Numerical study of coastal sandbar migration, by hydro-morphodynamical coupling

We present a numerical model based on the hydro-morphodynamical coupling to study coastal sandbar migration. In order to improve both nonlinear and dispersive wave processes in relatively shallow water, we developed a finite element model based on the Legendre polynomials and on the Extended Boussinesq model. This model reproduces the propagation of wave trains with a high degree of accuracy on a greater range of depths than the standard Boussinesq models. We also implemented the Total Variation Diminishing schemes to improve the quality of the computed hydrodynamic fields, especially in areas where sharp flow gradients occurred. The coupled morpho-hydrodynamical model is then used to simulate the migration of real sandbars observed at Rousty beach (Mediterranean French coast). For verification the model results are compared with field measurements obtained from a small-scale field campaign carried out over two years at Rousty beach, and the results of this comparison are thoroughly discussed and analyzed.     

Carbon monoxide levels at a toll plaza near Durban, South Africa

Reliable measurements of pollutant levels in the vicinity of a toll plaza appear to be rare. In order to assess the exposure of toll booth operators to carbon monoxide, a continuous carbon monoxide monitor was installed at head height in the booth of a medium density traffic lane at the Mariannhill toll plaza, situated on a busy highway near Durban, South Africa. Measurements in excess of 500 ppmv were recorded and the high daily mean carbon monoxide concentrations may account for some of the symptoms such as headaches and general malaise that have been reported by workers in the booths. Generally, carbon monoxide levels recorded far exceed the recommended limit set by the South African authorities. These results have led to recommendations regarding the structure of new and existing toll booths to minimize the exposure of toll booth workers to adverse effects of vehicle-emitted pollutants.     

Integrated remote sensing and GIS techniques for landslide hazard zonation: a case study Wadi Watier area,South Sinai,Egypt

Natural hazard analysis involves mapping and identifying future hazardous zones through the analysis of the controls influencing hazard initiation and occurrence. One of such natural hazard is the landslide. Landslides are amongst the most costly and damaging natural hazards especially in mountain regions and are triggered mainly by seismic activity and/or rainfall. The aim of the present study is to integrate Remote Sensing (RS) and Geographic Information System (GIS) tools to create thematic layers for assessment and the estimation of landslide hazard zones in and surrounding the Wadi Watier area, South Sinai, Egypt. Various factors, variables and/or parameters can be derived from thematic layers such as lithology, structural lineaments, land-cover/land-use, terrain analysis and earthquakes. Intensity risk layers were created by using ERDAS Imagine 9.2, ARC GIS 9.2 and ARC INFO 7.2.1 software. Enhanced Thematic Mapper (ETM+7) Landsat satellite images were used to discriminate and extract structural lineaments, lithology and land-use/land-cover variables for the study area. The Digital Elevation Model (DEM) was generated from digitized topographic maps to produce terrain analysis maps such as; slope, aspect, height elevation, and 3D. The weighting score rating system based on the relative importance of various causal factors derived from RS data and other thematic layers was used for landslide hazard zonation (LHZ). Based on these data, a simple algorithm was created to classify the area into different risk zones. By overlaying all hazard layers a final landslide hazard map was produced. Using trial and error and statistical methods the weight score rating values have been readjusted. GIS integration with RS data can greatly facilitate classifying landslide hazard zones into low risk, moderate risk and high risk by using a slicing operation. Seismic data are integrated with final the LHZ to generate a LHZ scenario map for the future and to draw up an action plan of mitigation measures to avoid the damage, loss of life and socio-economic impacts in the study area.     

Are sea snakes pertinent bio-indicators for coral reefs? a comparison between species and sites

Classical sampling methods often miss important components of coral reef biodiversity, notably organisms that remain sheltered within the coral matrix. Recent studies using sea kraits (sea snakes) as bio-indicators suggest that the guild of predators represented by anguilliform fish (Congridae, Muraenidae, Ophichthidae, henceforth “eels” for simplicity) were far more abundant and diverse than previously suspected. In the current study, eel diversity (similarity and species richness indices) estimated via sea snake sampling (SSS) was compared among six areas of one of the main oceanic biodiversity hotspot of the Pacific Ocean (southwest lagoon of New Caledonia). Based on the eel diversity in the snakes’ diet, the results obtained in six areas, in two snake species, and using different estimates (ANOSIM, Shannon index…) were consistent, suggesting that SSS provided robust information. Analyses also suggested subtle, albeit significant, differences in the eel assemblages among islets. Such spatial differences are discussed in light of local management practices. As SSS is easy to use, cost-effective, and provides the best picture of eel assemblages to date, it can be employed to monitor the eel assemblages in addition to the snakes themselves in many areas of the Indo-Pacific Ocean, thereby providing an index of the top predator biodiversity of many coral reefs.     

北方低温条件下沼渣资源化培育佛甲草的应用研究

为克服厌氧发酵沼渣中碳氮磷比严重失调、可生化性差、总氮和总磷浓度高等难以直接资源化利用的难题,同时为北方秋冬季节低温条件下海绵城市建设过程中推广绿色屋顶提供技术支撑,通过调节基质中本地砂质壤土与厌氧发酵沼渣的比例,在北方秋冬季节室外培育佛甲草并研究其生长状态。结果表明:沼渣显著降低了基质的容重,减轻了屋顶的承受负荷;增大了基质的孔隙度,更适宜佛甲草根系下扎生长。基质中添加沼渣改善了低温条件下佛甲草的生长状况,增加了佛甲草的株高和覆盖度,提高了其分蘖能力及叶绿素总量;品质评价得分均高于6分,表明佛甲草的生长基本正常;低温条件下,沼渣和砂质壤土按4:5混配后的基质培育出的佛甲草综合品质最优。     

Coxsackievirus B4 as a Causative Agent of Diabetes Mellitus Type 1: Is There a Role of Inefficiently Treated Drinking Water and Sewage in Virus Spreading?

This study proposed to detect the enterovirus (EV) infection in children with type 1 diabetes mellitus (T1D) and to assess the role of insufficiently treated water and sewage as sources of viral spreading. Three hundred and eighty-two serum specimens of children with T1D, one hundred serum specimens of children who did not suffer from T1D as control, and forty-eight water and sewage samples were screened for EV RNA using nested RT-PCR. The number of genome copies and infectious units of EVs in raw and treated sewage and water samples were investigated using real-time (RT)-PCR and plaque assay, respectively. T1D markers [Fasting blood glucose (FBG), HbA1c, and C-peptide], in addition to anti-Coxsackie A & B viruses (CVs A & B) IgG, were measured in control, T1D-negative EV (T1D–EV^?), and T1D-positive EV (T1D–EV⁺) children specimens. The prevalence of EV genome was significantly higher in diabetic children (26.2%, 100 out of 382) than the control children (0%, 0 out of 100). FBG and HbA1c in T1D–EV^? and T1D–EV⁺ children specimens were significantly higher than those in the control group, while c-peptide in T1D–EV^? and T1D–EV⁺ children specimens was significantly lower than that in the control (n = 100; p < 0.001). Positivity of anti-CVs A & B IgG was 70.7, 6.7, and 22.9% in T1D–EV⁺, T1D–EV^?, and control children specimens, respectively. The prevalence of EV genome in drinking water and treated sewage samples was 25 and 33.3%, respectively. The prevalence of EV infectious units in drinking water and treated sewage samples was 8.5 and 25%, respectively. Quantification assays were performed to assess the capabilities of both wastewater treatment plants (WWTPs) and water treatment plants (WTPs) to remove EV. The reduction of EV genome in Zenin WWTP ranged from 2 to 4 log₁₀, while the reduction of EV infectious units ranged from 1 to 4 log₁₀. The reduction of EV genome in El-Giza WTP ranged from 1 to 3 log₁₀, while the reduction of EV infectious units ranged from 1 to 2 log₁₀. This capability of reduction did not prevent the appearance of infectious EV in treated sewage and drinking water. Plaque purification was performed for isolation of separate EV isolates from treated and untreated water and sewage samples. Characterization of the EV amplicons by RT-PCR followed by sequencing of these isolates revealed high homology (97%) with human coxsackievirus B4 (CV B4) in 60% of the isolates, while the rest of the isolates belonged to poliovirus type 1 and type 2 vaccine strains. On the other hand, characterization of the EV amplicons by RT-PCR followed by sequencing for T1D–EV⁺ children specimens indicated that all samples contained CV B4 with the same sequence characterized in the environmental samples. CV B4-contaminated drinking water or treated sewage may play a role as a causative agent of T1D in children.     

南京冬季典型霾天气过程多元对比分析

选取2017～2020南京地区冬季3个典型霾天气过程,综合分析了霾天气过程中污染物、气象要素以及边界层条件等影响机制与特征变化.结果表明,3次过程中,AQI指数峰值分别为304(严重污染)、227(重度污染)与176(中度污染),且与PM2.5、PM10浓度变化基本趋于一致,PM25与PM10比值基本都大于0.7;污染...     

降雨和土地利用对地表径流的影响-以北京北护城河周边区域为例

以北京北护城河周边区域为例,探讨了降雨和土地利用对地表径流的影响。选取了2011-2012 年4-11 月的15 场降雨,分别代表小雨、中雨、大雨、暴雨、大暴雨和特大暴雨这6 个雨量级。利用校准的雨洪管理模型（Storm Water Management Model, SWMM）分别模拟每次降雨事件下研究区7 个控制断面的地表径流深度。结果表明,地表径流深度随降雨量的增加显著线性增加。当降雨量在不同量级之间变化时,地表径流深度的变化幅度不尽相同。在不同的降雨事件中,降雨量和地表径流深度随时间的动态变化趋势可能有很大的差异,但地表径流深度在某一时刻的值的高低均决定于之前1~2 h 的降雨量,而地表径流深度的总体上升或下降趋势均决定于前期累积的降雨量。地表径流深度随渗透面积比例的增加显著下降,且变化曲线存在临界阈值（为15%~20%）。在暴雨、大暴雨和特大暴雨时,渗透面积比例对地表径流的影响更大。研究结果可为控制汛期城市地表径流量和洪峰流量、减少城市内涝提供土地利用和管理方面的理论依据和决策建议。