Simultaneous Cd2+, Zn2+, and Pb2+ Uptake and Accumulation by Photosynthetic Euglena gracilis

The ability of Euglena gracilis to simultaneously remove and accumulate Zn²⁺, Cd²⁺, and Pb²⁺ from culture up- to media was evaluated. E. gracilis was able to remove up to 80% of the Cd²⁺ present in the medium when cultured with 20 or 50 μM CdCl₂. Higher external Cd²⁺ concentrations increased Cd²⁺ accumulation per cell but decreased cell growth, thus decreasing the capacity of the cell culture to remove Cd²⁺. E. gracilis removed 70% to 80% of the Zn²⁺ present in the medium when cultured with 5 to 50 μM ZnSO₄. Zn²⁺ did not affect Cd²⁺ removal capacity. E. gracilis was much less efficient in removing Pb²⁺ (<15%) when cultured with 100 or 200 μM Pb(NO₃)₂. Moreover, Pb²⁺ decreased the efficiency to remove Cd²⁺, but it did not affect Zn²⁺ removal. Cd²⁺ induced a generalized increase in the cellular thiol compounds, including phytochelatins, and Pb²⁺ had an additive effect only at 200 μM. Zn²⁺ did not stimulate phytochelatin synthesis. Cd²⁺ and Pb²⁺ colocated in the same cytosolic high-molecular-weight fraction. Because Pb²⁺ is a weak phytochelatin inducer, competition between Pb²⁺ and Cd²⁺ for transportation across the plasma membrane and binding to phytochelatins and other thiol compounds is proposed to explain the detrimental effects of Pb²⁺ on the Cd²⁺ removal capacity of E. gracilis.     

Enhanced Heavy Metal Tolerance in Two Strains of Photosynthetic Euglena gracilis by Preexposure to Mercury or Cadmium

The effects of different concentrations of Hg, Cd, and Pb on cell growth, oxygen consumption, and production and contents of chlorophyll a and b of Z and B strains of Euglena gracilis was studied. Cell uptake of Cd and Pb was also determined. A greater cell density reached in the presence of Cd²⁺ correlated with a lower metal uptake capacity in B-strain cells. Cells of Z strain, preexposed to low concentrations of either Hg²⁺ (1.5 μM) or Cd²⁺ (50 μM) for several generations showed improved heavy metal tolerance (greater cell density and viability) together with similar metal uptake capacity. Because Cd²⁺ preadaptation but not Hg²⁺ pretreatment induced a significant increase in the content of acid-soluble thiols, the data suggest the existence of different mechanisms of heavy metal detoxification in Euglena. The fact that Z-strain cells showed a greater Cd²⁺ uptake under all the conditions assayed suggests that Z strain would be more suitable for bioremediation of polluted waters. Received: 18 April 1997/Accepted: 9 September 1997     

Heavy Metal Uptake by Euplotes mutabilis and its Possible Use in Bioremediation of Industrial Wastewater

A ciliate protozoan, Euplotes mutabilis, isolated from heavy metal laden industrial wastewater, has been shown to tolerate multiple heavy metals thus suggesting its significance in bioremediation of industrial effluents. This ciliate tolerated Zn²⁺ up to 33 μg/mL, Cd²⁺ up to 22 μg/mL and Ni²⁺ up to 18 μg/mL. The ciliate could uptake 85% Zn²⁺, 84% of Cd²⁺ and 87% of Ni²⁺ after 96 h of inoculation of growth medium containing 10 μg/mL of Zn²⁺ and 5 μg/mL of Cd²⁺ and Ni²⁺, with actively growing ciliates. After 6 days of incubation the ciliate removed 87% Cd²⁺, 92% Ni²⁺, and 93% Zn²⁺ from the wastewater. The heavy metal uptake capability of Euplotes mutabilis may be employed for metal detoxification operations.     

Effects of Ca<Superscript>2+</Superscript> or Na<Superscript>+</Superscript> on Metallothionein Expression in Tilapia Larvae (<Emphasis Type="Italic">Oreochromis mossambicus</Emphasis>) Exposed to Cadmium or Copper

The objectives of this study were to try to determine the reasons of the external Ca²⁺ and Na⁺ enhancement of Cd²⁺ and Cu²⁺ resistance in fish. Tilapia larvae at 3 days posthatch were exposed to (A) 0 (control), 40 μg/L Cd²⁺, 40 μg/L Cd²⁺ + 2 mM Ca²⁺ (Cd/hyper-Ca), and 2 mM Ca²⁺ or (B) 0 (control), 75 μg/L Cu²⁺, 75 μg/L Cu²⁺ + 0.52 mM Na⁺ (Cu/hyper-Na), and 0.52 mM Na⁺. After 48 hours, results indicated that (1) Cd/hyper-Ca and Cu/hyper-Na treatments showed decreased growth inhibition induced by the metals; (2) metal accumulation in Cd/hyper-Ca–treated larvae was lower compared with those exposed only to Cd; and (3) metallothionein (MT) expression was significantly higher in Cu/hyper-Na–treated larvae than in the group treated with Cu only. Taking all of this into account, either supplementary Ca²⁺ or Na⁺ in ambient water may help fish to maintain Ca²⁺ or Na⁺ homeostasis, which could decrease metal accumulation and its detrimental effects. Consequently, the fish increase MT expression and retard the growth inhibition caused by metals.     

Cadmium and Zinc in Mar Chiquita Coastal Lagoon (Argentina): Salinity Effects on Lethal Toxicity in Juveniles of the Burrowing Crab Chasmagnathus granulatus

The large Argentine marine littoral zone is characterized by great number of wetlands and includes only one coastal lagoon, Mar Chiquita, which has been declared as a Biosphere Reserve by the Man and Biosphere Reserve Program from UNESCO. Its margins present populations of Chasmagnathus granulatus, a semiterrestrial crab distributed along wide salinity gradients that plays an important role as a key species within the corresponding trophic web. Dissolved cadmium (Cd) and zinc (Zn) concentrations present in this ecosystem were determined. Cadmium concentrations ranged between n.d. and 0.82 μg/L and zinc levels ranged between n.d. and 1224.38 μg/L within the mentioned coastal lagoon. Cd and Zn acute semistatic toxicity bioassays were carried out for 96 h on juvenile crabs of C. granulatus. LC₅₀ 96-h values were 2.24 mg Cd²⁺/L and 7.07 mg Zn²⁺/L at 5 psu, and 15.42 mg Cd²⁺/L and 11.41 mg Zn²⁺/L at 25 psu. Higher salinities resulted in lower metal toxicity. This effect was stronger for Cd than for Zn. C. granulatus juveniles LC₅₀ 96-h values determined for Cd were three to four orders of magnitude higher than the corresponding dissolved metal concentrations in the Mar Chiquita coastal lagoon; nevertheless, those Zn values determined were similar to several ones corresponding to natural water samples.     

Acrosome Reaction of Sperm in the Mud Crab Scylla serrata as a Sensitive Toxicity Test for Metal Exposures

In order to test the sensitivity of the sperm cell of the mud crab Scylla serrata to heavy metals, the toxic effects of Ag⁺, Cd²⁺, Cu²⁺, and Zn²⁺ on the acrosome reaction (AR) were studied by artificially inducing the AR of sperm exposed to heavy metals, counting the AR rates by light microscopy, and observing structural changes in sperm by transmission electron microscopy. The AR in S. serrata occurs at two stages. The first stage (ARI) is the eversion of the subacrosomal material. The second stage (ARII) is the ejection of the acrosomal filament. The results showed the EC₅₀ values of the AR based on (ARI + ARII)% for Ag⁺, Cd²⁺, Cu²⁺, and Zn²⁺ were 10.02, 2.14, 13.69, and 2.21 μg/L, and the EC₅₀ values based on ARII % of Ag⁺, Cd²⁺, Cu²⁺, and Zn²⁺ were 1.96, 0.20, 1.46, and 0.34 μg/L. The order of toxicity is Cd²⁺ > Zn²⁺ > Cu²⁺ > Ag⁺ based on the percentage of reacted sperm at the second stage. Sperm cells exposed to heavy metals showed an increased rate of swelling, shape irregularities, and the acrosomal filament of some sperm cells was, crooked, ruptured, and even dissolved. The AR of the sperm cell from S. serrata is more sensitive to the tested heavy metals compared to sea urchin sperm cell toxicity tests.     

Air Quality Status During Diwali Festival of India: A Case Study

The PM_2.5 and PM₁₀ samples were collected during Diwali celebration from study area and characterized for ionic concentration of four anions (NO₃ ⁻, NO₂ ⁻, Cl⁻, SO₄ ²⁻) and five cations (K⁺, Mg²⁺, NH₄ ⁺, Ca²⁺, Na⁺). The results showed that the ionic concentrations were three times compared to those on pre and post Diwali days. Predominant ions for PM_2.5 were K⁺ 33.7 μg/m³, Mg⁺ 31.6 μg/m³, SO₄ ²⁻ 22.1 μg/m³, NH₄ ⁺ 17.5 μg/m³ and NO₃ ⁻ 18 μg/m³ and for PM₁₀ the ionic concentrations were Mg⁺ 29.6 μg/m³, K⁺ 26 μg/m³, SO₄ ²⁻ 19.9 μg/m³, NH₄ ⁺ 16.8 μg/m³ and NO₃ ⁻ 16 μg/m³. While concentration of SO₂ and NO₂ were 17.23, 70.33 μg/m³ respectively.     

Cadmium Accumulation and Antioxidative Responses in the Sesbania drummondii Callus

The effect of cadmium (Cd) on growth, accumulation, and antioxidative response was studied in Sesbania drummondii callus, cultivated on different concentrations of Cd (0–250 μM) for four weeks. Callus growth was comparable to that of the control for concentrations up to 50 μM Cd; however, concentrations higher than 50 μM affected growth. A concentration of 100 μM Cd inhibited growth by 16%, with respect to control. Cd concentration in callus increased with increasing Cd concentrations in the growth medium. Callus accumulated 530 mg Cd kg⁻¹ of their dry weight at 100 μM Cd concentration. Sesbania callus responded to Cd-induced oxidative stress by modulating antioxidants (glutathione and other non-protein thiols) level and antioxidative enzymes: superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). The content of the glutathione (GSH) and GSH/GSSG ratio first increased up to a concentration of 50 μM Cd and then decreased. The content of other non-protein thiols significantly increased with increasing Cd concentrations in the growth medium. The activities of antioxidative enzymes, SOD, APX, and GR, followed the same trends as antioxidants first increasing up to a concentration of 50 μM Cd and then decreasing. These results suggest that antioxidative defense mechanisms play a significant role in Cd detoxification and accumulation in Sesbania drummondii.     

Protective Effect of High Alkalinity Against the Deleterious Effects of Chronic Waterborne Cadmium Exposure on the Detection of Alarm Cues by Juvenile Silver Catfish (<Emphasis Type="Italic">Rhamdia quelen</Emphasis>)

The objective of the present study was to analyze the effect of chronic cadmium (Cd) exposure at two alkalinity levels (63 and 92 mg l⁻¹ CaCO₃) on the antipredatory behavior of juvenile silver catfish (Rhamdia quelen) exposed to conspecific skin extract and predator odor. At an alkalinity of 63 mg l⁻¹ CaCO₃, 30 days of exposure to either 4.5 or 8.0 μg l⁻¹ Cd impaired the catfish’s antipredatory response to alarm cues. However, silver catfish exposed to 4.5 μg l⁻¹ Cd at an alkalinity of 92 mg l⁻¹ CaCO₃ responded to skin extract and predator odor. In catfish exposed to 8.0 μg l⁻¹ Cd at the same alkalinity, only the number of feeding bites decreased, and this occurred only for specimens exposed to predator odor. Our results show that higher alkalinity protected against the deleterious effects of Cd on alarm cue detection but only in the larvae exposed to the lowest waterborne Cd level.     

Effect of Major Cations and pH on the Acute Toxicity of Cadmium to the Earthworm <Emphasis Type="Italic">Eisenia fetida</Emphasis>: Implications for the Biotic Ligand Model Approach

The purpose of this study was to characterize the individual effect of different cations (Ca²⁺, Mg²⁺, Na⁺, K⁺, and H⁺) on the acute toxicity of Cd to the earthworm Eisenia fetida. Higher activities of the considered cations increased the 48-h LC₅₀ (expressed as Cd²⁺ activities) linearly to different extents in simulated soil solution. The conditional constants for the binding of H⁺ (log K = 5.41), Cd²⁺ (log K = 4.0), Ca²⁺ (log K = 3.35), Mg²⁺ (log K = 2.82), Na⁺ (log K = 1.57), and K⁺ (log K = 2.31) to the biotic ligand (BL) of E. fetida were derived from the toxicity data based on the biotic ligand model (BLM). Furthermore, it was calculated that on average 72% of the BL sites needed to be occupied by Cd²⁺ to induce 50% lethal effect. Autovalidation of the model with the results of the test sets showed that 48-h LC₅₀ could be predicted within a factor of two.     

Toxicity Testing of Waterborne Mercury with Red Sea Bream (<Emphasis Type="Italic">Pagrus major</Emphasis>) Embryos and Larvae

Acute toxicity tests revealed that, in red sea bream (Pagrus major) embryos, 24 and 48 h LC₅₀ values of waterborne HgCl₂ were 67.3 and 39.1 μg Hg²⁺ L⁻¹. In larvae, 48, 72 and 96 h LC₅₀ values were 41.9, 36.1 and 34.8 μg Hg²⁺ L⁻¹, respectively. Sub-chronic toxicity tests indicated that mercury concentrations ≥20 μg Hg²⁺ L⁻¹ decreased hatching success, increased mortality and induced teratogenicity in embryos and larvae. The NOEC, LOEC and MATC values were 8.0, 16.3 and 11.4 μg Hg²⁺ L⁻¹ for hatching success, mortality and teratogenicity; while those were 27.0, 36.9 and 31.6 μg Hg²⁺ L⁻¹ for body length and specific growth rate, respectively.     

Metal Concentrations in Two Bioindicator Fish Species, <Emphasis Type="Italic">Merlangius merlangus</Emphasis>, <Emphasis Type="Italic">Mullus Barbatus</Emphasis>, Captured from the West Black Sea Coasts (Bartin) of Turkey

The Black Sea is very vulnerable to originating from land based human activities and its health is equally dependent on the coastal and non-coastal states of its basin. Total concentrations of cadmium, copper, zinc, lead, nickel, aluminum, iron, manganese, boron and chromium concentrations were determined in Merlangius merlangus (whiting) and Mullus barbatus found in Amasra in the West Coast of the Black Sea (Turkey). The metal contents that were measured in head and muscle was expressed in μg g⁻¹ wet weight. On average, while the highest Fe (344.25 μg g⁻¹), Mn (10.35 μg g⁻¹), Cr (0.96 μg g⁻¹) and Al (76.77 μg g⁻¹) concentrations were measured in the heads of M. merlangus and the highest Zn (77.99 μg g⁻¹), Cu(8.53 μg g⁻¹), B (44.83 μg g⁻¹), Ni (1.96 μg g⁻¹), Cd (0.40 μg g⁻¹) and Pb (6.80 μg g⁻¹) concentrations were detected in the muscles of M. merlangus. There were significant differences between metal levels of muscles in these two species. In terms of permissible levels reported by WHO FAO and TSE, there is not any risk for human consumption for both M. merlangus and M. barbatus, for Pb.     

Silicon Influence on Maize, Zea mays L., Hybrids Exposed to Cadmium Treatment

Thirty Zea mays L. hybrids were screened using hydroponically—grown seedlings treated in the medium with high cadmium content (100 μM Cd(NO₃)₂·4H₂O). Measurements showed conspicuous differences between the hybrids in the growth parameters in Cd treated plants. Hybrids differed greatly in Cd accumulation and translocation. Root/shoot ratio in Cd concentration ranged from 2.78 to 12.83. The majority of the heavy metal was localized in the root system. Five hybrids were chosen and the effect of silicon (5 mM) effect on high-level cadmium toxicity symptoms was investigated. Silicon decreased Cd accumulation in roots and its translocation into the shoots.     

Effects of Environmental Factors on the Uptake Rates of Dissolved Nitrogen by a Salt-water Green Alga (<Emphasis Type="Italic">Oocystis borgei</Emphasis> Snow)

Uptake rates for dissolved nitrogen (DN) by a marine alga (Oocystis borgei) were examined in a ¹⁵N tracer experiment. Maximal uptake rates for all forms of DN were observed at temperatures between 25 and 30°C and at algal concentrations between 3.22 × 10⁸ and 4.78 × 10⁸ cell L⁻¹. Light intensity required to achieve the maximal uptake rate was 45 μmol m⁻² s⁻¹ for dissolved inorganic nitrogen (DIN = NO₃ ⁻, NO₂ ⁻, NH₄ ⁺) and methionine, and 126 μmol m⁻² s⁻¹ for urea. Salinity required to achieve the maximal uptake rate was 12.85 ppt for DIN, 19.89 ppt for urea and 26.2 ppt for methionine.     

Determination of Trace Metals in Airborne Particulate Matter of Kuala Terengganu,Malaysia

Results from the present study in Kuala Terengganu, Malaysia indicated a significant spatial variation but generally the total suspended particulate concentrations (mean = 17.2–148 μg/m³) recorded were below the recommended Malaysia guideline for total suspended particulate (mean of 24-h measurement = 260 μg/m³). Some of the elemental composition of particulate aerosol is clearly affected by non crustal sources, e.g. vehicular emission sources. Based on correlation and enrichment analyses, the elements could be grouped into two i.e. Pb, Cd and Zn group with sources from vehicular emission (r > 0.6; enrichment factor > 10) and Al, Fe, Mn and Cr group that appears to be of crustal origin (r > 0.6; enrichment factor < 10). It can also be concluded that the mean levels of Pb (1 ng/m³), Cd (0.02 ng/m³) and Zn (2 ng/m³) in the study area are generally lower than other urban areas in Malaysia (Pb < 181 ng/m³; Cd < 6 ng/m³; Zn < 192 ng/m³).     

Effects of Sublethal Chronic Copper Exposure on the Growth and Reproductive Success of the Florida Apple Snail (Pomacea paludosa)

Florida apple snails (Pomacea paludosa) were exposed to three concentrations of copper (Cu), in water (8 μg/L, 16 μg/L, 24 μg/L), for one generation to examine uptake and the effects on survival, growth, and reproduction of the F₀ generation and survival, growth, and whole body Cu of the F₁ generation. During a 9-month Cu exposure, apple snails exposed to 8–16 μg/L Cu had high Cu accumulation (whole body, foot, viscera, and shell) and significantly reduced clutch production (8–16 μg/L) and egg hatching (16 μg/L). Apple snails exposed to the 24 μg/L Cu had low survival and the treatment was therefore terminated. Concentrations of minerals (Na⁺, K⁺, Mg²⁺, Ca²⁺) in tissues were maintained regardless of Cu exposure, but the distribution of Cu in the body of snails differed, depending on exposure concentrations. Higher exposure concentrations resulted in a greater percentage of Cu accumulated in the viscera of the snail. Copper exposure to the F₀ generation did not affect the survival, growth, or whole body Cu concentrations in the F₁ generation. These finding are significant, given the importance of the Florida apple snail in the Everglades food chain. Changes in the abundance of apple snail populations, as a result of Cu exposure, could ultimately affect foraging success of predators.     

Characteristics and Sources of Water-Soluble Ionic Species Associated with PM10 Particles in the Ambient Air of Central India

PM₁₀ aerosol samples were collected in Durg City, India from July 2009 to June 2010 using an Andersen aerosol sampler and analyzed for eight water-soluble ionic species, namely, Na⁺, NH₄ ⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃ ⁻ and SO₄ ²⁻ by ion chromatography. The annual average concentration of PM₁₀ (253.5 ± 99.4 μg/m³) was four times higher than the Indian National Ambient Air Quality Standard of 60 μg/m³ prescribed by the Central Pollution Control Board, India. The three most abundant ions were SO₄ ²⁻, NO₃ ⁻, and NH₄ ⁺, with average concentrations of 8.88 ± 4.81, 5.63 ± 2.22, and 5.18 ± 1.76 μg/m³, respectively, and in turn accounting for 27.1 %, 16.5 %, and 15.5 % of the total water-soluble ions analyzed. Seasonal variation was similar for all secondary ions i.e., SO₄ ²⁻, NO₃ ⁻, and NH₄ ⁺, with high concentrations during winter and low concentrations during monsoon. Varimax Rotated Component Matrix principal component analysis identified secondary aerosols, crustal resuspension, and coal and biomass burning as common sources of PM₁₀ in Durg City, India.     

Acidic Gases and Nitrate and Sulfate Particles in the Atmosphere in the City of Guadalajara,México

Atmospheric concentrations of nitrous acid, nitric acid, nitrate and sulfate particles were obtained in this study from April to June 2008 in the center of the city of Guadalajara, while concentrations of ozone, sulfur dioxide, nitrogen dioxide and meteorological parameters (temperature and relative humidity), were acquired by the Secretaría del Medio Ambiente para el Desarrollo Sustentable del Estado de Jalisco (SEMADES). The results showed that nitric acid (2.7 μg m⁻³) was 2.7 times higher than nitrous acid (1.0 μg m⁻³). The sulfur dioxide (SO₂) concentration indicated an opposite trend to sulfate (SO₄ ²⁻), with the average concentration of SO₂ (6.9 μg m⁻³) higher in almost the entire period of study. The sulfur conversion ratio (Fs, 24.9%) and nitrogen conversion ratio (Fn, 6.2%), were revealed to be similar to that reported in other urban areas during warm seasons. It is also noted that ozone is not the main oxidizer of nitrogen dioxide and sulfur dioxide. This determination was made by taking into account the slightly positively correlation determined for Fn (r² = 0.084) and Fs (r² = 0.092) with ozone that perhaps suggests there are other oxidizing species such as the radical OH, which are playing an important role in the processes of atmospheric oxidation in this area.     

Characterization of Copper-Resistant <Emphasis Type="Italic">Agrobacterium</Emphasis> Isolated from Legume Nodule in Mining Tailings

A copper-resistant bacteria CCNWSX2332 was isolated from root nodules of Lespedeza cuneata growing in a gold mining tailing region in northwest of China. The specific growth rate of the strain was 0.62 μh⁻¹ in the presence of 2.0 mM Cu²⁺ in TY liquid media, and the maximum copper accumulation of whole cell reached 147.03 μM Cu²⁺ per gram (dry weight) after 4 h incubation. A partial sequence of the copper resistance gene copA was amplified from the strain, and the phylogenetic analysis based on 16S rDNA sequence showed that CCNWSX2332 belonged to Agrobacterium, and it had 100% similarity with Agrobacterium tumefaciens type strain IAM13129^T.     

The study of TSP and PM10 concentration and their heavy metal content in central area of Tehran, Iran

Atmospheric particulate matter may exert serious health hazards because of its chemical characteristics. The main objective of this study is to assess the concentrations of total suspended particles (TSP), particulate matter (PM) with an aerodynamic diameter ≤10 μm (PM₁₀), and air-transmitted particulate trace metals in Tehran University (a central location in Tehran, capital of Iran) ambient air, for the period of 5 months viz. February–June 2007. Furthermore, the present work examines the daily levels of fine particles in comparison with the proposed limiting values from the U.S. Environmental Protection Agency (65 μg m⁻³ for PM₁₀). The sampling for TSP and PM₁₀ was performed using a high-volume sampler. The TSP and PM₁₀ levels were determined by gravimetry and the metals by flame atomic absorption spectrometry. Arithmetic means of 151 ± 44 μg m⁻³ and 90 ± 38 μg m⁻³ were determined for TSP and PM₁₀, respectively. Comparing with EPA primary and secondary air quality standards, only PM₁₀ concentrations in 3 days were higher than the standard values. Heavy metal content of both TSP and PM₁₀, such as chromium (Cr), cadmium (Cd), and lead (Pb), were also analyzed separately during the same period using atomic absorption spectrometry. The average concentrations of heavy metal in TSP were Pb: 183.63 ± 147.81 ng m⁻³; Cr: 13.72 ± 2.40 ng m⁻³; and Cd: 6.80 ± 1.97 ng m⁻³ and for PM₁₀ were: 150.36 ± 157.01 ng m⁻³; Cr: 9.12 ± 2.14 ng m⁻³ and Cd: 6.87 ± 2.22 ng m⁻³.