The Contribution of Environmental Impact Assessment Studies to the Flora Biodiversity in Sudan

Environmental Impact Assessment Studies (EIA) for four developmental projects were chosen for this study viz-a-viz., oil and gas, river diversion, hydropower and gold mining. The EIA studies for these activities have been conducted in three different ecological regions: the flood region in the former southern Sudan, low rainfall Savannah and desert region. Trees, shrubs and herbaceous species were identified and recorded in each region. Species encountered for the first time, endangered, invasive and increasers were also reported. The EIA studies have produced lists of natural flora in areas which were difficult to access without the EIA missions. During the EIA study for Jonglei Canal project the new mono specific genus Suddia sagitifolia was discovered in the flood region as the only endemic aquatic plant in Sudan. Within the same region, the smallest floating plant in Sudan (Wollfia hyaline) was reported. The critically endangered “Argon Palm” (Medemia argun) was encountered in the Nubian Desert of the Red Sea State during a gold mining EIA study. The Seha (Belpharis persica), not reported to exist in desert conditions, has been found in the Great Desert west of the Nile during an EIA study for Kajbar Hydropower project. The paper calls for the publication of the above findings and highlights the need for further detailed studies in order to enhance knowledge of the Sudanese biodiversity status.

Population structure,age and growth rates of conifer species and their relation to environmental variables at Malam Jabba,Swat District,Pakistan

This study focuses on age,growth rate and diameter distribution of pine forests in the Malam Jabba area,Swat District,Pakistan.Wood core samples were taken from twenty stands.Picea smithiana was the oldest at 234 years with a 112-cm diameter.Abies pindrow was 125 years with an 80-cm diameter while the oldest Pinus wallichiana was 122 years with 75-cm diameter.The fastest overall growth rate of 1.5±0.1 year/cm was for P.wallichiana on a west-facing aspect,while the slowest 5.8±2.6 year/cm growth was P.smithiana on an eastfacing exposure.P.wallichiana and A.pindrow exhibited marked differences in growth rates over a 5-year period.The highest growth was by P.wallichiana from 1966 to 2006.A.pindrow showed less growth over the same years,such pattern simultaneously reverse from 1911 to 1965.The relationship between diameter and age,diameter and growth rate and age and growth rate were correlated.P.wallichiana and A.pindrow ages were correlated with diameter and growth rates.P.smithiana age was positive correlated with diameter.Generally,topographic and edaphic factors did not show significant correlations with growth rates,although some appreciable correlations were recorded.The growth of P.wallichiana was correlated with elevation while A.pindrow was correlated with maximum water retaining capacity.Diameter and age produced uneven size classes and many size gaps,which could be the result of anthropogenic disturbances.

Assessment the Effectiveness of Preparedness for Relative Constant Factors in Environmental Disaster Management: A Case Study from Riyadh City, Saudi Arabia

The preparedness phase is considered as backbone of environmental disaster management. The aim of this study is to identify the effect of relatively constant factors of preparedness phase on environmental disaster management in Riyadh City, Saudi Arabia. The study used descriptive and analytical approach besides the comprehensive survey depends upon questionnaire for purposive data surveyed all employees in the field of environmental disaster management in Riyadh city including administrations, department, and contains 21 sector including public and private sector for total population of about 397 persons and sample size about 353 persons using statistical tests, frequencies, percentage, average, standard deviation and t test and × square test as well as Likert procedure on which depends on the measurement such as: very high, high, average, weak and very weak. The main results reveal that the constant factors of environmental disaster management are more important for evaluating the preparedness phase. Since the relatively constant factors of environmental disaster management are more important. The study recommends that: 1) Enhancement of the systems and procedures in particular disaster management procedures. 2) It is so necessary to publish a new unit for disaster management in the sectors have not. 3) Increase and encouragement of environmental disaster management studies in particular for preparedness phase because it considers as backbone of disaster management and suggestion of regional and local organizations link generally and in information trade off and the details studies in particular by providing the different types of support and encouragement.

Water Quality Evaluation of Chapurson Valley in Hunza Nagar, Gilgit Baltistan, Pakistan, Based on Statistical Analysis and Water Quality Index

Water borne ailments are of serious public health concern in Gilgit Baltistan’s (GB) region of Pakistan. The pollution load on the glacio-fluvial streams and surface water resources of the Chapurson Valley in the Hunza Nagar area of the GB is increasing as a result of anthropogenic activities and tourism. The present study focuses on the public health quality of drinking water of Chapurson valley. The study addressed the fundamental drinking water quality criteria in order to understand the state of the public health in the valley. To ascertain the current status of physico-chemical, metals, and bacteriological parameters, 25 water samples were collected through deterministic sampling strategy and examined accordingly. The physico-chemical parameters of the water samples collected from the valley were found to meet the World Health Organization (WHO) guidelines of drinking water. The water samples showed a pattern of mean metal concentrations in order of Arsenic (As) > Lead (Pb) > Iron (Fe) > Zinc (Zn) > Copper (Cu) > Magnesium (Mg) > Calcium (Ca). As, Cu, Zn, Ca and Mg concentration were under the WHO guidelines range. However, results showed that Pb and Fe are present at much higher concentrations than recommended WHO guidelines. Similarly, the results of the bacteriological analysis indicate that the water samples are heavily contaminated with the organisms of public health importance (including total coliforms (TCC), total faecal coliforms (TFC) and total fecal streptococci (TFS) are more than 3 MPN/100mL). Three principal components, accounting for 48.44% of the total variance, were revealed using principal component analysis (PCA). Bacteriological parameters were shown to be the main determinants of the water quality as depicted by the PCA analysis. The dendrogram of Cluster analysis using the Ward’s method validated the same traits of the sampling locations that were found to be contaminated during geospatial analysis using the Inverse Distance Weight (IDW) method. Based on these findings, it is most likely that those anthropogenic activities and essentially the tourism results in pollution load from upstream channels. Metals may be released into surface and groundwater from a few underlying sources as a result of weathering and erosion. This study suggests that the valley water resources are more susceptible to bacteriological contamination and as such no water treatment facilities or protective measure have been taken to encounter the pollution load. People are drinking the contaminated water without questioning about the quality. It is recommended that the water resources of the valley should be monitored using standard protocol so as to protect not only the public health but to safe guard sustainable tourism in the valley.

Estimating Ecological Characteristics and Carbon Stock in Uneven-Aged Plantations of Acacia senegal L. in the Savannah Woodlands of Sudan

The aim of this study was to assess Acacia senegal trees’ characteristics as well as evaluate the carbon stock under a variety of ages in the El Demokeya forest in Sudan, where the Gum Arabic belt is located. 12 sample plots, in 2021 were randomly distributed to represent the entire area of the forest prior to the required measurements. The sample was designed as squire plots with one hectare. In each sample plot, all trees were counted, their height (m), and Diameters Breast Height (DBH in cm), respectively. The results showed the highest number of trees per ha at age 20 years old and the lowest number at age 47 years, while the highest values of DBH and volume were found at age 47 years old. As a result, the maximum and minimum values of the aboveground biomass were found in the age 47 years old and 16 years, accounting for 19.87 tons and 1.9 tons respectively. Thus, the amount of carbon stock was 11.92 tons/ha in the 35-years-old and 1.19 tons/ha in the 21-year stands. Furthermore, the average carbon stock in all plots was estimated as 18.70 tons/ha and hence the total carbon stock in the El Demokeya forest is equal to 620.11 tons. Conclusively, the characteristics of trees, amount of aboveground biomass and carbon stock in the El Demokeya forest varied among the uneven-aged plantation groups. The study recommends and encourages the protection of A. senegal in order to increase the carbon sink as well as protect the environment in the era of climatic changes.

Laboratory simulated dissipation of metsulfuron methyl and chlorimuron ethyl in soils and their residual fate in rice, wheat and soybean at harvest

Two sulfonylurea herbicides, metsulfuron methyl (Ally 20 WP) and chlorimuron ethyl (Classic 25 WP) were evalu-ated for their dissipation behaviour in alluvial, coastal saline and laterite soils under laboratory incubated condition at 60% water holding capacity of soils and 30 °C temperature was maintained. In field study herbicides were applied twice for the control of grasses, annual and perennials broad leaves weeds and sedges in rice, wheat and soybean to find out the residual fate of both the herbicides on different matrices of respective crops after harvest. Extraction and clean up methodologies for the herbicides were standardized and subsequently analyzed by HPLC. The study revealed that the half-lives of metsulfuron methyl and chlorimuron ethyl ranged from 10.75 to 13.94 d irrespective of soils and doses applied. Field trials with rice, wheat and soybean also revealed that these two herbicides could safely be recommended for application as no residues were detected in the harvest samples.

The urbanization process of Bohai Rim in the 1990s by using DMSP/OLS data

This paper firstly derived urban information from Defense Meteorological Satellite Program/Operational Linescan System （DMSP/OLS） data in 1992, 1996 and 1998 with the support of statistical data, and then developed three basic urban models of polygon-urbanization, line-urbanization and point-urbanization in urban agglomerations from viewpoint of spatial analysis. The conclusions are as follows： （1） Urban patch numbers in the Bohai Rim increased from 1659 to 2053 with an annual average increase number of about 66. Meanwhile, the small urban patches accounted for a larger proportion in the region and the patch density increased fast. In addition, the urban barycenter of the region showed a moving trend toward northwest from 1992 to 1998. Urbanization in the Bohai Rim in the 1990s is fast and obvious. （2） Urbanization in the Bohai Rim can be reflected by three basic processes, i.e., the polygon-urbanization around the big cities, the line-urbanization around the transportation lines and the point-urbanization emerging in large areas. Of them, the polygon-urbanization has been in dominance. It is obviously within an effective range of 3-4 km surrounding the urban patches. The line-urbanization and point-urbanization in the region was relatively small, both of which showed an obvious increasing trend.

Composition,Structure and Regeneration Dynamics of Olea ferruginea Royle Forests from Hindukush Range of Pakistan

The abundance of Olea ferruginea in Malakand Division has been significantly reduced across its distribution range due to anthropogenic pressure in the recent past. A number of initiatives were taken for grafting this species to obtain better seeds for oil production, without the basic information on their ecology and management. To address this knowledge gap, we quantified the composition, structure and regeneration dynamics of Olea ferruginea forests in Malakand Division, Hindukush range of Pakistan. In the present study, five communities dominated by Olea ferruginea were identified using Ward's agglomerative cluster analysis.Total tree density ranged from 153-2602 plants/ha, and basal area from 19.55 to 2353 m2 ha-1 with Olea having a relative density of 51% to 87% and basal area of 48% to 93%, respectively. The density of juveniles of the dominant and subordinate tree species were generally low which reflect their narrow distribution in the study area. Size-class distributions of O. ferruginea disclosed a bell-shaped pattern, indicating that forests were heavily exploited by local inhabitants in previous periods and recently by armed forces owing to security risks in the study area. The age(mean max. 300±34 years) and annual increment(3.2±1.2 years/cm) indicates that the species is long lived and generally slow growing among the different broad leaved species studied so far. However, the oldest trees can be found by the exploration of large diameter trees in the area. In addition, we found a stable linear relationship between the age and diameter(r2 = 0.779), indicating that diameter is a good predictor of age for this broad leaved species. In view of its relatively slow growth, longevity and positive ring-width characteristics O. ferruginea seems to be a suitable choice for dendroecological and dendrochronological studies in lesser Himalayan and Hindukush ranges of Pakistan. The results obtained from this study may help in understanding the composition, structure and regeneration dynamics of other subtropical broad leaved species.

Positive association between forest management, environmental change, and forest bird abundance

Background: The global decrease in wildlife populations, especially birds, is mainly due to land use change and increasing intensity of land use(Parmesan and Yohe 2003). However, impacts of management tools to mitigate biodiversity loss at regional and global scales are less apparent in forest regions that have a constant forest area,and which did not suffer from habitat degradation, and where forests are sustainably managed, such as in Central Europe or the northeastern USA. A biodiversity assessment for Germany suggested, for example, that bird populations were constant(Bundesamt für Naturschutz 2015).Results: This study shows that changes in the environment and in forest management over the past 45 years have had a significant, positive effect on the abundance of non-migratory forest bird species in Central Europe. Economy(timber prices and GDP), forest management(timber harvest and mixed forest area), and environmental factors(atmospheric CO_2 concentration and nitrogen deposition) were investigated together with changes in abundances of migratory and non-migratory forest birds using partial least squares path modeling. Climate change, resulting in longer seasons and milder winters, and forest management, promoting tree diversity, were significantly positively related to the abundance of non-migratory forest birds and explained 92% of the variation in their abundance in Europe. Regionally-migrating forest birds had stable populations with large variation, while birds migrating across continents declined in recent decades, suggesting significant, contrasting changes in bird populations in Europe. In northeastern North America we also found evidence that non-migratory forests have experienced long-term increases in abundance, and this increase was related to management. The increase of populations of nonmigratory forest birds in Europe and North America is associated with an increase in structural diversity and disturbances at the landscape level.Conclusions: Our results suggest that reports about bird decline in forests should separate between migratory and non-migratory bird species. Efforts to mitigate the general decline in bird abundance should focus on land-use systems other than forests and support sustainable forest management independent of economic conditions.

Butterfly-plant interactions and body size patterns along an elevational gradient in the Manang region of central Nepal

Butterflies are widely studied due to their key ecosystem functions.For this reason,they are used in ecosystem assessment,formulating conservation plans and in raising the environmental awareness.Quantification of different factors affecting diversity of butterflies is important for their effective conservation.In this study,we investigated abiotic and biotic factors affecting species richness and community composition of butterflies along an elevational gradient in Manang region,central Nepal.We also tested if butterfly species follow the Bergmann’s rule.A total of 57 butterfly species belonging to 39 genera and 8 families were recorded in the study area.Out of a total of 127 plant species identified in the study region,only 67 plant species were visited by butterflies as nectar sources.Species richness of butterflies increased with increasing elevation.Species richness was significantly higher in places with shrubs compared to other places and also in autumn than in summer.Species richness of butterflies also depended on composition of plant species occurring at the localities.Butterfly species composition varied among sampling localities.It was also determined by habitat type,elevation,sampling time,plant species and interactions of elevation×time.The relationship between butterfly size and elevation was in the opposite direction than expected according to the Bergmann’s rule.In conclusion,protection of butterfly diversity can only be achieved by protecting different habitats across the diverse physiography of the region and different plant species,in particular herbs and shrubs.Our results do not support the Bergmann’s rule for butterflies along an elevational gradient in our region.

Geo-Spatial Assessment of Water Quality in Shigar Valley, Gilgit Baltistan, Pakistan

The current study attempted to evaluate the water quality in terms of physico-chemical properties, metals, and bacteriological characteristics of the surface water available in Shigar Valley located along Shigar River in sub-district Shigar of district Skardu, Gilgit Baltistan (GB), Pakistan. A total of 17 water samples were collected during 2020 and analysed to perform multivariate analysis through principal component analysis (PCA) and cluster analysis (CA). Spatial distribution using inverse distance weight (IDW) interpolation was also utilised to determine the water quality in the valley to elucidate public health concerns. The study reveals that physico-chemical characteristics are the most important that affect water quality, followed by metals and bacteriological variables, according to a PCA application based on multivariate analysis. Examinations found that some of the metals including arsenic (As), copper (Cu), lead (Pb), iron (Fe), zinc (Zn), manganese (Mn), and molybdenum (Mo) and all bacteriological parameters enlisting total coliform count (TCC), total faecal coliform (TFC), and total faecal streptococci (TFS) are not following the WHO guidelines that could be hazardous from the public health viewpoint. The IDW-based spatial distribution indicates that water samples have an intermittent and unusual distribution of observed parameters. Having considerable community settlements, people in the valley have limited options and have no choice except to consume the available water as no alternate source is available. People hardly question the water quality and rarely examine the water potability. The study also demonstrated that combining PCA with IDW would be a powerful method for assessing water quality. It is suggested that the sources of contamination be investigated further in detail to reduce the pollution load of the surface water in the valley, which could aid in the development of sustainable ecotourism.

Decrease of TSP, PM₁₀, and Lead Concentration in a Lead Company in Alexandria City, Egypt

The study was carried out in a lead company inside Alexandria which exists in a residential area. Different sites have been selected inside the Department of Lead Improvement to measure TSP, PM10, and heavy lead during the melting process which takes place inside big alloying kettles and from the stack emissions. After that, the company made evaluation of the old factory and decision makers decided to make development for this factory through buying a complete unit for treatment with a special filter to make abatement for the level of emission especially for lead. The aim of this work is: 1) Put a plan for monitoring the level of different pollution after modification and to calculate the percentage of decrease (efficiency) of the new control unit through concentration of TSP, PM10, and lead through different processes;2) Install a new filter to abate the different air pollutants such as TSP, PM10, and lead. Total Suspended Particulate (TSP) and Respiratory dust (PM10) measured by using Volume sampler and Air mitrix. Lead was measured by the digestion of the samples with a mixture of hydrochloric and nitric acids and using Atomic Absorption Spectropho- tometer. Results of measuring TSP, PM10, Lead in working environment, and lead inside stack before and after installation of the new filter showed percentage of decrease from 22% to 120%, 33% to 160%, 26% to 102%, and 51% to 56.5% respectively.

The Bowati in Kordofan, Sudan: Unique Aquatic Ecosystems of a Non-Nilotic In-Land Delta

This paper describes the unique in-land, non-Nilotic delta of Wadi El Galla, a seasonal water course which originates in the Nuba Mountains of Kordofan region and terminates in a chain of small ponds each known locally as a Bouta (pl Bowati). The Bowati are inhabited by a community of aquatic plants forming a wide spectrum ranging from small true (Euophytes) to large woody trees. The euophytes encountered were grouped into six categories. The free-floating species were represented by the small Lemna purpusilla Torr. and the larger Pistia stratiotes L. while only one submerged species was found: Ottelia alismoides (Planch.) Welp. One suspended species was found, Utricularia stellaris L. F. Three species of the floating-leaved plants were encountered namely, Nymphaea lotus L., N. micrantha Guill. & Perrott and Nymphoides nilotica (Kotschy & Peyr.) Léonard. The emergent Limnophyton obtusifolium (L.) Miq. was very prominent in all the Bowat constituting with N. lotus the two dominant species. Trailing from the Bouta edge and forming thick mats on the open water is Neptunia oleracea Lour., a member of the Fabaceae family. Within these euophytes and towering to over ten meters is the woody tree Mitragyna inermis Kuntze. Some of herbaceous plants are a source of food for the local community such as the bulbils of Nymphaea micrantha. These meagrely studied ecosystems are under threat from natural and anthropogenic factors. The former are the recurrent drought, climate change, and the latter are due to urbanization, overexploitation and oil activities. There is an urgent need for delineating and mapping the geomorphology, drainage patterns of Al Muglad in-land delta as well as the number and sites of the Bowati. The taxonomy of the aquatic species, their nutritive and medicinal values are other areas of research. Within such a context, a concerted national and international endeavour is called for to conserve these unique ecosystems and conceivably, declaring them as protected sites.

用ORP作为氧化沟同步硝化反硝化控制参数

同步硝化反硝化（simultaneous nitrification and denitrification，简称SND）是氧化沟工艺实现优良脱氮效果的主要原因，为了较好实现SND，采用ORP作为氧化沟工艺SND的控制参数．采用缺氧-厌氧-氧化沟模型对市政污水进行了生物脱氮研究．UORP在-30～30mV，NH4^＋和NO3^-的含量均比较低，发生了较好的SND；UORP在30mV以上，出水的总无机氮（TIN）中95％以上为NO3^-，该状况下硝化效果良好，UORP在-30mV以下，硝化不充分，出水的TIN中78％以上为NH4^＋；UORP在-30～30mV，TN的去除率在88％以上，SND作用去除的NO3^-占总的NO3^-去除的99％以上；氧化沟中的NH4^＋和NO3^-之比的对数与UORP有着很好的相关性，相关系数R=-0．97．

城市污水SBR法短程生物脱氮系统硝化菌群的定量分析

为了研究实时控制对短程生物脱氮中试系统内硝化菌群结构组成的影响,在考察系统常温条件下处理城市污水时短程硝化效果的同时,采用FISH、PCR-DGGE和PCR-克隆序列(Cloning Sequencing)分子生物学方法对SBR中试系统(有效容积为54 m^3)硝化菌群中的氨氧化菌(AOB)和亚硝酸氧化菌(NOB)进行定性与定量化分析.FISH结果表明,在短程脱氮系统中,AOB相比于NOB已成为明显的优势菌群,占总菌群的3%～12%;且没有检测出NOB.PCR-DGGE结果表明,SBR短程脱氮中试系统中的AOB均以Nitrosomonas-like为主.污泥样品的PCR-Cloning-Sequencing结果表明,所有的克隆相似于Nitrosomonas,其中60%以上的克隆相似于Nitro- somonas europaea.

Combined Fenton process and sulfide precipitation for removal of heavy metals from industrial wastewater:Bench and pilot scale studies focusing on in-depth thallium removal

Thallium (Tl) in industrial wastewater is a public health concern due to its extremely high toxicity. However, there has been limited research regarding Tl removal techniques and engineering practices to date. In this investigation, bench and pilot studies on advanced treatment of industrial wastewater to remove Tl to a trace level were conducted. The treatment process involved a combination of hydroxide precipitation, Fenton oxidation, and sulfide precipitation. While hydroxide precipitation was ineffective for Tl^+ removal, it enabled the recovery of approximately 70%-80% of Zn as Zn hydroxide in alkaline conditions. The Fenton process provided good Tl removal (>95%) through oxidation and precipitation. Tl was then removed to trace levels (< 1.0 μg/L) via sulfide precipitation. Effective removal of other heavy metals was also achieved, with Cd < 13.4 μg/L, Cu < 39.6 μg/L, Pb < 5.32 μg/L, and Zn < 357 μg/L detected in the effluent. X-ray photoelectron spectroscopy indicated that T12S precipitate formed due to sulfide precipitation. Other heavy metals were removed via the formation of metal hydroxides during hydroxide precipitation and Fenton treatment, as well as via the formation of metal sulfides during sulfide precipitation. This combined process provides a scalable approach for the in-depth removal of Tl and other heavy metals from industrial wastewater.

Imidacloprid in processed tea and tea liquor

Imidacloprid 是最新介绍的用途广泛的 chloronicotinyl 杀虫药剂并且将在农业生产发现它的方法，特别地在亚洲。然而，在庄稼植物的 imidacloprid 的命运的信息正在缺乏。在处理 CTCtea 和茶白酒的 imidacloprid 的降级在 imidacloprid 以推荐申请率(30.0 g a.i./ha ) 并且两次在被使用的现在的学习被调查为三个连续季节的推荐申请率(60.0 ga.i./ha ) 。Imidacloprid 很快在申请评估的根本首先跟随顺序反应动力学的处理的茶被驱散并且有在茶白酒的残余发现了在第三件天样品上的可检测的限制下面的 0.91-1.16 dwith 的一半生活。学习表明 imidacloprid 为人的消费是安全的并且不提出任何剩余毒性问题。

Ecological Zones Degradation Analysis in Central Sudan during a Half Century Using Remote Sensing and GIS

Since the last assessment of ecological zones of Sudan conducted in 1958 by Harrison and Jackson, the vegetation types, cover, and its distribution have undergone remarkable changes;this change occurs in most of the predominant ecological zones, particularly those which are currently affected by environmental degradation and desertification due to climate change impact on vegetation cover and rainfall amounts and its distribution. In addition, during the last five decades, Sudan has suffered from environmental devastating changes that have undermined food security, which is strongly linked to human displacement and related conflicts. In this study, SPOTVEG NDVI data acquired between 2000 and 2010 were used to produce a vegetation cover map, which was integrated with rainfall map to produce updated ecological zones map for the study area in 2010. This map was compared to that produced in 1958 to analyze the change during the last five decades. The obtained results showed drastic change concerning different ecological zones. The desert class increased by 11%. The Semi-Desert class decreased by approximately 13.2%. The woodland savannah class increased by 6.8%. While, the Mountain vegetation areas decreased approximately by 3%. Finally, the wetland areas completely disappeared in 2010. These results show that during the period 1958-2010, climate change impact increased desertification process, destroyed ecological zones, especially wetland, as well the ecosystems diversity in Central Sudan.

Suggested Exercise Protocol for High Risk Population with COVID-19

Background: People who have underlying medical conditions and those over 60 years old have a higher risk of developing coronavirus disease complications (COVID-19) with more mortality rate. Breathing exercises is good for clearing the mucus from lungs and improves chest expansion while circulatory exercises enhance cardiopulmonary/vascular systems. Aim: This study aims to suggest exercise program for prevention, decrease morbidity and mortality in COVID-19 patients and patients with other respiratory co-morbidities. Conclusion: Regular simple exercises include respiratory and circulatory exercises may have a great effect on improving lung function and immunity in addition to relieving psychological stress thus can help in treatment of high risk people from COVID-19.