Cadmium Concentrations In Water Research Articles

Contagion and health threats scrutiny of Cadmium and Phosphate ions concentration in water physiques in South-South, Rainforest belt of Edo State, Nigeria

Non-nutritive metals and anions, for examples cadmium (Cd) and phosphate (p), persistence in the environment (land, discharge into both ground and surface water etcetera), besides intake of its accumulation whether consumption through food or water intake make Cd plus P, a public health issues. In this research, phosphorus and cadmium concentrations in water- physiques in ten sites at Ikpoba River Southern, Nigeria was ascertained in both arid and wet season by obvious spectrophotometric technique and modelled for contagion and health risks scrutiny. Result shown that Water quality index (WQI) and skewness for cadmium was 0 ± 1.559 in wet season and zero throughout dry season, but phosphate values ranges from 3.005 ± 14.72 and 304.89 ± 6.261 for dry and wet season respectively. Equating results with World Health Organization (WHO) permissible limits, it discovered that cadmium was 90% above permissible during rainy season, but 100% within limit throughout arid season. Phosphate was high in nearly all the sites in wet season except site eleven. The water- physiques in all sites at Ikpoba River in both seasons revealed low disparities (<20%) with positive linear relationship (R 0 ≤ 089) for cadmium and (R 0.904 ≥ 0.319) for phosphate in dry and wet seasons respectively. Also, the nutrient contagion index displayed slightly to extremely contagion during rainy period and no to slightly contagion throughout dry period, whereas the water physiques will pose very high non-carcinogenic health risks and threats to users through the oral pathway.

Intensification of the wastewater treatment process using magnesium-containing materials

An analysis was made of the use of magnesium-containing materials of natural and technogenic origin in complex systems for the purification of wastewater from mining enterprises from heavy metals. The transfer mechanisms of dissolved heavy metals into the precipitate and onto the surface of the sorbent have been theoretically studied. Magnesium-containing minerals in water partially undergo hydration, forming an association of complex molecules. The main purification mechanism is the formation of sparingly soluble metal hydroxides. The mechanisms of adsorption, co-precipitation, co-crystallization of impurities with products of hydration and hydrolysis of magnesium-containing minerals also work. Exploratory studies of the intensification of the wastewater treatment process using magnesium-containing materials have been carried out, which have shown that the residual concentration of almost all metals, with the exception of nickel and chromium, when using brucite at the same pH level is lower. The highest water purification efficiency is observed for zinc and lead ions. The addition of dolomite to brucite in an amount of less than 10% makes it possible to reduce the residual concentration of cadmium in water at 20-60 minutes of contact and other equal experimental conditions.

Cadmium concentration in water and sediment from lake Lau Kawar, North Sumatra

Heavy metals are easy to bind organic matter and settle to the bottom of the waters and unite with sediments, which is cadmium. Cadmium (Cd) is found from volcanic eruptions, from various human activities, and is carcinogenic. This study aims to analyze the concentration of cadmium in water and sediment in Lake Lau Kawar. Water samples were collected by purposive sampling at three stations using Horizontal Bottle samples. Sediment samples were collected compositely using an Eckmann grab then analyzed by the Atomic Absorption Spectrophotometer method. Descriptive data analysis used comparative quantitative methods, namely comparing the level of cadmium in water and sediment in Lau Kawar Lake with the quality standards set by WHO and IADC/CEDA. The water quality in Lake Lau Kawar is in good condition. The concentration of heavy metal Cd in water and sediment still meets the established water quality standard criteria. The source of Cd contamination in the lake, which comes from the volcanic ash of Mount Sinabung, is only carried in low quantities. The largest source of contamination comes from the activities of residents as fertilizers and pesticides used on agricultural land.

The effect of cadmium toxicity on Oreochromis niloticus and human health

Cadmium levels below permissible limits can be toxic, affecting the health of exposed aquatic organisms and ultimately human health. Although cause and effect links between aquatic organisms and human health have not been elicidated, this study evaluated the effect of cadmium exposure on the health status of Oreochromis niloticus and human fish consumers. Clinical and post-mortem examinations were performed in situ on fish samples collected monthly from the Abo-Saleh, Ehnasia fish farm and Nile River. Cadmium was measured in water and fish musculature from the two fish farms and in water samples from the Nile River. Human blood samples of consumers of fish from the two fish farms, as well as non-fish consumers as a control, were collected for estimation of cadmium, uric acid, creatinine and calcium levels. Clinical signs and post-mortem abnormalities of Oreochromis niloticus from Ehnasia fish farm showed congestion of gills, liver, intestine and spleen. Cadmium concentrations in water and musculatures of Oreochromis niloticus obtained from the Ehnasia fish farm was significantly higher than the permissible limit, whereas cadmium concentrations in the Abo-Saleh fish farm and Nile River were within the permissible limit. There were increased levels of cadmium in human blood and creatinine and uric acid in human serum, but decreased levels in calcium in serum of human consumers of fish from the Ehnasia fish farm. The presence of cadmium can be toxic, even at levels below the permissible limit, negatively affecting health, as observed for aquatic organisms and subsequently for humans.

High Field Modulated Field Effect Transistors Coated By Ion Selective Membrane for Cadmium Ion Detection in Water

Cadmium is one among the most hazardous heavy metals. Heavy metal cannot be metabolized or digested by human body, therefore, heavy metal accumulates in our body through time. Cadmium in human body causes lung cancer, osteomalacia and even proteinuria. Mostly cadmium ions get in to human body by ingestion, so detecting cadmium ion in drinking water, tap water and liquid form of food is very important. However, traditional laboratory detection methods of cadmium ion are complex and time consuming and requires heavy and expensive machinery. Though the electrochemical ion selective electrode is easy to use, its poor stability and larger detection limit are huge disadvantages. In this research, we devised a small size, high sensitivity, low detection limit, short response time and easy to fabricate cadmium ion selective membrane field effect transistor (ISMFET). This device is easy to use and can measure the cadmium concentration in water quickly with the combination of ion-selective membrane and field effect transistor. The sensing mechanism depends on electrical double layer (EDL) gating coupled with high electric field to enhance the sensitivity of ISHEMT beyond the limit of ideal Nernst sensitivity. World Health Orgnization (WHO) suggests that cadmium ion in drinking water should be lower than 3 ppb, equal to 2.68 10-8 M. This device can detect cadmium ion concentration form 10-7 M to 10-11 M, covering the wide dynamic range according to WHO’s suggestion. Such high sensitivity and low detection limits devices are highly desirable for consumers who intend to regularly monitor the water quality, for food and environmental safety. In contrast, testing cadmium ion in water by ICP-MS takes several hours and the instrument occupies larger space. To improve the yield and sensitivity of our sensor, we are studying on different condition of ISM. With this cadmium, ISMFET, we can determine the cadmium concentration in water in 15 minutes and even higher sensitivity and lower detection limit, in comparison with conventional laboratory based techniques. Not only Cadmium, but also other heavy metals, for example lead and mercury, can use similar methodology to get better detection time and detection limit. This design makes quality monitoring of water we consume in daily life become much easier and convenient.

High Field Modulated Field Effect Transistors Coated by Ion Selective Membrane for Cadmium Ion Detection in Water

Cadmium is one among the most hazardous heavy metals. Heavy metal cannot be metabolized or digested by human body, therefore, heavy metal accumulates in our body through time. Cadmium in human body causes lung cancer, osteomalacia and even proteinuria. Mostly cadmium ions get in to human body by ingestion, so detecting cadmium ion in drinking water, tap water and liquid form of food is very important. However, traditional laboratory detection methods of cadmium ion are complex and time consuming and requires heavy and expensive machinery. In this research, we devised a small size, high sensitivity, low detection limit, short response time and easy to fabricate cadmium ion selective membrane field effect transistor (ISMFET). This device is easy to use and can measure the cadmium concentration in water quickly with the combination of ion-selective membrane and field effect transistor. The sensing mechanism depends on electrical double layer (EDL) gating coupled with high electric field to enhance the sensitivity of ISHEMT beyond the limit of ideal Nernst sensitivity. World Health Orgnization (WHO) suggests that cadmium ion in drinking water should be lower than 3 ppb, equal to 2.68*10-8 M. This device can detect cadmium ion concentration form 10-7 M to 10-11 M, covering the wide dynamic range according to WHO’s suggestion. Such high sensitivity and low detection limits devices are highly desirable for consumers who intend to regularly monitor the water quality, for food and environmental safety.

Effect of water cadmium concentration and water level on the growth performance of Salix triandroides cuttings.

The growth performance of Salix triandroides cuttings at three water cadmium (Cd) concentrations (0, 20, and 40mgL-1) and three water levels (- 40cm, water level 40cm below the soil surface; 0cm, water level even with the soil surface; and 40cm, water level 40cm above soil surface) was investigated to evaluate its potential in phytoextraction strategies. Compared to cuttings in the - 40 or 0cm water levels, cuttings in the 40cm water level showed significantly lower biomass, height, and adventitious root length and significantly fewer leaves and adventitious roots. However, these growth and morphological parameters were not different among the three water Cd concentrations. Water level decreased stomatal conduction and transpiration rate but showed no significant effects on chlorophyll concentration or photosynthetic rate. Chlorophyll concentration and stomatal conductance were higher at 40mgL-1 Cd treatment than at 0 or 20mgL-1 Cd treatment; yet, photosynthetic rate and transpiration rate were not different. Cd concentration in the leaves and stems increased as the water level increased, but the highest Cd concentration in the roots occurred in the 0cm water level. As water Cd concentration increased, Cd concentration in the leaves, stems, and roots increased in all three water levels, except in stems in the - 40cm water level. Under Cd stress, cuttings in the - 40 or 0cm water levels were characterized by a higher bioaccumulation coefficient, but a lower translocation factor, than those in the 40cm water level. However, the bioaccumulation coefficient increased with increasing water Cd concentration in all three water levels, as did the translocation factor in the 40cm water level. The tolerance index for the cuttings was the same among all water levels and water Cd concentrations. The results clearly indicated that the low water level increased plant growth and Cd accumulation in underground parts, while the high water level decreased plant growth but increased Cd accumulation in aboveground parts.

PENURUNAN KADAR LOGAM KADMIUM MENGGUNAKAN ADSORBEN NANO ZEOLIT ALAM ACEH

&#x0D; The presence of Cadmium (Cd) in groundwater is an issue that needs serious handling as it causes problems to human health. The removal of Cadmium (Cd) can be done by various methods such as adsorption, oxidation, filtration, and many more. In this study, the method used was adsorption using Aceh natural zeolite. This process was expected to reduce Cd metal as effectively as possible. The adsorption was conducted by varying contact time, adsorbent dosage, pH and initial concentration of Cd metal. The crystallized Aceh natural zeolite was characterized by X-Ray Fluorescence (XRF) with Si/Al zeolite ratio of 4.36 %. The concentration of Cadmium in water was analyzed by means of Atomic Adsorption Spectrophotometer (AAS) standard AA 630. The results showed that the adsorption of cadmium in water solution by Aceh natural zeolite occurred according to the Freundlich adsorption model. While the adsorption kinetic from the process was found to be a pseudo second order with k2 value of 1.53.&#x0D;

Measuring the Spectrum of Extinction Coefficient and Reflectance for Cadmium Compounds from 400 to 900 nm

The key to extract the contents of cadmium in water by using remote sensing technique is to measure the spectrum of extinction coefficient per g·L(-1) and reflectance for its compounds. So in this paper, firstly, we choose two kinds of cadmium compounds, cadmium sulfide (CdS) and cadmium oxide (CdO), which are most commonly exsit in natural water, to measure the spectrums of extinction coefficient and reflectance for them. We use the equipment, designed on our own, which can adjust the path length of light passing and make our measuring results more accurate at visible and near-infrared wavelength range than others. Then we use Analytical Spectral Devices (ASD) spectrometer to measure the radiance of the light spot, which is from the direct light passed through cadmium compounds solutions of different concentrations reflected by the standard board. Using the ratio method to eliminate environmental errors and the effects of the thimbleful of suspended solids in water, we obtain the extinction coefficient per g·L(-1) of these two kinds of cadmium compounds from 400 to 900 nm. Secondly, we use ASD spectrometer to measure the reflectance spectrum of them in the sunny day at outdoor. The reflectance we obtain in this paper can help us to calculate the absorption and scattering coefficient per g·L(-1) in the future. The measuring results show that the extinction coefficient spectrum of CdS has two troughs at 550 and 830 nm and one peak at 675 nm. And the extinction coefficient spectrum of CdO decrease from purple to near-infrared. Both of their coefficient spectrums in blue are larger than green and red. And the value of the extinction coefficient per g·L(-1) of CdS is larger than CdO in the whole measuring wavelength range. The reflectance of CdS in yellow and red is larger than purple and blue, which increases rapidly from 500 to 650 nm and then leveling off. While the reflectance of CdO increase linearly from 525 to 900 nm. Both have obvious spectral characteristic. According to our results, the largest extinction coefficient appear at blue color, while the largest reflectance appear at yellow and red, which means that those bands are the most sensitive wavelength to detect the change of cadmium concentration in water. This study carries out with optical parameters measurements for optical activity of cadmium compounds specifically for water quality remote sensing for the first time. We conclude that the extinction coefficient and reflectance spectrums we obtained are reasonable, and the results can be used as the base parameter in the remote sensing inversion model for cadmium contents in water, which provides a breakthrough on using remote sensing technique to extract the heavy metal contents in water. Obtained these two optical parameters in this paper can provide powerful reference for band selection of the remote sensing image, which is used to extract cadmium contents in water, as well as provide the necessary important parameters of the remote sensing inversion model of cadmium contents in water.

Arsenic and Cadmium Contamination in Water, Sediments and Fish is a Consequence of Paddy Cultivation: Evidence of River Pollution in Sri Lanka

The upper Malwathu Oya is a seasonal river. The main livelihood of people living in the immediate vicinity of the river is paddy cultivation, and chronic kidney disease is reported among them. Farmers utilize different types of agricultural chemicals in their fields expecting bumper harvests. Several agricultural chemicals have been reported to contain toxic trace elements in Sri Lanka. Therefore, arsenic and cadmium might end up in the river water. The presence of these trace elements in the river water and sediments can result in their bioaccumulation in fish tissues. The main purpose of this study was to investigate the presence of two trace elements in water and sediments, as well as in fish tissues (gills, kidney, liver and muscle) of three food fish species, Etroplus suratensis, Anabas testudineus and Channa striata during cultivating and non-cultivating seasons of the year. Further, the level of bioaccumulation of two trace elements in fish tissues in relation to the contamination level of water and sediments was assessed. Data were gathered for 43months. Arsenic and cadmium concentration in water showed a significant (P<0.05) seasonal variation. Generally, the two trace elements in the river water were highest during the cultivating seasons than in other seasons. In all species, both trace elements in the gills highly depended on the concentration in the water. In all species, two trace elements in water and sediment did not significantly affect the levels in muscle tissue. Therefore, the trace element levels in the edible parts of these three fish were well below the maximum permissible levels of international institutions.

Heavy Metals Assessment In Water, Sediments And Selected Aquatic Organisms In Lake Asejire, Nigeria

Rapid urbanization and industrialization in developing countries have been associated with production and deposition of hazardous wastes in aquatic environments. Heavy metals are major components of these wastes which have been implicated in several metal-related diseases and food poisoning in man. This study evaluated iron, lead, cobalt, nickel, chromium and cadmium concentrations in water, sediment, Nile Tilapia (Oreochromis niloticus) and African river prawn (Macrobrachium vollenhovenii) samples of Lake Asejire, Oyo State, Nigeria. The concentration of these metals was determined spectrophotometrically in three locations along the course of the lake. Results revealed that only iron and lead were detected in water samples. However, all the metals were found in sediments, Nile Tilapia and African river prawn. Iron had the highest mean concentrations (mg kg-1) of 2.392±0.015, 7.4314±1.184, and 1.6100±0.099 in sediments, fish and prawn respectively. Significant differences was found across each sample type for the metals determined. The detection of these metals in Lake Asejire call for close environmental monitoring and adequate public awareness. This is necessary to discourage further pollution which could lead to high metal concentration and metal poisoning.

Lead Release to Drinking Water from Galvanized Steel Pipe Coatings

Abstract Problems identified with elevated lead in drinking water associated with galvanized steel pipes were recently hypothesized to result from lead accumulation on galvanized steel pipe surfaces from upstream lead service pipes. However, historical research documents that the grade of zinc typically used for galvanizing contains a minimum of 0.5% lead and can itself be a significant long-term source of lead, which may explain some recent lead contamination problems associated with galvanized steel. Surface analysis of various galvanized steel pipes and fittings installed from 1950 to 2008 demonstrated that the concentration of lead in the original zinc coating can range from nondetect to nearly 2%, dependent on the manufacturer and fitting type. Since cadmium is also present in many zinc coatings, but not in lead pipe, leaded solder, or brass, correlation of zinc concentration to both lead and cadmium concentrations in water was considered as a possible fingerprint implicating the coating on galvanize...

ASSESSMENT OF THE BLACK SEA ECOSYSTEM POLLUTION WITH COPPER AND CADMIUM IN SELECTED BAYS OF SEVASTOPOL REGION

A high level of anthropopressure has been registered in Sevastopol region, connected with its strategic role as the main city in the region, but also due to Russian Black Sea Fleet stationing there for many years. A significant source of the Black Sea contamination in Sevastopol area is the industry located in this city, municipal waste and agriculture. Implementing measures aimed at protection of the Black Sea and the evolution of their results requires monitoring conducted in the regions with various levels of anthropopressure. The work was aimed at the assessment of copper and cadmium content in water and algae in selected bays of the Black Sea in the vicinity of Sevastopol. Samples of water and algae were collected in August 2012 from eight Sevastopol bays (Galubaja, Kozacha, Kamyshova, Kruhla, Strieletska, Pishchana, Pivdenna and Sevastopolska) and from the open sea in the vicinity of Fiolent. Algae (Cystoseira barbata and Ulva rigida) were collected from the same places. Collected water was preserved on the sampling place and brought to the laboratory where its copper and cadmium concentrations were assessed. Collected algae were rinsed in distilled water, dried, then homogenised and mineralised. Copper and cadmium content were determined in the mineralizates using ASA method with electrothermal atomisation. Cadmium concentration in water ranged from 0.13 to 1.74 μg Cd∙dm-3, and copper from 7.07 to 22.56 μg Cd∙dm-3. Considerable differences in the content of the analysed elements were registered in individual bays. The highest content was assessed in Galubaja and Sevastopolska bays, whereas the lowest one in the water collected in the open sea and in Pivdenna bay. Copper concentrations in the analysed algae fluctuated from 3.375 to 14.96 mg Cu∙kg-1 d.m. No differences were noted in this element content between the algae species. Cadmium content in the algae ranged from 0.133 to 1.133 mg Cd∙kg-1 d.m. Higher accumulation of cadmium was observed in Cystoseira barbata than in Ulva rigida. The value of copper bioaccumulation coefficient (BC) ranged from 181 to 1201, whereas cadmium from 181 to 5256. The contents of the analysed metals, both in biotic and abiotic elements of the studied ecosystems point to anthropogenic enrichment and the results obtained for Sevastopolska, Galubaja and Kozacha bays indicate a hazardous, excessive bioaccumulation of copper and cadmium and to potential threat to the life of aquatic organisms and seafood consumers.

Synthesis and Characterization of Silver–PVA Nanocomposite for Sensor and Antibacterial Applications

Silver–polyvinyl alcohol (PVA) nanocomposite is synthesized by a simple chemical reduction method in aqueous media and characterized by various techniques such as UV–Visible spectroscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy. The morphology of the obtained silver nanoparticles is spherical in shape with an average diameter of 24 nm. The prepared silver–PVA nanocomposite is demonstrated to detect the concentration of heavy metal contaminant cadmium in water based on linear change in surface plasmon resonance absorption strength. The antibacterial tests show the inhibiting action of this nanocomposite against pathogenic bacteria Escherichia coli and Pseudomonas aeruginosa (gram negative), Bacillus cereus and Staphylococcus aureus (gram positive), which are found commonly in water. These observed optical and antibacterial properties, suggest the possible utilization of prepared silver–PVA nanocomposite in the water purification application.

Seasonal distribution of cadmium among components of sewage treatment ponds: an eco-tech for heavy metal remediation

The study was designed to quantify cadmium accumulation in different components of sewage treatment ponds during different seasons and to assess risk for human consumption perspective. The study estimated cadmium concentration in water, sludge, Eichhornia, plankton and tilapia fish from anaerobic, facultative, maturation-1 and -4 ponds during pre-monsoon, monsoon and post-monsoon periods. It resulted that cadmium accumulated among different components of anaerobic, facultative, maturation-1 and -4 ponds ranging 0–18, 0–10, 0–7 and 0–15.4 ppb, respectively. During monsoon, highest accumulation was observed in tilapia in both facultative and maturation ponds, but during post-monsoon, plankton community showed highest value in all. The highest bio-magnification of cadmium was recorded during monsoon with varying degrees (facultative pond: 4.39, maturation pond-1: 3.03 and maturation pond-4: 7.08). Cadmium concentration in tilapia lied within WHO’s safe level and may be recommended for human consumption. The concentration of cadmium was estimated by Flame Atomic Absorption Spectrophotometer. The above findings occurred due to chelation, adsorption and sedimentation, absorption and bio-accumulation, ionization, leaching through sediment and rainfall. Water pH (6.7–8.8), dissolved oxygen (0–17 mg L−1), total solids (251–650 mg L−1), iron (Fe2+) concentration (0.61–4.87 mg L−1) and sedimentation rate (278.9–2,409.6 g day−1 m−3) were conducive for the distribution of cadmium into different ecosystem components of treatment ponds. These ponds reclaimed 28.57–61.11 % of sewage-cadmium and may be promoted as a low-cost eco-tech for sewage treatment.

English

&nbsp; All intensive agriculture, like periurban agriculture, uses massive inputs such as agrochemicals. This study aims to assess the environmental impacts of agrochemical use in periurban agriculture in Togo. It was based on the chemical analyses of soil, water and vegetable samples.&nbsp;These analyses were carried out by gas chromatography on extracts from soil, water and vegetable samples.&nbsp;In soil samples, the concentrations of pesticide residues are lower than 20 &micro;g/kg of&nbsp;dry material. For water samples, contamination levels vary from 0.02 to 1.1 &micro;g/L ofdry material with&nbsp;the&nbsp;highest levels for metalaxyl&nbsp;M (1.1 &micro;g/L) and for dimethoate (1 &micro;g/L). In vegetables, the concentrations measured are between 0.01 and 0.1 mg/kg of&nbsp;dry material.&nbsp;All these concentrations are affected by a positive factor of the maximum limits of residues. These agrochemicals, coupled with periurban environmental management led to the high concentrations of trace elements. Lead and cadmium concentrations in water are 10 and 21 times respectively higher than the maximum concentration allowable for drinking water by the WHO. The study showed that inappropriate use of agrochemicals in Togolese periurban agriculture creates ecological disturbances that could affect produce quality. &nbsp; Key words:&nbsp;Togo, periurban agriculture, agrochemicals, pesticide residues, trace element

Performance of constructed wetlands in the reduction of cadmium in a sewage treatment cum fish farm at Kalyani, West Bengal, India

The distribution pattern of cadmium was investigated in waste stabilization ponds designed for three-step sewage treatment processes. The overall mean concentration of cadmium in water and sludge was reduced by 30% and 33%, respectively, from the inlet of the anaerobic pond to the final outlet of the maturation pond. The level of cadmium in water hyacinth, plankton and fish remained higher in all the samples collected from the anaerobic or facultative pond compared to the last maturation pond. It may be reasonable to conclude that three-step ecological treatments accompanied by physical, chemical and biological processes of the waste stabilization ponds were effective in reducing the load of cadmium from sewage effluents.

水中镉含量的激光诱导击穿光谱高灵敏快速检测

水中镉含量的激光诱导击穿光谱高灵敏快速检测

Bayesian modelling of daphnid responses to time-varying cadmium exposure in laboratory aquatic microcosms

Experiments were carried out to test the effects of cadmium on five aquatic species in 2-L indoor freshwater/sediment microcosms. Experimental data were collected over 21 days in static conditions, i.e. the microcosms evolved without water renewal. Because of speciation, the total cadmium concentration in water decreased with time. Here we present a focus on Daphnia magna responses. For the three life history traits we considered (survival, growth and reproduction), mathematical effect models were built based on threshold stress functions involving no effect concentrations (NECs). These models took the time-varying conditions of exposure into account through a time-recurrent formalism. Within a Bayesian framework, four kinds of data were fitted simultaneously (exposure, survival, growth and reproduction), using an appropriate error model for each endpoint. Hence, NECs were determined as well as their associated estimation uncertainty. Through this modelling approach, we demonstrate that thresholds for stress functions can be successfully inferred even in experimental setup more complex than standard bioassays.

Expression of metallothionein cDNA in a freshwater crab, Sinopotamon yangtsekiense, exposed to cadmium

This paper aims at evaluating the induction of metallothionein (MT) synthesis in gills, heart and hepatopancreas of a freshwater crab, Sinopotamon yangtsekiense. Crabs were exposed to different cadmium concentrations (from 0 to 5 mg/L) from 24 to 96 h. The amount of cadmium (Cd) accumulated in gills, heart and hepatopancreas of the crab showed an increase with an increase in the treatment concentration. Furthermore, the amount of Cd accumulated in these tissues showed an increase with an increase in duration. On the other hand, MT and β-actin genes were amplified using reverse transcription PCR (RT-PCR). Metallothionein gene expression induced by Cd was analyzed using real-time quantitative polymerase chain reaction. Its expression levels were correlated to duration time and increased with cadmium concentrations in water, whilst β-actin was expressed at a relatively constant level. The MT transcript levels in gills and hepatopancreas were higher than that in heart. Furthermore, the MT mRNA expression was not time dependent, and no relationship with Cd accumulation followed the time course of treatment at the same dose Cd treatment. But the clear dose response of MT to cadmium exposure of S. yangtsekiense is a proof of the feasibility of MT as a biomarker for testing cadmium pollution.