also found in bivalves exposed to Cd²⁺. The DSS occurring in a specimen of a field-collected bivalve is also shown. Formation of distinctive DSS can be explained by a disturbance of the shell calcification mechanism. Although the occurrence of DSS is not exclusively associated with metal bioavailability to the mussels, the morphology of DSS seems to be linked to the speciation of the metal used in the uptake experiments.     

Effect of cement dust on the growth and yield of Brassica campestris L

Plants of Brassica campestris L. var. G-S20 were treated with cement dust, at rates of 3 (B(1)), 5 (B(2)) and 7 (B(3)) gm(-2) day(-1) for 90 days. Treated plants showed a consistent reduction in growth, photosynthetic pigments, yield and oil content over control plants. The overall phytomass of treated plants was significantly decreased, the maximum reduction being 64.8% in B(3) plants, followed by B(2) plants (55.3%) and B(1) plants (43.69%) at 60 days. The effect on oil content was also greatest in B(3) plants, where it was decreased by 6.13%.     

Microalgae biosynthesis of silver nanoparticles for application in the control of agricultural pathogens

The occurrence of diseases in cultivars has caused significant losses in global food production. The advancement of nanobiotechnology makes it possible to obtain new products to be used in the control of pathogens in cultivars. Silver nanoparticles can be synthesized by microalgae and are widely known for their antimicrobial activity. In addition, the biomass produced in microalgal culture for the biosynthesis of the nanoparticles also demonstrates antimicrobial properties, as it can increase the antibacterial and antifungal potential of the silver nanoparticles. In this context, this article addresses the use of microalgae to biosynthesize silver nanoparticles simultaneously with biomass production. In addition, we demonstrate the antimicrobial potential of these nanomaterials, as well as of the microalgal biomass produced in biosynthesis, to use in the control of pathogens in agriculture.     

镉胁迫对向日葵幼苗生长和生理特性的影响

采用溶液培养方法,研究了不同浓度镉(0、0.05、0.1、0.5和1 mg/L)处理7 d对向日葵幼苗生长和生理特性的影响。结果表明：随着镉处理浓度的增加,向日葵幼苗对镉的吸收显著增加。1 mg/L镉浓度处理时,叶、茎和根中镉浓度分别为0.05 mg/L镉处理时的16.3、19.2和581倍;根中积累的镉含量明显高于叶和茎, 各浓度根部积累的镉分别为叶和茎的37.8～63倍和29.4～41倍。镉胁迫显著抑制向日葵幼苗生长和叶绿素合成,当镉浓度达1 mg/L时,整株植物生物量和总叶绿素含量分别为对照的55.9%和52.6%。镉胁迫下向日葵幼苗游离脯氨酸和丙二醛（MDA）含量显著增加,1 mg/L镉浓度时,根中含量分别为对照的4和5.8倍。向日葵幼苗可溶性蛋白含量和过氧化物酶(POD)活性变化与镉胁迫浓度呈明显的倒U字型关系,可溶性蛋白含量在0.05 mg/L镉浓度时达到最大值,叶、茎、根中的POD活性分别在0.1、0.1和0.05 mg/L镉浓度时达到最大值。     

Metal accumulation in Raphanus sativus and Brassica rapa: an assessment of potential health risk for inhabitants in Punjab,Pakistan

Pakistan is an agricultural country and due to the shortage of clean water, most of the irrigated area (32,500 ha) of Pakistan was supplied with wastewater (0.876?×?109 m³/year). Concentrations of heavy metals in radish (Raphanus sativus) and turnip (Brassica rapa) taken from vegetable fields in Sargodha, Pakistan, were measured. Untreated wastewater was used persistently for a long time to irrigate these vegetable fields. A control site was selected that had a history of fresh groundwater irrigation. Mean metal concentrations were found for irrigation water, soil, and vegetables. In irrigation water, concentrations of Mo and Pb at three sites and Se at sites II and III were higher than the recommended limits. In vegetables, concentrations of Mo and Pb were above the maximum permissible limits. High bioconcentration factor was observed for Zn (12.61 in R. sativus and 11.72 in B. rapa) at site I and high pollution load index was found for Pb (3.89 in R. sativus and 3.87 in B. rapa) at site II. The differences in metal concentrations found in samples depended upon different soil nature and assimilation capacities of vegetables at different sites which in turn depended upon different environmental cues. The entrance of metal and metalloids to human body may happen through different pathways; however, the food chain is the chief route through which metals are transferred from vegetables to individuals. Health risk index observed for metals, (Mo, As, Ni, Cu, and Pb) higher than 1 indicated high risk through consumption of these vegetables at three sites.

     

Effects of Cd and Zn on physiological and anatomical properties of hydroponically grown Brassica napus plants

Environmental Science and Pollution Research - Clarifying the connection between metal exposure and anatomical changes represents an important challenge for a better understanding of plant...     

镉胁迫对万寿菊生长及生理生态特征的影响

通过水培实验,研究了不同Cd浓度(0、0.1、0.5、1、2和5 mg/L)胁迫对万寿菊生长及生理生化指标的影响.研究表明,低浓度Cd(＜0.5 mg/L)胁迫下,万寿菊的生长末受到显著影响,说明万寿菊对低浓度Cd有一定的耐性.而Cd浓度超过0.5 mg/L时,万寿菊的相对生长速率较对照明显降低(P＜0.05),最高可...     

Influence of Suwannee River humic acid on particle properties and toxicity of silver nanoparticles

Adsorption of natural organic matter (NOM) on nanoparticles can have dramatic impacts on particle dispersion resulting in altered fate and transport as well as bioavailability and toxicity. In this study, the adsorption of Suwannee River humic acid (SRHA) on silver nanoparticles (nano-Ag) was determined and showed a Langmuir adsorption at pH 7 with an adsorption maximum of 28.6 mg g⁻¹ nano-Ag. It was also revealed that addition of <10 mg L⁻¹ total organic carbon (TOC) increased the total Ag content suspended in the aquatic system, likely due to increased dispersion. Total silver content decreased with concentrations of NOM greater than 10 mg TOC L⁻¹ indicating an increase in nanoparticle agglomeration and settling above this concentration. However, SRHA did not have any significant effect on the equilibrium concentration of ionic Ag dissolved in solution. Exposure of Daphnia to nano-Ag particles (50 μg L⁻¹ and pH 7) produced a linear decrease in toxicity with increasing NOM. These results clearly indicate the importance of water chemistry on the fate and toxicity of nanoparticulates.     

微囊藻毒素-RR对反硝化细菌生长及生理特性的影响

用0.01、5.00 mg/L微囊藻毒素-RR(MC-RR)处理反硝化细菌,研究了MC-RR对反硝化细菌的生长、培养液中NO3--N和NO2--N含量以及细胞内硝酸还原酶活性的影响.结果表明,高浓度MC-RR能显著抑制反硝化细菌的生长,延缓其细胞增殖,抑制培养液中硝酸盐含量的降低和亚硝酸盐含量的升高以及细胞内硝酸还原酶的活性,因而可能抑制或减缓生态系统中氮循环的进程.这表明,微囊藻毒素在一定程度上可能调节水体细菌群落.