Investigating the determinants of marine environmental degradation in Africa: What roles can economy, population, capture and energy play?

This study firstly examines the quality of marine eco-environment in Africa using Tapio decoupling model, and analyzes the sustainability level of the development of "population agglomeration - marine environment - economic growth". Secondly, a series of econometric tools, such as ARDL, FMOLS, AMG model and DH panel causality test, are used to investigate the long- and short-term impacts of economic growth, population agglomeration, marine capture and energy consumption on the African marine eco-environment, and to analyze the differences between the sub-regions in Africa. The results indicate that: Adebayo and Kirikkaleli (2021) (Adebayo and Kirikkaleli, 2021) the decoupling state of "population-environment" has shifted from expansive negative decoupling to more optimized strong decoupling, and "economy-environment" has gradually changed from strong negative decoupling and expansive negative decoupling to strong decoupling. Ali et al. (2017) (Ali et al., 2017) There existed a bi-directional causal relationship between the degree of marine environment degradation and economic growth, population agglomeration, marine capture and energy consumption. Al-Mulali and Sab (2012) (Al-Mulali and Sab, 2012) In the short term, the economic EKC hypothesis does not hold in North and West Africa, while Central, East and Southern Africa are consistent with the EKC hypothesis. In the long term, the EKC hypothesis is valid in Central, East and Southern Africa, while is not valid in North and West Africa. Overall, reducing population agglomeration levels, marine fishing and energy consumption might mitigate marine environmental degradation in Africa.

How does virtual water influence the water stress pattern in Africa? A research perspective from the perspectives of production and trade.

Northern Africa has become the first region in the world to exhaust its water resources, with a 40 % decrease in per capita water availability south of the Sahara over the past decade. While adjusting production structures and consumption can regulate the supply-demand dynamics of water resources, the extent of the impact of virtual water-induced pressure on both the regional and national levels in Africa remains largely understudied. Applying the standard Penman formula, this research calculates the water footprint of eight cereal crops in 54 African countries from 1990 to 2021. By integrating corresponding data on cereal trade, the study analyzes changes in virtual water stress. The findings indicate a decline in the per-unit production and consumption water footprints for African cereals. However, the continuous expansion of cultivation areas contributes to a rising water stress. In comparison to 1990, the water stress for soybeans, sorghum, rice, maize, and cassava increased by 149.72 %, 146.88 %, 133.89 %, 123.30 %, and 90.8 %, respectively, in 2021. Only barley showed a reduction in water stress by 23.22 %. The study underscores the growing interconnectedness of virtual water trade (VWT) among African nations from 1990 to 2021, leading to a more balanced trade distribution. VWT has reduced water stress by 7.65 %, 2.08 %, and 1.8 % in Western, Central, and Northern Africa, respectively, while increasing pressure in Southern and Eastern Africa by 10.51 % and 1.01 %. The flow of virtual water in Africa is most influenced by spatial proximity, primarily occurring between adjacent countries or regions. Forecasts for water stress under the five scenarios of SSPs-RCP8.5 have been conducted, revealing a continuous increase in water stress across Africa. Furthermore, analysis of the SSP2-RCP8.5 scenario indicates that by 2030 and 2040, African cereal crops are projected to face virtual water resource stress increases of 7 % and 18.76 %, respectively, compared to 2020 levels. During the same period, Sierra Leone is anticipated to experience a growth rate in virtual water stress of approximately 1903.38 %. Consequently, altering crop cultivation structures and enhancing VWT are poised to alleviate water resource pressure, promoting the scientific management of agricultural water resources in Africa.

A hybrid ensemble learning merging approach for enhancing the super drought computation over Lake Victoria Basin.

This study introduces a novel Hybrid Ensemble Machine-Learning (HEML) algorithm to merge long-term satellite-based reanalysis precipitation products (SRPPs), enabling the estimation of super drought events in the Lake Victoria Basin (LVB) during the period of 1984 to 2019. This study considers three widely used Machine learning (ML) models, including RF (Random Forest), GBM (Gradient Boosting Machine), and KNN (k-nearest Neighbors), for the emerging HEML approach. The three SRPPs, including CHIRPS (Climate Hazards Group Infra-Red Precipitation with Station), ERA5-Land, and PERSIANN-CDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Climate Data Record), were used to merge for developing new precipitation estimates from HEML model. Additionally, classification and regression models were employed as base learners in developing this algorithm. The newly developed HEML datasets were compared with other ML and SRPP products for super-drought monitoring. The Standardized precipitation evapotranspiration index (SPEI) was used to estimate super drought characteristics, including Drought frequency (DF), Drought Duration (DD), and Drought Intensity (DI) from machine learning and SRPPs products in LVB and compared with RG observation. The results revealed that the HEML algorithm shows excellent performance (CC = 0.93) compared to the single ML merging method and SRPPs against observation. Furthermore, the HEML merging product adeptly captures the spatiotemporal patterns of super drought characteristics during both training (1984-2009) and testing (2010-2019) periods. This research offers crucial insights for near-real-time drought monitoring, water resource management, and informed policy decisions.

Bioturbation analysis of microbial communities and flavor metabolism in a high-yielding cellulase Bacillus subtilis biofortified Daqu.

In this study, a fortified Daqu (FF Daqu) was prepared using high cellulase-producing Bacillus subtilis, and the effects of in situ fortification on the physicochemical properties, flavor, active microbial community and metabolism of Daqu were analyzed. The saccharification power, liquefaction power, and cellulase activity of the FF Daqu were significantly increased compared with that of the traditional Daqu (CT Daqu). The overall differences in flavor components and their contents were not significant, but the higher alcohols were lower in FF Daqu. The relative abundance of dominant active species in FF Daqu was 85.08% of the total active microbiota higher than 63.42% in CT Daqu, and the biomarkers were Paecilomyces variotii and Aspergillus cristatus, respectively. The enzymes related to starch and sucrose metabolic pathways were up-regulated and expressed in FF Daqu. In the laboratory level simulation of baijiu brewing, the yield of baijiu was increased by 3.36% using FF Daqu.

Combined microbiome and metabolomics analysis of Taorong-type baijiu high-temperature Daqu and medium-temperature Daqu.

Background: Daqu is an essential starter for baijiu brewing in China. However, the microbial enrichment and metabolic characteristics of Daqu formed at different fermentation temperatures are still unclear. Methods: High-throughput sequencing technology and the non-targeted metabolomics were used to compare the microbial communities and metabolites of Taorong-type high-temperature Daqu and middle-temperature Daqu. In this study, the relationship between microorganisms and metabolites was established. Results: The study found that the composition and metabolites of the microbial community differed due to the difference in Daqu-making temperature. The bacterial diversity of Taorong-type high-temperature Daqu was higher than that of middle-temperature Daqu, while the fungal community diversity of Taorong-type middle-temperature Daqu was higher than that of high temperature Daqu. A total of 1,034 differential metabolites were screened from the two types of Daqu, and 76 metabolites with significant differences were detected (P < 0.001 and variable importance in projection (VIP) > 1.15). Tetraacetylethylenediamine is the metabolite with the largest differential fold among the 76 differential metabolites, which can be used as a potential marker metabolite of high-temperature Daqu. Conclusion: This study helps elucidate the microbial assembly mechanisms and functional expression under different processing conditions through a further understanding of the composition and metabolic profile differences of different types of Daqu microflora in Taorong-type baijiu.

The Driving Influence of Multi-Dimensional Urbanization on PM2.5 Concentrations in Africa: New Evidence from Multi-Source Remote Sensing Data, 2000-2018.

Africa's PM2.5 pollution has become a security hazard, but the understanding of the varying effects of urbanization on driven mechanisms of PM2.5 concentrations under the rapid urbanization remains largely insufficient. Compared with the direct impact, the spillover effect of urbanization on PM2.5 concentrations in adjacent regions was underestimated. Urbanization is highly multi-dimensional phenomenon and previous studies have rarely distinguished the different driving influence and interactions of multi-dimensional urbanization on PM2.5 concentrations in Africa. This study combined grid and administrative units to explore the spatio-temporal change, spatial dependence patterns, and evolution trend of PM2.5 concentrations and multi-dimensional urbanization in Africa. The differential influence and interaction effects of multi-dimensional urbanization on PM2.5 concentrations under Africa's rapid urbanization was further analyzed. The results show that the positive spatial dependence of PM2.5 concentrations gradually increased over the study period 2000-2018. The areas with PM2.5 concentrations exceeding 35 µg/m3 increased by 2.2%, and 36.78% of the African continent had an increasing trend in Theil-Sen index. Urbanization was found to be the main driving factor causing PM2.5 concentrations changes, and economic urbanization had a stronger influence on air quality than land urbanization or population urbanization. Compared with the direct effect, the spillover effect of urbanization on PM2.5 concentrations in two adjacent regions was stronger, particularly in terms of economic urbanization. The spatial distribution of PM2.5 concentrations resulted from the interaction of multi-dimensional urbanization. The interaction of urbanization of any two different dimensions exhibited a nonlinear enhancement effect on PM2.5 concentrations. Given the differential impact of multi-dimensional urbanization on PM2.5 concentrations inside and outside the region, this research provides support for the cross-regional joint control strategies of air pollution in Africa. The findings also indicate that PM2.5 pollution control should not only focus on urban economic development strategies but should be an optimized integration of multiple mitigation strategies, such as improving residents' lifestyles, optimizing land spatial structure, and upgrading the industrial structure.

Recent Evolution of the Intertidal Sand Ridge Lines of the Dongsha Shoal in the Modern Radial Sand Ridges, East China.

The Dongsha Shoal is one of the largest shoals in the South Yellow Sea and has important marine ecological value. The shoal extends in a south-north direction and is controlled by the regional dominating tidal currents. Recently, due to human activities and some natural factors, the geomorphic dynamics of the Dongsha Shoal has undergone drastic changes. However, few people have proposed quantitative research on the changes of tidal flat morphology, let alone the long-term sequence analysis of sand ridge lines. Hence, we attempt to take the Dongsha Shoal in the Radial Sand Ridges as the research area, and analyze the trends of the long-term morphological evolution of the sand ridge lines over the period 1973-2016 based on a high-density time series of medium-resolution satellite images. The sand ridge line generally moves from southeast to northwest, and the position distribution of the sand ridge line from north to south has gradually changed from compact to scattered. We also found that the geomorphological dynamics at different positions of the sand ridge line are inconsistent. The north and south wings are eroded on the west side, while the central area is eroded on the east side. Most of the sand ridge line is moving eastward. In addition, the change of sand ridge line is affected by multiple factors such as sediment supply, typhoon, reclamation and laver cultivation.

Impact of ENSO events on phytoplankton over the Sulu Ridge.

Phytoplankton response to interannual climate variability has an important regulatory effect on the regional marine ecological environment and carbon cycle. In this study, we focused on the phytoplankton response in the upwelling region of the Sulu Ridge to the El Niño-Southern Oscillation (ENSO) based on monthly remote sensing chlorophyll-a concentration (Chl-a) and physical parameters from various sources from September 1997 to December 2017. We selected two El Niño events in 1997/1998 and 2015/2016 and two La Niña events in 1998/1999 and 2010/2011 to examine the response of Chl-a to ENSO events in this region. Results showed that El Niño and La Niña could enhance and inhibit the growth of phytoplankton in the Sulu Ridge in winter, respectively. For other seasons, the influence of ENSO on the Chl-a was inconsistent. Specifically, during El Niño events, the largest Chl-a increases occurred in winter, and the low sea surface temperature (SST) center appeared northwest of Sulu Ridge. The significant decrease of SST (~1.5 °C) during El Niño events in winter in the northeastern Sulu Ridge was mainly caused by the increase in Ekman transport (ET) and Ekman pumping velocity (EPV), which brought nutrient-rich subsurface water to the surface layer through the thin barrier layer and enhanced Chl-a. During La Niña events, the SST was higher (~0.8 °C) than the average and the high SST center generally appeared in the middle of the Sulu Ridge with the east-west direction in winter, which was resulted from the intensification of barrier layer thickness (BLT) and the decrease of ET, thus reducing the Chl-a. The different responses to El Niño and La Niña events indicate the high sensitivity of Chl-a in this region to the ENSO.

Expression of hMSH2 gene and mutant p53 in sporadic digestive tract tumors.

OBJECTIVE: To investigate the role of mutated mismatch repair gene hMSH2 and mutant p53 gene in the carcinogenesis and development of sporadic digestive tract tumors. METHODS: hMSH2 gene in normal and tumor tissue of 30 digestive tract tumor specimens was examined using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) silver staining. The PCR product with an abnormal strand was sequenced directly. Mutant p53 protein in the tumor tissue was analyzed immunohistochemically. RESULTS: Six patients were identified as having mutated strands, three on hMSH2 exon 1 and three on hMSH2 exon 5. DNA sequencing revealed that all 6 patients had mutated basic groups that led to decrease in function of the hMSH2 protein. Forty percent (12/30) of patients were p53 positive. The frequency of mutated hMSH2 in p53 positive patients (41.7%) was significantly higher than in p53 negative patients (5.6%, P < 0.05). CONCLUSION: The mutation of hMSH2 plays an important role in the carcinogenesis and development of digestive tract tumors through stimulating p53 mutation.