Emerging Perfluorobutane Sulfonamido Derivatives as a New Trend of Surfactants Used in the Semiconductor Industry.

The semiconductor industry has claimed that perfluorooctanesulfonate (PFOS), a persistent per- and polyfluoroalkyl substance (PFAS), has been eliminated from semiconductor production; however, information about the use of alternative compounds remains limited. This study aimed to develop a nontarget approach to discovering diverse PFAS substitutions used in semiconductor manufacturing. A distinct fragment-based approach has been established to identify the hydrophobic and hydrophilic features of acidic and neutral fluorosurfactants through fragments and neutral losses, including those outside the homologous series. Ten sewage samples from 5 semiconductor plants were analyzed with target and nontarget analysis. Among the 20 identified PFAS spanning 12 subclasses, 15 were reported in semiconductor sewage for the first time. The dominant identified PFAS compounds were C4 sulfonamido derivatives, including perfluorobutane sulfonamido ethanol (FBSE), perfluorobutane sulfonamide (FBSA), and perfluorobutane sulfonamido diethanol (FBSEE diol), with maximum concentrations of 482 µg/L, 141 µg/L, and 83.5 µg/L in sewage, respectively. Subsequently, three ultrashort chain perfluoroalkyl acids (PFAAs) were identified in all samples, ranging from 0.004 to 19.9 µg/L. Three effluent samples from the associated industrial wastewater treatment plants (WWTPs) were further analyzed. This finding, that the C4 sulfonamido acetic acid series constitutes a significant portion (65%-82%) of effluents from WWTP3 and WWTP4, emphasizes the conversion of fluorinated alcohols to fluorinated acids during aerobic treatment. The identification of the intermediate metabolites of FBSEE diol, further supported by our laboratory batch studies, prompts the proposal of a novel metabolic pathway for FBSEE diol. The total amount of perfluorobutane sulfonamido derivatives reached 1934 µg/L (90%), while that of PFAAs, which have typically received attention, was only 205 µg/L (10%). This suggests that perfluorobutane sulfonamido derivatives are emerging as a new trend in fluorosurfactants used in the semiconductor industry, serving as PFAS precursors and contributing to the release of their metabolites into the environment.

Amount and characteristics of microplastic and organic matter in wind-blown sediment at different heights within the aeolian sand saltation layer.

Soils of croplands especially where plastic film mulch is commonly applied, are normally contaminated by Microplastics (MPs). Microplastics can threaten air quality, food and water health, as well as human health by wind erosion processes. In this research, we investigated MPs collected in four wind erosion events at sampling heights between 0 and 60 cm in typical semiarid farmlands in northern China that employ plastic film mulch. Height distribution and enrichment heights of the MPs were measured. The results revealed that the average amounts of MPs for 0-20 cm, 20-40 cm and 40-60 cm sampling heights were 868.71 ± 249.21, 799.87 ± 271.25, 1102.54 ± 317.44 particles kg-1. The average enrichment ratios of MPs for the different heights were 0.89 ± 0.54, 0.85 ± 0.56, 1.15 ± 0.73. Height distribution of MPs was combined affected by shape (fiber and non-fiber) and size of MPs, wind speed and soil aggregate stability. The amount of fibers approximately <4 mm in size and non-fibers <2 mm in size increased with sampling height, while both shapes of larger MPs than these two sizes was almost independent of the sampling height. Enrichment ratios of microfibers were positively related to wind speed but negatively related to soil aggregate stability at each sampling height. The results revealed that although MPs have similar density to organic matter (OM), the MPs' amount and enrichment were independent of height but the OM content and enrichment ratios increased with height. These results suggested that more attention should be paid to the exploration of the influence of higher sampling heights (>60 cm) on the distribution of MPs in the future and the MPs characteristics for different sampling heights require carefully parameterization in detailed models of atmospheric MPs transport by wind erosion.

An evaluation of topsoil carbon storage in Chinese deserts.

Deserts are important components of the terrestrial ecosystem, and significantly affect the terrestrial carbon cycle. However, their carbon storage is poorly understood. To evaluate the topsoil carbon storage in Chinese deserts, we systematically collected topsoil samples (to a depth of 10 cm) from 12 deserts in northern China and analyzed their organic carbon storage. We used partial correlation and boosted regression tree (BRT) analysis to analyze the factors influencing the spatial distribution of soil organic carbon density based on climate, vegetation, soil grain-size distribution, and element geochemistry. The total organic carbon pool of Chinese deserts was 4.83 × 108 t, the mean soil organic carbon density was 1.37 ± 0.18 kg C m-2, and the mean turnover time was 16.50 ± 2.66 yr. With the largest area, the Taklimakan Desert had the highest topsoil organic carbon storage (1.77 × 108 t). The organic carbon density was high in the east and low in the west, whereas the turnover time showed the opposite trend. The soil organic carbon density was >2 kg C m-2 in the four sandy lands in the eastern region, and was greater than the values for the eight deserts (0.72 to 1.22 kg C m-2). Grain-size (i.e., the silt and clay contents) had the strongest influence on the organic carbon density in Chinese deserts, followed by element geochemistry. Precipitation was the main climatic factor that affected the distribution of organic carbon density in the deserts. Based on climate and vegetation cover trends during the past 20 years, Chinese deserts have a high potential for future organic carbon sequestration.

Wind erosion induced low-density microplastics migration at landscape scale in a semi-arid region of northern China.

Microplastics (MPs) have been extensively investigated in terrestrial environments, while the occurrence and movement of MPs at the landscape scale in semi-arid regions with serious wind erosion are less well studied. Here, we sampled film mulching farmland and downwind nearby grassland surface soils in a semi-arid region of northern China to explore the distribution of MPs at different downwind distances and the potential environmental risk to the local landscapes. The results revealed that the MP abundances presented a decreasing trend with increasing downwind distance (Mann-Kendall test, P < 0.01). The MP size distributions at different distances showed similar sigmoid trends described by logistic models. MP fiber size (500-2000 µm) abundance in the farmland was higher than that of the grassland. By contrast, MP non-fiber size (<1000 µm) abundance of farmlands was less than that of the grassland. The abundances of fibers larger than 500 µm and non-fibers larger than 1000 µm in size decreased exponentially with increasing downwind distance. The size of transported MPs at the landscape scale was larger than that of long-distance dispersal. The migration of MPs from farmlands can pose a potential threat to the downwind landscape, leading the downwind grassland to be a potential MP emission source. This study presents the first insights into the MPs distribution among different downwind distances at the landscape scale. Future research is required to deploy aeolian sediment sampling devices and establish the connection between the field data and the MP emission models.

Regional Potential Wind Erosion Simulation Using Different Models in the Agro-Pastoral Ecotone of Northern China.

Wind erosion is crucial for assessing regional ecosystem services and sustainable development. The Agro-Pastoral Ecotone of northern China (APEC) is a typical region undergoing wind erosion and soil degradation. In this study, the National Wind Erosion Survey Model of China, the Integrated Wind Erosion Modeling System, and the regional versions of the Revised Wind Erosion Equation and Wind Erosion Prediction System were used to evaluate the regional potential wind erosion of the APEC during 2000 and 2012. The results showed that the potential wind erosion predicted by National Wind Erosion Survey Model of China (NWESMC), Revised Wind Erosion Equation (RWEQ), Wind Erosion Prediction System (WEPS), and Integrated Wind Erosion Modeling System (IWEMS) were significantly related to the observed wind erosion collected from published literature, but the observed data were generally smaller than the predicted values. The average potential wind erosions were 12.58, 25.87, 52.63, and 58.72 t hm-2 a-1 for NWESMC, RWEQ, WEPS, and IWEMS, respectively, while the spatial pattern and temporal trend of annual potential wind erosion were similar for different wind erosion models. Wind speed, soil moisture, and vegetation coverage were the dominant factors affecting regional wind erosion estimation. These results highlight that it is necessary to comprehensively calibrate and validate the selected wind erosion models. A long-term standard wind erosion monitoring network is urgently required. This study can serve as a useful reference for improving wind erosion models.

Simultaneous telemetry of temperature and vibration by laser dispersion spectroscopy.

In many industrial applications, temperature and mechanical vibration are closely coupled but measured separately. A novel, to the best of our knowledge, method for simultaneous telemetry of temperature and vibration parameters was proposed in this work from laser dispersion spectroscopy profiles at two different central wavelengths. The temperature was extracted from the peak-to-peak ratio of these two absorption spectra. The vibration amplitude as well as its frequency were derived from the time-varying baselines of the two spectra. A telemetry sensor was designed and evaluated on a thermal vibration coupled experiment platform. The extracted temperatures agree well with the readings of a reference thermocouple, and the signal-to-noise ratio is at least 18 dB higher than those by classical direct laser absorption spectroscopy (DLAS). The extracted vibration frequencies are the same as the outputs of a commercial laser Doppler vibrometer (LDV), and the sensitivity of the extracted vibration amplitudes is 3.64 micrometers, in terms of the Allan variance.

Plastic mulch film induced soil microplastic enrichment and its impact on wind-blown sand and dust.

Microplastics (MPs) pollution is being increasingly recognized as a global concern in all environments. Wind-blown sand and dust contaminated by MPs are an important pathway of MPs transport across different environments, which can result in on-site and off-site potential MP pollution. Here, we designed field experiments to detect MPs in surface soil and wind-blown sand and dust in farmlands with and without film mulch in a semi-arid region of northern China. This study provides the first insights into MPs enrichment in wind-blown sand and dust deposited by natural storms. The results reveal that fibers, fragments, and films constitute the major types of MPs in farmland soil and wind-blown sand and dust. The MPs abundances of 1-3 mm, <1 mm, and 3-5 mm items kg-1 successively decrease. The enrichment of MPs in wind-blown dust is one to two orders of magnitude higher than that in wind-blown sand. For the farmlands with (without) film mulch, the MPs enrichment ratios ranged from 0.22 (0.29) to 1.35 (2.26) in the wind-blown sand and that varied from 1.79 (1.01) to 16.6 (25.79) in the wind-blown dust. Fibers are preferentially transported by wind erosion compared to fragments and films. Soil aggregating processes, wind speed, and MPs shape may influence enrichment in wind-blown sand and dust. Film mulch debris and the application of manure may be the primary sources of MPs in farmland soils. This study further highlights the importance of the transport of airborne MPs from surface soil into the atmosphere. Future research is required to establish the quantitative relationships between the MPs shape, wind speed, and surface soil properties and the MPs enrichment in wind-blown sand and dust.

Spatial characteristics of the PM2.5/PM10 ratio and its indicative significance regarding air pollution in Hebei Province, China.

Particulate matter (PM) is the primary air pollutant in northern China. The PM2.5/PM10 ratio has been used increasingly as an indicator to reflect anthropogenic PM pollution, but its advantages compared with individual PM2.5 or PM10 concentrations have not been proven sufficiently by experimental data. By dividing Hebei Province (China) into seven natural ecological regions, this study investigated the spatial characteristics of the PM2.5/PM10 ratio and its relationships with PM2.5, PM10, economic density, and wind speed. Results showed that the PM2.5/PM10 ratio decreased from east to west and from south to north, with an annual average value in 2019 of 0.439-0.559. The characteristics of the spatial variation of the PM2.5/PM10 ratio were different to those of either PM2.5 or PM10 concentration, indicating that PM pollution reflected by the PM2.5/PM10 ratio is not entirely consistent with that by PM2.5 and PM10 concentrations. In comparison with PM2.5 or PM10 concentration, the PM2.5/PM10 ratio had higher (lower) correlation with economic density (wind speed), indicating that the PM2.5/PM10 ratio is a better indicator used to reflect the intensity of anthropogenic emissions of PM pollutants. According to the characteristics of the spatial variations of the PM2.5/PM10 ratio and the PM2.5 and PM10 concentrations, the seven ecological regions of Hebei Province were categorized into four different types of atmospheric PM pollution: "three low regions," "three high regions," "one high and two low regions," and "one low and two high regions." This reflects the comprehensive effect of the intensity of anthropogenic PM emissions and the atmospheric diffusion conditions.

A Robust Distributed Multipoint Fiber Optic Gas Sensor System Based on AGC Amplifier Structure.

A harsh environment-oriented distributed multipoint fiber optic gas sensor system realized by automatic gain control (AGC) technology is proposed. To improve the photoelectric signal reliability, the electronic variable gain can be modified in real time by an AGC closed-loop feedback structure to compensate for optical transmission loss which is caused by the fiber bend loss or other reasons. The deviation of the system based on AGC structure is below 4.02% when photoelectric signal decays due to fiber bending loss for bending radius of 5 mm, which is 20 times lower than the ordinary differential system. In addition, the AGC circuit with the same electric parameters can keep the baseline intensity of signals in different channels of the distributed multipoint sensor system at the same level. This avoids repetitive calibrations and streamlines the installation process.

Spatial distribution and source apportionment of atmospheric dust fall at Beijing during spring of 2008-2009.

Beijing is a megacity, where atmospheric dust fall amount is great, and its resultant air pollution is serious. So, analyzing the chemical elements in atmospheric dust fall and revealing its various sources can provide a scientific basis for taking effective measures to improve atmospheric environmental quality. In this paper, we investigated the spatial and temporal distribution of dust fall in Beijing, based on the dust samples collected in the spring of 2008 and 2009 at 18 observation sites laid out in Beijing and then analyzed the sources of atmospheric dust fall based on the test of samples, adopting enrichment factor and factor analysis methods. Our results found that the dust fall quantity in the observation periods was respectively 33.6230 t km(-2) and 28.7130 t km(-2); the dust fall quantity varied significantly in different months in the spring, but the variation trend was similar at the sites. There were two centers of large quantity in Beijing; one was in the southwest of downtown, and the other was in the northeast of downtown. The spatial distribution of dust fall generally showed a structural feature of three loops; the northwestern mountainous area was a small quantity belt; the plain area around the downtown was a large quantity belt, and the central downtown was a center of small quantity. Soil dust, construction dust, coal dust, and vehicle exhaust were the four major sources of dust fall in spring of Beijing, respectively, accounting for 38.50, 22.25, 14.06, and 20.82 % of the total dust fall quantity.

Sweeping technique combined with micellar electrokinetic chromatography for the simultaneous determination of flunitrazepam and its major metabolites.

A sweeping technique, in conjunction with micellar electrokinetic chromatography, for the simultaneous determination of flunitrazepam and its major metabolites, 7-aminoflunitrazepam and N-desmethylflunitrazepam, is described. The optimized conditions for the sweeping and separation were a pH 9.5 buffer, 25mM borate, 50mM cetyltrimethylammonium bromide, 30% MeOH (v/v), and a 151-mm injection length. The calibration functions were all linear with the coefficient of determination (r(2)) exceeding 0.996 for the three target compounds. Using the sweeping procedure, the limits of detection were determined to be 13.4, 5.6, and 12.0ng/mL for flunitrazepam, 7-aminoflunitrazepam, and N-desmethylflunitrazepam, respectively, and the sensitivity enhancement for each compound was within the range of 110-200 fold. The RSDs for the retention time and the peak area were less than 4.10%. The optimized sweeping method was also used to examine a spiked urine sample. We conclude that sweeping with micellar electrokinetic chromatography has considerable potential use in clinical and forensic analyses of flunitrazepam and its metabolites.