A detailed investigation has been conducted to evaluate the distribution of heavy metals and metalloid in the surface sediments of a bauxite mining area in association with the potential ecological and human health risk. Field sampling was carried out within the Pengerang bauxite mining areas, including mine tailings, ex-mining pond and streams. Distribution of heavy metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Pb, Sr, Zn) and metalloid such as As in sediments indicated that Fe and Al constituted the greatest portion of metal elements in the sediment while Pb and Cu were found exceeding the recommended guideline values at some locations. 

The case study has summarizes the concentration of heavy metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Pb, Sr, Zn and metalloid As in sediments of Pengerang bauxite mining area. The mean heavy metals (and metalloid) concentrations in the surface sediments for all stations were found to be in the order of Fe > Al > Mn > Pb > Zn > Cu > Cr > As>Sr > Co > Cd. Generally, Al and Fe are the major elements in most sediments and soils and is usually present in high concentrations compared to other heavy metals (Hutchison, 2009; Iqbal and Shah, 2014). This is usually followed by relatively high amount of Mn particularly in mining-related soils and sediments (Diami et al., 2016; Kutty and Al-Mahaqeri, 2016; Kusin et al., 2016). This has been anticipated because Al and Fe are known to be the most abundant elements in most upper and lower earth's crust (Wedepohl, 1995). 

As in the case of bauxite mining, formation of bauxite requires long term weathering under intense leaching condition, i.e. of Si, with subsequent formation of gibbsite (Al(OH)3) (Jusop, 2016). Apparently, this has resulted in relatively high amount of Al in the mined-impacted sediments, i.e. mean value of 22,824 mg/kg (Table 6). The variation of Fe and Al concentration was quite similar because these elements are important in the stabilization and formation of most soil aggregates (Bartoli et al., 1992; Tarchitzky et al., 1993). 

From the mining perspective, heavy metals such as Cu and Pb have been reported to be present in the main ore body (Taylor, 1971; Zin et al., 2015). The presence of metal sulfides such as galena (PbS) and chalcopyrite (CuS) is typically associated with the presence of sulfide minerals already exist in most soils and sediments. Copper were mainly attributed to covellite (CuS), chalcocite (Cu2S) and native copper (Cu). Copper also tends to accumulate in sediments because of its correspondence for particulate organic matter (Campbell and Tessier, 1996). The organic matter could be coming from various sources most importantly from the topsoil of the mine land (Jusop, 2016). In most acidic soils, Pb and Cu were strongly retained, due to greater competitive adsorption of these metals onto the soil (Pérez-novo et al., 2008). 

CONCLUSION 

The potential ecological and human health risks, due to heavy metal composition and metalloid (Cr, Cu, Fe, Mn, Pb, Sr, Zn and As), in the surface sediments associated with bauxite ore mining area have been assessed in the sediments of Pengerang bauxite mining area. The mean heavy metals (and metalloid) concentrations in the surface sediments for all locations were found to be in the order of Fe > Al > Mn > Pb > Zn > Cu > Cr > As>Sr > Co > Cd. Fe and Al were found the greatest portion of metal elements in the sediment while Pb and Cu were found exceeding the recommended guideline values at some locations. 

 Sediments constitute important carriers for trace metals in marine systems. Studies of heavy metal contaminants in undisturbed sediment cores has proved as a tool to provide records of pollution history. The contamination of coastal environments through human activities has increased over the past years as populations have increased. Thus, the long-term data from chemical, physical and biological indicators is need in order to understand this scenario. The characteristics of trace metals in sediments could provide useful information of contaminants including sources, transformation and migration. Combination of sediment characteristics with the statistical analysis can give more in depth information concerning trace metal origins. High development projects will increase the sedimentation rate and cause major problems relating to the marine environment.

 Nagarajan et. al said that, the movement of cargo vessels, transportation of industrial products (timber logs), and the numerous coastal developments also lead to to higher level of contamination in the beach in Marine Pollution Journal.

Heavy metals can accumulate in sediments and may affect the health of bottom-dwelling (benthic) organisms and higher trophic-level species (fish) that depend on benthic organisms for food. Although some heavy metals, such as copper and zinc, are vital to the metabolic processes of aquatic organisms, they can still be toxic at high concentrations and can be harmful to the human health. For instance, the most important health effects that can be caused by cadmium are related to the lungs, kidneys, and bones. The chronic inhalation of cadmium leads to pulmonary emphysema, where the small air sacs of the lungs are distended or destroyed, which reduce lung capacity. Moreover, chromium is carcinogenic to humans, and a long-term exposure to it can result lung cancer. The other health hazards that are caused by chromium include respiratory problems and kidney and liver damage. Additionally, massive doses of copper can cause headache, stomachache, dizziness, vomiting, and diarrhea. Considerably high uptake of copper may cause liver and kidney damage and even death. Furthermore, lead can have a number of effects on the human health, such as nausea, vomiting, abdominal pain, anorexia, constipation, insomnia, anemia, irritability, mood disturbances, and loss of coordination. In more severe situations, neurological effects, including restlessness, hyperactivity, confusion, and impairment of memory, can result in coma and death. In addition, the health effects that can be caused by nickel are malfunctioning of the lung and respiratory system. Furthermore, nickel may be carcinogenic to humans. Moreover, zinc can cause health problems, such as stomach cramps, skin irritations, vomiting, nausea, and anemia. Very high levels of zinc can damage the pancreas and disturb the protein metabolism and cause arteriosclerosis. Additionally, arsenic has deleterious effects on human health, including cardiovascular problem and gastrointestinal, hematological, neurological, and carcinogenic effect.

https://www.sciencedirect.com/science/article/pii/S0969804317301793 

In this study, the status of metal contamination in Langat River sediments, Cd, Ni, Cr, and Sn concentrations was estimated in nine sites. The results of the present study showed that Cd, Ni, and Cr concentrations in sediments from downstream of the River were greater than the concentrations upstream. The tested heavy metals decreased in concentration in the order of Sn > Cr > Ni > Cd. This suggests that Cd and Sn are likely to pose greater risks than other metals and hence should be monitored periodically. The correlation analysis of mean concentrations showed that the organic carbon, dissolved oxygen, and salinity in polluted surface sediments correlated highly with heavy metal concentrations.

 

Pb was used in this study to investigate changes in metal concentrations on a decadal time scale. Pb is widely used for dating recent sediment deposits (less than 100 years) because of their respective half-life of 22.3 years. The sedimentation rate was estimated from the graph of ln Pb versus depth. From the graph it can be concluded that the sedimentation rate at Tanjung Pelepas harbour was estimated 0.57 cm/year. Sediment dating was estimated by assumed constant sedimentation rate along the sediment core. Sediment age can be determined by dividing the sediment depth with the sedimentation rate. We predict that sediments in the upper 60 cm at Tanjung Pelepas harbour were deposited during the past 105 years started from 1907 to 2013. 

Generally, the concentration of Al, Fe and Ti do not show any major changes with depth. However, the concentrations of Al and Fe decrease slightly at the 9 cm layer and increases slightly at 28 cm. The decreasing value of Al and Fe at 9 cm was due to increasing porosity at this layer, while increasing values of Al, Fe and Ti at 28 cm layer was due to decreasing porosity at this layer. Previous studies have shown that concentrations of major elements such as Fe and Al are inversely proportional to the sediment size . Elements such as Al, Fe and Ti are commonly used as proxies to determine changes in sediment input over time. The consistent values of Fe, Al and Ti together with strong significant correlation of Al with Fe (R2 =0.933, P < 0.01) and Ti (R2 =0.807, P < 0.01) (Table 2) indicate no major changes of natural elements in this area. Furthermore, almost consistent porosity values indicate no major changes in sediment texture. Previous studies have shown that, the changes of metal inputs in a given system over long periods of time can be examined if there are no major changes in the sediment texture. Thus, we can consider this area was stable and suitable to analyze the additional input of anthropogenic metals such as Pb, Zn and Cu. The concentrations of Pb, Zn and Cu show fluctuating values along the sediment core. The variability in the Pb, Zn and Cu concentrations with depth might be due to the anthropogenic input. The origin of trace metals will be discussed in the next section. 

The sources of trace elements were investigated by using Principal Component Analysis (PCA) and Pearson’s correlations coefficient. PCA is a method which has been used in geochemical research in recent years due to its ability to reduce data in large datasets into a smaller number of Principal Components (PCs) that explain from the variance data. PCA can be used to group the elements based on their correlations to each other. In this study, PCA was applied to the entire data set of trace elements. The PCA results are shown. The correlation matrix was used for the analysis. The principal components that have eigenvalues higher than one were extracted. The results indicate that there were three eigenvalues higher than one. The first component explains 56.67% of the total variance and loads heavily on Al, Fe, Ti and Pb. The second component, dominated with Cu and Zn, accounts for 23.89% of the total variance. The third component is loaded by negative loading of Pb, accounting for 10.97% of the total variance. These results indicate Al, Fe, Ti and Pb show similar behaviour and might originate from natural sources. However, Pb also shows some different characteristic from other elements with high negative loading at component 3. This result indicates, Pb might originate from both natural and anthropogenic sources. High positive loading of Zn and Cu at component 2 might suggest both are from similar anthropogenic sources. These suggestions were then supported with Pearson correlation values. 

The result show the Pearson correlation of heavy metals and also the ratio of metals over Al where Al was considered as a reference element. The normalization techniques by using Al was conducted in an attempt to account for natural variations and to provide baseline relationships to assess trace metal contamination. Al was strongly correlated with Fe (R2 =0.933, P0.05), which indicates it also originates from another origin. These results support the suggestions from PCA analysis which indicate that Al, Fe and Ti were originate from natural sources, while Pb was originates from both anthropogenic and natural sources. Al shows negative correlation with Cu (R2 =-0.17), and weak correlation with Zn (R2 = 0.375). However, significant correlation was noticed between Cu and Zn/Al (R2 =0.518, P<0.05). These results strengthen the earlier suggestion that Cu and Zn were dominated with anthropogenic sources. 

Estimating “Enrichment Factor” (EF) is based on Al normalized values. The EF values for Pb, Zn and Cu in the sediment core of Tanjung Pelepas harbour. EF is defined as the ratio between normalized concentrations of a metal in the sediments divided by the normalized concentrations of the same metal in the background sediments (EF= (Met/Al) sample/ (Met/Al) background). The background values were determined from the lowest metal concentrations in the sediment core. Values of the EF are characterized as follows: EF < 1 indicates no enrichment; 1 < EF < 3 is minor enrichment; 3 < EF < 5 is moderate enrichment; and 5 < EF > 10 is considerable moderate severe enrichment1 . The EF values for Pb, Zn and Cu in sediment core of Tanjung Pelepas harbor were < 3 which indicate minor enrichments (Fig. 3). Based on the geochronology of this core, the highest peak of EF values for Zn and Ni occurs in the late 1990s when the harbor was started to be developed. EF values for Zn and Cu were increased slightly from the past to the recent years which indicate the increasing input of Zn and Cu to the Tanjung Pelepas harbour. 

 

Conclusion 

 The vertical profiles of trace metal concentrations have been successfully determined in a dated sediment core from Tanjung Pelepas harbour. PCA analysis and Pearson Correlation Coefficient analysis proved to be an efficient tool in classifying the metals based on their origin. Al, Fe and Ti were classified as natural origin while Cu and Zn were classified as anthropogenic origin. Pb was dominated with both natural and anthropogenic sources. Low EF values (<3) of Pb, Zn and Cu indicate no serious contamination at this harbour. However the increasing trend of EF values of Zn and Cu from past to the recent years should be taken into consideration. The results of this research can be used for future environmental monitoring and conservation management at Tanjung Pelepas harbour. 

https://www.sciencedirect.com/science/article/pii/S1878029615006325 

 

However, with continuous socio-economic development, a certain level of industrialization may also be the future choice of the Kelantan region. Therefore, it is necessary to carry out systematic research on heavy metal content and pollution risk assessment in sediments from the Kelantan River channel-estuary-shelf system and understand the status of heavy metal pollution and the origin and fate of heavy metal pollutants.

The Kelantan River is located in the northwestern part of Malaysia. There are two tributaries, the Galas and Lebir Rivers, which converge at Kuala Krai ~100 km upstream of the estuary and the Kelantan River flows from south to north for a total river length of 248 km. The whole range of the river basin is under the control of monsoons. From October to January, the basin area is controlled by the northeast monsoon and receives more rainfall (also known as the wet season), with large wind waves in the estuary and adjacent shelf area (Adnan and Atkinson, 2011). In other periods, the basin area is controlled by the southerly or southwesterly winds, and the weather is relatively dry (also known as the dry season), with a smooth sea condition in the estuary and adjacent shelf area. The Kelantan River estuary directly faces the South China Sea. Divided by a sand bar, the estuary forms multi-level braided channels . The length of the sand bar ranges from 400 to 800 m (Zakaria,

1975). Mangrove wetlands and inter-tidal flats are commonly developed within the braided estuary, with mangroves covering an area of ~3.4 km2 (Satyanarayana et al., 2011). A sand beach is formed on the shore adjacent to the main river mouth, ranging from 20 to 150 m in width (Tilmans, 1991). The water depth generally ranges between 5 and 25 m (Radzir et al., 2016), and the sea floor slope is gentle in the shelf area adjacent to the estuary .The estuary area has irregular tides, with a 1.5:1 ratio of diurnal to semidiurnal tides; the maximum tidal range is 1.2 m, and the mean spring range is 0.6 m (Raj et al., 2007). The Kelantan River basin has a mean annual runoff into the sea of1.8 × 1010 m3 and a mean sediment load of 2.5 × 106 t (Milliman and Farnsworth, 2011). The samples used in this study were collected in the Kelantan region from November 28 to December 3, 2014. River channel surficial sediments were mainly taken near the waterline of the river channel point bar, and 10 sediment samples were obtained. Estuary and adjacent shelf seabed surficial sediments were mainly collected using a clamshell bucket. The samples used for analysis were composite samples of 1-cm-thick surface layers, and surficial sediments samples were taken from a total of 26 stations . In the braided channel of the estuary, a typical sandbar inter-tidal flat was selected for sampling. The upper inter-tidal flat was covered with dense mangroves, the middle part was covered with sparse mangroves, and the mid-lower part was bare. During the low-tide period, 6 surficial sediment samples were collected from six stations by walking into the inter-tidal flat (station distribution as shown in Fig. 1d). All the collected samples were stored in ice bags, refrigerated for transport to the laboratory, and oven-dried at a low temperature (40 °C).

 

Grain size composition, median grain size, total organic carbon (TOC) content (a), and typical heavy metal contents (b) in surface sediments from the Kelantan River channel and estuarine inter-tidal flat.

Sediment sample collection in the inter-tidal region of the beaches was done during 2011 based on the tourist population history visiting the particular locations. Surface sediment samples (N = 43) were collected from six tourist beaches, viz Lutong Beach (LB) (n = 9), Park Everly Beach (PE) (n = 4), Tanjong Lobang Beach (TL) (n = 8), Esplanade Beach (EP) (n = 9), Hawaii Beach (HB) (n = 8) and Bungai Beach (BB) (n = 5) respectively. The concentration pattern of PLTMs along the beaches of Miri City is presented in figure below 

General distribution pattern of PLTMs indicate that mostly the beaches in the southern part (EP, HB, BB) is enriched by majority of metals (except Co, Cu) which might be due to the long shore currents transporting the materials to the southern part as this coastal region is actively eroded throughout the year (Cheong, 2000; James, 1984). The above inference is also supported by the huge cargo ship traffic, Miri River (draining in the coastal region), smaller channels (>15) that brings in domestic, industrial and agricultural effluents into the coastal beaches. Our results also indicate that the concentration pattern of PLTMs in the study area varies depending on the nature of input through the local channels that drains in the region. The concentration pattern of PLTMs indicates higher values of Fe in EP (avg. 3030 lg g[1]1), HB (avg. 4408 lg g[1]1) and BB (avg. 3625 lg g[1]1) and Mnin EP (avg. 26.25 lg g[1]1), HB (avg. 52.94 lg g[1]1) and BB (avg. 34.89 lg g[1]1) respectively. The use Fe in construction, transportation industries indicates that it is easily in contact with either fresh or marine water and as it is chemically reactive, the process of corrosion is very high, which in turn accumulates in the sediments. Moreover, naturally Fe leaches from the clastic sediments also contributing Fe content to beach sediments which is common phenomenon of the beaches of Miri particularly, in Tanjong Labung and Bungai beaches. The presence of electrical, pigment, ceramics and fertilizer plants indicates the use of Mn in higher level and the discharges from these will also increase the concentration level. 

The comparative results for the beach sediments with that of other selected beaches and bay regions around the World suggest a fourfold increase of Co, Cr, Cu; twofold increase of Ni, Pb and Zn in the study area indicating that mostly the elements are anthropogenic due to the increased human activities in those region . This is also due to the non-proper planning and uncontrolled discharge of contaminated industrial sewage and domestic sludge into the drains which gets accumulated in time and then drains into the open ocean during monsoon seasons. Even though various control measures are adopted, the human activities still impact the coastal beach quality and there is an urgent need to protect the beaches of Miri in Sarawak, Malaysia before it goes out of control.

percentages of clay, silt and sand were determined based on the mathematical formula (Gavlak et al., 2003). The percentages of sand, silt and clay of the sediments at all stations are shown in table below.

Element          Certificated value (C)        Measured value (M)      Percentage of recovery (M/C)     
Cd                      | 0.148                                 | 0.153                            | 103
Cr                       | 40.9                                   | 38.443                          | 94
Cu                      | 10.1                                   | 9.524                            | 98
Pb                      | 11.7                                   | 11.356                          | 97
V                        | 44.84                                 | 41.725                           | 93
Zn                      | 48.9                                   | 45.018                           | 92
The metal contents in this study compared with some reports from Malaysia and regional studies. Data obtained from present study is within comparable with most studies in Malaysia. All metal contents were within the range of sediments in Malaysia except Cu. High concentration of Cu at stations of 3–6 in Keluang River could be related to releases of wastewater from electronic factories since 39% of factories in Bayan Lepas FIZ are associated to electronic industry. Although the maximum Cu, Ni, Cd, and Pb contents in the Bayan Lepas FIZ were higher than mangrove (Singapore) and Yangtze estuary (China), Cu, Cd and Pb were lower than Victoria Harbor (Hong Kong) and Kaoshiung Harbor (Taiwan). Cr and Zn contents in Bayan Lepas were also lower than Victoria Harbor (Hong Kong), Gulf of Thailand (Thailand) and Yangtze estuary (China), but Cr and Zn were higher than mangrove (Singapore) and Dumai (Indonesia), respectively. Yap and Pang (2011).

 Sediments constitute important carriers for trace metals in marine systems. Studies of heavy metal contaminants in undisturbed sediment cores has proved as a tool to provide records of pollution history. The contamination of coastal environments through human activities has increased over the past years as populations have increased. Thus, the long-term data from chemical, physical and biological indicators is need in order to understand this scenario. The characteristics of trace metals in sediments could provide useful information of contaminants including sources, transformation and migration. Combination of sediment characteristics with the statistical analysis can give more in depth information concerning trace metal origins. High development projects will increase the sedimentation rate and cause major problems relating to the marine environment.

 Nagarajan et. al said that, the movement of cargo vessels, transportation of industrial products (timber logs), and the numerous coastal developments also lead to to higher level of contamination in the beach in Marine Pollution Journal.

Average total concentrations of As, Zn, Pb, U, and Th are greater in Johor sediments than in both types of “average materials”. Higher Johor sediment concentrations of both U and Th are primarily due to a greater concentration of monazite minerals in the Johor Strait drainage basins. 

Some differences in trace metal concentrations between Johor and Penang sediments can be attributed to the fact that Johor sediments contain about 20–29% more of chemically unreactive Al, Ti, and Sc than do the Penang sediments. Elements expected to be principally associated with finer grained Al, Ti, and Sc rich detrital particles may therefore be about 30% greater in Johor sediments due to grain size effects, rather than to differences in chemical cycling or extra inputs. Allowing for such grain size effects, total concentration ranges and means of Cr, U, Th, Ni, Cd, V, Co and the rare earths do not appear significantly different in the two Malaysian regions. However, grain size differences alone cannot explain why concentrations of Sb, As, Cu, Pb, and Zn are higher in Johor sediments than in Penang sediments. None of the elements in Table 2 has lower concentrations in Johor Strait sediments than in Penang sediments.

Strait of Johor sediments (Table 2, Table 3) have higher Pb concentrations, similar Cu concentrations, and lower concentrations of Mn, Cd, and Zn than Ismail et al. (1993) reported in sediments from the Strait of Melaka to the west. Ismail et al. (1993) reported higher concentrations in sediments adjacent to the three major ports along the Strait of Melaka, and near rivers suspected of discharging contaminated waters, but they did not mention any analyses of reference sediments to test the accuracy of their results.
https://www.sciencedirect.com/science/article/pii/S0278434397000113

In conclusion, no ecosystem is entirely free of sediment. In aquatic environments, its presence can threaten the health of ecosystems. Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Here, contents of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and trace elements (Ga, In, Mo, and Se) were determined for river waters and bed sediments that received sewage discharged from traditional and semiconductor industries. We used principal component analysis (PCA) to determine the metal distribution in relation to environmental factors such as pH, EC, and organic matter (OM) contents in the river basin. While water PCA categorized discharged metals into three groups that implied potential origins of contamination, sediment PCA only indicated a correlation between metal accumulation and OM contents. Such discrepancy in metal distribution between river water and bed sediment highlighted the significance of physical-chemical properties of sediment, especially OM, in metal retention.