The geoaccumulation index and enrichment factor of mercury in mangrove sediment of Port Klang, Selangor, Malaysia

Mangrove areas are important to the ecosystem. One of its crucial functions is as a sink of pollutants, especially metal ions. However, the accumulation of metals in mangrove sediment can generate negative impacts on plant growth, microbial activity, and soil fertility. Apart from that, the severity of the impact is highly influenced by the type of metal found in the sediment and the quality of sediment itself. One of the metals that have adverse effects on the environment is mercury. The objectives of this study are to determine the concentration and distribution of mercury and to assess the enrichment of mercury in Port Klang mangrove sediment by using geoaccumulation index and enrichment factor. Sediment samples were collected from 30 sampling points that cover Langat River and Klang River estuaries, Lumut Straits, Pulau Klang, and Pulau Indah. During sampling, water parameters such as pH, salinity, electrical conductivity, and total dissolved solids were measured in situ, whereas the total mercury in sediment samples was determined at the laboratory using inductively coupled plasma mass spectrometry. In this study, mercury was found to be concentrated along Lumut Strait especially in the mixing zone near the confluence of Langat River and at the jetty to Pulau Ketam. The geoaccumulation index and enrichment factor (calculated using logarithmized data of the reference element) found that three stations were enriched with mercury. In addition, geoaccumulation index was also observed to be more objective compared to enrichment factor whose results were influenced by the concentration of reference element used.     

The 2015 eruption of Gamalama volcano (Ternate Island–Indonesia): precursor,crisis management,and community response

GeoJournal - Gamalama is an active stratovolcano on Ternate, a small volcanic island in Maluku Utara, Indonesia. Since 1510, a total of 77 eruptions have been recorded, with various impacts on the...     

Hydrological Characteristics of Estuary in Wulan Delta in Demak Regency,Indonesia

Water Resources - Understanding estuarine characteristics is crucial for managing aquatic ecosystem and aquaculture. A delta is a dynamic area that influence by both sea and river. Research on a...     

Experiment on visualizing micro-level surface characters of sediment sections: a methodological approach to reflectance-based alternative petrographic image analysis

This paper discusses an experiment on digital imaging and visualizing the surface condition of the sediment depositions. For that purpose, a part of South Tripura district was selected as sampling site. Physically, the selected area is located in a fold belt and preserves the history of Tertiary–Quaternary landform evolution in the main types of sediment depositions. Three samples, each from the different types of Tertiary depositions, were finally taken for thick section making, optical microscopy under reflected light, and soft computing. Geometric optical measurement and physical optical measurement were done to understand the surface condition of Bokabil, Tipam, and Duplitila samples by bidirectional reflectance distribution function and radiometric scales (within 0–255 digital number values). Maximum surface smoothness or near-perfect reflection surface was measured by brightness–contrast slicing operation.     

Cyanobacteria and microcystin in the Nebraska (USA) Sand Hills Lakes before and after modern agriculture

Chlorophyll a, zeaxanthin, and pheophytin a were measured from sediment core samples from three lakes (Dewey, Island, and Two Mile Lakes) in the Nebraska Sand Hills. Pigments were extracted and identified by high performance liquid chromatography (HPLC) and used to estimate changes in the relative proportion of cyanobacteria to the algal community. The cyanobacterial toxins microcystin-LR and LA were extracted and measured using electrospray ionization liquid chromatography tandem mass spectrometry (LC/MS/MS). Microcystin-LR was found in core sections estimated to be as early as 1832, and was present in all three lake cores. Pigment and toxin data were used to determine if there were changes that occurred in the algal community structure with the onset of modernized agriculture in the region. No significant changes were found in the relative percent of cyanobacteria or chlorophyll a accumulation, indicating the frequency and intensity of cyanobacterial blooms has not changed over the last century. Despite this trend, there was a dramatic increase in microcystin-LR accumulation during the 1980s in Dewey Lake, which may be human induced.     

Evaluation of heavy metal contamination in groundwater samples from Kapas Island,Terengganu, Malaysia

An attempt has been made to delineate the hydrochemistry for a small island based on the major ions and heavy metal concentrations. In this investigation, six sampling campaigns were conducted to measure the concentrations of major ions (Ca, Mg, Na, K, HCO₃, Cl, and SO₄) and heavy metals (Zn, Cr, Pb, Mn, As, and Cu) in groundwater samples collected from seven sampling stations (boreholes) located on Kapas Island, Terengganu, Malaysia. The distribution of major ions is illustrated by a piper plot where Ca–HCO₃ is the dominant type. In addition, the concentrations of heavy metals demonstrate that Mn shows as being the highest concentrated heavy metal in the groundwater sampled in the sampling campaigns; the average Mn content in groundwater sampled was 54.05 μg/L. However, a comparison of the heavy metal (Mn, Cr, Zn, As, Pb, and Cu) concentrations in groundwater samples with the Drinking Water Quality Standard prescribed by World Health Organization reveals that none of these heavy metals exceeded the recommended threshold limits. The principal component analyses (PCA) extracted four components that control the groundwater chemistry. Components 1 and 2 from the PCA analyses extracted approximately 52.11 % of the total variance, which represent the heavy metals (As and Mn) and physical parameters (pH, redox potential, electrical conductivity, temperature, and total dissolved solids). Based on the output of the PHREEQC hydrogeochemical software, several species of heavy metals exist, in which the dominant species found are Mn²⁺, PbCO₃, Cu(OH)₂, and Zn⁺.     

Sustainable groundwater management on the small island of Manukan,Malaysia

Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. This paper focuses on numerical modeling and water balance approaches in the search for a sustainable management plan in Manukan Island. The impacts of pumping and recharge rates represented by groundwater scenarios were investigated by means of hydraulic heads, chloride concentrations and water balance components. Overpumping and inconsistency in recharge rate are the stresses shown in Scenario A. Scenario B involved with reduction pumping rate by 25% has shown an increase in groundwater levels, chloride concentration and groundwater storage. Scenario C showed the most promising finding compared with Scenarios A and B. Highest hydraulic heads, lowest chloride concentration (1,552.2 mg/L) and positive groundwater storage (254.3 m³/day) were obtained in Scenario C. Chloride concentration in pumping wells still exceeds World Health Organization International Standard limit in Scenario C which illustrates an additional water treatment is needed. Nevertheless, in view of a compromise groundwater management plan in study area, Scenario C is the best plan so far to protect the groundwater resources in the study area. More understanding of the artificial recharge method (percolation tank) and study site by means of modeling studies is needed. Additionally, further progress is needed in obtaining the water usage data from each part to determine the best pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as well as to protect the ecological balance of Manukan Island.     

A lumped conceptual approach for modeling hydrological processes: the case of Scopia catchment area,Central Greece

In the catchment area of Scopia, Central Greece, a lumped applied approach of water balance was accomplished, by applying the Zygos model, which delineates an essential water balance forms. The model is in view of Thornthwaite model, in its modified version. It can be adjusted automatically, with the evolutionary annealing-simplex technique for nonlinear optimization, or manually and the input data are precipitation and the potential evapotranspiration. In the present study, both programmed and manual calibration occurred. Programmed calibration took place, utilizing a specimen of measured runoff values from October 2009 to March 2011. Despite the fact that the Nash–Sutcliffe coefficient (NSC) value was high (0.87), the simulated parameters of water balance had abnormal significance for Scopia catchment area. On the contrary, manual calibration uncovered that the actual evapotranspiration constitutes 64.6% (450.1 mm) of the precipitation. Runoff and percolation represent 20.6% (143.6 mm) and 14.8% (102.9 mm) of the precipitation, respectively. The NSC (0.70) and the validation criteria exhibit an ideal adjustment of simulated to measured runoff, while the hydrological parameters appeared to have a physical significance for the study site. Zygos model connects the emergence of springs with the development of the karstification in the carbonate rocks of the region and affirms the predominance of runoff versus percolation due to the hydrolithological structure of the Scopia catchment. This is related to the presence of episodic floods in the area. The yearly precipitation values were found with an error of 0.2% and are viewed as insignificant.     

Hydrochemical changes in a small tropical island’s aquifer: Manukan Island, Sabah, Malaysia

Small islands groundwater are often exposed to heavy pumpings as a result of high demand for freshwater consumption. Intensive exploitation of groundwater from Manukan Island’s aquifer has disturbed the natural equilibrium between fresh and saline water, and has resulted increase the groundwater salinity and leap to the hydrochemical complexities of freshwater–seawater contact. An attempt was made to identify the hydrochemical processes that accompany current intrusion of seawater using ionic changes and saturation indices. It was observed that the mixing between freshwater–seawater created diversity in geochemical processes of the Manukan Island’s aquifer and altered the freshwater and seawater mixture away from the theoretical composition line. This explained the most visible processes taking place during the displacement.