Assessing the US Clean Water Act 303(d) listing process for determining impairment of a waterbody

This study evaluated the US Clean Water Act (CWA) Section 303(d) listing and delisting processes, based on historical and current federal and state guidelines, to determine whether there are regional differences in water quality assessment criteria used by various states to determine impairment of a waterbody for inclusion in the 303(d) list. A review of almost 50 total maximum daily load (TMDL) and delisting documents revealed that the basis for listing or delisting a waterbody varies considerably and that, in many cases, determination of impairment was based on insufficient water quality information. Historical USEPA guidance on the 303(d) listing and delisting processes has been generally broad, resulting in wide interpretation of the assessment criteria by various states. This has led to unclear or conflicting listing methodologies among states, leading to inconsistencies in impairment determination. Common problems include inconsistent data quality and quantity, differences in frequency of monitoring, variable interpretation of narrative water quality standards, and differences in specificity of implementation and monitoring plans, resulting in significant difference in the basis for listing and delisting waterbodies. In response, several states have taken the initiative to provide much more specific guidance for their internal agencies. Listing and delisting criteria are generally clearer at the state level, but the development of differing state guidance documents has resulted in diversity in the development of the 303(d) lists and in the process of delisting a waterbody. While state guidelines are better able to address local considerations, such as variations in climate, landuse, and water quality objectives, as well as social and economic preferences, the variation in listing criteria has led to inconsistencies across state boundaries in the levels of attainment of national water quality objectives. For stakeholders that participate in the 303(d) listing process within a particular state, these types of discrepancies may not have a significant impact. However, these inconsistencies can lead to confusion for some stakeholders who participate in the process in multiples states, and must deal with differing and sometimes conflicting requirements depending on the location of their facilities.     

Sustainable use of water from a tropical aquifer

The objective of this work is to analyze and interpret the components or hydrogeological, physical, and chemical variables of the San Diego aquifer to describe it and explain its influence on the sustainable use of groundwater for the providing of this locality. The San Diego municipality covers most of the area of the aquifer and is an area of high urban development that currently needs the contribution of groundwater due to the deficit presented by the main supply from the Central Regional System. Said aquifer is a set of geological strata located within the limits of the San Diego River basin, in the state of Carabobo, which are capable of storing groundwater and transmitting it. Data on lithology, porosity, and pumping level were investigated, which allows calculating an estimate of the volume of water available in the aquifer. Regarding the quality of the water, the data on hardness, chlorides, sulfates, nitrates, conductivity, calcium, magnesium, and pH, show that the water towards the center and north of the aquifer is of good quality, being able to classify it as type 1A, while toward the southern end—this is of lower quality, where the mineral parameters are higher, which is related to the probable intrusion of brackish water from Lake Valencia. It is concluded by establishing that the volume of groundwater, its availability, extraction feasibility, and its quality, make it suitable for urban supply and that said extraction is sustainable. But a better-integrated type of management must be designed, considering the contribution of the Regional System of the Center and the adequacy of the distribution networks.     

Management of Urban Road Runoff Containing PAHs: Probabilistic Modeling and Its Application in Beijing,China1

Abstract: Pollutant loading from storm runoff is considered to be an important component of nonpoint source pollution in urban areas. In developing countries, because of the accelerated urbanization and motorization, storm runoff pollution has become a challenge for improving aquatic environmental quality. An effective storm runoff management plan needs to be developed, and questions concerning how much and which proportion of a storm should be treated need to be answered. In this study, a model is developed to determine the fraction of storm runoff that needs to be treated to meet the discharge standard within a given probability. The model considers that the pollutants can be mobilized during the early stage of a storm. The model is applied to a field study of polycyclic aromatic hydrocarbons (PAHs) in road runoff in Beijing, China. In this case, the probability that the PAH load will be mobilized with suspended sediments by the earlier portion of the flush is 73%. Given the high PAH loading in the study area and the referenced discharge standard, the probability that the entire runoff should be captured and treated is 94%. Thus, urban planners need to consider treatment systems for the majority of the storms in this area, whether the PAH load is in the first flush or not. This methodology can be applied to other regions where PAH loads may result in different management outcomes.     

Removal of organochlorine pesticides from lindane production wastes by electrochemical oxidation

This study is focused on the effective removal of recalcitrant pollutants hexaclorocyclohexanes (HCHs, isomers α, β, γ, and δ) and chlorobenzenes (CBs) present in a real groundwater coming from a landfill of an old lindane factory. Groundwater is characterized by a total organic carbon (TOC) content of 9 mg L^?1, pH₀?=?7, conductivity?=?3.7 mS cm^?1, high salt concentration (SO₄^2?, HCO₃^?, Cl^?), and ferrous iron in solution. The experiments were performed using a BDD anode and a carbon felt (CF) cathode at the natural groundwater pH and without addition of supporting electrolyte. The complete depletion of the four HCH isomers and a mineralization degree of 90% were reached at 4-h electrolysis with a current intensity of 400 mA, the residual TOC (0.8 mg L^?1) corresponding mainly to formic acid. A parallel series reaction pathway was proposed: HCHs and CBs are transformed into chlorinated and hydroxylated intermediates that are rapidly oxidized to non-toxic carboxylic acids and/or mineralized, leading to a rapid decrease in solution pH.     

Effects of Land Use Changes on the Ecosystem Service Values of Coastal Wetlands

Changes in the coastal landscape of Southern Sinaloa (Mexico), between 2000 and 2010, were analyzed to relate spatial variations in wetlands extent with the provision and economic value of the ecosystem services (ES). Remote sensing techniques applied to Landsat TM imagery were used to evaluate land use/land cover changes while the value transfer method was used to assess the value of ES by land cover category. Five wetland types and other four land covers were found as representative of the coastal landscape. Findings reveal a 14 % decrease in the saltmarsh/forested mangrove area and a 12 % increase in the area of shrimp pond aquaculture (artificial wetland) during the study period. ES valuation shows that the total value flow increased by 9 % from $215 to $233 million (2007 USD) during the 10-year period. This increase is explained as result of the high value worldwide assigned to saltmarsh. We recognize limitations in the transfer-based approach in quantifying and mapping ES values in the region, but this method provides with value estimates spatially defined, and also provides some guidance in the preliminary screening of policies and projected development in the context of data-scarce regions.     

Lightning protection scenarios of communication tower sites; human hazards and equipment damage

This paper provides comprehensive analysis on the lightning protection scenarios in 48 communication and broadcasting towers situated in similar isokeraunic contours in Sri Lanka at 79°–81° East and 5°–10° North. The investigation has been conducted to study the hazardous environment created on the tower and in the neighbourhood in the event of a lightning strike to the tower. The results show that a direct strike to an antenna structure in a metallic tower is rare irrespective of the presence of an air-termination or a down conductor. However, side flashing or arcing to antenna structures is highly possible once the air-termination and/or down conductor is installed and attempts are made to insulate the system from the tower. The outcome also shows that equipotential bonding of the grounding system, a distributed grounding network including a ring conductor and a suitable system of surge protective devices play a much vital role in lightning protection of equipment and safety of people compared to the effects of simply achieving a low grounding resistance. However, in the absence of such integrated, distributed and equipotentialized grounding system, a high value of ground resistance will sharply increase the possibility of accidents and damage. Considering the observations of the investigations into account we have designed a concrete embedded grounding system for tower sites at problematic locations. Finally, the scenarios for safety management at telecommunication tower sites have been discussed.     

Sampling Global Deforestation Databases: The Role of Persistence

One of the concerns regarding transformation of land cover in tropical areas has been the large degree of uncertainty associated with both rates of deforestation over time and total deforestation. Special monitoring mechanisms must be taken into consideration if a program toward deforestation control is going to be implemented at the national or regional scale. The premise of this paper is that any attempt to quantify tropical deforestation and deforestation rates—at regional level, by randomly selecting sites within a population of satellite scenes—would require an overwhelming number of samples. This paper suggests a methodological approach for sampling remote sensing databases to be used as part of land use/cover change or joint implementation projects. This paper uses the concept of stratification and persistence as main tools.     

The valuation of forest carbon services by Mexican citizens: the case of Guadalajara city and La Primavera biosphere reserve

Adequate demand for, and recognition of, forest carbon services is critical to success of market mechanisms for forestry-based conservation and climate change mitigation. National and voluntary carbon-offsetting schemes are emerging as alternatives to international compliance markets. We developed a choice experiment to explore determinants of local forest carbon-offset valuation. A total of 963 citizens from Guadalajara in Mexico were asked to consider a purchase of voluntary offsets from the neighbouring Biosphere Reserve of La Primavera and from two alternative more distant locations: La Michilía in the state of Durango and El Cielo in Tamaulipas. Surveys were applied in market stall sessions and online using two different sampling methods: the snowball technique and via a market research company. The local La Primavera site attracted higher participation and valuation than the more distant sites. However, groups particularly interested in climate change mitigation or cost may accept cost-efficient options in the distant sites. Mean implicit carbon prices obtained ranged from $6.79 to $15.67/tCO_2eq depending on the surveying methodology and profile of respondents. Survey application mode can significantly affect outcome of the experiment. Values from the market stall sessions were higher than those from the snowball and market research samples obtained online; this may be linked to greater cooperation associated with personal interaction and collective action. In agreement with the literature, we found that valuation of forest carbon offsets is associated with cognitive, ethical, behavioural, geographical and economic factors.     

Public Perception as a Barrier to Introducing Wood in Rivers for Restoration Purposes

Reintroduction of wood in rivers for restoration purposes is now recognized in a positive way by scientists. Nevertheless, the perception of wood in riverscapes is strongly affected by the socio-cultural environment. This cultural influence might explain why wood reintroduction is accepted and promoted in some regions of the world but not in others, despite the demonstrated ecological benefits. From an extensive student perception survey, we show that most of the groups from nine countries in the world considered riverscapes with wood to be less aesthetic, more dangerous, and needing more improvement than riverscapes without wood. By contrast, this way of thinking was not observed in Germany, Sweden, and Oregon (USA), where the first instances of wood reintroduction occurred.     

Building Consensus in Environmental Impact Assessment Through Multicriteria Modeling and Sensitivity Analysis

Multicriteria decision analysis (MCDA) increasingly is being applied in environmental impact assessment (EIA). In this article, two MCDA techniques, stochastic analytic hierarchy process and compromise programming, are combined to ascertain the environmental impacts of and to rank two alternative sites for Mexico City’s new airport. Extensive sensitivity analyses were performed to determine the probability of changes in rank ordering given uncertainty in the hierarchy structure, decision criteria weights, and decision criteria performances. Results demonstrate that sensitivity analysis is fundamental for attaining consensus among members of interdisciplinary teams and for settling debates in controversial projects. It was concluded that sensitivity analysis is critical for achieving a transparent and technically defensible MCDA implementation in controversial EIA.