Methane fluxes from Zambian tropical wetlands

<p>Airborne measurements of methane (CH<sub>4</sub>) were recorded over three major wetland areas in Zambia in February 2019 during the MOYA (Methane Observations and Yearly Assessments) ZWAMPS field campaign. Enhancements of up to 600 ppb CH<sub>4</sub> were measured over the Bangweulu (11°36’ S, 30°05’ E), Kafue (15°43’ S, 27°17’ E), and Lukanga (14°29’ S, 27°47’ E) wetlands. Three independent methods were used to quantify methane emission fluxes; aircraft mass balance, aircraft eddy covariance, and atmospheric inversion modelling. Results yielded methane emission fluxes of 10-20 mg CH<sub>4</sub> m<sup>-2</sup> hr<sup>-1</sup>, which were up to an order of magnitude greater than the emission fluxes simulated by various wetland process models (WetCHARTs ensemble and LPX-Bern). Independent column CH<sub>4</sub> observations from the TROPOMI instrument were used to verify these fluxes, and investigate their applicability for timescales longer than the duration of the MOYA flight campaign.</p>

Analisa Persebaran Wetland Berdasarkan Metode Geolistrik di Kecamatan Pandak, Kab. Bantul, DIY

ABSTRAKWetland merupakan tanah lunak tersaturasi air yang berada di dekat permukaan yang menjadi permasalahan dalam pembangunan di sekitar daerah penelitian di Desa Gilangharjo, Kab. Bantul, DIY. Oleh karena itu dilakukan pengukuran metode geolistrik untuk mengetahui persebaran kedalaman wetland di sekitar daerah penelitian sebagai bahan kajian pendukung dalam program pembangunan desa. Dalam penelitian ini dilakukan pengukuran metode geolistrik sounding sebanyak lima titik sounding, kemudian data lapangan diproses menggunakan pemodelan inversi 1 Dimensi (1D) untuk mendapatkan kurva model 1D resistivitas batuan. Berdasarkan kurva model 1D resistivitas batuan didapatkan nilai resistivitas wetland berkisar antara 5.66 - 29.6 ohm.m dan kedalaman wetland berkisar antara 0.592 - 2.25 meter yang meningkat ke arah tenggara. kata kunci : Wet soils, resistivitas, geolistrik sounding ABSTRACTWetlands is a soft water saturated rocks in near surface which becomes a problems of developement in surrounding area of Gilangharjo Village, Bantul District, DIY. Therefore, the research with using geoelectrical methods has been conducted to delineating spreading of wetlands depth in surrounding research areas as a supporting data for village developing programs. In this research is conducted sounding geoelectrical methods measurements as much five sounding points, then the field data is processes with using 1D inversion modelling to get 1D resistivity models curve of rocks. Based on 1D resistivity models curve of rocks is obtained wetlands resistivity value is between 5.66 - 29.6 ohm.m and the depth of wetlands is between 0.592 - 2.25 meters which increase to southwest. keywords : Wet soils, resistivity, sounding geoelectric.

Exploration Disaster Source of Mine Water by Electromagnetic Radiation

geological hazard in deep underground mining. Before the rock mass explosion, electromagnetic energy will radiate outward during the deformation and rupture of the coal rocks. Hence, it is possible to use the electromagnetic radiation to predict geological disasters in coal mines. A challenging task using the active source electromagnetic survey technique is to detect geological anomalies, such as disaster water sources and geological structures. To this end, this paper proposes a new electromagnetic radiation solution based on the forward and inversion theory to detect geological anomalies in the coal seam. Based on typical coal mine geological models, the forward modelling and inversion modelling have been performed, respectively. The forward modelling explained the geological anomalies inside the coal seam, which were very sensitive to the response of the radiated electromagnetic field; especially, for the water-bearing geological anomalies. The inversion modelling discovered that the inversion geo-electric parameter distribution agreed well with the actual model. As a result, the proposed method is feasible for geological anomalies detection.

Early Eocene rapid exhumation record in the region of Nima, central Tibet, as determined by low-temperature thermochronology

<p>Knowledge of the geological history of the Tibetan plateau is critical to understanding crustal deformation process, and the plateau’s influence on climate. However, the timing of Tibetan plateau development remains controversial. The Nima Basin along the Jurassic-Cretaceous Bangong Suture in central Tibet provides well-dated records of exhumation in this area. Here, we present detrital zircon U-Pb, apatite U-Th/He (AHe) and apatite fission track data (AFT) from upper Cretaceous and Oligocene red sandstones and conglomerates in the Nima Basin, as well as from the Xiabie granite in the hanging wall of the basin-bounding Muggar Thrust. 4 granite conglomerate clasts from the above yield zircon U-Pb ages ranging between 114-122 Ma, which likely come from the Xiabie granite. 7 granitoid/sandstone conglomerate clasts yield AHe ages ranging from 21-58 Ma, while AFT ages range from 34-83 Ma. Thermal history inversion modelling for five of the above samples show a consistent rapid cooling from 100 ℃ to 30 ℃ between 50-40 Ma, the cooling rate decreased significantly after 40 Ma. Implications of these data, integrated in the context of previously published data for the wider region (e.g. Rohrmann et al. 2012; Haider et al., 2013; Li et al., 2019) will be discussed.</p><p> </p><p><strong>Reference</strong></p><p>Rohrmann, A et al., 2012, Thermochronologic evidence for plateau formation in central Tibet by 45 Ma: Geology, v. 40, p. 187-190.</p><p>Haider, V. L et al., 2013, Cretaceous to Cenozoic evolution of the northern Lhasa Terrane and the Early Paleogene development of peneplains at Nam Co, Tibetan Plateau: Journal of Asian Earth Sciences, v. 70-71, p. 79-98.</p><p>Li, H. A et al., 2019, The formation and expansion of the eastern Proto-Tibetan Plateau: Insights from low-temperature thermochronology: Journal of Asian Earth Sciences, v. 183, 103975.</p>

Self Potential (SP) and Resistivity Methods of Discriminating Lithologies in a Landslide Areas of Ohafia Town, Nigeria

This research presents the application of geophysical self-potential (SP) and resistivity methods in evaluating subsurface phenomenon in Ohafia Area. Two communities were covered with three profile lines of 200 m spread occupied in each location. The data were acquired using ABEM SAS 300C Terrameter and later processed with EarthImager 1D inversion modelling software. Self-Potential values ranged from -107.8 to 112.3 mV in Amaekpu and -100 to 150 mV in Elu area. Positive SP values indicated lithologies with low permeability while negative SP values showed permeable lithologies. Six geologic layers were inferred for Amaekpu area while seven layers were inferred from Elu area. Layer 1, 3 and 5 are low permeable lithologies while Layer 2, 4 and 6 are permeable intervals in Amaekpu. In Elu, Layers 1, 3, 5 and 7 are having low permeability while Layers 2, 4 and 5 are highly permeable lithologies. Lithologic intervals inferred from inverted resistivity data which include sands, sandstones and gravels conformed with regions having negative SP values. Similarly, depth intervals identified as topsoil, siltstones and clay conformed with positive SP values.