The water budget myth revisited: why hydrogeologists model

Within the ground water community, the idea persists that if one can estimate the recharge to a ground water system, one then can determine the size of a sustainable development. Theis addressed this idea in 1940 and showed it to be wrong-yet the myth continues. The size of a sustainable ground water development usually depends on how much of the discharge from the system can be "captured" by the development. Capture is independent of the recharge; it depends on the dynamic response of the aquifer system to the development. Ground water models were created to study the response dynamics of ground water systems; it is one of the principal reasons hydrogeologists model.     

Pore water testing and analysis: the good,the bad,and the ugly

The increasingly common practice of collecting and assessing sediment pore water as a primary measure of sediment quality is reviewed. Good features of this practice include: pore water is a key exposure route for some organisms associated with sediments; pore water testing eliminates particle size effects; pore water analyses and tests can provide useful information regarding contamination and pollution. Bad features include: pore water is not the only exposure route; pore water tests lack chemical or biological realism: their "sensitivity" relative to other tests may be meaningless due to manipulation and laboratory artifacts; many sediment and surface dwelling organisms are not directly influenced by pore water. Bad features can become ugly if: other exposure pathways are not considered (for toxicity or bioaccumulation); manipulation techniques are not appropriate; pore water tests are inappropriately linked to population-level effects. Pore water testing and analyses can be effective tools provided their limitations are well understood by researchers and managers.     

中途日落油田利用水平井优化成熟蒸汽驱

钻在中途日落油田陡倾斜的Ｓｕｂ－Ｈｏｙｔ“Ｅ”砂层上的三口短半径水平井显示了很好的开采动态。这些成功促使进行一项三维热采数值模拟研究以评价其它水平井潜力，及优化其余的蒸汽驱开发方案。     

Geography and math: a technique for finding population centers

In the absence of core requirements that secondary and/or college-level students fulfill specific geography proficiency standards prior to graduation, geography will continue to be taught informally by teachers as a corollary to other major disciplines. These teachers, however, generally lack formal training in the concepts and sheer information of the geography field. Moreover, available texts at these levels tend to simply present statistical data on countries and maybe compare them to those for other countries. The duty of explaining spatial distribution and density implications falls upon the teacher. The basic mathematical concepts of mean and media are easy measures which can be used by teachers to teach the concepts of mean center and median of a population distribution. The processes by which these central points are determined are described and applied respectively to province and state data for China and the US as suggested student activities for practice and discussion.     

Signatures of Divergence and Self-Organization in Soils and Weathering Profiles

Complex system behaviors such as self-organization are difficult to address in geology. System evolution often cannot be directly observed and, in geology models and theory, must be reconciled with field evidence. However, self-organization can be addressed within the historical-interpretive paradigm by applying a measure of the degree of self-organization of geologic features, using standard interpretive methods to determine the nature of changes, and determining whether those changes result in an increase or decrease in organization. In this way, stable non-self-organizing convergent development can be distinguished from unstable chaotic self-organizing divergent development. Kolmogorov entropy (K-entropy) was used as a measure of the self-organization of soil profiles in eastern North Carolina. In general, the profiles are low in K-entropy, indicating a generally high level of predictability and information in the vertical arrangement of pedogenetic horizons. As a broad generality, the study profiles appear to be decreasing in entropy if or when surface erosion is minimal and increasing in entropy otherwise. However, results show that whether the profiles demonstrate evidence of convergent or divergent behavior is determined by the relative rates or magnitudes of three main processes: (1) horizon differentiation in surficial horizons by the formation of transitional AE or A&E horizons due to secondary podzolization, (2) thickening of the solum at the weathering front, and (3) surface erosion. There is no direct relationship between the degree of pedogenic development and self-organization. The results suggest that complex system behaviors are controlled by, and can be linked to, specific pedologic and geomorphic processes and that soils and regoliths may be characterized by both convergent and divergent developmental pathways.     

Water Discharge and Sediment Load from the Western Slopes of the Colombian Andes with Focus on Rio San Juan

Small rivers draining high-rainfall basins and mountainous terrain west of the Cordilleras in South America have disproportionately high water discharge and sediment load. Fifteen rivers in western Colombia discharge a combined 254 km3 yr-1 or 8020 m3 s-1 of water into the Pacific. Sediment yield is strongly correlated with basin area (R2=0.97), and sediment load is correlated with water discharge (R2=0.73). Rio San Juan occupies a 16,465-km2 basin with a mean annual rainfall of 7277 mm. It has the highest water discharge (2550 m3 s-1), sediment load (16x106 t yr-1), and basin-wide sediment yield (1150 t km-2 yr-1) on the entire west coast of South America. Rio Patía drains a 23,700-km2 basin with a mean annual rainfall of 2821 mm. Its water discharge, sediment load, and basin-wide sediment yield are 1291 m3 s-1, 14 t yr-1, and 972 t km-2 yr-1, respectively. Rio San Juan and Rio Patía deliver 30x106 t of suspended sediment annually into the Pacific. Analysis of data for an additional 22 rivers in Colombia that drain into the Caribbean Sea indicates that the Pacific rivers have at least twice the sediment yield compared with the larger Rio Magdalena. Our results confirm that the Pacific rivers of Colombia need to be accounted for in global sediment budgets.     

Relative risk assessment of cruise ships biosolids disposal alternatives

A relative risk assessment of biosolids disposal alternatives for cruise ships is presented in this paper. The area of study encompasses islands and marine waters of the Caribbean Sea. The objective was to evaluate relative human health and ecological risks of (a) dewatering/incineration, (b) landing the solids for disposal, considering that in some countries land-disposed solids might be discharged in the near-shore environment untreated, and (c) deep ocean disposal. Input to the Bayesian assessment consisted of professional judgment based on available literature and modeling information, data on constituent concentrations in cruise ship biosolids, and simulations of constituent concentrations in Caribbean waters assuming ocean disposal. Results indicate that human health and ecological risks associated with land disposal and shallow ocean disposal are higher than those of the deep ocean disposal and incineration. For incineration, predicted ecological impacts were lower relative to deep ocean disposal before considering potential impacts of carbon emissions.     

The atmospheric lead record preserved in lagoon sediments at a remote equatorial Pacific location: Palmyra Atoll, northern Line Islands

Anthropogenic lead (Pb) inputs to the atmosphere increased greatly over the past century and now dominate Pb supply to the oceans. However, the Pb content of sediments across the equatorial Pacific region is relatively unknown, and data exist only for deep sea sites where Pb deposition lags surface water inputs by up to a century. Here we present ICP-MS analyses of Pb of a core from a lagoon at Palmyra Atoll, northern Line Islands, that spans approximately the past 160 years. The non-bioturbated sediments of the euxinic lagoon, coupled with rapid rates of deposition, provide a unique fine-scale record of atmospheric Pb supply at a remote Pacific location. These first observations of historic Pb sedimentation in an atoll lagoon reveal a 63-fold increase in Pb flux to sediments during the past century and correlate directly with the North American consumption of leaded gasoline that began in 1926.