Dissertation Title Assessments of chromium contamination in surface sediment in the inner Gulf of Thailand. Patcha Leelakun: Assessments of Chromium Contamination in Surface Sediment of the Inner Gulf of Thailand.
- Background and Significance of the Research
- Research Objectives
- Scope of the Research
- Research Outcomes
Therefore, it is important to determine the spatial heterogeneity of chromium concentrations in the surface sediments of the inner Gulf of Thailand, to evaluate the pollution status and to assess the ecological risk of its presence in polluted areas. While a potential ecological risk factor was used to assess ecological risk in the surface sediment of the inner Gulf of Thailand.
Heavy Metals
- Definition
- Toxicity
- Carcinogenicity
Limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals or. Insufficient evidence of carcinogenicity in humans but sufficient evidence of carcinogenicity in experimental animals or.
Chromium
- Chemical properties
- Speciation in the marine environments
- Geochemical fractionation of Cr in sediments
- Sources and uses of chromium
- Fate and transport of chromium in the marine environments
- Effects of chromium
Chromium released into the environment due to human activities appears mainly in the hexavalent form (Cr6+) [3]. Consequently, chromium contamination of the marine ecosystem can cause ecological and human health effects (Figure 2.1).
Contamination Status Assessment
- Chromium concentrations in the marine environments
- Sediment quality guidelines
- Enrichment factor
- Geo-accumulation index
The main distribution areas for chromium with higher concentrations were in the Chao Phaya River. The ERL and ERM measurements are expressed as the specific chemical concentrations of the toxic substance in the sediment.
Ecological Risk Assessment
The purpose of creating an ecological risk index is to be used in the control of pollution of the aquatic environment. Potential Ecological Risk Index (RI), developed by [75], is a popular method for assessing ecological risks for water pollution control.
Problems of Chromium Analysis
However, the most effective acid mixture found in microwave digestion (set at 100% power at 1000 watts for 20 minutes) is reverse aqua regia. The aqua regia (HNO3−HCl, 1:3) digestion process (ISO standard 11466) has been considered sufficient for the analysis of all recoverable heavy metals in the soil of some regions and is used to maximize the availability of constituents to plants. determined [ 82].
The Gulf of Thailand
- The inner Gulf of Thailand
- Mae Klong River
- Tha Chin River
- Chao Phraya River
- Bangpakong River
In particular, the Mae Klong River is the most important river in the study area and is located in the west of the upper Gulf of Thailand. The Chao Phraya River is the largest river located in northern and central Thailand (Fig. 2.7), accounting for about half of the river flowing into the Gulf of Thailand.
- Study Areas
- Sampling Points
- Research Materials
- Measurement Parameters
- Sampling and Sample Preparations
- Chemical Analysis
- Data Analysis
- Quality Control
- Statistical Analysis
While other stations were established in the sedimentation zones of the estuaries to characterize the deposition of chromium in the surface sediments (Figure 3.1). All surface sediment samples were placed in cleaned polyethylene zip-top bags and stored in a refrigerated container (4 °C) in the dark during field sampling until laboratory analysis. All samples of TOC in surface sediment were determined in the sample segment after carbonate removal with 1.2 N HCl (at 60 ºC, 24 hours) using a TOC analyzer (Analytik Jena, multi N/C® 3100, Germany).
Classes of chromium contamination status in the surface sediment based on different Igeo values. Potential ecological risk (Er) is an index of ecological risk assessment proposed by [75] and widely used to evaluate the degree of pollution of element in the sediment.
Spatial Distributions and Seasonal Variations of Chromium
- The inner Gulf of Thailand
- River estuary
The spatial heterogeneity distributions of Cr in the surface sediment were shown throughout the inner Gulf of Thailand (Figure 4.1a−c). Compared to these criteria (42 mg/kg), the average concentration of Cr in the inner Gulf of Thailand was low. In the dry season (May 2018), the spatial heterogeneity distribution of Cr concentrations in the surface sediment of the inner Gulf of Thailand ranged from mg/kg (Figure 4.1c).
The average concentration of Cr in the surface sediments of Thailand's inland gulf similarly changes over three seasons. The spatial distribution of Cr in the surface sediment of 4 estuaries is shown in Figure 4.3.
Physicochemical factors
TOC concentrations in surface sediments in the southwest monsoon season ranged from mg C/g (Figure 4.10a) while the highest TOC concentration was in the middle part of the inner Gulf of Thailand at station GT35 and the lowest TOC concentration it was at the mouth of the Mae Klong River at station MK9. TOC concentrations in surface sediments in the dry season ranged from mg C/g (Figure 4.10c) while the highest TOC concentration was in the middle part of the inner Gulf of Thailand at station GT6 and the lowest TOC concentration was inland Thachin River at station TC2. AVS concentrations in surface sediments in the southwest monsoon season ranged from 0.00-1.86 mg/g.dw (Figure 4.12a) while the highest AVS concentration was in the Thachin River estuary at station TC14.
AVS concentrations in surface sediments in the northeast monsoon season ranged from 0.00-2.21 mg/g.dw (Figure 4.12b) while the highest AVS concentration was in the Thachin River estuary at station TC14. AVS concentrations in surface sediments in the dry season ranged from 0.15-1.14 mg/g.dw (Figure 4.12c) while the highest AVS concentration was in the Thachin River estuary at station TC14.
Regulating Factors of Total Chromium Variation
According to these results, Cr, Fe, TOM, TOC, TP, AVS and water content could be grouped in a two-component model, which was responsible for 72.55% of all the data variation. According to these results, Cr, Fe, TOM, TOC, TP, AVS and water content could be grouped in a one-component model, which was responsible for 66.65% of all the data variation. The first principal component (PC1) with high loadings of Cr, Fe, TOM, TOC, TP, AVS and water content accounted for 66.65% of the total variance.
According to these results, Cr, Fe, TOM, TOC, TP, AVS and water content could be grouped into a one-component model, which accounted for 65.34%. The first principal component (PC1) with high loadings of Cr, Fe, TOM, TOC, TP, AVS and water content accounted for 65.34% of the total variance.
Sequential Fractions of Chromium
The carbonate fraction of Cr varied from 0.92% at BK16, where located at the mouth of the Bangpakong River, to 4.38% at GT3, where located at the western part of the inner Gulf of Thailand. The exchangeable fraction of Cr varied from the lowest value of 4.14% at CP16, where it was located at the mouth of the Chao Phraya River, while the highest value (29.75% at GT3) at the western part of the inner Gulf of Thailand was found. . The carbonate fraction of Cr varied from 0.35% at CP16, where located at the mouth of the Chao Phraya River, to 15.03% at GT3, where located at the western part of the inner Gulf of Thailand.
The exchangeable fraction of Cr ranged from the lowest value of 5.81% at BK16, where it was located at the mouth of the Bangpakong River, while the highest value (27.75% at GT3) was found in the western part of the inner Gulf of Thailand. The carbonate fraction of Cr varied from 1.99% at CP16, where it was located at the mouth of the Chao Phraya River, to 12.92% at MK6, where it was located at the inner part of the Mae Klong River.
Contamination Status
- Sediment quality guidelines
- Enrichment factor
- Geo-accumulation index
In the southwest monsoon season, the EF values of Cr ranged from the lowest value of 0.72 at GT29, located in the middle part of the inner Gulf of Thailand, suggesting no enrichment. Comparisons of the EF values of the Cr concentration in surface sediments of the inner Gulf of Thailand in all seasons are shown in Figure 4.16. Comparisons of the Igeo values of the Cr concentration in surface sediments of the inner Gulf of Thailand in all seasons are shown in Figure 4.19.
The average Igeo values of the estuary and inner gulf of Thailand in all seasons are shown in figure. A Comparison of the Geoaccumulation (Igeo) in Surface Sediments of the Inner Gulf of Thailand between the Southwest Monsoon Season, the Northeast Monsoon Season and the Dry Season.
Potential Risk of Chromium in the Surface Sediment
- Ecological risk assessment
- Assessment of mobility and availability of chromium
A comparison of the ecological risk (Er) in surface sediments in the inner Gulf of Thailand between the southwest monsoon season, the northeast monsoon season and the dry season. The sum of the Fexc and Fca Cr fractions represents the amount of loosely bound Cr. In the southwest monsoon season, the RAC for Cr varied from the lowest value of 5.23% at CP1, where it was located at the mouth of the Chao Phraya River, while the highest value (14.24% at GT3) was in the western part of the river. the inner Gulf of Thailand.
In the northeast monsoon season, the RAC of Cr ranged from the lowest value of 4.49% at CP16, located at the mouth of the Chao Phraya River, while the highest value (44.78% at GT3) was located in the western part of the inner gulf of Thailand. In the dry season, the RAC of Cr ranged from the lowest value of 8.03% at BK16, located at the mouth of the Bangpakomg River, while the highest value (35.42% at GT3) was located in the western part of the inner wave. from Thailand.
Conclusion
Changes of physicochemical factor, including TOM, TOC, TP, AVS and water content in surface sediments in the Inland Gulf of Thailand, affected the abundance of Cr concentration in the surface sediment. The next fraction of chromium in the surface sediment in the inner Gulf of Thailand, the residual and organic fraction, was the most abundant fraction for the Cr concentration in the studied sediment. Based on SQGs, chromium pollution score compared to US National Oceanic and Atmospheric Administration (NOAA), Canadian SQGs, National Oceanic Administration of China (NOAC), Australian Environment and New Zealand Conservation Council (ANZECC), Canadian, Wisconsin United States Sediment Quality Guideline and Thailand SQGT, suggesting that most of the area may not cause adverse biological effects, but some areas were occasionally associated with adverse biological effects within the Gulf of Thailand .
Cr contamination levels depending on the reference material and the quantitative index used, the EF values of Cr were mainly small enrichment. The Er of all stations was less than 40, which indicated that there is no ecological risk in the inner gulf of Thailand.
Future research
Distinguishing between natural and aquaculture-derived sediment concentrations of heavy metals in the Broughton Archipelago, British Columbia. The study of the concentration of heavy metals (As, Cd, Cr, Hg, Ni and Pb) in the sediment of the coastal area receiving wastewater from the Phetchaburi Municipal Wastewater Treatment System: The Royally LERD Project, Phetchaburi Province. Distribution and enrichment of trace metals in surface sea sediments in the Gulf of Pozzuoli and off the coast of the metallurgical area of Ilva in Bagnoli (Campania, Italy).
Evaluation of heavy metal pollution in urban river sediments in the Jiaozhou Bay catchment, Qingdao, China. Ecological risk assessment of heavy metals in sediment and human health risk assessment of heavy metals in fish in the middle and lower reaches of the Yangtze River Basin. Evaluation of heavy metals in sediments of the Don Hoi Lot area in the Mae Klong estuary, Thailand.
Mobility and bioavailability of trace metals in the water-sediment system of the highly urbanized Darkhead watershed.
