**Native Gold as a Specific Indicator Mineral for Gold Deposits**

Editor

**Galina Palyanova**

Basel ' Beijing ' Wuhan ' Barcelona ' Belgrade ' Novi Sad ' Cluj ' Manchester

*Editor* Galina Palyanova V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch of the Russian Academy of Sciences Novosibirsk Russia

*Editorial Office* MDPI St. Alban-Anlage 66 4052 Basel, Switzerland

This is a reprint of articles from the Special Issue published online in the open access journal *Minerals* (ISSN 2075-163X) (available at: www.mdpi.com/journal/minerals/special issues/native gold).

For citation purposes, cite each article independently as indicated on the article page online and as indicated below:

Lastname, A.A.; Lastname, B.B. Article Title. *Journal Name* **Year**, *Volume Number*, Page Range.

**ISBN 978-3-0365-9381-4 (Hbk) ISBN 978-3-0365-9380-7 (PDF) doi.org/10.3390/books978-3-0365-9380-7**

Cover image courtesy of Galina Palyanova

© 2023 by the authors. Articles in this book are Open Access and distributed under the Creative Commons Attribution (CC BY) license. The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) license.


**8. Conclusion**

Cloud computing offers on-demand services (CPU, memory, network bandwidth, storage, applications, etc.) to users by allocating virtual instances and software services. Security is a major concern in the cloud wherein investigation of security attacks and crimes are very difficult. Due to the distributed nature of attacks and crimes in cloud, there is a need for efficient security mechanism. As cloud logs are spread across different virtual/physical machines (VM instances), switches, routers, etc., and also the customer (end user) is not aware of the activities of VM instances, cybercriminals exploit these sources to exhaust all the resources running in the cloud. Hence, evidence collection plays a crucial role to identify the suspects. However, collecting logs from the cloud infrastructure is extremely difficult because the investigator/security analyst has to depend on CSPs for collecting the logs and they have little control over the infrastructure. So, in order to identify the suspicious activity involved in the cloud, this chapter surveys the various forensic processes, evidence collection techniques for cloud forensics and the various challenges faced in cloud environment for forensic investigation.


**4. Cellular factors with inhibitory activity on HIV replication and implications in viral pathogenesis**

Innate immunity had evolved as a mechanism to defend eukaryotes from bacterial and viral infections. These mechanisms rely on different cellular restriction factors that suppress the replication of the pathogens, namely retroviruses [22].

During HIV-1 infection, incoming viral RNA triggers a TLR7/8-mediated innate immune response, resulting in the production of type I interferon (IFN). In particular IFNα has been shown to be up-regulated after TLR sensing during acute infection with HIV-1 or SIV [23-25]. Accordingly, initial observations *in vitro* revealed that pre-treatment of macrophages with type-I IFN inhibited the replication of HIV-1, indicating that potent inhibitory factors were induced after IFN exposure [26, 27]. Most of them are still uncharacterized.

The identification of cellular restriction factors and the viral proteins that antagonize those restrictions have stimulated an active area of research that explores crucial mechanisms underlying HIV interference with cellular restriction factors and innate immunity. In this subchapter specific cellular factors with inhibitory activity on HIV replication are discussed including how viral-encoded proteins counteract these factors.

#### **4.1. TRIM5α**

The search for the mechanisms underlying the innate cellular resistance to retroviral infections shown by different non-human primate species, has led to the identification of a cytoplasmic factor that prevented infection of Old World monkeys by HIV-1 [28]. This factor – TRIM5α – was identified as a member of the tripartite motif (TRIM) family of proteins, a large family of cellular proteins with distinct biological activities including innate immune signaling [29]. After its initial identification in rhesus macaques (rhTRIM5α) [28] and owl monkeys (TRIM‐ Cyp) [30], TRIM5α was also identified as a retroviral restriction factor in humans [31, 32] that is induced by both type I and type II IFN [33].

Different models have been proposed for retroviral inhibition mediated by TRIM5 proteins [34]. They suggest that these proteins mediate restriction by directly binding to specific determinants in the viral CA protein, blocking HIV replication soon after viral release in host cell cytoplasm. The TRIM proteins family is defined by three domains (RING, B-Box2, and Coiled- Coil), which are present in all members of this family. The N-terminal RING domain possesses E3 ubiquitin ligase activity that is crucial for retrovirus restriction [35, 36]. The B-Box2 and Coiled Coil (CC) domains are thought to contribute to the higher and low order multimerization of TRIM5α, respectively. The TRIM5α also possesses a C-terminal capsid binding domain that mediates specific recognition and restriction of certain retroviruses [37]. The recognition of viral capsid determinants (CA protein) relies on three variable regions present in the C-terminal domain of TRIM5α, and apparently they are equally involved in retrovirus recognition and restriction [38-41].

Several studies have addressed the mechanisms by which TRIM5α protein prevents viral infection and different models have been proposed to explain this restriction. The "accelerated uncoating" model was based on the observation that cytosolic CA protein was specifically dissociated in rhTRIM5α-expressing cells [42] leading to the proposal of a "proteasome independent capsid degradation" mechanism. This model suggests that the stripping of capsid protein prevents viral RTC to proceed to subsequent steps in infectious replication cycle, namely the reverse transcription and nuclear import [42]. An alternative model was primarily based on the observation that proteasome inhibitors allows reverse transcription and integra‐ tion, without affecting the TRIM5α-mediated restriction [43, 44]. Accordingly, a "two-step restriction mechanism" was proposed, suggesting that restriction activity of TRIM5α occurs by both proteasome-dependent and -independent pathways. The relative contribution of each pathway is apparently dependent on host cells-viruses combinations [45].


*Article* **On the Way to Integrate Increasing Shares of Variable Renewables in China: Activating Nearby Accommodation Potential under New Provincial Renewable Portfolio Standard**

**Yinhe Bu 1 and Xingping Zhang 1,2,3,\***

**Abstract:** More than 1.2 billion kW wind and solar power generation will be integrated in China by 2030. The new provincial renewable portfolio standard, officially implemented in 2020, establishes an efficient bridge between rapid capacity growth and limited accommodation capability. A datadriven prospect analysis framework was proposed to evaluate the activated potential under two kinds of nearby accommodation approaches and to explore the completion prospect of this new obligated quota from provincial levels. Empirical results illustrate diverse prospects across regions. Particularly, it is hard for two kinds of provinces to complete their obligated quotas merely via the single nearby accommodation approach: The first one is close to renewable energy resources but lacks flexible peak regulation capability in Northeast and Northwest China, and the other is close to the nationwide load center but lacks nearby integration from renewables in Southeast, North, and Middle China. Therefore, the pathway for the former is to activate more provincial accommodation potential either via releasing system flexibility or by substituting generation right, and the pathway for the latter is to introduce trans-regional or trans-provincial accommodation and import more renewable energy power.

**Keywords:** renewable energy; renewable portfolio standard; nearby accommodation; peak regulation; prospect analysis


*4.2.1 rs247616, rs1968905 and rs1270922 polymorphisms (CETP)*

The CETP polymorphisms (rs247616, rs1968905 and rs1270922) are SNPs that occur as a result of substitutions in their nucleotide bases [89, 133]. These polymorphisms have previously been used to determine the CETP levels in a CVD population [133]. Mutations in the CETP gene have been found to cause hyperalphalipoproteinaemia 1 (HALP1). Furthermore, it's also been shown that different variants code for distinct isoforms within this gene. This eventually influences the metabolism of HDL-C [89]. Reports on the link between the CETP polymorphisms, CVR and the concentrations of CETP through LDL-C are inconsistent [89, 132, 133].

#### **4.3 Metabolic biomarkers**

## *4.3.1 Gly972Arg polymorphism*

The Gly972Arg polymorphism occurs as a result of a substitution between glycine and arginine (GGG ↔ AGG substitutions) in codon 972 (G972R). It has been demonstrated that this mutation is involved in the development of type 2 diabetes mellitus (type 2 DM) [141]. This is due to the fact that it's been described to influence tyrosine phosphorylation at a specific site of IRS-1 which may lead to the development of insulin resistance (IR) and impair insulin secretion [142]. The Gly972Arg polymorphism has been investigated in a number of studies and found to have a high prevalence in type 2 diabetic subjects and other conditions like obesity [143, 144].

#### **4.4 Oxidative stress**

## *4.4.1 C677T and A1298C polymorphisms (MTHFR)*

The *MTHFR* C677T polymorphism is a SNP where cytosine (C) is replaced with thymine (T) at position 677 resulting in the gene to code for valine as opposed to

alanine at exon 4. The change between alanine and valine nucleotide bases happens on codon 222 resulting in this polymorphism sometimes being described as Ala222Val polymorphism. It has been reported to have the alleles heterozygous *C677T and* homozygous *T667T* which are mutant, whereas the homozygous *C677C* is a wild type allele [145–149].

The A1298C polymorphism causes a change where glutamate is substituted with an alanine at position 429. Each of these genotypes have been shown to reduce the MTHFR enzymatic activity resulting in the methyl group to be unavailable for attachment to homocysteine in order to generate methionine. Hyperhomocysteinaemia has been reported in the development of a number of conditions, for example, CVR, chronic myeloid leukaemia (CML), multiple abortions, autism, osteoporosis, multiple sclerosis, psoriasis, and Alzheimer's disease [106, 108, 135, 145, 146].

### **4.5 Haemostasis**

#### *4.5.1 R353Q polymorphism (factor VII)*

In the R353Q polymorphism, guanine is substituted with adenine at the 353rd codon of the *FVII* gene. This missense replacement of arginine (R) by glutamine (Q) in this polymorphism has been reported to influence the factor VII levels [150].  Nonetheless, the findings on the association between the R353 Q polymorphisms and CVR (thrombosis) are inconclusive [151]. Increased levels of factor VII are linked to thromboembolic disorders risk. A relationship between defects in the factor VII gene and CVD has been reported [114, 150, 151].


**3. Results**

#### *3.1. Time Series for Test E3*

In Figure 4, a time series for test E3 is given. The tests were conducted under the conditions for test E3 (see Table 1 for details) for 1, 2, 4, 8, 16, and 24 h, after which bed profile measurements along the symmetry plane at *Z*/*D* = 0 were acquired. It can be seen that the depth of the scour hole upstream of the cylinder increased incrementally with time throughout the first 24 h of the experiment. However, between 16 and 24 h, the profiles in the upstream region were very similar, showing minimal di fferences. In terms of the relative scour depth, *dse*/*D*, and its relation to the foundation head, this indicates that 24 h can be seen as an acceptable time to equilibrium, *te*, under the described experimental conditions.

**Figure 4.** Bed profile measurements in the *XY* (symmetry) plane at *Z*/*D* = 0 for *t* = {1, 2, 4, 8, 16, 24} h.

Downstream of the cylinder, it can be seen that the dune-like primary deposit increased in height and length with time until 16 h elapsed. At 24 h, the profile further increased in length, but the height of the dune decreased slightly when compared with the dune formed after 16 h. It can be seen that changes in the scour formation in the downstream region were more significant than changes in the upstream region with time; however, since the primary quantity for the foundation head design is *dse*/*D* located near the upstream face of the cylinder, the best indication of an equilibrium condition with respect to design can be taken from this region.

This is further indicated by comparison of the scour profiles in the *XY* plane between tests E1 and E3 in Figures 5 and 6. For this pair of tests, the relative coarseness *D*/*d*50, flow shallowness *h*/*D*, and blockage ratio *D*/*b* were very similar (refer to Table 1); only the duration of the tests (48 h for test E1 compared with 24 h for test E3) differed among the two tests.

**Figure 5.** Bed profile measurements in the *XY* (symmetry) plane at *Z*/*D* = 0 for tests E1 and E3.

**Figure 6.** Bed profile measurements in the *XZ* plane at *Y*/*D* = 0 for tests E1 and E3.

As was indicated by the time series shown in Figures 4–6, when all other scour-governing parameters are held constant, the scour formation upstream of the cylinder does not change significantly as time progresses beyond 24 h. From the bed profiles in the *XY* plane, the scour hole profiles in the upstream region were very similar between tests E1 and E3. Downstream of the cylinder, the length of the dune increased, and the height of the dune decreased with time. This was also observed in the time series profiles in Figure 4.

The contour profiles of the scour formation in Figure 6 similarly show that the geometry of the scour hole did not change significantly with time upstream of the cylinder. Downstream of the cylinder, the width of the dune changed slightly. However, as previously mentioned, since changes in the

downstream region do not affect design of the foundation head, the equilibrium state is evaluated primarily based on the region in which the depth of scour is at a maximum (i.e., upstream).

#### *3.2. E*ff*ect of Blockage Ratio D*/*b on Equilibrium Scour Formation*

Figures 7 and 8 show profiles of the equilibrium scour formations for tests E1 and E2. For this pair of tests, all scour-governing parameters (*U*/*Uc*, *D*/*d*50, and *h*/*D*) were held constant. Movable sidewalls were installed in the flume in order to alter flume width *b* and, therefore, blockage ratio *D*/*b* as well. Test E1 was conducted for 48 h, and test E2 was conducted for 24 h. However, the results of the previous section indicated that the scour formation in the vicinity of the cylinder was virtually unchanged beyond 24 h, and any significant changes were only observed in the downstream region. Therefore, the following discussion will pertain mainly to the scour formation upstream and close to the cylinder.

In Figure 7, the depth of the scour hole is shown to be higher for the test with the lower blockage ratio. This is indicative of the strong effect of sidewall proximity on the mechanism of local scour. In test E1, the channel was significantly wide (*b* = 1.22 m) such that the spanwise pressure gradient imposed by the sidewalls did not significantly affect the flow field mechanisms surrounding the cylinder (i.e., the HSV and the wake vortices). Therefore, scour was allowed to progress unimpeded.

In contrast, the width of the channel for test E2 was approximately one-third of that of test E1 (*b* = 0.4 m). It is then very likely that the secondary flows (boundary-induced currents at right angles to the main flow) were capable of interacting with the flow field mechanisms surrounding the cylinder, particularly the wake vortices. Furthermore, the aforementioned spanwise pressure gradient that is a noted feature of horizontally confined flows was more likely to influence the cylinder as the confinement increased. All of these effects of sidewall proximity served to disrupt and weaken the removal and deposition of sediment, reducing the size of the scour hole and the primary deposit.

**Figure 7.** Bed profile measurements in the *XY* (symmetry) plane at *Z*/*D* = 0 for tests E1 and E2.

**Figure 8.** Bed profile measurements in the *XZ* plane at *Y*/*D* = 0 for tests E1 and E2.

Although the above discussion is restricted to the upstream region due to the previously mentioned time differences between tests E1 and E2, the alteration in the dune formation for test E2 can also be attributed to the effect of channel blockage. Beyond the crest of the dune for test E2, the form of the primary deposit differs from that of test E1. Since the wake region is in closer proximity to the sidewalls, it is reasonable that the effect of horizontal confinement would affect the deposition of sediment downstream of the cylinder in addition to the removal of sediment in the vicinity of the cylinder as previously discussed.

This is further illustrated in Figure 8 which shows the effect of *D*/*b* on the extents of the scour formation in the horizontal plane at *Y*/*D* = 0. It can be seen that the size of the scour hole was much smaller in plain view for test E2 with *D*/*b* = 0.15 than for test E1 with *D*/*b* = 0.05. Again, the increase in sidewall proximity appears to have suppressed the lateral progression of scour. This is also observed downstream of the scour hole, where the primary deposit became narrow as horizontal confinement increased.

#### *3.3. E*ff*ect of Blockage Ratio D*/*b on the Progression of Local Scour*

In Figure 9, a description of the progression of relative scour depth *ds*/*D* with dimensionless time *t*/*te* (where *t* is time and *te* is the time to equilibrium) is given. Test E3 of the present investigation was included as well as two tests from the investigation of Yanmaz and Altinbilek [22]. All tests had similar values of *D*/*d*50 and *h*/*D*; only *D*/*b* differed within the presented data set. For all tests, it can be seen that *ds*/*D* increased rapidly, attaining most of the maximum relative scour depth within half of the time to equilibrium. The values of the measured equilibrium scour depth (at *t*/*te* ≈ 1) are shown to be very similar among all tests as well. The figures also include curves calculated using predictive methods for the progression of *ds*/*D* with time from Melville and Chiew [21] (Equation (2)) and Aksoy et al. [23] (Equation(3)).

$$d\_s/d\_{sc} = \exp\{-0.03|(\mathcal{U}\_\mathcal{L}/\mathcal{U})\ln(t/t\_\varepsilon)|^{1.6}\}\tag{2}$$

$$d\_s/D = 0.8 \times (l\text{\textdegree\textdegree\textdegree C}/l\text{\textdegree\textdegree T}\_c)^{3/2} \times (h\text{\textdegree D})^{0.15} \times (\log T\_s)^{0.6} \tag{3}$$

$$T\_s = td\_{50} \times (\Delta g d\_{50})^{0.5} / \text{D}^2 \tag{4}$$

**Figure 9.** Comparison of *dse*/*D* with *t*/*te* for test E3 and data from [22] with *D*/*d*50 ≈ 76 as well as estimation curves [21,23] and points [19] from literature.

In Equation (4), Δ = (ρ*s* − ρ)/ρ, where ρ*s* is the density of the bed material, and ρ is the density of water. In Figure 9, the experimental parameters for test E3 were used to calculate the predictive curves. In Figure 10, the parameters for the test by D'Alessandro [17] were used for the prediction. The value of *dse*/*D* calculated using the predictive method presented in Williams et al. [19] (Equation (5)) was also included for each test as shown by the starred data points.

$$d\_{\rm s\%} \text{D} = 0.76 k\_{\rm c}^{1.69} \times \text{(h\%)}^{0.32} \tag{5}$$

In Equation (5), *kc* is the ratio between the velocity along the separating streamline *Us* and *Uc*. In Figure 9, it can be seen that there were small differences in *dse*/*D* observed in the middle of the scour process (i.e., approximately between 0.1 < *t*/*te* < 0.7). However, there was no specific trend which can be noted between the development of scour and blockage ration *D*/*b*. In the described middle section of the scour process, the scour depth was slightly lower for *D*/*b* = 0.1 when compared with *D*/*b* = 0.05; however, *dse*/*D* was slightly higher for *D*/*b* = 0.09 than either of the other tests. (Although unlikely, this could possibly be attributed to the small changes in *D*/*d*50 or *h*/*D* among the tests.). In general, for *D*/*d*50 < 100, it can be concluded that changes in *D*/*b* have a very small influence on both the progression of local scour as well as the equilibrium depth of scour.

The predictive method described by Equation (2) is represented by the solid curve in Figures 9 and 10, and this method slightly over-predicted the depth of scour (*ds*) throughout the time to equilibrium. The method described by Equation (3) over-predicted the depth of scour for *t*/*te* < 0.5, beyond which the curve approached the results of Yanmaz and Altinbilek [22]. Equation (2) showed good prediction of *dse*/*D* for all tests.

**Figure 10.** Comparison of *dse*/*D* with *t*/*te* and data from [17,27] with *D*/*d*50 ≈ 137 as well as estimation curves [21,23] and points [19] from literature.

However, the results presented in Figure 10 indicate that the effect of *D*/*b* was amplified as *D*/*d*50 increased. The results presented in Figure 10 had similar values of *U*/*Uc* and *D*/*d*50. The value of *h*/*D* was also altered among the tests; however, the literature indicated that the effect of flow depth on *dse*/*D* is minimal when *h*/*D* > 1.4 [3]. Therefore, in terms of influencing parameters, only *D*/*b* differed among the tests. In contrast to the data set presented in Figure 9, there were significant changes noted with changing *D*/*b*. For *D*/*b* = 0.09, the depth of scour was significantly higher throughout the progression to equilibrium when compared with *D*/*b* = 0.06. This was also in contrast to the results of the previous section which indicated that the relative scour depth increased as *D*/*b* decreased. This indicates that the effect of blockage ratio on local scour is also dependent on the value of *D*/*d*50, and the effect is amplified when *D*/*d*50 > 100.

This is in agreement with the results of Tejada [18] who conducted a series of experiments with varying sizes of bed material (*d*50) and similarly reported that the effect of *D*/*b* was minimal when *D*/*d*50 < 100 when compared with *D*/*d*50 > 100. This is reasonable, since larger values of relative coarseness are usually indicative of smaller sediment particles which would be more susceptible to changes in the flow field surrounding a cylinder.

Interestingly, Equation (2) provides a good estimation of the progression of scour for the results of Chabert and Engeldinger [27], while Equation (3) provides a better estimation for the test of D'Alessandro [17]. Furthermore, Equation (5) shows a much closer prediction of the test of Chabert and Engeldinger [27] than D'Alessandro [17]. This also indicates that further investigation on higher values of *D*/*d*50 is required in order to establish the role of *D*/*b* on local scour.


**4. Discussion**

**Figure 22.**

*Resources of Water*

*sub-basins.*

**Figure 23.**

*sub-basins.*

**Figure 24.**

**140**

*Spatial distribution of fluoride concentration in the study area.*

*Box plot for the maxi, min and average of the fluoride content in groundwater according to TDS of three*

*Box plot for the max, min and average of electrical conductivity and total dissolved solids according to study*

Fluoride concentration variation is widely in the study area from 0.1 mg/L (in well No.93 in Al-Burayhi and Hedran sub-basin) to 6 mg/L [in Well No. 83, of the same sub-basin (Al-Burayhi and Hedran sub-basin)]. We observed that the concentration of fluoride in the Al-Dhabab sub-basin is the optimal concentration according to the WHO drinking water guidelines value of 1.5 mg/L.

Waters with high fluoride concentrations occur in large and extensive geographical belts associated with (a) sediments of marine origin in mountainous areas, (b) volcanic rocks and (c) granitic and gneissic rocks [21], and the high concentration of fluoride widely accepted that most of the F are derived mainly from acidic volcanic rocks such as pumice, obsidians, pyroclastic deposits, ignimbrites and rhyolite, and the main minerals for F are fluorite, fluorapatite, micas and hornblende [22]. Because the geology of study mainly constituent from the acid and basic volcanic and grants rocks, the level of fluoride concentration in the Al-Dhabab sub-basin can be explained by the nature on aquiver in this study area (Cretaceous Tawilah Sandstone), while the groundwater in the other sub-basin is produced either from Tertiary fractured volcanic (that have F- bearing mineral and the groundwater in this aquiver have long-time contact with aquiver, which adjudge the important factors leading to the high fluoride concentration result of interaction between the groundwater and the aquiver) or from the Quaternary alluvium aquiver, where the Wadi sediments deposited are derived from the alteration of volcanic ash and tufa mainly of (Tr1); this quiver depends on their recharge mainly on the wastewater of the urban and industrial activates; this aquiver exposed to over exploration of their groundwater and finally the dry and semi-dry condition plays an important role in the degradation of groundwater in this aquiver.

It is clearly observed that the Al-Burayhi and Hedran and Al-Hawban sub-basins have the highest concentration of fluoride ion in the chemistry of water. Highest

concentrations were found to be 6 mg/L from Al-Burayhi and Hedran sub-basin, 5.81 mg/L from Al-Hawban unlike the Al-Dhabab sub-basin which remains unaffected by the contamination fluoride of groundwater. According to the report of [23], the dental fluorosis is the widely fluoride disease observed in the affected areas, and there is a positive relationship between fluoride in water and the occurrence of dental fluorosis in Taiz region.

On the other hand, the use of fluoridated water for cooking increases the fluoride content significantly especially in dry foods like maize flour which absorbs much water during cooking. It has been reported that fluoride availability may be influenced by simultaneous intake of food and fluoride containing compounds in a positive or negative manner depending on the food type, mode of administration

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer…*

Much of the fluoride entering the body is from water and the high concentration of fluoride in water's sources is therefore a major concern. The fluoride is found in the atmosphere, soil and water. It enters the soil through weathering of rocks, precipitation or waste runoff. Understanding of the fluoride occurrence is important in the management of the fluoride related epidemiological problems. Al-Hawban and Al-Burayhi and Hedran are the worst sub-basins affected by fluoride contamination in drinking water. 71% of samples (66 samples out of 93 samples) in the study area have F- concentration (mg/L) above the permissible limit and alternate water sources will be difficult. Therefore, defluoridation of drinking water is the only practicable option to overcome the problem of excessive fluoride in drinking water in these areas. More refined studies however need to be done before any long-term intervention efforts can be planned. In the meantime, there is a critical need to educate young Yemenis about fluorosis and simple intervention measures to avoid long-term health problems. Other studies in the region are urged studying the cause and effect relationship between the abnormal content fluoride and

Ramzy Saeed Mahbob Naser1,2\*, Mohammed El Bakkali3 and Driss Belghyti4

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

1 Al-Hodeidah University, Al-Hodeidah, Yemen

3 National Mutual Aid, Kenitra, Morocco

4 Ibn Tofail University, Kenitra, Morocco

provided the original work is properly cited.

2 Ministry of Public Works and Roads, Sana'a, Yemen

\*Address all correspondence to<EMAIL_ADDRESS>
and type of fluoride compound [37].

*DOI: http://dx.doi.org/10.5772/intechopen.91329*

**5. Conclusion**

population health.

**Author details**

**143**

In order to understand the vertical distribution of the fluoride ion concentration from the water of the study area, the type of the sample water (dug well, bore well and spring) evaluated separately. There was no significant difference between the three well types, dug well sample, springs and bore wells. It can be concluded that shallow aquifers do not reflect higher fluoride contamination than deeper aquifers. It is observed that most of the water samples showed enhanced concentrations with generally increasing trends to the low elevated area (Al-Burayhi and Hedran sub-basin), while the high elevation shows low concentration of fluoride (Al-Dhabab sub-basin). All the water samples collected from the uphill zones of Al-Dhabab sub-basin were exhibited low fluoride concentration.

Compared with Na-HCO3 type groundwater, Ca-HCO3 type groundwater is known to generally contain lower fluoride [24]. Its hydrochemistry is characterized by increased Ca2+ ion concentration with increasing total dissolved solid due to the gradual dissolution of carbonate minerals or Ca2+ bearing plagioclase in aquifer materials [25, 26]. The Na-HCO3 type groundwater is generally enriched in fluoride and sodium ions, due to the dissolution of silicates as well as the removal of Ca2+ by calcite precipitation and cation exchange [27, 28]. The solubility limits for fluorite and calcite provide a natural control on water composition in a view that calcium, fluoride and carbonate activities are interdependent [29, 30]. In addition to the effect of those areas by different liquid waste by runoff and sewage disposal, the heavy pumping of well water is also contributed because of the scarcity of water which leads to the increase of the concentration of salt in the water. TDS levels ranged widely from 291 to 6188 mg/L with most station levels above 400 mg/L and many of the samples studied were higher than the permissible limit of 1500 mg/L according to WHO (2003). This wide variation in TDS values indicates that the area hydrochemistry is influenced by diverse processes such as water-rock interaction and anthropogenic pollution. Fluoride concentrations frequently are proportional to the degree of water-rock interaction because fluoride primarily originates from the geology [9, 31–34]. Due to the high rainfall, rugged topography, factories, lack of total coverage per sewerage network, population density and faults in the study areas could also explain this high fluoride content by runoff and infiltration of chemical fertilizers in agricultural areas, septic and sewage treatment system discharges with fluoridated water supplies and liquid waste from industrial sources. The topography of the study areas varies from level plain to steep slopes. Study area ranges in elevation between 900 and 3000 m above sea level. Taiz plain receives about 500 mm/year of rainfall and significant recharge form runoff of surrounding mountains [35]. In addition to this groundwater fluoride pollution that can affect human health, there have been indications that uptake of fluoride from other sources like food, dust and beverages may be many times higher than that of water [36]. About the fluorosis in selected villages of Taiz Governorate, the percentage of children with fluorosis was very high.  In AL-Hawban sub-basin, some of children, especially from Jabal Sabir area, used to chew Qat daily, and the Qat are cultivated in the man-made terraces of Jabal Sabir alkali granite, where it expected to be the main source of F- reach minerals like fluorite [23].

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer… DOI: http://dx.doi.org/10.5772/intechopen.91329*

On the other hand, the use of fluoridated water for cooking increases the fluoride content significantly especially in dry foods like maize flour which absorbs much water during cooking. It has been reported that fluoride availability may be influenced by simultaneous intake of food and fluoride containing compounds in a positive or negative manner depending on the food type, mode of administration and type of fluoride compound [37].


**Author details**

Koki Kawamura, Shinichiro Maeshima\*, Aiko Osawa and Hidenori Arai National Center for Geriatrics and Gerontology, Obu, Japan

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Overarching Goal and Intervention for Healthy Aging in Older People… DOI: http://dx.doi.org/10.5772/intechopen.106787*


Coronary Syndrome

Clinical Treatment, Prevention and Management for Better Outcomes

Edited by Koichi Node and Atsushi Tanaka

www.mdpi.com/journal/jcm

## **Coronary Syndrome: Clinical Treatment, Prevention and Management for Better Outcomes**