Abstract. In 2018 Typhoon Mangkhut (locally known as Typhoon Ompong) triggered thousands of landslides in the Itogon region of the Philippines. A landslide inventory of the affected region is compiled for the first time, comprising 1101 landslides over a 570 km2 area. The inventory is used to study the geomorphological characteristics and land cover more prone to landsliding as well as the hydrometeorological conditions that led to widespread failure. The results showed that landslides mostly occurred on grassland and wooded slopes of clay superficial geology, predominantly facing east-southeast. Rainfall (Integrated Multi-satellitE Retrievals for Global Precipitation Measurement, IMERG GPM) associated with Typhoon Mangkhut is compared with 33 high-intensity rainfall events that did not trigger regional landslide events in 2018. Results show that landslides occurred during high-intensity rainfall that coincided with the highest soil moisture values (estimated clays saturation point), according to Soil Moisture Active Passive level 4 (SMAP-L4) data. Our results demonstrate the potential of SMAP-L4 and GPM IMERG data for landslide hazard assessment and early warning where ground-based data are scarce. However, other rainfall events in the months leading up to Typhoon Mangkhut that had similar or higher rainfall intensities and also occurred when soils were saturated did not trigger widespread landsliding, highlighting the need for further research into the conditions that trigger landslides in typhoons.

An island province in the Philippines exposed to acid mine drainage for about 22-25 years, uncovered new discovery in selected agricultural yields. The acid mine drainage was from two open mine pits of higher elevation flowing to Boac and Mogpog River system. A total of 78 various agricultural yields samples with 234 specimens were collected and analyzed from six municipalities of Marinduque, Philippines in 2019. These agricultural yields were (A) vegetables, (B) root crops, (C) fruits, and (D) rice. Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES) Perkin Elmer Optima 8000 with ICP multi-element standard solution IV were used to detect metals concentration in the agricultural samples. Digestion of samples followed the EPA Method 200.3. Results were compared with the WHO/FAO limit followed by the identification of yields and areas that pose risks to public health. Determination of the spatial distribution was by ArcGIS. The six municipalities; i.e., Boac, Buenavista, Gasan, Mogpog, Torrijos and Sta. Cruz, were labelled as B, BV, G, M, T and S, respectively. Record showed that Sample A from G contain higher metal concentration among other yields. Manganese concentration in Samples A, B, and D were found to be higher than WHO/FAO limit. However, copper and zinc concentration in Sample C in all municipalities exceeded the allowable limit. Elevated total chromium concentration was found in Sample D collected from G, T, and S. These results would help relevant government agencies and units design strategies to mitigate the degraded agricultural lands and protect public health.

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The unique two-dimensional structure and chemical properties of graphene oxide (GO) provide a convenient method for preparing novel membranes. In this study, GO membranes were prepared through filtration by a pressure-assisted self-assembly method involving the cross-linking of three diamine monomers on a polyethersulfone (PES) support. The different small molecular diamines, ethylenediamine, butanediamine, and p-phenylenediamine, were introduced as cross-linking agents to investigate the effect of diamine on the properties of GO membranes. The hydrophobic substances ibuprofen, gemfibrozil, and triclosan were selected as target pharmaceuticals and personal care products (PPCPs). The adsorption and molecular sieving activities of PPCPs by cross-linked GO membranes at a pH of 3 were investigated. The permeate water was analyzed for dissolved organic carbon, ultraviolet absorption at 254 nm, molecular weight distribution, and fluorescence excitation–emission matrices. The results showed that the removal of hydrophobic PPCPs by GO membranes was mainly due to their adsorption and molecular sieving activities. Adsorption was mainly determined by the hydrophilic and hydrophobic properties of the membranes and PPCPs. The interception effect was mainly determined by the interlayer spacing between the GO membranes and the molecular weight and steric hindrance of the PPCPs. A smaller spacing of the GO membrane layers resulted in greater steric hindrance and a higher removal rate.

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