How does cyanide get into water

Free cyanide consists of hydrogen cyanide HCN and the cyanide ion CN- , which represent the more toxic forms of cyanide. However, cyanide in water may be stably bound to metals such as iron. The total cyanide measurement shows the combined amount of both free and metal bound cyanide in the water. In Australia, background levels of cyanide in drinking water range up to 0. The World Health Organisation recommends that people should not consume water with a cyanide concentration above 0.

This is to protect against short term health risks. They rapidly evaporate and are broken down by microbes. They do not bind to soils and may leach to groundwater.

My Cart. Water And Health. Learn About Water Quality. Water Can Heal! Contaminants Fact Sheets. Top Water News. Learning Center Categories:. Exposure can also occur by absorption via the skin dermal absorption , occupational exposure via electroplating or metallurgy OSHA Chronic exposure to low concentration of cyanide is supposed to be accountable for several thyrotoxic and neuropathic conditions in humans Dube and Hosetti Cyanide can form a stable cytochrome oxidase complex, an enzyme that facilitates electrons transfer within the mitochondria cells through the fabrication of adenosine triphosphate Yen et al.

Exposure to HCN causes bleeding, dermatitis, scarlet rash, itching, nose irritations and papules Nagasawa et al. Fish and aquatic invertebrates are sensitive to cyanide exposure.

Moreover, the sensitivity of aquatic organisms to cyanide exposure is species-specific, which is influenced by water oxygen content, temperature and pH, as well as the condition and life stage of the organism Hosetti Hydrological factors, such as temperature, total dissolved solids TDS , pH and conductivity can affect the decomposition rate of cyanide-related compounds in water resources Sawaraba and Rao WHO has set 0.

Research has shown that cyanide affects individuals who have regular long-term consumption of cassava Flynn and Haslem To the best of our knowledge, there has been no report on the levels of cyanide in tuber crops, such as cassava and cocoyam in Kenyasi, a Mining Community in the Brong Ahafo Region of Ghana.

Moreover, people living around mining sites rely on these crops as the major source of food consumption. However, since the plants take up cyanide from soils polluted by organic salts with cyanide ion from mining activities and industrial effluents, their effects on consumers need to be addressed. Therefore, the main aim this study was to evaluate the levels of free and total cyanide in fish, water, cassava and cocoyam in Kenyasi, a mining community in the Brong-Ahafo region of Ghana.

Kenyasi is located in the Brong Ahafo Region of Ghana. Kenyasi, where the Ahafo mine is located produced approximately , equity ounces of gold with about 9. Kenyasi is the capital of the Asutifi district in the Brong Ahafo region of Ghana. The region lies in the forest zone. Kenyasi is a major cocoa and timber producing area. The northern part of the region lies in the savannah zone with a major production of grain and tuber. The total population of the region is approximately 1,,, representing 9.

The main occupation in the region is agriculture, which employs about The Asutifi District is one of the smallest in the Brong Ahafo Region with a total of settlements and land surface area of km 2 sq. The Asutifi District has abundant natural resources including areas of forestry products, the soil of high agronomic value, sand, clay and mineral deposits, such as gold, bauxite and diamond Government of Ghana Topographically, Kenyasi lies within the forest dissected plateau with an average height of about ft above sea level and the highest point is a chain of mountains, while the lowest part is along the river basins Government of Ghana Geologically, the area is covered by rocks of Dahomeyan and formations, which are known to be Bauxite, manganese and gold-bearing rocks Government of Ghana This explains why currently gold is being mined in Kenyasi.

The current operation of gold mining activities by Newmont Ghana Gold Limited has created severe anxiety about the implications of the mining activities on the local economy. A total of sixteen 16 water samples was collected from the study area of which seven 7 were from the dam, two 2 from the surface water to serve as a control for the dam and seven 7 from boreholes close to the mining area during March The pH and electrical conductivity EC of the water samples were measured in situ using Yogokawa pH meter and Orion Thermoscientific meter, respectively.

A total of five 5 fish samples were sampled from the dam with hook and line into a black polyethene bag. They were then kept in an ice-cooled container, transported to the laboratory and refrigerated prior to analysis. The samples were found to belong to the Oreochromis niloticus. Three Oreochromis niloticus were obtained from a pond in Kumasi to serve as a control Fish C. A total of twenty 20 randomly selected cassava and cocoyam tubers were harvested from local farms close to the mining area.

This was done by picking four samples from four divided portions of a farm. In all, four different farms were considered each for cassava and cocoyam. Adhering soils were thoroughly washed with distilled water. The cassava and cocoyam samples were then labelled. Three samples, each of cassava and cocoyam were collected from a non-mining area Hwidiem treated the same way and labelled CvC for cassava and CyC for cocoyam to serve as a control. The cassava and cocoyam samples were wrapped in a black polythene bag in an ice-cooled container and transported to the laboratory for further analysis.

Total and free cyanide concentrations were determined in the water, fish, cocoyam and cassava samples from Kenyasi and Hwidiem. The solid samples were first distilled before the cyanide concentrations were determined.

The distillation method was adopted for the treatment of the solid samples fish, cassava and cocoyam to bring into solution the hydrogen cyanide for the continuous flow analysis ISO Approximately To each sample in the round bottom flask, a The heating mantle was then turned off, the distillate cooled for 20 min, poured into a mL volumetric flask and diluted to the mark with distilled water.

Blanks were prepared with the same procedure without the sample. The automated procedure for the determination of total cyanide involves the decomposition of the complex bound cyanide in a continuously flowing stream at pH of 3. The hydrogen cyanide present at pH of 3. The hydrogen cyanide produced react with chloramine-T to form cyanogens chloride, which then reacts with 4-pyridine carboxylic acid and 1,3-dimethyl barbituric acid to give a red colour with a maximum absorbance at nm.

The determination was repeated for each sample twice and their means were taken. The instrument has a detection limit of 0. About 20 g of each solid sample was ground into a mL pyrex beaker, followed by the addition of a mL distilled water and stirred for 10 min with a magnetic stirrer to ensure complete homogeneity. The mixture was then filtered into a small sterilised plastic container and the pH of the filtrate was determined by immersing the pH electrode into the filtrates of the solid samples.

A steady reading was recorded in each case. The electrodes were washed thoroughly with distilled water after every determination to avoid cross-contamination.

For each sample, the pH determinations were made in triplicate and the mean taken to represent the pH of the sample. The conductivity readings of both the solid samples were also taken in the same manner using the Orion Thermo Scientific meter from Fairland, Johannesburg. The samples were then cooled in a desiccator and then reweighed. The drying process was repeated at the same temperature at time intervals of 1 h until a constant weight was recorded for each of them.

Non-carcinogenic health risk models presented by the United States Environmental Protection Agency, have been proven successful and are now adopted globally. The exposure factors and values utilised in the evaluation of health risk evaluation are shown in Table 2. The non-carcinogenic risk can be expressed as HQ using Eq.

The RfD of cyanide is 6. The Tukey method is a single-step multiple comparison statistical test Morrison et al. This method is applicable for pairwise comparisons. The Tukey method assumes independence of the observations being tested, as well as equal variation across observations. The Tukey method can be used on raw data or in conjunction with a post-hoc analysis to analyse data that are significantly different from each other.

The analytical result of free and total cyanide level in the seven borehole and dam water samples collected from Kenyasi are shown in Table 3. The free cyanide levels of the dam and borehole water samples range from 0. Moreover, the free cyanide levels of the borehole samples appeared to be higher than those of the dam samples because cyanide might leach into the subsurface groundwater and hence, cause an increase in the cyanide concentration.

The free cyanide levels of the control dam water samples were averagely greater compared to the borehole control samples and fall below the acceptable level.

Moreover, the free cyanide levels at almost all the sampling sites, except at Dam 4, Dam 7 and BH1 were below the maximum contaminant level of 0. According to these guidelines, the free cyanide concentrations were found to be in safe levels owing to the low evaporation rates of cyanide in the water resources. The free cyanide concentration recorded in the present study was relatively lower than those found in the surface water of Obuasi area Ndur and Amegbey and Bogoso Obiri et al.

The total cyanide level of the dam samples ranged from The total cyanide concentration in the dam and borehole water samples were higher than the Ghana EPA permissible limit of 1. Significantly, the total cyanide concentration of the borehole water samples was higher than those of the dam samples due to the complex nature of the cyanide species in the borehole water samples.

Since the decomposition rate of cyanide-related compounds in water is affected by TDS, pH, temperature and conductivity, water samples polluted with cation hydrolysis of dissolved ions or acid mine drainage makes the water acidic. The pH value of dam water samples ranged from 3. The pH of the control samples was more acidic compared to that of the dam samples since the water was contained and not properly mixed. An increase in acidity increases the dissociation of cyanide compounds, which also increases the free cyanide concentrations in the water resources Meeussen et al.

This explains why samples with the lowest pH values recorded the highest free cyanide concentrations. The pH values of the borehole samples ranged from 5. The borehole water samples were less acidic compared to the dam water samples, which might explain why the free cyanide concentrations were high for high pH water samples. The conductivity values for the dam samples Cyanides are fast-acting poisons that can be lethal. They were used as chemical weapons for the first time in World War I.

Low levels of cyanides are found in nature and in products we commonly eat and use. Cyanides can be produced by certain bacteria, fungi and algae. Cyanides are also found in cigarette smoke, in vehicle exhaust, and in foods such as spinach, bamboo shoots, almonds, lima beans, fruit pits and tapioca. There are several chemical forms of cyanide. Hydrogen cyanide is a pale blue or colorless liquid at room temperature and is a colorless gas at higher temperatures.

It has a bitter almond odor. Sodium cyanide and potassium cyanide are white powders which may have a bitter almond-like odor. Other chemicals called cyanogens can generate cyanides. Cyanogen chloride is a colorless liquefied gas that is heavier than air and has a pungent odor. While some cyanide compounds have a characteristic odor, odor is not a good way to tell if cyanide is present.

Some people are unable to smell cyanide. Other people can smell it at first, but then get used to the odor. Historically, hydrogen cyanide has been used as a chemical weapon. Cyanide and cyanide-containing compounds are used in pesticides and fumigants, plastics, electroplating, photodeveloping and mining. Dye and drug companies also use cyanides. Some industrial processes, such as iron and steel production, chemical industries and wastewater treatment can create cyanides.

During water chlorination, cyanogen chloride may be produced at low levels. People may be exposed to low levels of cyanides in their daily lives from foods, smoking and other sources. Eating or drinking cyanide-containing foods may cause health effects.