Peat Materials Research Articles

Detection Of Peatland Coastline Changes Due To Land Use Change On Bengkalis Island, Riau, Indonesia

Abstract Beaches with peat soil material, especially in small island areas, are very vulnerable to coastline deterioration. Many things cause the back and forth of the coastline, including the occurrence of landslides of peat material towards the sea, commonly called Peat Bog Bursts. This research aims to reveal shoreline changes on the north and west coasts of Bengkalis Island using a remote sensing technology approach. As well as analyzing factors related to shoreline changes. The use of Landsat 8 and 9 images in 2013, 2015, 2017, 2019, 2021, and 2023 were processed on Google Earth Engine using the Canny method to produce shoreline data. Furthermore, modeling was carried out using DSAS (Digital Shoreline Analysis System) to analyze changes in the coastline and reveal the causes of coastal damage. There has been a conversion of land use from forests or fields to oil palm plantation areas on the west side of Bengkalis Island from 2004 to the present. Based on the modeling results, it was found that a Peat Bog Burst occurred in 2015 causing significant changes in the coastline until 2017. Sediments were deposited in the southern area of the west side of Bengkalis Island (Zone A).

On the detailed mapping of peat (raised bogs) using airborne radiometric data

This study concerns the applied use of the natural radioactivity in soils. The relevance of airborne radiometric (gamma ray) survey data to peat mapping is now well established and such data have been used in a stand-alone sense and as covariates in machine learning algorithms. Here we present a method to use these data to accurately map the boundaries of peat (raised bogs). This has the potential to assist with the estimation of carbon stocks using a property-based assessment of soil. The significance of such regionally-uniform survey data lies in the subsurface information carried by the measurement which contrasts with the surficial nature of many other covariates. Soils attenuate radiometric flux by virtue of their bulk density (and associated carbon content) and water saturation level. The high attenuation levels in low density, wet peat materials give rise to a distinctive soil response. Here an entirely physics-based assessment of flux attenuation is carried out both theoretically and empirically. Radiometric data from the ongoing Tellus airborne survey of Ireland are used. The study area is characterised by an extensive assemblage of discrete raised peat bogs in a framework of largely mineral soils. Peat is detected by a property contrast with adjacent soils and so we consider all soils within the study area. The relatively low lateral resolution of the airborne data is demonstrated by modelling and we examine the behaviour of a combined spatial derivative of the data. The procedure allows the identification of the edges of the 128 peat polygons considered and indicates other additional potential areas of subsurface peat. The data appear to resolve the differences that exist across three available soil/peat databases that are used for the validation of the results obtained.

Genetic relationship between formation, accumulation and migration and dispersion of peat materials in Paleogene–Take the Qiongdongnan Basin as an example

Genetic relationship between formation, accumulation and migration and dispersion of peat materials in Paleogene–Take the Qiongdongnan Basin as an example

Nutrient Uptake in Different Maize Varieties (Zea mays L.) Planted in Tropical Peat Materials

Oligotrophic tropical peat soils are usually deemed unsuitable for cropping common crops such as maize due to low pH and nutrient deficiency. This research aims to compare potassium, calcium, and magnesium uptake between different varieties of maize planted in two types of peat materials. This study investigated the growth of selected maize varieties by comparing the nutrient uptake between three different varieties of maize (V1-Asia Manis, V2-Super A, and V3-Pearl Waxy) planted on hemic and sapric, respectively, without any application of fertilisers. Significant interactions were found where different maize varieties responded differently in the nutrient uptake when planted in different peat materials. Super A (V2) significantly recorded the highest uptake for all nutrients (679.71 mg) when planted in hemic, followed by V1 (422.03 mg) and V3 (314.77 mg) when planted in sapric. Super A was found to be superior to the two varieties, where it was more efficient in absorbing nutrients from the peat materials, having significantly higher dry matter weight (26.37 g) than V1 (19.26 g) and V3 (13.67 g). Hemic and sapric could support the growth of all three maize varieties up till the tasselling stage without any fertiliser application.

Insights for restoration: Reconstructing the drivers of long-term local fire events and vegetation turnover of a tropical peatland in Central Kalimantan

Fire events in tropical peatlands often relate to dry peat conditions associated with climate variability (drought) and anthropogenic-driven ecosystem degradation. However, drought is not the only driver of long-term fire events and peatland ecosystem changes. This study used palaeoecological and geochemical proxies to investigate the long-term drivers of charcoal influx to identify local fires and examine the associated responses to the tropical peatland ecosystem in Central Kalimantan, Indonesia. The results showed local fire events increased after 756 cal. yr BP, and possible drivers of charcoal influx include changes in sea level, increased frequency of El Niño events, increased biomass, and anthropogenically-driven ecosystem degradation. However, the vegetation composition showed changes since ∼2300 cal. yr BP from a mix of peat swamp forest (PSF) and open vegetation (OV) during the late Holocene (∼2300 to 1129 cal. yr BP), to predominantly PSF from 1128 to 375 cal. yr BP, dry lowland mixed with swamp forest (LMS) and open vegetation (OV) from 374 to 135 cal. yr BP, and predominantly OV and freshwater swamp forest (FSF) from 134 to −62 cal. yr BP. The possible drivers of the vegetation turnover were hydrological conditions and the availability of peat nutrients, while the vegetation turnover affected the accumulation and decomposition of recalcitrant organic matter in peat. The thresholds of the peatland ecosystems over longer-term timeframes provided the following restoration insights: 1) PSF species (i.e. Eurya and Ilex) showed high fire tolerance and increased in abundance up to charcoal influx threshold of ∼23 grains mm−2 cm−3 yr−1 while LMS and OV species increased up to a lower threshold of ∼13 grains mm−2 cm−3 yr−1before declining; 2) PSF species expanded during periods of wet conditions and high peat nutrients (i.e. TN - enriched); and 3) Future revegetation in the region can focus on tree taxa such as Euphorbiaceae, Arenga, Ficus, and Trema as they were historically able to thrive in fire events and dry hydrological conditions.

Analisis Awal Gerak Butiran pada Transport Sedimen Tanah Gambut Jenis Fibrik

Peat beaches are beaches whose land can be easily abraded than beaches with other types of land. This is due to the light density of peat soil so that it can be easily carried away by the flow of sea water. One of the peat beaches in Indonesia whose coastline has changed significantly in recent decades is the peat beach on Bengkalis Island, Riau Province. Peat samples were taken from Tanjung Jati Beach, Perapat Tunggal Village, Bantan District, Bengkalis Island, Bengkalis Regency, Riau Province and then the sample is carried out an initial motion analysis on peat soil sediment transport. The peat sample that is obtained is a type of fibric peat soil. This research is a basic research that aims to determine at what speed the peat soil begins to move by the flow of water so that it can be seen the relationship between flow velocity and particle diameter at the beginning of the particle movement. The analysis was carried out by visual observation during simulation in the laboratory using a modified flume which was then compared with the results of Shields' theoretical calculations. Simulations were also carried out using sand sediment as a comparison. The flume flow velocity is determined from 0.00989 m/s to 0.10112 m/s for peat material, and 0.03973 m/s to 0.18900 m/s for sand material. The velocity is considered to have met the required simulation conditions, starting from the sediment not moving, starting to move, and being carried away by the flow. The results of the analysis carried out show that the peat material begins to move at a lower speed than the sand material. This is due to the specific gravity of the peat material being lighter than the specific gravity of the sand material as a comparison. This research is also expected to be a reference for further research on related topics.
 Keywords : Peat, Flow Velocity, Initial Particle Motion, Critical Shear Stress, Shields Theory

Dissolved organic matter in peat and marl marshes varies with nutrient enrichment and restored hydrology

Dissolved organic matter (DOM) drives biogeochemical processes in aquatic ecosystems. Yet, how hydrologic restoration in nutrient‐enriched ecosystems changes DOM and the consequences of those changes for the carbon cycle remain unclear. To predict the consequences of hydrologic restoration on carbon cycling in restored wetlands, we need to understand how local environmental factors influence production, processing, and transport of DOM. We collected surface water samples along transects in restored peat (organic‐rich, macrophyte‐dominated) and marl (carbonate, periphyton‐dominated) freshwater marshes in the Everglades (Florida, U.S.A.) that varied in environmental factors (water depth, phosphorus [P] concentrations [water, macrophytes, periphyton, and soil], and primary producer biomass) to understand drivers of dissolved organic carbon (DOC) concentrations and DOM composition. Higher water depths led to a “greening” of DOM, due to increasing algal contributions, with decreasing concentrations of DOC in peat wetlands, and a “browning” of DOM, due to increasing humic contributions, with increasing DOC concentrations in marl wetlands. Soil total P was positively correlated with DOC concentrations and microbial contributions to DOM in peat wetlands, and periphyton total P was positively correlated with algal contributions to DOM in marl wetlands. Despite large variations in both vegetation biomass and periphyton biovolume across transects and sites, neither were predictors of DOC concentrations or DOM composition. Hydrologic restoration differentially alters DOM in peat and marl marshes and interacts with nutrient enrichment to shift proportions of green and brown contributions to surface water chemistry, which has the potential to modify wetland food webs, as well as the processing of carbon by micro‐organisms.

Effect of pH, surface charge and soil properties on the solid–solution partitioning of perfluoroalkyl substances (PFASs) in a wide range of temperate soils

The pH-dependent soil–water partitioning of six perfluoroalkyl substances (PFASs) of environmental concern (PFOA, PFDA, PFUnDA, PFHxS, PFOS and FOSA), was investigated for 11 temperate mineral soils and related to soil properties such as organic carbon content (0.2–3%), concentrations of Fe and Al (hydr)oxides, and texture. PFAS sorption was positively related to the perfluorocarbon chain length of the molecule, and inversely related to solution pH for all substances. The negative slope between log Kd and pH became steeper with increasing perfluorocarbon chain length of the PFAS (r2 = 0.75, p ≤ 0.05). Organic carbon (OC) alone was a poor predictor of the partitioning for all PFASs, except for FOSA (r2 = 0.71), and the OC-normalized PFAS partitioning, as derived from organic soil materials, underestimated PFAS sorption to the soils. Multiple linear regression suggested sorption contributions (p ≤ 0.05) from OC for perfluorooctane sulfonate (PFOS) and FOSA, and Fe/Al (hydr)oxides for PFOS, FOSA, and perfluorodecanoate (PFDA). FOSA was the only substance under study for which there was a statistically significant correlation between its binding and soil texture (silt + clay). To predict PFAS sorption, the surface net charge of the soil organic matter fraction of all soils was calculated using the Stockholm Humic Model. When calibrated against charge-dependent PFAS sorption to a peat (Oe) material, the derived model significantly underestimated the measured Kd values for 10 out of 11 soils. To conclude, additional sorbents, possibly including silicate minerals, contribute to the binding of PFASs in soil. More research is needed to develop geochemical models that can accurately predict PFAS sorption in soils.

A New Method for Sequential Fractionation of Nitrogen in Drained Organic (Peat) Soils.

The aim of this study was to assess the transformation of organic matter in organic soils undergoing a phase of secondary transformation, based on a new method of nitrogen compound fractionation. Laboratory tests were carried out for 31 layers of muck (after secondary transformation) and peat (parent material of the soil) of drained organic soils (peat). The new method consists of sequential extraction in the following steps: (1) 0.5 M K2SO4 (extraction at room temperature); (2) 0.25 M H2SO4 (hot hydrolysis) (3) 3.0 M H2SO4 (hot hydrolysis); and (4) concentrated H2SO4 (mineralization of the post-extraction residue). As a result of the extraction process, the following fractions (operating forms) were obtained: mineral nitrogen (Nmin), dissolved organic nitrogen (N-DON), readily hydrolyzing organic nitrogen (N-RH), non-readily hydrolyzing organic nitrogen (N-NRH), and non-hydrolyzing organic nitrogen (N-NH). The study demonstrates the usefulness of the applied method for assessing the degree of secondary transformation of drained organic soils. The obtained results of nitrogen fractionation indicate the significant dynamics of nitrogen forms' transformations and a significant relationship between these forms and soil properties. Nitrogen transformation processes during the secondary transformation process after dehydration resulted in an increase in the share of N-DON (on average: 1.47% of Norg for the peat layers and 2.97% of Norg for the muck layers) and in an increase in the share of NRHON (on average: 20.7% of Norg for the peat layers and 33.5% of Norg for the muck layers). The method of sequential nitrogen fractionation used in our study allowed us to define an index determining the degree of transformation of organic matter in peat after drying. We defined it as the ratio of readily hydrolyzable forms (the fraction is very variable in the secondary transformation process) to non-readily hydrolyzable forms (relatively stable fraction in the secondary transformation process): N-RH/N-NRH. The average value of this index was significantly lower in the peat layers (0.64 on average) than in the muck beds (1.04 on average). The value of this index is significantly correlated with soil properties: bulk density (R2 = 0.470); general porosity (R2 = 0.503); total carbon content (TC) (R2 = 0.425); total carbon to total nitrogen ratio (TC/TN) (R2 = 0.619); and share of carbon of humic substances (C-HS) (R2 = 0.466). We believe that the method of sequential nitrogen fractionation may be useful for other soils and organic materials.

Lake Tagimaucia Montane Lake as a Potential Late Holocene Environmental Archive in Fiji's Volcanic Highlands

Lake Tagimaucia, a montane volcanic lake on Taveuni Island, is Fiji's only high-elevation lake. This study examined a lacustrine sediment core to explore the lake's potential as a palaeoenvironmental archive through the Late Holocene. Dating reveals no simple age–depth relationship due to sediment age-reversals. However, phases of fire activity are evidenced by two distinct charcoal bands. Catchment burns were probably related to significant ENSO-driven drought, although fire ignition by volcanic eruptions on Taveuni cannot be ruled out. Above the dominant charcoal band, the sediment profile exhibits notable positive shifts in organic matter, bulk density, δ13C, and C:N ratio. These peaks suggest a phase of accelerated catchment erosion, possibly triggered by post-burn instability. We introduce a conceptual model to explain the influence of sedge peat swamps on lake sedimentation processes. Surrounding sedge-dominated peatlands have extensively encroached Lake Tagimaucia. Floating peat mats, gradually accumulating through time, act as a repository of organic material that is stored directly on the lake surface. Episodes of drought and fire release old organics directly into the lake itself, probably contributing to the complex chronological sequence in the Late Holocene stratigraphy.

Mineralisasi Nitrogen pada Komposisi Bahan Gambut dan Kotoran Ayam

Peat soils contain high concentrations of organic nitrogen, but in a form that is not available to plants. South Kalimantan has NH4+ in the range 4.51- 736.86 mg.kg-1 and NO3- content is in the range of 0.37-54.69 mg.kg-1. The low availability of N nutrients in peatlands is due to the slow nitrogen mineralization process and the very high mobility of N in the soil. This study aims to determine the effect of the composition of peat and chicken manure on nitrogen mineralization. This study used a single factor in completely randomized design (CRD) with 5 treatments and 4 replications. carried out in greenhouses and in the Soil Laboratory of the Faculty of Agriculture, Lambung Mangkurat University, Banjarbaru. The treatment is the composition of peat and chicken manure, namely 100% peat material, 80% peat material + 20% chicken manure, 60% peat material + 40% chicken manure, 40% peat material + 60% chicken manure, 20% peat material + 80% chicken manure. The best composition for nitrogen mineralization is based on the high nitrate content, which is found in the composition of 80% peat soil + 20% chicken manure in the first month of incubation, and on the composition of 80% peat soil + 20% chicken manure in the second month. This composition is the best composition from a combination of peat material and chicken manure against nitrogen mineralization in the form of nitrates.

Iron‑sulfur geochemistry and acidity retention in hydrologically active macropores of boreal acid sulfate soils: Effects of mitigation suspensions of fine-grained calcite and peat

Acid sulfate soils discharge large amounts of sulfuric acid along with toxic metals, deteriorating water quality and ecosystem health of recipient waterbodies. There is thus an urgent need to develop cost-effective and sustainable measures to mitigate the negative effects of these soils. In this study, we flushed aseptically-prepared MQ water (reference) or mitigation suspensions containing calcite, peat or a combination of both through 15-cm-thick soil cores from an acid sulfate soil field in western Finland, and investigated the geochemistry of Fe and S on the surfaces of macropores and in the solid columnar blocks (interiors) of the soil columns. The macropore surfaces of all soil columns were strongly enriched in total and HCl-extractable Fe and S relative to the interiors, owing to the existence of abundant Fe oxyhydroxysulfates (schwertmannite and partly jarosite) as yellow-to-brownish surface-coatings. The dissolution/hydrolysis of Fe oxyhydroxysulfates (predominantly jarosite) on the macropore surfaces of the reference columns, although being constantly flushed, effectively buffered the permeates at pH close to 4. These results suggest that Fe oxyhydroxysulfates accumulated on the macropore surfaces of boreal acid sulfate soils can act as long-lasting acidification sources. The treatments with mitigation suspensions led to a (near-)complete conversion of jarosite to Fe hydroxides, causing a substantial loss of S. In contrast, we did not observe any recognizable evidence indicating transformation of schwertmannite. However, sulfate sorbed by this mineral might be partially lost through anion-exchange processes during the treatments with calcite. No Fe sulfides were found in the peat-treated columns. Since Fe sulfides can support renewed acidification events, the moderate mineralogical changes induced by peat are desirable. In addition, peat materials can act as toxic-metal scavengers. Thus, the peat materials used here, which is relatively cheap in the boreal zone, is ideal for remediating boreal acid sulfate soils and other similar jarosite-bearing soils.

Laccase activity as an indicator of peat degrading microbes in several types of peatlands use in West Sumatra, Indonesia

Land clearing and drainage activities on peatlands had boosted the decomposition rate of organic matter, caused by an increase in soil temperature and soil microbial activity. Enzyme activity is a sensitive indicator to measure changes in the decomposition process. The enzyme activity associated with the decomposition of organic matter is Laccase. This research aimed to study Laccase as an indicator of lignin degradation in several types of peatland use in Pesisir Selatan, West Sumatra, namely forests, shrubs, oil palm plantations, agricultural land, and bare land. The Laccase activity was measured by using the ABTS method. The results of our study show that Laccase activity in several types of peatland use from the highest to the lowest follows the order: agricultural land (LP) 3.20 μg.g-1.hour-1 > bare land (LT) 1.46 μg.g-1.hour-1 > shrub (SB) 1.17 μg.g-1.hour-1 > smallholder oil palm plantation (PSr) 0.66 μg.g-1.hour-1 > private company oil palm plantation (PSs) 0.70 μg.g-1.hour-1 > forest (H) 0.06 μg.g-1.hour-1. Soil characteristics that affect the enzyme activity are water content, which is negatively correlated with the Laccase enzyme. The higher the water content in the peat material, the lower the Laccase activity. Therefore, it is necessary to control the soil water content high to prevent the rate of peat decomposition. 
 Keywords: Laccase, enzyme, oil palm plantation, land use, peatland.

Subsidence and Percentage of CO2 Emission from Decomposition to Subsidence of Peatland on Oil Palm Plantations

Peatlands drainage system aimed to eliminate the limiting factors to support better growth of plants. Drainage practices will cause subsidence and be associated with CO2 emission. The purpose of this study was to observe the subsidence rate on tropical peatlands of oil palm plantations at different ages and to establish the percentage of decomposition of peat materials from the subsidence rate. Subsidence was measured in 9-, 12-, and 17-year-old of adjacent oil palm planting blocks with peat thickness of about 5 m and have been drained for 10–18 years, two samples taken for each block every three month. Peat decomposition was measured in the 12-year-old block automatically using LiCor Li-8100A with 30 minutes recording interval. Peat decomposition (heterotrophic respiration) considered as actual CO2 emission was compared to emission calculated from subsidence and considered as potential CO2 emission. The average subsidence rate observed for one year in the three age classes of oil palm plantations was 2.47 ± 0.76 cm/year. The percentage of CO2 emissions from the decomposition process to subsidence on drained 12-year-old oil palm on tropical peatlands was 41.05%. The subsidence data indicates that consolidation still the main process of subsidence in this peatland.

Binding of per- and polyfluoroalkyl substances (PFASs) by organic soil materials with different structural composition – Charge- and concentration-dependent sorption behavior

The charge- and concentration-dependent sorption behavior of a range of per- and polyfluoroalkyl substances (PFASs) was studied for three organic soil samples with different organic matter quality, one Spodosol Oe horizon (Mor Oe) and two Sphagnum peats with different degrees of decomposition (Peat Oi and Peat Oe). Sorption to the two peat materials was, on average, four times stronger compared to that onto the Mor Oe material. In particular, longer-chained PFASs were more strongly bound by the two peats as compared to the Mor Oe sample. The combined results of batch sorption experiments and 13C NMR spectroscopy suggested sorption to be positively related to the content of carbohydrates (i.e., O-alkyl carbon). Sorption of all PFAS subclasses was inversely related to the pH value in all soils, with the largest pH effects being observed for perfluoroalkyl carboxylates (PFCAs) with C10 and C11 perfluorocarbon chain lengths. Experimentally determined sorption isotherms onto the poorly humified Peat Oi did not deviate significantly from linearity for most substances, while for the Mor Oe horizon, sorption nonlinearity was generally more pronounced. This work should prove useful in assessing PFAS sorption and leaching in organic soil horizons within environmental risk assessment.

The system design of the peat-based microbial fuel cell as a new renewable energy source: The potential and limitations

The microbial fuel cell (MFC) is considered as a renewable, non-toxic, reliable, clean, efficient, and also an alternative source for bioenergy. It provides numerous opportunities to improve sustainable applications in various sites, ranging from industrial to home. The low power output of microbial fuel cells is one of the important factors that hinder their commercialization. Power outputs must be improved to contribute to the commercialization of MFCs. In this study, organic peat material was used as a substrate for a double chamber MFC. In addition, since Clostridium bacteria were detected in the organic peat material, an additional bacterial strain was not used. In this MFC application, where graphite is used as both anode and cathode electrodes, 1 mol/L NaOH solution was employed as the cathode chamber solution. This peat-based MFC provided the highest electrical power density of 438.116 mW/m2. The most important limiting factor of the peat-based MFC was the spreading of the NaOH solution throughout the cell due to the rupture of the proton exchange membrane after 9 h of operation.

A three-dimensional (3D) printing approach to fabricate an isolation chip for high throughput in situ cultivation of environmental microbes.

The full plethora of environmental bacteria is often poorly represented in vitro as the majority remain difficult, if not impossible, to culture under standard laboratory settings. These bacteria often require native conditions for the formation of cell masses that collectively have higher chances of survival. With that, a 3D-printed version of the isolation chip (iChip) was used to cultivate bacteria from a tropical peat swamp in situ prior to growth and maintenance in vitro. Briefly, plates made from either acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), or epoxy resin were tested in terms of their usability and durability under acidic conditions similar to those of peat matter. The epoxy resin plates were then found to be most optimal for the sampling conditions. Peat soil samples were collected from the base of a Koompassia malaccensis tree and reconstituted in molten 10% (wt/vol) tryptone soy agar (TSA) prior to inoculation. The iChips were subsequently assembled and buried in the site of origin. As a comparison, bacteria from the same soil sample were cultivated directly on TSA and incubated at 28 °C for two weeks. Thereafter, agar plugs from the iChip were transferred to TSA plates to allow microcolonies within each plug to grow. Each pure isolate from both cultivation approaches that grew was then pooled and extracted for total DNA prior to 16S rRNA gene amplification and sequencing via Illumina MiSeq. Taxonomic abundance comparison revealed that the bacterial taxa at the level of order were significantly different between the two approaches, particularly in the orders, Burkholderiales, Xanthomonodales, Enterobacteriales, and Actinomycetales (differences of 12.0, 7.1, 8.0, and 4.2%, respectively). This indicated that the 3D-printed iChips present a possible low-cost tool for the isolation of bacterial genera that may not be able to grow on media directly in vitro.

Methods Development for the Constrained Elastic Modulus Investigation of Organic Material in Natural Soil Conditions.

Compressibility is one of the most important mechanical properties of soil. The parameter that characterizes compressibility is the constrained modulus of elasticity. Knowledge of this is important to calculate the settlement of a structure foundation on peat material. According to soil classification by EN ISO 14688-2, peat is an organic soil that contains min. 20% organic matter. It is a highly organic type of soil. Peat material has large compressibility. The value of the constrained elasticity modulus for peat is ca. 400 kPa, while it may be ca 1.0–1.6 MPa for consolidated peat. Due to the extensive range of the modulus, experimental research in this field is proposed. It is suggested to load the peat material layer with an embankment and to determine its total settlement. Based on this, a program was developed to determine the settlement–strain relationship. The authors propose an approach according to two models: the first is based on constant stress distribution in the soil with an oedometer test. The second considers the variability of stresses in the soil and the influence of the loaded area. Both methods were tested based on numerical simulations, and then an experimental field in Szczecin was used. The formulae for the constrained modulus of elasticity measurement were derived; in practical conditions, a uniaxial deformation state can be used with the combination of the total settlement.

Physical Modelling for the Analysis of Wave Characteristics on Tropical Peat Coast

Coastal erosion problems have been occurring continuously during at least the last 30 years along the coast of eastern Sumatra, particularly in the north part of Bengkalis Island that facing directly the Malacca Strait. In the extreme case, the coastal setback on Bengkalis Island has reached 30 m/year. The transport and deposition of peat material in the tropical coastal area is a unique phenomenon that has apparently never been explored until nowadays. Most studies have focused on the transport and deposition dynamics of sediment of cohesive and sandy material. It is therefore very important to understand the wave characteristics on tropical peat coast in order to countermeasure the problems triggered by this degradative process. The purpose of this research is to develop a physical modelling to understand the wave characteristics on tropical peat coast. Two important parameters such as wave reflection and dissipation were analysed using wave channel and artificial beach in laboratory. The artificial beach was simulated using peat, permeable, and impermeable material with 15° and 90° beach slope. The results showed that the reflection and the dissipation coefficient at peat coast tend to close with the impermeable coast both for 15° and 90° slope.

Study of Dissolved Organic Carbon Concentration in KHDTK Forest Peatland Area, Central Kalimantan, Indonesia

The study was conducted to determine whether are differences in dissolved organic carbon (DOC) in three different types of peatland conditions. The study was conducted from March 1st to April 30, 2020. The research was carried out in the Tumbang Nusa Special Purpose Forest Area (KHDTK). Furthermore, the analysis of DOC samples was carried out at the BALITRA Laboratory, Banjar Baru, South Kalimantan. The analysis of water pH samples was conduct at the UPT. LLG – CIMTROP, UPR Laboratory. The results showed that DOC in degraded peatlands site ranged from 36.18 mg L-1 to 76.86 mg L-1 with an average of 53.1 mg L-1, water pH between 3.6 to 4 with an average of 3.88, and the water table of 26.51 cm. Then in the forest site ranged from 37.12 mg L-1 to 49.81 mg L-1 with an average of 40.95 mg L-1, water pH ranged of 4 to 4.4 with an average of 4.32, and water table -5.13 cm. Furthermore, the re-vegetation site ranged from 29.27 mg L-1 to 34.90 mg L-1 with an average of 30.73 mg L-1, water pH between 4 to 4.3 with an average of 4.18, and water table 36.28 cm. Based on the results of the study it can be concluded that there is a difference in DOC in three sites, in the degradation site contributes higher dissolved organic carbon than other sites with an average amount of 53.1 mg L-1, compared to forest site with an average amount of 40.95 mg L-1, and re-vegetation site with an average amount of 30.73 mg L-1. Therefore, sustainable management of peat is expected to minimize the rapid decomposition of organic material in peat.