Srilert Chotpantarat

Effect of pH on transport of Pb2+, Mn2+, Zn2+ and Ni2+ through lateritic soil: Column experiments and transport modeling

This study investigated the effects of pH on the transport of Pb2+, Mn2+, Zn2+ and Ni2+ through lateritic soil columns. Model results by fitting the symmetric breakthrough curves (BTCs) of bromide (Br-) with CXTFIT model suggested that physical non-equilibrium processes were absent in the columns. The heavy metal BTCs were, however, asymmetrical and exhibited a tailing phenomenon, indicating the presence of chemical non-equilibrium processes in the columns. The retardation factors of Pb2+ were the largest of the four metal ions at both pH 4.0 (33.3) and pH 5.0 (35.4). The use of Langmuir isotherm parameters from batch studies with HYDRUS-1D did not predict the BTCs well. Rather the two-site model (TSM) described the heavy metal BTCs better than the equilibrium linear/nonlinear Langmuir model. The fraction of instantaneous sorption sites (f) of all four metal ions on the lateritic soil was consistently about 30%-44% of the total sorption sites.

Competitive sorption and transport of Pb2+, Ni2+, Mn2+, and Zn2+ in lateritic soil columns.

Knowledge of sorption and transport of heavy metals in soils in the presence of other metals is crucial for assessing the environmental risk of these metals. Competitive sorption and transport of four metals, Pb(2+), Ni(2+), Zn(2+), and Mn(2+), were investigated using multi-metal column experiments with lateritic soils obtained from a gold mine impacted by acid mine drainage. Based on Pb(2+) breakthrough time for single-metal system at a pH of approximately 5, the sorption capacity of Pb(2+) was estimated to be higher in lateritic soil than the other metals. For multi-metal systems, the estimated retardation factors for the metals from highest to lowest were: Pb(2+)>Zn(2+)∼ Ni(2+)>Mn(2+), suggesting the mobility of metals through lateritic soil for a multi-metal system would be in the order of Mn(2+)>Ni(2+)∼ Zn(2+)>Pb(2+). For binary and multi-metal systems, the estimated sorption capacities of individual metals were found to be lower than the sorption capacities in single metal system - indicating possible competition for sorption sites. Mass recoveries estimates showed that the sorption of metals was more reversible under competitive multi-metal systems than in single metal systems.

Hydrogeologic characteristics and groundwater potentiality mapping using potential surface analysis in the Huay Sai area, Phetchaburi province, Thailand

The Huay Sai Royal Development Study Centre, located in southern Thailand, one of the agricultural areas still faces a lack of water, especially in the drought season. The aims of this study were to explain the hydrogeological characteristics of aquifers and evaluate the groundwater potentiality. The results revealed three types of aquifer: unconsolidated floodplain deposits aquifer (Qfd) and the consolidated Permo-Carboniferus metasedimentary (PCms) aquifer and granitic (Gr) aquifer. The main groundwater direction of the Qfd and PCms aquifers flow from the south-western to the north-eastern area. The groundwater potential, as assessed by potential surface analysis (PSA), using the rainfall, recharge, lithology, lineament density, slope, drainage density, depth to groundwater and water quality as thematic layers in a GIS system. Groundwater potentiality classes ranged from very high (in the Rai Mai Pattana area) to very low (in the Sam Praya area). The output groundwater potential map was congruent with the maximum yield data carried out by the Department of Groundwater Resources (DGR). The map declared that the Huay Sai area is commonly of moderate groundwater potentiality, where this category covers an area of 116.6 km2 (56.74% of the study area).

Non-Carcinogenic Hazard Maps of Heavy Metal Contamination in Shallow Groundwater for Adult and Aging Populations at an Agricultural Area in Northeastern Thailand

ABSTRACT The Hua-ruea sub-district has long been a major agricultural area of Thailand. Shallow groundwater from farm wells is a main source of drinking water for most locals. This study assessed the human health hazards associated with consuming groundwater contaminated with heavy metals among adults age 15–60 years and the aging, greater than 60 years. Twelve groundwater wells were sampled in the Hua-ruea agricultural area. The results showed adults’ average groundwater consumption was high at 3.6 ± 2.1 L/day/person and for the aging group was 2.6 ± 1.0 L/day/person. The hazard quotients for As, Cu, Pb, and Zn exceeded 1 among both the adult and aging populations. Residents of the Hua-ruea subdistrict may be at risk of developing diseases from consumption of water contaminated with these four metals at seven of the 12 wells. These wells are located in intensely cultivated chili fields. All non-carcinogenic hazards of all heavy metals were higher in adults than for the aging population due to a higher intake rate of water by the former. One well had the highest hazard index, 91.8 and 66.2 for adults and the aging, respectively. This study suggested that local people living in intensively agricultural areas should take precautions before drinking contaminated groundwater.

Effects of kaolinite colloids on Cd2 + transport through saturated sand under varying ionic strength conditions: Column experiments and modeling approaches

Column experiments were performed under various ionic strengths (0.0-0.9 mM) using 10 mg L(-1) of Cd(2+) without kaolinite colloids and 10 mg L(-1) Cd(2+) mixed with 100 mg L(-1) kaolinite colloids. The nonequilibrium two-site model (TSM) described the behavior of both Cd(2+) transport and Cd(2+) co-transported with kaolinite colloids better than the equilibrium model (CD(eq)) (R(2)=0.978-0.996). The results showed that an increase in ionic strength negatively impacted the retardation factors (R) of both Cd(2+) and Cd(2+) mixed with kaolinite colloids. The presence of kaolinite colloids increased the retardation factors of Cd(2+) from 7.23 to 7.89, 6.76 to 6.61 and 3.79 to 6.99 for ionic strengths of 0.225, 0.45 and 0.9 mM, respectively. On the other hand, the presence of kaolinite colloids decreased the retardation factor of Cd(2+) from 8.13 to 7.83 for ionic strength of 0.0 mM. The fraction of instantaneous sorption sites (f) parameters, kinetic constant for sorption sites (α) and Freundlich constant (K(f)) were estimated from HYDRUS-1D of TSM for Cd(2+) transport. The fraction of instantaneous sorption sites was found to increase for an increase in ionic strength. K(f) values of Cd(2+) transport without kaolinite colloids for 0.0, 0.225 and 0.45 mM were found to be higher than those of Cd(2+) transport with kaolinite colloids, except for ionic strength of 0.9 mM. Hence, the presence of kaolinite colloids probably retarded the mobility of Cd(2+) in porous media for higher ionic strengths. Furthermore, retardation factors and K(f) values of both Cd(2+) transport and Cd(2+) co-transport were shown to decrease when ionic strength increased. Interestingly, according to TSM, the fraction of instantaneous sorption sites tends to increase for an increase in ionic strength, which imply that the mechanism of Cd(2+) sorption onto quartz sand can be better described using equilibrium sorption rather than nonequilibrium sorption for an increase in ionic strength.

Using hair and fingernails in binary logistic regression for bio-monitoring of heavy metals/metalloid in groundwater in intensively agricultural areas, Thailand

Abstract In this study, the hair and fingernails of the local people in an intensively cultivated agricultural area in Ubon Ratchathani province, Thailand, were used as biomarkers of exposure to arsenic (As) and heavy metals. The study area has shallow acidic groundwater that is contaminated with As and heavy metals. The local people often consume this shallow groundwater; thus, they are exposed to As and heavy metals. Hair and fingernail samples were collected to characterize the differences between shallow groundwater drinking (SGWD) and tap water drinking (TWD) residents. The concentrations of As and the heavy metals Cd, Pb and Hg were significantly higher in the hair samples from the SGWD group than those from the TWD group, especially for As (0.020–0.571 vs. 0.024–0.359 &mgr;g/g) and Cd (0.009–0.575 vs. 0.013–0.230 &mgr;g/g). Similarly, the concentrations of As and the heavy metals in the fingernail samples collected from the SGWD group were larger than those of the TWD group, especially for As (0.039–2.440 &mgr;g/g vs. 0.049–0.806 &mgr;g/g). The χ2 statistic and binary logistic regression were used to find the associated factors and assess the associated probabilities. The regression results show that the factors associated with the concentrations of As and the heavy metals in the hair samples were drinking water source, rate of water consumption, gender, bathing water source, education, smoking and underlying disease, whereas the factors associated with the concentrations of these species in the fingernail samples were drinking water source, gender, occupation, work hours per day, alcohol consumption, and the use of pesticides. Graphical abstract Figure. No caption available. HighlightsThe heavy metals (HMs) in hairs and nails of people in agricultural areas were measured.HMs in hairs and nails from GW drinking group were significantly higher than the other.High drinking rate for long term of GW even low concentration of HMs had adverse health effects to human.The associated factors and probabilities were found by χ2 statistic and binary logistic regression.Not only HMs in groundwater, but this study found other associated factors affecting to human.

Variations of characteristics of consecutive rainfall days over northern Thailand

The Chao Phraya basin, Thailand, is frequently inundated by flooding during the southwest monsoon period. Most floods coincide with consecutive rainfall days. This study investigated consecutive rainfall days during the southwest monsoon period at 11 stations over northern Thailand, the upstream area of this basin. The Markov chain probability model was used to study the consecutiveness of days with at least 0.1, 10.1, and 35.1 mm of rainfall. The consecutive length of rainfall days from the model showed good agreement with the observed value. A chi-square test of independence was applied to assess the significance of the consecutiveness, and it was found that days with at least 10.1 mm of rainfall tend to be consecutive over the entire area. Moreover, days with at least 35.1 mm of rainfall were found to be consecutive over the joint area where the mountainous region meets the plain area. However, the consecutiveness of days with less than 10.1 mm of rainfall was not obvious. The rainfall amount on days with at least 10.1 mm of rainfall was also calculated and it showed lower values over the mountainous region than over the plain. Hence, this study established the characteristics of consecutive rainfall days over the plain, mountainous region, and joint area.

Factors controlling the release of metals and a metalloid from the tailings of a gold mine in Thailand

This study focused on assessing the release potential of various metals and a metalloid (arsenic; As) leached from gold mine tailings under three different degrees of acidity (pH 2, 4 and 6.5) using a synthetic precipitation leaching procedure (SPLP). Tailings were collected from four pits from 0 to 16 m depth, approximately. The samples were divided into the three types, based on their position in the tailings and on other physical characteristics, of the sulphide (c. 5 m depth), mixing (c. 1 m depth) and oxide (c. 10 m depth) zones. This study was primarily concerned with the concentrations of As and Mn, which were found to exceed the Thailand Industrial Effluent Standard (TIES) in the tailings from all zones. Principal component analysis revealed that the release of metals and As from the tailings under acidic conditions, as well as the metals and As mobility, was mainly controlled by the pH and redox conditions. Moreover, the first principal component had high positive loadings of Mn, Pb, Co and Ni (R2 > 0.80), indicating that these four metals are either released into the environment from a common source or/and their geochemical behaviour in the aqueous phase is similar. Supplementary material: Concentration of metals and As leached from the sulphide mixing and oxide zones at differing pHs are available at https://doi.org/10.6084/m9.figshare.c.3840154

Impacts of land-use changes on watershed discharge and water quality in a large intensive agricultural area in Thailand

ABSTRACT The objectives of this research were to evaluate the effect of land-use change on streamflow, sediment and water quality data along the Lower Yom River, Thailand, covering an intensively agricultural area of 14 613.6 km2, and to assess the relative impact of point and non-point sources of pollution from multiple-land-use watersheds. Long-term calibration and validation of the SWAT (Soil and Water Assessment Tool) model was performed on data for 2000–2013. Land-use change led to a 13–49% increase in runoff in the basin and resulted in 37–427% increased sediment yield. The amount of NO3-N load doubled in the upper and middle parts of the study area, while the increase in PO43– ranged from 37 to 377%, reflecting the increase in agricultural lands and urban areas. It is concluded that the changed land use is closely associated with the quantity of runoff, sediment yield and the NO3-N and PO43– concentrations.

Removal of Cd2+, Pb2+ and Zn2+ from contaminated water using dolomite powder

ABSTRACT Dolomite collected from Surat Thani Province in Thailand was investigated for use as a sorbent for the removal of divalent heavy metal cations from an aqueous solution. The sorbent had a surface area of 2.46 m2/g and a pH of zero point charge (pHzpc) of 9.2. Batch sorption was used to examine the effect of the pH (pH 3–7) on the sorption capacity of Cd2+, Pb2+ and Zn2+, alone or together as an equimolar mixture at various concentrations. Alone, each heavy metal cation was adsorbed faster at a higher pH, where the sorption of Cd2+ and Pb2+ fitted a Langmuir isotherm, but Zn2+ sorption best fitted a Freundlich isotherm. Under equimolar competitive sorption, the sorption capacity of each cation was decreased by 75.8% (0.29–0.07 mM/g), 82.8% (0.53–0.09 mM/g), and 95.7% (0.84–0.04 mM/g) for Cd2+, Pb2+ and Zn2+, respectively, compared to that with the respective single cation. Desorption of these heavy metal cations from dolomite was low, with an average desorption level of 0.06–17.4%. Furthermore, since dolomite is readily available and rather cheap, it is potentially suitable for use as an efficient sorbent to sorb Cd2+ and Pb2+, and perhaps Zn2+, from contaminated water.