Coasting疗法在预防卵巢过度刺激综合征中的应用

卵巢过度刺激综合征(OHSS)是一种医源性疾病,常发生于体外受精-胚胎移植(IVF-ET)过程中行控制性超排卵(COH)的患者,严重者可危及健康和生命,目前没有很好的预防方法。近十年来,对有OHSS发生高危因素的患者,国外流行coasting疗法。本文根据国外文献报道,围绕coasting疗法的概念、原理、方法、对卵子和胚胎质量的影响、预防并降低OHSS的发生率和严重程度的有效性等进行综述。

Control Algorithm of Electric Vehicle in Coasting Mode Based on Driving Feeling

Coasting in gear is a common driving mode for the conventional vehicle equipped with the internal combustion engine（ICE）, and the assistant braking function of ICE is utilized to decelerate the vehicle in this mode. However, the electric vehicle（EV） does not have this feature in the coasting mode due to the relatively small inertia of the driving motor, so it will cause the driver cannot obtain the similar driving feeling to that of the conventional vehicle, and even a traffic accident may occur if the driver cannot immediately adapt to the changes. In this paper, the coasting control for EV is researched based on the driving feeling. A conventional vehicle equipped with continuously variable transmission（CVT） is taken as the reference vehicle, and the combined simulation model of EV is established based on AVL CRUISE and MATLAB/Simulink. The torque characteristic of the CVT output shaft is measured in coasting mode, and the data are smoothed and fitted to a polynomial curve. For the EV in coasting mode, if the state of charge（SOC） of the battery is below 95%, the polynomial curve is used as the control target for the torque characteristic of the driving motor, otherwise, the required torque is replaced by hydraulic braking torque to keep the same deceleration. The co-simulation of Matlab/Simulink/Stateflow and AVL CRUISE, as well as the hardware-in-loop experiment combined with d SPACE are carried out to verify the effectiveness and the real-time performance of the control algorithm. The results show that the EV with coasting braking control system has similar driving feeling to that of the reference vehicle, meanwhile, the battery SOC can be increased by 0.036% and 0.021% in the initial speed of 100 km/h and 50 km/h, respectively. The proposed control algorithm for EV is beneficial to improve the driving feeling in coasting mode, and it also makes the EV has the assistant braking function.

The Influence of Cabergoline and Coasting in Prevention of the Ovarian Hyperstimulation Syndrome in Patients Undergoing IVF/ICSI-ET Treatment: A Systematic Review and Meta-Analysis

Objective: To compare the effectiveness of two methods in preventing ovarian hyperstimulation syndrome (OHSS) with cabergoline and coasting. Design: Systematic review and meta-analysis of randomized clinical trials (RCTs). Patients: Women were considered as have risk of OHSS undergoing fertility treatment. Interventions: Cabergoline, coasting. Result: There were included five RCT studies. The clinical pregnancy rate was no significantly difference between two groups (RR 1.22, 95% CI [0.86, 1.71]), implantation rate (RR 1.00, 95% CI [0.75, 1.32]), severe OHSS (RR 0.93, 95% CI [0.38, 2.31]), fertilization rate (SMD 0.70, 95% CI [-0.10, 1.50]), number of oocytes retrieved (SMD 0.80, 95% CI [0.30, 1.30]), number of embryo transfer (SMD-0.04, 95% CI [-0.24, 0.17]), E2 value on the day of HCG injection (SMD 0.21, 95% CI [-0.25, 0.68]), number of MII oocytes (SMD 0.71, 95% CI [0.32, 1.11]), abortion rate (RR 0.61, 95% CI [0.21, 1.83]), number of follicles > 17 mm on day of HCG (SMD -0.01, 95% CI [-0.26, 0.24]), number of follicles 15 - 17 mm on day of HCG (SMD -0.08, 95% CI [-0.33, 0.17]), number of follicles 10 - 14 mm on day of HCG (SMD -0.06, 95% CI [-0.31, 0.19]). Conclusion: Both cabergoline and coasting prevent the occurrence of OHSS, but no statistically significant difference between them. Compared with coasting group, a daily dose of 0.5 mg cabergoline significantly increased the number of oocytes retrieved, MII oocytes, and fertilization rate, but decreased the abortion rate.

Follicular Aspiration Is Superior to Coasting as Effective Prophylactic Procedure against Ovarian Hyperstimulation Syndrome

Objectives: Evaluation of outcome follicular aspiration compared to coating procedure for infertile women undergoing ICSI regarding frequency and severity of ovarian hyperstimulation syndrome (OHSS). Patients & Methods: Infertile PCOS women underwent controlled ovarian stimulation with luteal phase GnRH-agonist long down-regulation protocol. Women developed serum E2 level > 4000 pg/ml and/or >20 follicles of ≥10 mm in diameter were randomly divided to receive coasting strategy (Coasting group) or TVU-guided aspiration (Aspiration group). When ≥3 follicles were ≥18 mm and serum E2 level was and 10,000 IU was administered 36 h before oocyte retrieval, and ICSI was performed 72-hr thereafter and the frequency of moderate-to-severe OHSS was determined. Results: 82 women developed criteria for categorization and 21 women (25.6%) developed moderate-to-severe OHSS;5 women of aspiration and 16 of Coasting group;with significantly (P = 0.005) lower frequency in aspiration group. Twenty women developed ascites;3 women had clinically detectable, while 17 women had US detected ascites with significantly (P = 0.039) higher frequency among women that had coasting. All other manifestations of OHSS were significantly lower with aspiration procedure. Both coasting and aspiration therapy significantly reduced serum E2 and ovarian diameter on day of hCG injection compared to estimates taken at time of categorization. Conclusion: Coasting procedure prior to hCG injection could decrease incidence of OHSS and lessens its manifestation. Follicular aspiration provided more superior results and improved outcome of these women. Any of these modalities could be provided to infertile high-risk women according to the availability of experiences and patients’ selection.

使用促性腺激素释放激素拮抗剂西曲瑞克进行控制性卵巢刺激患者Coasting疗法的影响

Coasting is the most popular modality for the prevention of ovarian hyperstimulation syndrome, but this procedure has not been evaluated in patients undergoing controlled ovarian hyperstimulation (COH) with GnRH antagonists. The impact of coasting in a cycle in which GnRH antagonist is used was evaluated in 29 women, and it was found that coasting did not deleteriously affect the outcome in high-responder patients undergoing COH with GnRH antagonists.

Coasting疗法对冻融胚胎移植后潜在种植能力的影响

Objective: To examine the effect of withholding gonadotropins on the outcome of embryos after cryopreservation and thawing. Design: Retrospective clinical evaluation of patients having cryopreserved-thawed ET trials with coasting during the corresponding ovarian stimulation cycle. Setting: Academic tertiary clinical care unit. Patient(s): Patients with cryopreserved embryos having coasting in their fresh IVF cycle and age-matched controls without coasting, both groups receiving the same stimulation protocol (long GnRH agonist plus recombinant FSH). Intervention(s): All patients had a cycle in which embryos were transferred fresh and a cycle of thawing of cryopreserved embryos with the aim of transferring in a steroid-supplemented cycle. Main Outcome Measure(s): Embryo survival, implantation, and clinical pregnancy rates. Result(s): Post-thawing embryo survival (66.4%vs 73%), implantation (12.3%vs 13.0%), and clinical pregnancy rates (31.5%vs 38.0%) were similar in study and control groups, respectively. Patients with coasting for ≥3 days had significantly lower post-thawing embryo survival rates compared with patients having shorter duration of coasting (< 3 days) and controls. Implantation and pregnancy rates, however, were similar in the three groups. Conclusion(s): Coasting did not seem to have a detrimental effect on oocyte and embryo quality because the implantation competence of transferred concepti after cryopreservation and thawing was similar to that of controls. However, prolonged coasting (≥3 days) had a subtle negative impact on the post-thaw survival rate.

Coasting疗法对体外受精-胚胎移植治疗结局的影响

目的探讨在控制性超促排卵(COH)中coasting疗法与体外受精-胚胎移植(IVF-ET)治疗结局的关系。方法对南方医科大学南方医院生殖医学中心2005年1月至2005年12月222例不孕症患者的临床资料进行回顾性分析。根据是否行coasting疗法分为两组,比较两组的卵泡数、卵子数、临床妊娠率、种植率和分娩率。结果coasting组的coasting天数为(1.3±0.5)d,coasting组与非coasting组的卵泡数、卵子数分别为(33.0±7.6)个、(17.1±7.1)个和(17.4±7.7)个、(11.9±4.8)个,coasting组显著高于非coasting组,差异有显著性意义(P<0.05),而临床妊娠率、种植率和分娩率分别为51.4%、34.6%、48.6%和47.8%、28.8%、44.0%,差异无显著性意义(P>0.05)。结论coasting是预防重度卵巢过度刺激综合征(OHSS)的一种有效方法,不影响IVF-ET的妊娠结局。

Eco-Epidemiological Characteristics of Human Rabies in Côte d’Ivoire, 2012-2017

Introduction: Human rabies is a major public health problem in many African countries, including Côte d’Ivoire. The present work aims at describing the eco-epidemiological characteristics of human rabies cases recorded in Côte d’Ivoire. Methods: This was a retrospective and prospective cross-sectional descriptive study based on epidemiological surveillance data that ran from september 2014 to december 2017. The clinical data were extracted from the database of the human rabies epidemiological surveillance management service of the National Institute of Public Hygiene’s rabies centre. These data cover the period from 1 January 2012 to 31 December 2017. Results: Human rabies is endemic in Côte d’Ivoire, with most people exposed in the south and especially in the west of the country. There was no association between any of the climatological parameters (temperature, humidity, rainfall) and the occurrence of human rabies during the months of exposure to rabies infection. Conclusion: Ultimately, effective prevention and control of human rabies requires a thorough understanding of the links between climatological parameters and rabies. Health authorities must take ownership of these results if we are to achieve our goal of eliminating rabies by 2030.

Prevalence of Work-Aggravated Asthma among Bakery Workers in Abidjan (Cote d’Ivoire)

Introduction: Work-aggravated asthma is pre-existing or concomitant asthma whose symptoms are aggravated by the work environment. The aim of this study was to determine the prevalence of this pathology and its associated factors among bakery workers in Abidjan. Materials and Methods: This descriptive and analytical cross-sectional study was conducted over a period of four (4) months from 18 December 2019 to 18 April 2020. Two questionnaires were used, one on employees and the other on the indoor environment of bakeries. In addition, a spirometry test was performed on all bakery workers. Statistical analysis was performed using stata 15.1 software. Results: A total of 599 bakery employees, including bakers (59.73%), sales assistants/ cashiers (23.52%), cleaners (6.34%) and administrative staff (10.18%), were investigated. The mean age was 30.8 ± 8 years, with a sex ratio (M/F) = 2.2. Asthma symptoms were found in 95 (15.86%) employees, of whom 74 (77.9%) had work-related asthma and 11 (14.9%) had asthma aggravated by work. The factors associated with work-aggravated asthma were personal or family history of allergy or atopy [ORa = 3.75;CI95%: 1.56 - 8.93;p = 0.003], exposure to dust [ORa = 5.01;CI95%: 1.43 - 7.50;p = 0.011] and humidity level (60% - 70%) [ORa = 1.80;CI 95%: 0.99 - 3.28;p = 0.05]. Conclusion: Work-aggravated asthma is a reality in bakeries in Abidjan, with an estimated prevalence of 14.9%. Two of the three factors associated with this condition suggest a link with indoor air pollution. Combating air pollution in these establishments must therefore be a priority for the relevant authorities, in order to provide employees with a working environment that protects their health.

Contribution of GIS to Soil Landscape Mapping by Multi-Criteria Analysis Using Weighting: The Case of the Square Degrees of M’Bahiakro (Centre) and Daloa (Centre-West) in Ivory Coast

As part of the drive to improve coffee and cocoa production in Ivory Coast, studies are carried out to identify soils that are favourable for these crops. It is therefore necessary to orientate soil investigations based on reliable criteria that best discriminate soil cover. With this in mind, this study is being carried out to help improve survey methods by mapping soil landscapes. It uses GIS and weighted multicriteria analysis. To do this, satellite images were processed and the geological map of the square degrees of M’Bahiakro and Daloa was reclassified. The results show that relief is the main factor in soil landscape differentiation, with respective weights of 0.58 and 0.67 for the forest and pre-forest zones. In contrast, the weight of geological formation in soil landscape differentiation remains low (0.05 for the forest zone and 0.07 for the pre-forest zone). The criteria used on the base of aggregation sum methods have made it possible to formulate soil landscape mapping prediction functions according to agro-ecological environments in the humid intertropical zone. This is essential for the orientation of soil survey work. Nevertheless, other comparative methods, such as the coding mapping method, could provide elements for discussion to validate the models.

Micropenis Associated or Not with Cryptorchidism in the Endocrinology Department of Yopougon University Hospital in Ivory Coast: Epidemiological, Clinical, Paraclinical and Therapeutic Aspects

Background: Congenital malformations such as micropenis and cryptorchidism do not have immediate dramatic consequences. However, the diagnosis is often unknown at birth, and therefore late. In Ivory Coast, there are few studies on cryptorchidism and micropenis. We conducted this study to identify the epidemiological, clinical, etiological and therapeutic characteristics of the micropenis associated or not with cryptorchidism at Yopougon University Hospital. Methods: We conducted a retrospective descriptive study in the Department of Endocrinology-Diabetology of the Yopougon University Hospital carried out over 13 years from January 2005 to December 2018. All patients were included regardless of the presence of a micropenis associated or not with cryptorchidism in the clinical or paraclinical examination. Results: A total of 14 micropenis were reported associated in 6 cases with cryptorchidism. It was unilateral cryptorchidism in 4 patients or 66.66% of cases. The average age of affected patients was 21.32 years with extremes ranging from 10 months to 48 years. The reason for consultation was micropenis in 12 out of 14 cases or 85.75%. The associated signs apart from cryptorchidism were obesity in 42.86% of cases, gynecomastia in 35.71% of cases. The aetiology was dominated by idiopathic causes. Treatment with testosterone enanthate was more effective in pre-pubertal children than in adults. Conclusion: The diagnosis of micropenis associated or not with cryptorchidism is late because of the frustrations, taboos and psycho-social states that it causes. However, drug treatment is effective when treatment is started early.

Response of the Maize Variety EV87-28 to a Fertilization Strategy Involving Indorama Granular Urea on Ferralsol in the Central Ivory Coast

In Côte d’Ivoire, the decline in soil fertility strongly impacts the productivity of maize (Zea mays L.) on heavily leached ferralitic soil. In this study, the general objective was therefore to improve the productivity of maize EV87-28 on the Ferralsols in pre-forested areas during different cropping seasons. Eight (8) micro-plots were set up according to a total randomization device with three repetitions. Two factors were studied: nitrogen fertilizer modalities (main factor) and crop season (secondary factor). Growth, flowering and yield parameters were measured and analyzed. The results showed that there was no interaction between the nitrogen fertilizer factor and the cropping season factor. In addition, this study showed the short rainy season had the most positive impact on growth, flowering and yield parameters than the long rainy season. The results also showed that the different nitrogen fertilizer modalities had no statistically different effects on growth, flowering and yield parameters. However, quantitative differences were reported, highlighting one nitrogen fertilizer modality, which is the combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure). The combination of urea granule + farm manure (75% urea indorama granules and 25% farm manure) had the best effect on corn grain yield. So, the combination of urea (75%) and manure (25%), that resulted in yield gain, could be recommended for corn fertilization during the small rainy season.

Technical-Economic Performance, Carcass and Meat Quality of COBB500 Broilers Fed Rations Incorporating Mango By-Product Feeds in Ivory Coast (West Africa)

The study evaluated the growth performance and carcass quality of COBB500 broilers fed two experimental rations incorporating feed and mango fine ED10 for a batch of 83 birds, ED20 (batch of 83 birds) in comparison with a commercial control ration CCD (84 birds). For this purpose, 250 day-old chicks of this breed were purchased in Korhogo and transported to Tengréla in Ivory Coast for rearing. The results show that substituting mango provender ans and mango seed flour for maize resulted in rations with costs per kgMS of 215.35FCFA, 2016.93FCFA and 320FCFA for the ED10, ED20 and CCD rations respectively. The production costs per kg of chicken (FCPkgLW) of the CCD ration were significantly higher than those of the ED10 and ED20 (p 0.05). ADGs were significantly different and decreasing from CCD, ED20 to ED10 (p 0.05). Average weights at 42nd day for ED20 and CCD were homogeneous (p > 0.05) and significantly higher than for ED10 (p 0.05). By day 49th the average weight of ED20 had reached and exceeded that of CCD by day 42nd. PSLW, HCW and CCW were significantly different and decreasing from CCW, ED20 to ED10 (p 0.05). Average hot (HCY) and cooled (CCY) carcass yields of ED20 and CCD rations were comparable (p > 0.05) and significantly higher than those of ED10 ration (p = 0.009) and 0.003). Average drumstick and neck weights were significantly higher and lower for CCD, ED20 and ED10 (p 0.05). For all other parts of the cut, the average weights of the CCD ration were significantly higher (p 0.05) than those of the ED20 and ED10 rations, which were homogeneous (p 0.05). The incorporation of mango provender and mango seed flour in broiler rations offers the prospect of reduced production costs, less competition between man and animals over cereals, and lean meat production that is more appreciated than that of chickens fed conventional feed. As it stands, the ED20 ration can be recommended as a growth diet for broilers. It would be necessary to determine the levels of anti-nutritional substances in mango feeds and to assess the in vivo digestibility of mango ingredients and the diets incorporating them.

Acceleration of coasting enhances pregnancy rate in ICSI cycles at risk for ovarian hyperstimulation syndrome

Objective To assess the efficacy of adding Gn-releasing hormone antagonist（GnR HA） on the day of hC G triggering in a long luteal protocol without withholding the agonist in women who are at a risk to develop ovarian hyperstimulation syndrome（OHSS）.Methods This was a retrospective cohort study conducted upon 50 women who have elevated serum estradiol（E2） level 〉4 500 ng/L at the day of ovum triggering with hC G on a long agonist luteal protocol of controlled ovarian stimulation（COS）. When an exaggerated ovarian response was observed around day 10 of stimulation, immediately the next morning at 6 a.m. gonadotropin administration was stopped or reduced, and a single dose of ganirelix acetate（antagonist） was given sc continuation of the agonist dose hC G. Another serum E2 measurement was done at 6 p.m.（after 12 h of antagonist） then hC G, sc 250 mg and choriogonadotropin α were administered 14 h later after antagonist and documented the reduction of E2 level. Oocyte retrieval was conducted after 34-36 h of hC G administration. The measured outcomes were the level of E2 on the day of hC G injection, number of oocytes and their quality, pregnancy rate and the occurrence of OHSS and its grade in case it happened.Results The total dose for recombinant FSH was 25.3±6.4 ampoules（75 IU/ampoule） while it was 11.0±3.0 ampoules for the urinary hM G. A higher oocyte maturation rate（82.8%） and a high fertilization rate（87.8%） were observed. The mean endometrial thickness was 10.1±1.0 mm on the day of hC G triggering. The higher fertilization rate with the good endometrial thickness observed resulting in a higher pregnancy rate（78.0%, 39/50） with statistically significant（P〈0.05）. A significant reduction of E2 level was documented by a percentage around 40% before hC Ginjection. There were no reported cases of severe or moderate OHSS, however 13 cases（26%） were reported to have mild OHSS constituting.Conclusion Acceleration of coasting in cases of OHSS through treatment with GnR HA after pituitary suppression with GnR H agonist（GnR H-a） offered a novel approach to decrease E2 level, avoided cycle cancellation, and maintain excellent oocyte maturation rate, and finally result in high pregnancy rate with prevention of OHSS.

Analysis of the Quality of Physical and Chemical Parameters of Groundwater in Three Localities in the Sub-Prefecture of Zanzra (Ivory Coast)

The availability of groundwater of acceptable quality has become a difficult challenge to meet in many countries, particularly Côte d’Ivoire. The State of Côte d’Ivoire and rural populations are building hydraulic infrastructure for this purpose. However, the quality of water coming from these infrastructures remains to be determined. This study therefore aims to analyze certain physicochemical parameters of the groundwater of Gloazra, Kouezra and Trahonfla. These are temperature, pH, electrical conductivity, TDS, salinity level, hardness, alkalinity, chloride content and bicarbonate. To determine the pH, electrical conductivity, temperature, TDS, and salinity rate, an electrochemical analysis was carried out. The titrimetric analysis made it possible to determine the chloride and bicarbonate content, alkalinity, and hardness. The results indicate that the studied groundwater is soft and acidic with good mineralization. This water does not present a health hazard to consumers but can affect hydraulic equipment and household containers.

Contribution of SAR Radar Imagery in the Detection of Suspicious Vessels in the Ivorian EEZ

The present work proposed a method for match SAR and AIS data to detect vessels carrying out suspicious activity in the Ivorian EEZ. Two superposition methods, detected AIS and SAR data, based on point-to-point association on the one hand and point-to-line on the other hand, were used to detect suspicious vessels in Ivorian marine waters. The results showed that most vessels detected in the Ivorian EEZ do not declare their positions to avoid being spotted. These funds are likely to practice illegal, undeclared and unregulated fishing (INN fishing). This clandestine activity is very recurrent in Ivorian waters. This is illustrated by the number of suspicious vessels detected by SAR radar imagery which is greater compared to declared or authorized vessels.

Calcium-Magnesium Ca/Mg Ratios and Their Agronomic Implications for the Optimization of Phosphate Fertilization in Rainfed Rice Farming on Acidic Ferralsol in the Forest Zone of Ivory Coast

This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosphorus (P) nutrition of rice on these acidic soils, where this nutrient constitutes a limiting factor for agricultural production. Three (3) pot trials were conducted in Adiopodoumé in the forested south of Côte d’Ivoire. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg Ca ha−1) and magnesium sulfate (0, 25, 50 and 75 kg Mg ha−1) were evaluated on the response of NERICA 5 rice at doses 0, 25, 50 and 75 kg P ha−1 of natural phosphate from Togo, applied only once at the start of the experiment. Additional fertilizers of nitrogen (N) (100 kg N ha−1) and potassium (K) (50 kg KCl ha−1) were added to each of the tests in a split-plot device. The test results revealed a paddy production potential of approximately 3 to 5 t⋅ha−1 for NERICA 5 on an acidic soil, under the effect of the interaction of P, Ca and Mg. The quadratic response of rice yield to the doses of these fertilizers would be more dependent on their balance, itself influenced by Ca nutrition. For the sustainability and maintenance of rice production in agro-ecology studied, it was recommended doses of 38 kg Ca ha−1, 34 kg Mg ha−1 in a Ca/Mg ratio (1/1) with intakes of 41 kg P ha−1, overall in a ratio 1/1/1 (P/Ca/Mg) more favorable to the availability of free iron considered a guiding element of mineral nutrition. Thus, these promising results should be confirmed in a real environment for better management of the fertilization of rice cultivated on acidic plateau soils in Côte d’Ivoire.

Assessment of the Vulnerability of the Southwestern Coast of Benin to the Risk of Coastal Erosion and Flooding

The coastal zone of Benin is inherited from the last marine oscillations of the Quaternary. A rich and very fragile environment, it presented until the 1960s, a shoreline in dynamic equilibrium over the entire 125 km of coastal line. Since the 1960s, with the construction of important development infrastructures (ports, dams, groins), the Beninese coast is now subject to risks of coastal erosion and seasonal flooding due to the overflow of lagoon water bodies. The present study, based on socio-economic surveys in the communes of Ouidah, Comè and Grand Popo, exposes the extent of coastal risks and socio-economic and environmental damage in the southwestern coastal zone of Benin. The results show that in terms of land, 2.9 ha and 5.7 ha of land have been permanently lost to coastal erosion in the communes of Ouidah and Grand Popo respectively. Similarly, 212 ha of crops of all types were affected by the flooding, including 35 ha destroyed, i.e. 6.67 ha, 11.3 ha in Comè, 4.67 ha Ouidah and 14 ha Grand Popo. Also, 6435 buildings were affected, and 4235 huts were damaged. In addition, working tools, food stocks and other items are counted among the losses recorded by coastal hazards with their corollaries of diseases. The cost of losses and damages in the 08 districts amount to 418,000,000f cfa of which 266,000,000f cfa of damage and 152,000,000f cfa of loss.

Clay mineral compositions in the surface sediment of the Chanthaburi coast(northeastern Gulf of Thailand)and their implications on sediment provenance

Clay mineral composition represents an important tracer of sediment source area,migration processes,and paleoclimatic conditions.Clay mineral analysis was performed on 15 surface sediment samples collected from the coast of Chanthaburi,Thailand.Results show that the composition of clay minerals in the study area differs substantially from that in surrounding regions of the Gulf of Thailand.The clay minerals of the Chanthaburi coast are dominated by kaolinite(~56%),followed by smectite(~21%),illite(~14%),and low concentrations of chlorite(~8%).The average illite chemistry index and crystallinity are 0.93 and 0.32,respectively.Comparative analysis of the clay mineral composition of surface sediments in several typical areas around the Gulf of Thailand indicated that the clays of the Chanthaburi coast are mainly derived from parent rock weathering in the small watersheds of the Chanthaburi and Welu rivers and the surrounding islands.Terrestrial input from the northern coast of the Gulf of Thailand(excluding the Mekong River)was previously considered negligible;however,the present results indicate that such input has impact on the eastern Gulf of Thailand.The warm humid climatic conditions in Southeast Asia are the primary factors that affect the strong chemical weathering in the study area,followed by the nature of the parent rock.

Distribution of benthic macrofaunal communities in intertidal flat under hydrodynamic influence:a case study of Jiangsu coast,East China

To identify the distribution pattern of macrofaunal assemblages of the Dafeng intertidal flats in response to hydrodynamic and sediment dynamic processes in the northern Jiangsu coast,East China,macrofauna sampling and hydrodynamic observations were carried out simultaneously across the mud flat,mixed mud-sand flat,and silt-sand flat of the intertidal zone in June 2018.Results show that there was a clear zonal distribution pattern of the macrofaunal communities,as is controlled by local hydrological and sedimentary environments.Principal component analysis(PCA)revealed three types of intertidal area in terms of hydrological and surficial sediment parameters.Similarly,three distinct groups of the macrofaunal communities,i.e.,mud flat,mix mud-sand,and silt-sand groups,were recognized at similarity level of 24%based on the CLUSTER analysis in similarity profile(SIMPROF)test.Correlation analysis upon best variables stepwise search(BVSTEP)indicated the importance of the hydrodynamics(e.g.,water temperature and salinity,tidal duration,flow speed,suspended sediment concentration,and wave height)in the differentiation of macrofaunal communities with different taxonomic classes over the intertidal zone.Therefore,macrofaunal assemblages,similar to hydrology and surficial sediment,have a unique zonation pattern.Small-sized deposit feeders adapt better to low energy environments,thus dominated the upper part of the intertidal flat,whilst the heavy and large-sized filter feeders and deposit feeders were dominant over the middle and lower parts.The hydrodynamic and sediment processes cause biota-niche separation,which affected the biological processes across the intertidal flat.