Development of a new model tool for evaluating groundwater resources within the Floridan Aquifer System in Southern Florida,USA

The US Army Corps of Engineers (USACE) and the South Florida Water Management District (SFWMD) are partners in an ambitious plan to restore water flows throughout the Everglades ecosystem. An important component of the restoration plan involves storing excess stormwater deep underground in the Floridan Aquifer System using aquifer, storage and recovery (ASR) wells. In order to determine the optimal ASR system and to assess environmental impacts, USACE spent over 11 years and significant resources to develop a three-dimensional groundwater model of the Floridan Aquifer System covering a large portion of the Florida peninsula. This SEAWAT model is capable of evaluating changes in aquifer pressures and density-dependent flows in the entire study area. The model has been used to evaluate the Everglades ASR system already but could also be used by water managers for other important water resources studies in Florida including water supply estimates and adaptation to climate change. As part of an effort to make the model more readily available for other important studies, this study documents and summarizes the overall development of the SEAWAT model including a discussion regarding the intensive calibration and validation efforts undertaken during model development. The paper then demonstrates the use of the model using Everglades ASR project alternatives. Lastly, the paper outlines potential future uses of the model along with its overall limitations. Supplementary online resources are also included that provide researchers with further detail regarding the model development effort beyond the scope of this summary article as well as model development databases.     

Notes on the origin of inertinite macerals in coals: Observations on the importance of fungi in the origin of macrinite

Macrinite is a, generally, rare inertinite maceral, often incorporating remnants and fragments of other macerals, including vitrinite, liptinite, and other inertinite. The associated inertinites include multiple forms of funginite. Funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite. Together with the highly degraded macrinite, the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat. In any case, the origin of some macrinite is potentially distinct from that of inertinite generated by fire.     

Use of the clam Asaphis deflorata as a potential indicator of organochlorine bioaccumulation in Hong Kong coastal sediments

In order to test its ability as a bioaccumulator, the deposit feeding clam Asaphis deflorata, collected from a clean coastal area in Hong Kong (Ding Chau, Ma On Shan), was exposed to field-collected sediments representing a gradient of contamination. Sediments were collected from four sites, namely Shek O in the southeast of Hong Kong Island, Ap Lei Chau in Aberdeen district, Tai Kok Tsui in the Mong Kok waterfront, and To Kwa Wan near Kowloon City pier. Shek O was the cleanest and To Kwa Wan was the most polluted site. Replicate 30L fiberglass tanks containing equal numbers of organisms were maintained for 28 days, with equal quantities of sediment and filtered seawater. Prior to this the animals were depurated for 10 days in clean sediment. During the 28-day holding period, sampling of both sediment and clams was performed on days 0, 10 and 28, along with condition index measurements. Concentrations of organochlorine pesticides and PCBs in sediments showed that Shek O was the cleanest of the sites, followed by Ap Lei Chau, Tai Kok Tsui and To Kwa Wan. There were marked differences among the sites, especially in PAH concentrations, with To Kwa Wan showing extremely high sediment concentrations. Following exposure, the biota concentrations of various organochlorine pesticides and PCBs suggested that there was sediment concentration-dependent accumulation by A. deflorata on day 10 of the experiment. However, there was no significant increase on day 28 for any of the compounds tested. Contaminant concentrations in clams feeding on Shek O sediments were minimal and almost the same on all sampling days, indicating the presence of only baseline contaminant concentrations. The condition indices (CI) of the clams on various sampling days showed that the animals were relatively more stable in sediment from Shek O. There were some deaths in all the test tanks (including those containing Shek O sediments). In addition, clams appeared to bury faster in the cleaner Shek O sediment and remained buried, unlike those in the sediment from the other locations, where some remained predominantly on the surface. Nevertheless, despite not completely burying, the clams in other test sediments still exhibited sediment concentration-dependent tissue accumulation. The results of the investigation indicate the possibility of developing a standard test protocol for bioaccumulation by sediment dwelling invertebrates, for practical use in Hong Kong, using A. deflorata.     

Use of the clam Asaphis deflorata as a potential indicator of organochlorine bioaccumulation in Hong Kong coastal sediments

In order to test its ability as a bioaccumulator, the deposit feeding clam Asaphis deflorata, collected from a clean coastal area in Hong Kong (Ding Chau, Ma On Shan), was exposed to field-collected sediments representing a gradient of contamination. Sediments were collected from four sites, namely Shek O in the southeast of Hong Kong Island, Ap Lei Chau in Aberdeen district, Tai Kok Tsui in the Mong Kok waterfront, and To Kwa Wan near Kowloon City pier. Shek O was the cleanest and To Kwa Wan was the most polluted site. Replicate 30 L fiberglass tanks containing equal numbers of organisms were maintained for 28 days, with equal quantities of sediment and filtered seawater. Prior to this the animals were depurated for 10 days in clean sediment. During the 28-day holding period, sampling of both sediment and clams was performed on days 0, 10 and 28, along with condition index measurements. Concentrations of organochlorine pesticides and PCBs in sediments showed that Shek O was the cleanest of the sites, followed by Ap Lei Chau, Tai Kok Tsui and To Kwa Wan. There were marked differences among the sites, especially in PAH concentrations, with To Kwa Wan showing extremely high sediment concentrations.Following exposure, the biota concentrations of various organochlorine pesticides and PCBs suggested that there was sediment concentration-dependent accumulation by A. deflorata on day 10 of the experiment. However, there was no significant increase on day 28 for any of the compounds tested. Contaminant concentrations in clams feeding on Shek O sediments were minimal and almost the same on all sampling days, indicating the presence of only baseline contaminant concentrations. The condition indices (CI) of the clams on various sampling days showed that the animals were relatively more stable in sediment from Shek O. There were some deaths in all the test tanks (including those containing Shek O sediments). In addition, clams appeared to bury faster in the cleaner Shek O sediment and remained buried, unlike those in the sediment from the other locations, where some remained predominantly on the surface. Nevertheless, despite not completely burying, the clams in other test sediments still exhibited sediment concentration-dependent tissue accumulation. The results of the investigation indicate the possibility of developing a standard test protocol for bioaccumulation by sediment dwelling invertebrates, for practical use in Hong Kong, using A. deflorata.     

A steady-state model of NEA binaries formed by tidal disruption of gravitational aggregates

We present results of a simulation of a steady-state binary near-Earth asteroid (NEA) population. This study combines previous work on tidal disruption of gravitational aggregates [Walsh, K.J., Richardson, D.C., 2006. Icarus 180, 201-216] with a Monte Carlo simulation of NEA planetary encounters. Evolutionary effects include tidal evolution and binary disruption from close planetary encounters. The results show that with the best known progenitor (small Main Belt asteroids) shape and spin distributions, and current estimates of NEA lifetime and encounter probabilities, that tidal disruption should account for approximately 1-2% of NEAs being binaries. Given the best observed estimate of a ∼15% binary NEA fraction, we conclude that there are other formation mechanisms that contribute significantly to this population. We also present the expected distribution of binary orbital and physical properties for the steady-state binary NEAs formed by tidal disruption. We discuss the effects on binary fraction and properties due to changes in the least constrained parameters, and other possible effects on our model that could account for differences between the presented results and the observed binary population. Finally, we model possible effects of a significant population of binaries migrating to the near-Earth population from the Main Belt.     

Antibiotics in the Hong Kong metropolitan area: Ubiquitous distribution and fate in Victoria Harbour

We investigated the presence and fate of 16 antibiotics belonging to seven groups (β-lactams, fluoroquinolones, macrolides, sulfonamides, tetracyclines, trimethoprim and amphenicols) in effluents of sewage plants and receiving waters in Hong Kong. Cefalexin, amoxicillin, ofloxacin and erythromycin-H₂O were ubiquitous in sea water throughout Victoria Harbour, indicating continuous discharge to the environment. This is one of the few studies reporting the frequent occurrence of cefalexin and amoxicillin in sewage effluents and sea water (170-5070 and 64-1670 ng/L in sewage; 6.1-493 and 0.64-76 ng/L in sea water, respectively). Mass flows from seven sewage plants discharged an estimated total of 14.4 kg/day to the Harbour. Typhoon shelters also appeared to play an important role as sources of antibiotics, as evidenced by elevated concentrations within their boundaries. Mass balance estimations suggested significant quantities of antibiotics are discharged to the Harbour without passage through treatment plants.     

龙门山彭县-灌县断裂的活动构造与地表破裂

2008年5月12日在龙门山发生了8.0级特大地震,彭县-灌县断裂亦发生了同震地表破裂.在前期对龙门山活动构造研究的基础上,汶川特大地震发生后,在灾区进行了多次的野外调查和国际合作考察,重点对汶川地震的地表破裂和地质灾害开展了详细的详细野外地质填图,利用全站仪和GPS对地表破裂进行了精确的测量,研究了的地表破裂地貌错位、构造组合和运动学,已实地测得地表破裂数据70余组(其中彭县-灌县断裂地表破裂数据20余组).文章以彭县-灌县断裂地表破裂为切入点,在彭县-灌县断裂的关键部位开展了详细的野外地貌测量,主要测量了彭州磁峰、白鹿、绵竹金花和汉旺等地的地表破裂,标定了彭县-灌县断裂破裂带的垂向断距和水平断距,结果表明该地表破裂南西起于彭州磁峰,向北东延伸经白鹿、绵竹金花至绵竹汉旺,全长约40～50km.地表破裂带沿彭县-灌县断裂带的走向断续分布,单个破裂长度在几米到500余米不等,破裂带切割了多种类型的地貌单元,包括山脉基岩、河流阶地、冲洪积扇、公路、桥梁等,同时也使道路发生拱曲、破坏和桥梁垮塌或移位.其以脆性破裂为特征,以逆冲一右旋走滑为特点,断面倾角较陡,北西盘为上升盘,南东盘为下降盘,垂直位错介于0.39～2.70m之间,水平位错介于0.20～0.70m,平均垂直位错为1.6m,平均水平位错为0.6m;地表最大错动量的地点位于彭州白鹿镇,其中最大垂直断错为2.7±0.2m,最大水平断错为0.7±0.2m.垂直位错与水平位错量之间的比值为2:1,表明该地震地表破裂带不仅存在逆冲运动分量和右旋走滑运动分量,而且逆冲运动分量大于右旋走滑运动分量,显示了彭县-灌县断裂破裂带具有以逆冲和缩短作用为主、右旋走滑作用为辅的破裂性质.其与映秀-北川断裂带的地表破裂相比较,该断裂的地表破裂程度远小于映秀-北川断裂带的地表破裂程度,主要表现在地表破裂的长度较短,垂直位错和水平位错也相对较小,而且为以逆冲作用为主.初步研究结果表明,彭县-灌县断裂与映秀-北川断裂地表破裂的平面组合样式显示为两条在平面上近于平行的北东向地表破裂带,其间由一条南北向的次级地表破裂带(小鱼洞断裂)将它们相连结,地下破裂面的剖面组合样式显示为叠瓦状,并在汶川地震震源附近或震源的上方相连的,是同"根"的.     

The formation of asteroid satellites in large impacts: results from numerical simulations

We present results of 161 numerical simulations of impacts into 100-km diameter asteroids, examining debris trajectories to search for the formation of bound satellite systems. Our simulations utilize a 3-dimensional smooth-particle hydrodynamics (SPH) code to model the impact between the colliding asteroids. The outcomes of the SPH models are handed off as the initial conditions for N-body simulations, which follow the trajectories of the ejecta fragments to search for the formation of satellite systems. Our results show that catastrophic and large-scale cratering collisions create numerous fragments whose trajectories can be changed by particle-particle interactions and by the reaccretion of material onto the remaining target body. Some impact debris can enter into orbit around the remaining target body, which is a gravitationally reaccreted rubble pile, to form a SMAshed Target Satellite (SMATS). Numerous smaller fragments escaping the largest remnant may have similar trajectories such that many become bound to one another, forming Escaping Ejecta Binaries (EEBs). Our simulations so far seem to be able to produce satellite systems qualitatively similar to observed systems in the main asteroid belt. We find that impacts of 34-km diameter projectiles striking at 3 km s⁻¹ at impact angles of ∼30° appear to be particularly efficient at producing relatively large satellites around the largest remnant as well as large numbers of modest-size binaries among their escaping ejecta.     

Partitioning of rainfall in a eucalypt forest and pine plantation in southeastern australia: III determination of the canopy storage capacity of a dry sclerophyll eucalypt forest

The canopy storage capacity of a dry sclerophyll eucalypt forest was determined. This required destructive sampling of three major species of trees and development of a water soakage method for the measurement of water holding capacity of all above ground components. The influence of antecedent weather conditions on canopy storage capacity was assessed. It was shown that the interactive effects of leaf area and water holding capacity of all tree components were such that the estimated canopy storage capacity (0-39 mm) was likely to change little except under extreme conditions of drought and rainfall. The effect of species composition on forest canopy storage capacity is also presented. The wetting processes are described and compared with those discussed in other studies. They are shown to be relevant to the estimation of canopy storage capacity in almost any forest.