Measurement report: On the difference of aerosol hygroscopicity between high and low RH conditions in the North China Plain

Atmospheric processes, including both primary emissions and secondary formation, may exert complex effects on aerosol hygroscopicity, which is of significant importance in understanding and quantifying the effect of aerosols on climate and human health. In order to explore the influence of local emissions and secondary formation processes on aerosol hygroscopicity, we investigated the hygroscopic properties of submicron aerosol particles at a rural site in the North China Plain (NCP) in winter 2018. This was conducted by simultaneous measurements of aerosol hygroscopicity and chemical composition, using a self-assembled hygroscopic tandem differential mobility analyzer (HTDMA) and a capture-vaporizer time-of-flight aerosol chemical speciation monitor (CV-ToF-ACSM). The hygroscopicity results showed that the particles during the entire campaign were mainly externally mixed, with a more hygroscopic (MH) mode and a less hygroscopic (LH) particles mode. The mean hygroscopicity parameter values (κmean) derived from hygroscopicity measurements for particles at 60, 100, 150, and 200 nm were 0.16, 0.18, 0.16, and 0.15, respectively. During this study, we classified two distinct episodes with different RH/T conditions, indicative of different primary emissions and secondary formation processes. It was observed that aerosols at all measured sizes were more hygroscopic under the high RH (HRH) episode than those under the low RH (LRH) episode. During the LRH, κ decreased with increasing particle size, which may be explained by the enhanced domestic heating at low temperature, causing large emissions of non- or less-hygroscopic primary aerosols. This is particularly obvious for 200 nm particles, with a dominant number fraction (> 50 %) of LH mode particles. Using O : C-dependent hygroscopic parameters of secondary organic compounds (κSOA), closure analysis between the HTDMA_measured κ and the ACSM_derived κ was carried out. The results showed that κSOA under the LRH episode was less sensitive to the changes in organic oxidation level, while κSOA under the HRH had a relatively stronger dependency on the organic O : C. This feature suggests that the different sources and aerosol evolution processes, partly resulting from the variation in atmospheric RH/T conditions, may lead to significant changes in aerosol chemical composition, which will further influence their corresponding physical properties.

Mapping gaseous dimethylamine, trimethylamine, ammonia, and their particulate counterparts in marine atmospheres of China's marginal seas – Part 1: Differentiating marine emission from continental transport

To study sea-derived gaseous amines, ammonia, and primary particulate aminium ions in the marine atmosphere of China's marginal seas, an onboard URG-9000D Ambient Ion Monitor-Ion Chromatograph (AIM-IC, Thermo Fisher) was set up on the front deck of the R/V Dongfanghong-3 to semi-continuously measure the spatiotemporal variations in the concentrations of atmospheric trimethylamine (TMAgas), dimethylamine (DMAgas), and ammonia (NH3gas) along with their particulate matter (PM2.5) counterparts. In this study, we differentiated marine emissions of the gas species from continental transport using data obtained from 9 to 22 December 2019 during the cruise over the Yellow and Bohai seas, facilitated by additional short-term measurements collected at a coastal site near the Yellow Sea during the summer, fall, and winter of 2019. The data obtained from the cruise and coastal sites demonstrated that the observed TMAgas and protonated trimethylamine (TMAH+) in PM2.5 over the Yellow and Bohai seas overwhelmingly originated from marine sources. During the cruise, no significant correlation (P>0.05) was observed between the simultaneously measured TMAH+ and TMAgas concentrations. Additionally, the concentrations of TMAH+ in the marine atmosphere varied around 0.28±0.18 µg m−3 (average ± standard deviation), with several episodic hourly average values exceeding 1 µg m−3, which were approximately 1 order of magnitude larger than those of TMAgas (approximately 0.031±0.009 µg m−3). Moreover, there was a significant negative correlation (P<0.01) between the concentrations of TMAH+ and NH4+ in PM2.5. Therefore, the observed TMAH+ in PM2.5 was overwhelmingly derived from primary sea-spray aerosols. Using TMAgas and TMAH+ in PM2.5 as tracers for sea-derived basic gases and sea-spray particulate aminium ions, the values of non-sea-derived DMAgas, NH3gas, and non-sea-spray particulate DMAH+ in PM2.5 were estimated. The estimated average values of each species contributed 16 %, 34 %, and 65 % of the observed average concentrations for non-sea-derived DMAgas, NH3gas, and non-sea-spray particulate DMAH+ in PM2.5, respectively. Uncertainties remained in the estimations, as TMAH+ may decompose into smaller molecules in seawater to varying extents. The non-sea-derived gases and non-sea-spray particulate DMAH+ likely originated from long-range transport from the upwind continents based on the recorded offshore winds and increased concentrations of non-sea-salt SO42- (nss-SO42-) and NH4+ in PM2.5. The lack of a detectable increase in particulate DMAH+, NH4+, and nss-SO42- concentrations in several SO2 plumes did not support the secondary formation of particulate DMAH+ in the marine atmosphere.

An Integrated IR4.0 Software Enables Autonomous Casing Crossflow Rate Calculation

This paper will present an alternative calculation technique to predict wellbore crossflow rate in a water injection well resulting from a casing leak. The method provides a self-governing process for wellbore related calculations inspired by the fourth industrial revolution technologies. In an earlier work, calculations techniques were presented which do not require the conventional use of downhole flowmeter (spinner) to obtain the flow rate. Rather, continuous surface injection data prior to crossflow development and shut-in well are used to estimate the rate. In this alternative methodology, surface injection data post crossflow development are factored in to calculate the rate with the same accuracy. To illustrate the process an example water injector well is used. To quantify the casing leak crossflow rate, the following calculation methodology was applied:Generate a well performance model using pre-crossflow injection data. Normal modeling techniques are applied in this step to obtain an accurate model for the injection well as a baseline case.Generate an imaginary injection well model: An injection well mimicking the flow characteristics and properties of the water injector is envisioned to simulate crossflow at flowing (injecting) conditions. In this step, we simulate an injector that has total depth up to the crossflow location only and not the total depth of the example water well.Generate the performance model for the secondary formation using post crossflow data: The total injection rate measured at surface has two portions: one portion goes into the shallower secondary formation and another goes into the deeper (primary) formation. The modeling inputs from the first two steps will be used here to obtain the rate for the downhole formation at crossflow conditions.Generate an imaginary production well model: The normal model for the water injector will be inversed to obtain a production model instead. The inputs from previous steps will be incorporated in the inverse modeling.Obtaining the crossflow rate at shut-in conditions: Performance curves generated from step 3 & 4 will be plotted together to obtain an intersection that corresponds to the crossflow rate at shut-in conditions. This numerical methodology was analytically derived and the prediction results were verified on syntactic field data with very high accuracy. The application of this model will benefit oil operators by avoiding wireline logging costs and associated safety risks with mechanical intervention.

Necrotizing Ulcerative Gingivitis, a Rare Manifestation as a Sequel of Drug-Induced Gingival Overgrowth: A Case Report

Purpose. The purpose of this case report is to present a rare case of amlodipine-induced gingival overgrowth with a secondary formation of necrotizing ulcerative gingivitis involving the upper and lower arches of a 68-year-old female patient with a chief complaint of “swollen gums and pain on mastication which has been recurring for the past 5 years.” Materials and Methods. The treatment plan of this case was divided according to quadrants of the mouth. Each week, one quadrant was surgically excised, and the remaining quadrants were observed for any changes. The gingival overgrowths were excised using a 15 blade, and debris/plaque was removed with Gracey curettes. Results. Although full-mouth exodontia was performed, the patient unfortunately suffered with recurrences in GO. These results are suggestive of idiopathic causes of GO. Conclusion. Careful examination, physician referrals, and biopsy to rule out any specific anomalies and to assist in proper diagnosis are followed by sequential management of the case results in productive outcomes.