Sorption influenced transport of ionizable pharmaceuticals onto a natural sandy aquifer sediment at different pH

The pH-dependent transport of eight selected ionizable pharmaceuticals was investigated by using saturated column experiments. Seventy-eight different breakthrough curves on a natural sandy aquifer material were produced and compared for three different pH levels at otherwise constant conditions. The experimentally obtained K_OC data were compared with calculated K_OC values derived from two different log K_OW-log K_OC correlation approaches. A significant pH-dependence on sorption was observed for all compounds with pK_a in the considered pH range. Strong retardation was measured for several compounds despite their hydrophilic character. Besides an overall underestimation of K_OC, the comparison between calculated and measured values only yields meaningful results for the acidic and neutral compounds. Basic compounds retarded much stronger than expected, particularly at low pH when their cationic species dominated. This is caused by additional ionic interactions, such as cation exchange processes, which are insufficiently considered in the applied K_OC correlations.     

Willingness to pay to improve domestic water supply in rural areas of Central Tanzania: Implications for policy

This analysis estimates willingness to pay to improve community-based rural water utilities in the Dodoma and Singida Regions of Central Tanzania, using Multinomial Logit functions. An estimate of willingness to pay provides an indication of the demand for improved services and potential for them being sustainable. Surveys were conducted in a total of 30 villages in the two regions. In the Dodoma Region, about 14% of respondents indicated that they were satisfied with the status quo, 64% suggested increasing water discharge and watering points, and 22% proposed other improvements relating to water quality. In the Singida Region, 31% of the respondents were satisfied with the status quo, 59% wanted deeper boreholes and watering points, and 10% indicated other types of improvement relating to water quality. The Multinomial Logit functions indicated that the interaction between the water quality variable and proposed bids were important in making choices with reference to the type of improvement desired. Respondents who wanted to increase water supply in Dodoma Region were willing to pay 32 Tsh above the existing tariff of 20 Tsh/bucket. In the Singida Region, the analogous amount was 91 Tsh per household per year above the existing user fee of 508 Tsh per household per year. If the tariff or user fees have to be increased, the estimated average potential revenue for the surveyed villages was 252 million Tsh/year (US$265 263) in the Dodoma Region, and 5.2 million Tsh/year (US$5474) in the Singida Region. In the future, strategic planning is needed to ensure that improvements proposed potentially improve cost recovery initiatives and increase the level of consumer satisfaction. Also, care will be needed to ensure that more disadvantaged community members do not suffer unduly from increases in tariff or user fees.     

QUALITY ASSURANCE TECHNIQUES FOR ELECTRONIC DATA ACQUISITION1

ABSTRACT: Electronic instruments are increasingly being used to gather water quality data. Quality assurance protocols are needed which provide adequate documentation of the procedures followed in calibration, collection, and validation of electronically acquired data. The level of precision of many data loggers exceeds the technology which is commonly used to make field measurements. Overcoming this problem involves using laboratory quality equipment in the field or enhanced quality control at the time of instrument servicing. Time control procedures for data loggers are needed to allow direct comparisons of data between instruments. Electronic instruments provide a mechanism to study transient events in great detail, but, without time controls, multiple loggers produce data which contain artifacts due to timing errors. Individual sensors deployed with data loggers are subject to different degrees of drift over time. Certain measurements can be measured with defined precision and accuracy for long periods of time, while other sensors are subject to loss of both precision and accuracy with increasing time of use. Adequate quality assurance requires the levels of precision and accuracy be documented, particularly those which vary with increasing time deployment.     

INCREASES IN SODIUM AND CHLORIDE IN THE MOHAWK RIVER,NEW YORK,FROM THE 1950'S TO THE 1970'S ATTRIBUTED TO ROAD SALT1

Regression analyses of major ion concentration in relation to specific conductance of water from the Mohawk River during two separate periods, 1951–53 and 1970–74, indicate statistically insignificant changes in the linear relationship of all constituents studied except chloride. Mean values and changes in the slopes of these relationships indicate that sodium and chloride have had consistently higher yields, in kilograms per square kilometer per year, than the other ions, although all ions show a general 20 percent increase in yields during the two decades. This general increase in ion yields is attributed to an accelerated transport rate of ions out of the basin as a result of a 19 percent increase in mean stream discharge. Transport rates of sodium and chloride have increased by 72 and 145 percent, respectively, in the Mohawk River since the early 1950's. Analysis of the sodium and chloride sources indicates rock salt used as a road deicei to be the primary source. This salt use accounts for 96 percent of the sodium transport increase and 69 percent of the chloride transport increase within the basin during the last two decades.     

WATER FOR ENERGY: AN APPROACH TO COMPREHENSIVE IMPACT ASSESSMENT1

ABSTRACT: The effects of energy development on the water resources of the Colorado River and Great Basin regions is expected to be substantial. Complex physical, economic and institutional interactions may be expected. Most research on these impacts appears single purpose, fragmented, uncoordinated, and often inaccessible to potential users - particularly those with responsibility for energy/water policy and program decisions. A comprehensive, integrative framework for assessing alternative water allocation decisions is outlined, taking a heuristic decision making model for evaluating impacts on maximization of gross (or net) regional product, and regional social welfare, and for assessing the region's contribution to national objectives. The suggested model provides a structure for application and integration of data of various kinds to a range of situations arising from possible impacts from energy proposals. The focus is on water and energy relationships but the model may provide a framework for comprehensive analysis of a variety of environmental actions and resulting system perturbations and effects.     

Conservation of Biodiversity: How Are We Doing?

A question rarely raised in discussions on biodiversity conservation, but surely the biggest question of all, is “How much time do we have left before the mass extinction underway surpasses our best efforts to contain it?” This prompts a further prime question because—and unlike all other problems, whether environmental or otherwise—the biotic crisis threatens to leave a severely impoverished planet for millions of years ahead; “Why do we not undertake the necessary actions to get on top of the problem before it gets on top of us?”     

The biodiversity challenge: Expanded hot-spots analysis

Summary This paper aims to throw light on the mass extinction that is overtaking Earth's species. Using an analytic methodology developed for an earlier partial assessment, it focuses on a series of hot-spot areas, these being areas that (a) feature exceptional concentrations of species with high levels of endemism, and (b) face exceptional threats of destruction. The paper identifies another eight such areas, four of them in tropical forests and four in Mediterranean-type zones. The analysis reveals that the four tropical-forest areas contain at least 2,835 endemic plant species in 18,700 km², or 1.1 percent of Earth's plant species in 0.013 percent of Earth's land surface; and that the four Mediterranean-type areas contain 12,720 endemic plan: species in 435,700 km², or 5.1 percent of Earth's plant species in 0.3 percent of the Earth's land surface. Taken together, these eight hot-spot areas contain 15,555 endemic plant species in 454,400 km², or 6.2 percent of Earth's plant species in 0.3 percent of Earth's land surface. This is to be compared with the earlier hot-spots analysis of 10 tropical-forest areas, with 34,400 endemic plant species in 292,000 km², or 13.8 percent of Earth's plant species in 0.2 percent of Earth's land surface.Taking all 18 hot-spot areas together, we find they support 49,955 endemic plant species, or 20 percent of Earth's plant species, in 746,400 km², or 0.5 percent of Earth's land surface. This means that one fifth of Earth's plant species are confined to half of one percent of the Earth's land surface — and they occur in habitats that are mostly threatened with imminent destruction.By concentrating on these hot-spot areas where needs are greatest and where the pay-off from safeguard measures would be greatest, conservationists can engage in a more systematised response to the challenge of large scale impending extinctions.Dr Norman Myers is a consultant in environment and development, a member of this journal's Advisory Board, and a regular contributor to the journal. He is a Senior Fellow of World Wildlife Fund — US. This paper enlarges on an important theme developed by Dr Myers in a contribution which appeared inThe Environmentalist,8(3), 187–208. The research for this paper has been supported by the MacArthur Foundation, Chicago, USA.     

Simulated Impacts of Three Decadal Climate Variability Phenomena on Water Yields in the Missouri River Basin1

Mehta, Vikram M., Norman J. Rosenberg, and Katherin Mendoza, 2011. Simulated Impacts of Three Decadal Climate Variability Phenomena on Water Yields in the Missouri River Basin. Journal of the American Water Resources Association (JAWRA) 47(1):126‐135. DOI: 10.1111/j.1752‐1688.2010.00496.x Abstract: The Missouri River Basin (MRB) is the largest river basin in the United States (U.S.), and is one of the most important crop and livestock‐producing regions in the world. In a previous study of associations between decadal climate variability (DCV) phenomena and hydro‐meteorological (HM) variability in the MRB, it was found that positive and negative phases of the Pacific Decadal Oscillation (PDO), the tropical Atlantic sea‐surface temperature gradient variability (TAG), and the west Pacific warm pool (WPWP) temperature variability were significantly associated with decadal variability in precipitation and 2‐meter air temperature in the MRB, with combinations of various phases of these DCV phenomena associated with drought, flood, or neutral HM conditions. Here, we report on a methodology developed and applied to assess whether the aforementioned DCVs directly affect the hydrology of the MRB. The Hydrologic Unit Model of the U.S. (HUMUS) was used to simulate water yields in response to realistic values of the PDO, TAG, and WPWP at 75 widely distributed, eight‐digit hydrologic unit areas within the MRB. HUMUS driven by HM anomalies in both the positive and negative phases of the PDO and TAG resulted in major impacts on water yields, as much as ±20% of average water yield in some locations. Impacts of the WPWP were smaller. The combined and cumulative effects of these DCV phenomena on the MRB HM and water availability can be dramatic with important consequences for the MRB.