Influence of Soil Genesis Factors on Gurghiu Mountain Forest Soils’ Physical and Chemical Properties

This research aimed to determine the values of chemical properties and the relationships between the main pedoecological factors that characterize the soils in the Gurghiu Mountains. The mapping surveys were carried out on an area of 4,647.36 ha located in the mixed mountain forest sites (FM2) (1,000–1,400 m altitude). The area was stratified into homogeneous site units in terms of climate, hydricity, and trophicity. At the level of the elementary site units, 35 main soil profiles and 46 control profiles were placed. The number of profiles was determined statistically to ensure an error of no more than 10%. Soil samples collected from the main profiles were analyzed in the laboratory. Soil’s properties values decreased on the soil’s profile (humus content from 15 to 2%, nitrogen from 1.1 to 0.5%, sum of exchangeable hydrogen from 20 to 9 me/100 g soil, and total cationic exchange capacity from 38 to 20 me/100 g soil), except the pH and the base saturation degree (the pH increased on profile from 4.5 to 6, and the base saturation degree from 40 to 70%). The soil properties, except for moisture, were significantly affected by altitude, and decreased when the altitude increased. Soil trophicity can be characterized by a soil index, the values of which were between 17 and 42 for the analyzed soils. These values indicated soil-specific trophicity levels from oligotrophic to eutrophic.

PITTING MECHANISM OF MILD STEEL IN MARGINALLY SOUR ENVIRONMENTS: PIT PROPAGATION BASED ON ACIDIFICATION BY CATALYTIC OXIDATION OF DISSOLVED HYDROGEN SULFIDE

The present work studies pit propagation in marginally sour environments and proposes a credible mechanism. Both thermodynamic calculation and experimental measurement confirmed that H2S can be oxidized by traces of dissolved O2 into SO42- and H+ in the aqueous solutions near room temperature with the transitional metal ions serving as a catalyst. This acidification phenomenon would be more effective near the steel surface, especially inside a pit, where Fe2+ ions are most abundant. Therefore, the saturation degree of mackinawite would be lower inside the pit, which would prohibit the pitting from annihilation.

Effects of Surface Tension on the Stability of Surface Nanobubbles

The existence of surface nanobubbles has already been confirmed by variable detection methods, but the mechanism of their extraordinary stability remains unclear and has aroused widespread research interest in the past 2 decades. Experiments and theoretical analyses have tried to account for these stabilities such as the very long lifetime, very high pressure and very small contact angle. Attractive hydrophobic potential was applied to complement the pinning-oversaturation theory and successfully explain the survival of surface nanobubbles in undersaturation environment by some researchers. However, the survival of nanobubbles on hydrophilic surface still requires sizeable oversaturation. In this paper, we introduce the variable surface tensions, namely Tolman-dependence and state-dependence, and show that they effectively promote the stability of nanobubbles. The decrease in surface tension can lead to larger contact angle and even make the nanobubbles survivable on the highly hydrophilic surface. In Tolman-dependence, the changing rate in the contact angle evolution slows down, which is more obvious when the bubble size is close to the Tolman length. The contact angle is also getting larger in the state-dependence, and the increase of the gas saturation degree is beneficial to the stability of surface nanobubbles. With the gas saturation ratio of 3, the bubbles on the quite hydrophilic surface can also be stable, while grow up on the hydrophobic surface. The variable surface tensions weaken the need of saturation degree for the surface nanobubbles’ stability.

Forecasting the viscosity properties of water-oil systems

In article possibilities of predicting the viscosity of stable multicomponent water-oil systems in practice, when it is impossible, for a number of reasons, to obtain their experimental values, are considered. A predictive model is proposed to describe the change in the viscosity properties of various oil-water emulsions depending on the degree of water saturation. It is shown that the proposed formula allows to determine the effective viscosity of water-oil systems in the entire range of variation of the velocity gradient in the absence of experimental data and is acceptable for engineering practice. Keywords: viscosity; water-oil emulsions; matematical description; water saturation degree; heterogeneous systems.

Performance Analysis of Road Section and Unsignalized Intersections On Jalan Cileungsi Setu and Jalan Raya Narogong

The unsignalized intersection which is located in Cileungsi District, precisely on Jalan Cileungsi Setu and Jalan Raya Narogong, is a commercial area with dense economic activity and densely populated settlements. As a result of the dense activity, congestion occurs due to the large number of vehicles passing the road, especially during peak hours, namely the morning and evening. Seeing this problem, an analysis is needed that aims to determine the volume, performance of roads, and unmarked intersections as measured by capacity, degree of saturation, and level of service. In analyzing this study using the Indonesian Road Capacity Manual (MKJI) 1997 method which will determine the performance of roads and intersections without signs. The data needed in this research are primary data in the form of geometric road data, traffic volume, vehicle speed data, and side friction. As well as secondary data in the form of location maps, land use, and population data. From the results of data analysis and processing, the busiest traffic flow at the intersection occurred on Sunday, November 15, 2020 at 17.30 - 18.30 WIB, the saturation degree value was 1.17 with LOS F. By doing an alternative solution, the saturation degree value was 0.68 and LOS B with placing signs are prohibited from stopping around intersections, and prohibiting the flow of traffic turning right either from the main road D to the Minor C road or from the Minor C road to the main road B. On Jalan Raya Narogong, the degree of saturation is 0.74 LOS C service, this shows that the road sections do not exceed the figure required by MKJI 1997, namely ≤ 0.75.

A multi-sourced assessment of the spatiotemporal dynamics of soil moisture in the MARINE flash flood model

The MARINE (Model of Anticipation of Runoff and INundations for Extreme events) hydrological model is a distributed model dedicated to flash flood simulation. Recent developments of the MARINE model are explored in this work. On one hand, transfers of water through the subsurface, formerly relying on water height, now take place in a homogeneous soil column based on the soil saturation degree (SSF model). On the other hand, the soil column is divided into two layers, which represent, respectively, the upper soil layer and the deep weathered rocks (SSF–DWF model). The aim of the present work is to assess the accuracy of these new representations for the simulation of soil moisture during flash flood events. An exploration of the various products available in the literature for soil moisture estimation is performed. The efficiency of the models for soil saturation degree simulation is estimated with respect to several products either at the local scale or spatially distributed: (i) the gridded soil moisture product provided by the operational modeling chain SAFRAN-ISBA-MODCOU; (ii) the gridded soil moisture product provided by the LDAS-Monde assimilation chain, which is based on the ISBA-A-gs land surface model and assimilating satellite derived data; (iii) the upper soil water content hourly measurements taken from the SMOSMANIA observation network; and (iv) the Soil Water Index provided by the Copernicus Global Land Service (CGLS), which is derived from Sentinel-1 C-SAR and ASCAT satellite data. The case study is performed over two French Mediterranean catchments impacted by flash flood events over the 2017–2019 period. The local comparison of the MARINE outputs with the SMOSMANIA measurements, as well as the comparison at the basin scale of the MARINE outputs with the gridded LDAS-Monde and CGLS data, lead to the following conclusion: both the dynamics and the amplitudes of the soil saturation degree simulated with the SSF and SSF–DWF models are better correlated with both the SMOSMANIA measurements and the LDAS-Monde data than the outputs of the base model. Finally, the soil saturation degree simulated by the two-layers model for the deep layer is compared to the soil saturation degree provided by the LDAS-Monde product at corresponding depths. In conclusion, the developments presented for the representation of subsurface flow in the MARINE model enhance the soil saturation degree simulation during flash floods with respect to both gridded data and local soil moisture measurements.

High organic carbon input can accelerate global warming in rice paddy soil: increase unprotected soil organic carbon and CH4 emission

<p>Soil C sequestration is widely regarded as the most reasonable way to mitigate global warming. Traditionally, a high amount of organic carbon (OC) input is strongly recommended to increase soil organic carbon (SOC) stocks in croplands. However, according to the whole-soil saturation theory, stable SOC (mineral-associated SOC) accumulation can be limited at a certain point, relying on silt and clay contents. Most studies based on the theory were conducted in aerobic soil condition. This relationship is still uncertain in a rice paddy that makes up 10.8% of total arable land and has an anaerobic soil environment. In this study, we investigated high OC addition can enhance soil C sequestration in a rice paddy. We added different OC levels (0.5, 2.0, 2.9, and 4.6 Mg C ha<sup>-1</sup> yr<sup>-1</sup>) in rice paddy by incorporating cover crop biomass for nine years. SOC stock and soil saturation degree were determined. Unprotected, sand-associated, silt-associated, and clay-associated SOC were separated via density and size fractionation. Respired C losses (CO<sub>2</sub>-C and CH<sub>4</sub>-C) were monitored using the static closed chamber method. SOC stock did not linearly increase with higher amount of OC input. The carbon sequestration efficiency (i.e. the increase of SOC per unit of OC input) decreases with the amount OC added. Higher OM input significantly increased unprotected labile SOC content. Unprotected SOC (<1.85 g cm<sup>-3</sup>) exponentially increased as the SOC saturation degree was higher. On the other hand, stable SOC content did not exhibit a linear relationship with the SOC saturation degree. The higher OC addition level exponentially increased respired C loss. In particular, C loss via CH<sub>4</sub> was more sensitive to high OC addition. We conclude that higher OC addition in rice paddy without consideration in terms of SOC stock saturation point can accelerate global warming by increasing labile SOC accumulation and CH<sub>4</sub> emission.</p>