Regional distribution pattern of groundwater heavy metals resulting from agricultural activities

Contaminations of groundwater by heavy metals due to agricultural activities are growing recently. The objective of this study was to evaluate and map regional patterns of heavy metals (Cd, Zn and Cu) in groundwater on a plain with high agricultural activities. The study was conducted to investigate the concentration of heavy metals and distribution in groundwater in regions of Shush Danial and Andimeshk aquifers in the southern part of Iran. Presently, groundwater is the only appropriate and widely used source of drinking water for rural and urban communities in this region. The region covers an area of 1,100 km² between the Dez and Karkhe rivers, which lead to the Persian Gulf. For this study, the region was divided into four sub-regions A, B, C and D. Additionally, 168 groundwater samples were collected from 42 water wells during the earlier months of 2004. The flame atomic absorption spectrometry (AAS-Flame) was used to measure the concentration of heavy metals in water samples and the Surfer software was used for determination of the contour map of metal distribution. The results demonstrated that in all of the samples, Cd and Zn concentrations were below the EPA MCLG and EPA secondary standard, respectively. However, the Cu contents of 4.8 % of all samples were higher than EPA MCL. It is also indicated that the concentrations of metals were more pronounced at the southern part of the studied region than at the others. The analysis of fertilizers applied for agricultural activities at this region also indicated that a great majority of the above-mentioned heavy metals were discharged into the environment. Absence of confining layers, proximity to land surface, excess agricultural activities in the southern part and groundwater flow direction that is generally from the north to the southern parts in this area make the southern region of the Shush plain especially vulnerable to pollution by heavy metals than by other contaminants.     

Introducing a new conceptual instantaneous unit hydrograph model based on a hydraulic approach

ABSTRACT

A novel approach is introduced for simulation of instantaneous unit hydrographs (IUHs). The model consists of a series of linear reservoirs that are connected to each other, and is referred to as the inter-connected linear reservoir model (ICLRM). By assuming the flow between two reservoirs is a linear function of the difference between the water levels in the reservoirs, a system of first-order linear differential equations is obtained as the ICLRM governing equation. By solving the equations, the discharge from the last reservoir is considered as an IUH. A small-scale laboratory device was constructed for the simulation of IUHs using the model. By studying four hydrographs extracted from the literature, and simulating them using both the ICLRM and the Nash model, it is concluded that the ICLRM can predict these hydrographs more accurately than the Nash model. Due to the simplicity of the construction and operation of the ICLRM and, more importantly, its visual aspect, the ICLRM may be considered as an effective educational tool for studying IUHs.     

Petrogenesis of post-collisional A-type granitoids from the Urumieh–Dokhtar magmatic assemblage,Southwestern Kerman,Iran: Constraints on the Arabian–Eurasian continental collision

Three plutons (Deh-Siahan, Bande-Bagh and Baghe-Khoshk Sharghi, collectively referred to as the DBB hereafter) in southwestern Kerman, in the southeastern part of the Urumieh–Dokhtar magmatic assemblage (UDMA) of the Zagros orogenic belt differ from the typical calc-alkaline metaluminous, I-type intrusions of the region. The DBB intrusions have a distinct lithological assemblage varying from diorite through monzogranite and monzonite to alkali feldspar syenite and alkali granite. The DBB granitoids are metaluminous to slightly peraluminous, alkaline to shoshonitic in composition and have high total alkali contents with K₂O > Na₂O, high FeO_T/MgO values, and low CaO and MgO contents. They are enriched in some LILEs (such as Rb and Th) and HFSEs (such as Zr, Y and REEs except Eu) and depleted in Sr and Ba relative to primordial mantle, and have low concentrations of transitional metals. These features along with various geochemical discriminant diagrams suggest that the DBB granitoids are post-collisional A-type granitoids, which had not been recognized previously in the UDMA. The chondrite-normalized REE patterns of the DBB granitoids show slightly enriched light REEs [(La/Sm)_N = 2.26–4.13], negative Eu anomalies [(Eu/Eu*)_N = 0.19–0.74] and flat heavy REE patterns [(Gd/Yb)_N = 0.80–1.87]. The negative Eu anomaly indicates an important role for plagioclase and/or K-feldspar during fractional crystallization. Whole-rock Rb–Sr isotope analysis yields an isochron age of 33 ± 1 Ma with an initial ⁸⁷Sr/⁸⁶Sr value of 0.7049 ± 0.0001. Whole-rock Sm–Nd isotope analysis gives ε_Nd^t values from + 2.56 to + 3.62 at 33 Ma. The positive ε_Nd^t and low I_Sr values of the DBB granitoids together with their T_DM of 0.6–0.7 Ga suggest their formation from partial melting of a lithospheric mantle source, modified by fluids or melts from earlier subduction processes. Melting of lithospheric mantle occurred via a dehydration melting process at pressures below the garnet stability field, as a consequence of lithospheric mantle delamination or break-off of a subducted slab and melting of the lithospheric mantle by upwelling of hot asthenosphere. On the basis of Rb/Sr age dating and the post-collisional geochemical signatures of the DBB granitoids, along with extensive pre-collisional volcanic eruptions in Middle Eocene, we suggest Late Eocene for the time of collision between the Arabian and Central Iranian plates. This also implies that the calc-alkaline I-type intrusions in the southwestern Kerman and in other parts of the UDMA may have formed in a post-collisional context.     

Factors associated with unnecessary requests for an ambulance by non-traumatic patients after the acute earthquake responding phase: a qualitative content analysis

The pre-hospital emergency staff played a key role in transferring the injured patients to health centers. Usually, they reported changes in their decisions on the transfer of non-traumatic patients to hospitals. So, this study was aimed to explore the reasons for unnecessarily requesting an ambulance by non-traumatic patients after the acute responding-to-earthquake phase. This study was a qualitative study that data were analyzed by content analysis approach. Participants were eleven pre-hospital emergency technicians. Data were collected by three sessions of focus group discussion. Data analysis was led to emergence of a main theme: “feeling urgency due to turmoil and uncertainty.” This theme illustrates the basic approach of the inhabitants of the earthquake-stricken region when unnecessarily requesting an ambulance. This theme was derived from two main categories of “turbulent and uncertain conditions” and “psychological turmoil.” The category of “turbulent and uncertain conditions” was comprised of three subcategories: “unreliable care,” “inadequate facilities” and “turbulent living conditions.” The category of “psychological turmoil” was comprised of three subcategories: “psychological turmoil in survivors,” “healthcare providers deciding under pressure” and “turmoil in providing psychological and psychiatric services.” Ambulance dispatch may be unnecessarily performed owing to turbulent and unsure conditions and psychological turmoil in earthquake-stricken people and pre-hospital emergency staff. Providing earthquake-stricken people with psycho-medical services in their place of residence can significantly reduce the workload of pre-hospital emergency staff and consequently that of hospital staff and therefore save time and treatment costs and increase the quality of health services provided for the injured.

     

Assessing building vulnerability to tsunami using the PTVA-3 model: A case study of Chabahar Bay,Iran

Chabahar Bay, in southeastern Iran, lies at the north of the Gulf of Oman and close to the Makran Subduction Zone, which makes it a region that is susceptible to tsunamis. This bay has an increasingly important role in Iran’s international trade, and therefore the assessment of the regional vulnerability to the effects of a tsunami is vital. Based on both the details of historical events and the results of numerical modeling of the propagation pattern of a tsunami in this region, this study assessed the vulnerability of buildings within the Chabahar Bay region to a tsunami event. The Papathoma Tsunami Vulnerability Assessment (PTVA) model was used to calculate a relative vulnerability index (RVI) for the affected buildings based on their physical and structural characteristics. The results showed that in a postulated worst-case-scenario tsunami event in the Chabahar Bay area, approximately 60 % of the residential buildings would be affected, a level of damage that is categorized as “Average” in the RVI classification. Overall, the economic losses related to the damage of residential buildings due to a tsunami in the Chabahar Bay area are anticipated to be the equivalent of US$ 16.5 million.     

Soil bentonite wall protects foundation from thrust faulting: analyses and experiment

When seismic thrust faults emerge on the ground surface,they are particularly damaging to buildings,bridges and lifelines that lie on the rupture path.To protect a structure founded on a rigid raft,a thick diaphragm-type soil bentonite wall(SBW) is installed in front of and near the foundation,at sufficient depth to intercept the propagating fault rupture.Extensive numerical analyses,verified against reduced–scale(1 g) split box physical model tests,reveal that such a wall,thanks to its high deformability and low shear resistance,"absorbs" the compressive thrust of the fault and forces the rupture to deviate upwards along its length.As a consequence,the foundation is left essentially intact.The effectiveness of SBW is demonstrated to depend on the exact location of the emerging fault and the magnitude of the fault offset.When the latter is large,the unprotected foundation experiences intolerable rigid-body rotation even if the foundation structural distress is not substantial.     

Computing eddy-current response and current-channeling response of the spheroidal conductor for the separated receiver and transmitter systems

In this article the response of the induced eddy-current in an unlimited conduction spheroidal as well as the response of the current-channeling resulted from the presence of the spheroidal in a weakly conducted medium are derived. The common methods are based on receiving electromagnetic induction response from the homocentric and coaxial receiver and transmitter coils which are exactly over the anomaly. As the spheroidal location is unknown in the practice, it is suggested to measure the electromagnetic induction response in a case that the receiver and the transmitter have an arbitrary situation regarding to the anomaly. In this article, eddy-current response and current-channeling response of the spheroid have been computed in a more general case in which at least one axis of spheroid and the dipole axes of the receiver and transmitter coils are on the same plate; however, none of the coils are laid over the anomaly. Using this method, we can determine the location and the depth of the spheroid through fixing the transmitter’s position and of the receivers’ coil movements.