Diurnal variation of methane emissions from an alpine wetland on the eastern edge of Qinghai-Tibetan Plateau

Alpine wetland is a source for CH₄, but little is known about methane emission from such wetland, especially about its diurnal pattern. In this study we tried to probe the diurnal variation in methane emission from alpine wetland vegetation. The average methane emission rate was 9.6 ± 3.4 mg CH₄ m^???2 h^???1. There was an apparent diurnal variation pattern in methane emission with one minor peak at 06:00 and a major one at 15:00. The sunrise peak was consistent with a two-way transport mechanism for plants (convective at daytime and diffusive at night-time). CH₄ emission was found significantly correlated with redox potentials. The afternoon peak could not be explained by diurnal variation in soil temperature, but could be attributable to changes in CH₄ oxidation and production driven by plant gas transport mechanism. The results have important implications for sampling and scaling strategies for estimating methane emission from alpine wetlands.     

Assessment of groundwater quality near the landfill site using the modified water quality index

The purpose of this paper is to assess the groundwater quality near a landfill site using the modified water quality index. A total of 128 groundwater samples were analyzed for pH, electrical conductivity (EC), total organic carbon (TOC), polycyclic aromatic hydrocarbon (PAH), Cd, Pb, Zn, Cu, Cr, and Hg. The analytical results have showed a decreasing trend in concentration for TOC, Cd, Pb, Hg, and Cu and an increasing one for pH, EC, and PAH. The modified water quality index, which was called landfill water pollution index (LWPI), was calculated to quantify the overall water quality near the landfill site. The analysis reveals that groundwater in piezometers close to the landfill is under a strong landfill impact. The LWPI in piezometers ranged from 0.52 to 98.25 with a mean value of 7.99. The LWPI in groundwater from the nearest house wells varied from 0.59 to 0.92. A LWPI value below 1 proves that analyzed water is not affected by the landfill. Results have shown that LWPI is an efficient method for assessing and communicating the information on the groundwater quality near the landfill.     

Assessing environmental soil quality in rural areas

A base line study into the environmental quality of soils in the rural areas of the province of Zeeland, the Netherlands, was performed. The polder-landscape in this area was developed in a complex history of floodings and land-reclamation. Samples from 67 sites, at a density of roughly one per 25 km², were analyzed for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in addition to a physicochemical characterization by pH(KCl), dry solids, organic matter, and clay content. At about 2/3 of the sites samples were taken at more than one depth. Fluoride and pesticides were determined in partly overlapping selections of 30 samples. Four land use classes were distinguished (arable land, grass land, orchards, uncultivated), and samples were labelled by region within the province. Data evaluation was aided by a recursive statistical approach, whereby statistical tests confirm and strengthen geochemical reasoning. Single- and multivariate statistics were used both as exploratory tools and as a measure of significance and relevance of conditions and processes. In general the environmental quality of the soils is satisfactory. Exceedence of the legal standards for natural background values at more than one site occurs for Cd, Cu, Hg and the pesticides DDT/DDE, dieldrin and HCH, at most by a factor of three. High levels of Hg appear related to arable land use; enhanced levels of Cu are found in orchards. High Cd levels primarily seem to follow a regional or geological pattern; yet, a relation with arable land use and clayey soils cannot be excluded. Pesticides are not detected in grass land, incidence is highest in orchards as well as in uncultivated areas. DDT levels appear to be generally inherited from the past. Variation in soil type as described by the macro physico-chemical characteristics is essential in explaining the variation in concentration level of the potential contaminants. Variations with depth also appear largely related to concurrent variation in soil properties. For As redox conditions and hydrological regime seem of importance, in addition to the geologic history. The influence of atmospheric input is inferred for Pb. The available data do not fully resolve the causes for the regional pattern that remains when the influences of soil type, geology, and land use have been taken into account. In addition to current concentration levels, the base line study offers general insight as to what degree variations in potential contaminants are of natural or anthropogenic origin. A succession of similar studies at suitable time intervals, each with a new selection of sampling sites, may constitute an evolving, flexible monitoring system. When putting up a monitoring system, authorities should weigh the advantages and disadvantages of a network composed of fixed sites against this alternative.     

Assessing soil quality indicator under different land use and soil erosion using multivariate statistical techniques

Soil degradation associated with soil erosion and land use is a critical problem in Iran and there is little or insufficient scientific information in assessing soil quality indicator. In this study, factor analysis (FA) and discriminant analysis (DA) were used to identify the most sensitive indicators of soil quality for evaluating land use and soil erosion within the Hiv catchment in Iran and subsequently compare soil quality assessment using expert opinion based on soil surface factors (SSF) form of Bureau of Land Management (BLM) method. Therefore, 19 soil physical, chemical, and biochemical properties were measured from 56 different sampling sites covering three land use/soil erosion categories (rangeland/surface erosion, orchard/surface erosion, and rangeland/stream bank erosion). FA identified four factors that explained for 82 % of the variation in soil properties. Three factors showed significant differences among the three land use/soil erosion categories. The results indicated that based upon backward-mode DA, dehydrogenase, silt, and manganese allowed more than 80 % of the samples to be correctly assigned to their land use and erosional status. Canonical scores of discriminant functions were significantly correlated to the six soil surface indices derived of BLM method. Stepwise linear regression revealed that soil surface indices: soil movement, surface litter, pedestalling, and sum of SSF were also positively related to the dehydrogenase and silt. This suggests that dehydrogenase and silt are most sensitive to land use and soil erosion.     

Nitrous oxide fluxes from the littoral zone of a lake on the Qinghai-Tibetan Plateau

Nitrous oxide (N(2)O) fluxes were measured in six littoral mirco-zones of Lake Huahu on Qinghai-Tibetan Plateau in the peak growing season of years of 2006 and 2007. The weighted mean N(2)O flux rate was 0.08 mg N m(-2) h(-1) (ranged from -0.07 to 0.35 mg N m(-2) h(-1)). The result was relatively high in the scope of N(2)O fluxes from boreal and temperate lakes. Emergent plant zones (Hippuris vulgaris and Glyceria maxima stands) recorded the highest N(2)O flux rate (0.11 ± 0.24 and 0.08 ± 0.17 mg N m(-2) h(-1), respectively). Non-vegetated lakeshore recorded the lowest N(2)O flux (0.03 ± 0.11 mg N m(-2) h(-1)), lower than that from the floating mat zone of Carex muliensis (0.05 ± 0.18 mg N m(-2) h(-1)), the floating-leaved plant zone of Polygonum amphibium (0.07 ± 0.11 mg N m(-2) h(-1)), and the wet meadow (0.07 ± 0.15 mg N m(-2) h(-1)). Standing water depths were important factors to explain such spatial variations in N(2)O fluxes. Significant temporal variations in N(2)O fluxes were also found. Such temporal variation in N(2)O flux in the littoral zone may be dependent on the interaction of water regime and thermal conditions, instead of the latter solely. These results showed the importance of the littoral zone of lake, especially the emergent plant zone, as a hotspot of N(2)O fluxes in such grazing meadows.     

Assessing changes in the Presque Isle Bay watershed fish community using a modified index of biotic integrity: before and after the elimination of combined sewer overflows

An index of biotic integrity and species richness were used to assess changes in the Presque Isle Bay watershed fish community before and after the elimination of combined sewer overflows (CSOs). The fish community was sampled with a backpack electrofisher in 2011 at 12 stream locations on 4 tributaries of Presque Isle Bay, Erie County, Pennsylvania. All sites were previously sampled in 2001. Significant increases in species richness and index of biotic integrity (IBI) scores were observed in 2011 compared to 2001. The significant increases in species richness and IBI scores occurred following the elimination of 10 CSOs to Garrison Run, 7 CSOs to Cascade Creek, and 37 CSOs to Mill Creek. Despite the increased richness and IBI scores, the fish community remains in poor condition, which may be related to the highly urbanized land use of the watershed. Urban land uses comprise 77 % of the Presque Isle Bay watershed, and in both 2011 and 2001, the watershed as a whole did not meet warm-water habitat criteria. It is unlikely that the fish community will continue to recover without addressing urbanization throughout the watershed.     

Assessment of water quality along a recreational section of the Damour River in Lebanon using the water quality index

Considering that water is becoming progressively scarce, monitoring water quality of rivers is a subject of ongoing concern and research. It is very intricate to accurately express water quality as water quantity due to the various variables influencing it. A water quality index which integrates several variables in a specific value may be used as a management tool in water quality assessment. Moreover, this index may facilitate communication with the public and decision makers. The main objectives of this research project are to evaluate the water quality index along a recreational section of a relatively small Mediterranean river in Southern Lebanon and to characterize the spatial and temporal variability. Accordingly, an assessment was conducted at the end of the dry season for a period of 5 years from 2005 to 2009. The estimated water quality index classified the average water quality over a 5-year period at the various sites as good. Results revealed that water quality of the Damour River is generally affected by the anthropogenic activities taking place along its watershed. The best quality was found in the upper sites and the worst at the estuary. The presence of fecal coliform bacteria in very high levels may indicate potential health risks to swimmers. This study can be used to support the evaluation of management, regulatory, and monitoring decisions.     

Assessing regulatory violations of disinfection by-products in water distribution networks using a non-compliance potential index

Inactivating pathogens is essential to eradicate waterborne diseases. However, disinfection forms undesirable disinfection by-products (DBPs) in the presence of natural organic matter. Many regulations and guidelines exist to limit DBP exposure for eliminating possible health impacts such as bladder cancer, reproductive effects, and child development effects. In this paper, an index named non-compliance potential (NCP) index is proposed to evaluate regulatory violations by DBPs. The index can serve to evaluate water quality in distribution networks using the Bayesian Belief Network (BBN). BBN is a graphical model to represent contributing variables and their probabilistic relationships. Total trihalomethanes (TTHM), haloacetic acids (HAA5), and free residual chlorine (FRC) are selected as the variables to predict the NCP index. A methodology has been proposed to implement the index using either monitored data, empirical model results (e.g., multiple linear regression), and disinfectant kinetics through EPANET simulations. The index’s usefulness is demonstrated through two case studies on municipal distribution systems using both full-scale monitoring and modeled data. The proposed approach can be implemented for data-sparse conditions, making it especially useful for smaller municipal drinking water systems.     

Assessing the water quality index of water treatment plant and bore wells, in Delhi, India

Water quality monitoring exercise was carried out with water quality index (WQI) method by using water characteristics data for bore wells and a water treatment plant in Delhi city from December 2006 to August 2007. The water treatment plant received surface water as raw water, and product water is supplied after treatment. The WQI is used to classify water quality as excellent, good, medium, bad, and very bad. The National Sanitation Foundation WQI procedure was used to calculate the WQI. The index ranges from 0 to 100, where 100 represents an excellent water quality condition. Water samples were collected monthly from a bore well in Nehru Camp (site 1), a bore well in Sanjay Gandhi pumping station (site 2), and water treatment plant in Haiderpur (site 3). Five parameters were analyzed, namely, nitrate, pH, total dissolved solids, turbidity, and temperature. We found that the WQI was around 73–80 in site 3, which corresponds to “good,” and it decreased to 54.32–60.19 and 59.93–70.63 in site 1 and site 2, respectively, indicating that these bore wells were classified as “medium” quality.     

Assessing the influence of nutrient reduction on water quality using a three-dimensional model: case study in a tidal estuarine system

A coupled three-dimensional hydrodynamic and water quality model has been developed and applied to the Danshuei River estuarine system and adjacent coastal sea. The water quality model considers various species of nitrogen, phosphorus, organic carbon, and phytoplankton as well as dissolved oxygen and is driven by a three-dimensional hydrodynamic model. The hydrodynamic and water quality models were validated with observations of water surface elevation, velocity, salinity distribution, and water quality parameters. Statistical error analysis shows that predictions of hydrodynamics, salinity, dissolved oxygen, and nutrients from the model simulation quantitatively agreed with the observed data. The validated model was then applied to predict water quality conditions as a result of a reduction in nutrient loadings based on different engineering strategies. The simulated results revealed that the dissolved oxygen concentration would increase significantly and would be higher than 2 mg/L in the main stream and in three tributaries to meet the minimum statutory requirement for dissolved oxygen. Active estuarine management focused on the reduction of anthropogenic nutrient loads is needed for improvement in water quality.     

Assessing soil and groundwater contamination in a metropolitan redevelopment project

The purpose of this study was to assess contaminated soil and groundwater for the urban redevelopment of a rapid transit railway and a new mega-shopping area. Contaminated soil and groundwater may interfere with the progress of this project, and residents and shoppers may be exposed to human health risks. The study area has been remediated after application of first remediation technologies. Of the entire area, several sites were still contaminated by waste materials and petroleum. For zinc (Zn) contamination, high Zn concentrations were detected because waste materials were disposed in the entire area. For petroleum contamination, high total petroleum hydrocarbon (TPH) and hydrocarbon degrading microbe concentrations were observed at the depth of 7 m because the underground petroleum storage tank had previously been located at this site. Correlation results suggest that TPH (soil) concentration is still related with TPH (groundwater) concentration. The relationship is taken into account in the Spearman coefficient (α).     

Development of fuzzy air quality index using soft computing approach

Proper assessment of air quality status in an atmosphere based on limited observations is an essential task for meeting the goals of environmental management. A number of classification methods are available for estimating the changing status of air quality. However, a discrepancy frequently arises from the quality criteria of air employed and vagueness or fuzziness embedded in the decision making output values. Owing to inherent imprecision, difficulties always exist in some conventional methodologies like air quality index when describing integrated air quality conditions with respect to various pollutants parameters and time of exposure. In recent years, the fuzzy logic-based methods have demonstrated to be appropriated to address uncertainty and subjectivity in environmental issues. In the present study, a methodology based on fuzzy inference systems (FIS) to assess air quality is proposed. This paper presents a comparative study to assess status of air quality using fuzzy logic technique and that of conventional technique. The findings clearly indicate that the FIS may successfully harmonize inherent discrepancies and interpret complex conditions.     

Assessing water quality in a tropical lake using biomarkers in zebrafish embryos: developmental toxicity and stress protein responses

In order to achieve a more substantial appraisal of lake water quality, the assessment must not be based only on chemical measurements and analyses of the water itself, but even more so on the impact of existing conditions on aquatic biota. This is possible with the use of biotests or biomarkers, e.g. investigations of the developmental parameters (96-h embryotoxicity evaluate) or of the induction of heat shock proteins (proteotoxicity evaluate). To evaluate the suitability of these tests for environmental screening, fertilized zebrafish eggs were exposed to water samples collected from five sites of varying levels of stress from Laguna Lake, Philippines. Reconstituted water was used as laboratory control while water samples from a highly polluted freshwater source was used as positive control. Developmental parameters were noted and described within 48 and 96 h of exposure. Dilution experiments of the positive control were also done to further assess and compare toxicity potentials of Laguna Lake waters with those originating from a polluted freshwater. After the 96-h exposure, the levels of stress proteins (hsp 70) were determined in embryos from all exposure groups. Results showed 100% mortality in embryos exposed to undiluted positive control (PC) within only 12 h. Increasing dilution levels, however, resulted in lower mortality and lower abnormality rates. No detectable developmental differences were noted among embryos exposed to either the laboratory control or Laguna Lake waters at the end of 96 h, regardless of the source. Very high survival rates and high hatching success rates were observed in embryos exposed to lake waters as well as laboratory control, and the data did not differ significantly among the groups. Likewise, no significant malformations were noted among all developing embryos throughout the exposure period. However, the levels of heat shock proteins in the two sites located closest to Manila, the Philippine capital (Northern West Bay and Central West Bay), showed a pronounced elevation relative to the control, indicating that these stress proteins protect the embryos from the detrimental effects of pollutants in the water. Based on the 96-h early life stage (ELS) test, the water quality of the lake is good for fishery propagation despite the current levels of pollutants in the water. This finding is in accordance with the Class C status (i.e. suitable for fish growth and propagation) as given to the lake by the local environmental agency. On the other hand, data on proteotoxicity showed that the fish are under stress, presumably deriving from pollutants. This calls for a continuous monitoring and improvement of the lake water. The present study indicates that the two biomarker methods are very easy to use, practical, rapid, and sensitive for assessing water quality in a tropical lake and recommends for their incorporation into the future monitoring program of Laguna Lake.     

Phosphorus leaching from a sandy soil in the presence of modified and un-modified adsorbents

Phosphorus (P) leaching from a sandy soil was investigated in the presence of modified and unmodified clay minerals and nanoparticles (NPs). Compared with control soil, amended soil with NPs had the highest percentage of P retention than amended soil with clay minerals. Among the adsorbents used, the highest percentage of P retention was produced by Al₂O₃-chitosan while the lowest percentage of P retention was by zeolite. Data measured for P leaching after using adsorbents were used to predict P leaching using transport model. PHREEQC model was able to model P leaching from control and amended soil. After leaching, P values in control and amended soil were fractionated by a sequential extraction procedure. Concentration of P in Ca-bound fraction (HCl–P) after application of modified and unmodified clay minerals and NPs (except TiO₂ and Al₂O₃) increased and decreased, respectively. Saturation indices (SIs) and P speciation were assessed using the Visual MINTEQ version 2.3 program. According to the SIs, leaching P from control and amended soil with different adsorbent was controlled by dissolution of hydroxyapatite. The results indicated that used adsorbents can reduce P leaching from the sandy soil. Thus, retention of P by amended soil reduced a risk in terms of groundwater contamination with P.     

Utilization of the water quality index method as a classification tool

The study comprised modification of the Canadian Council of Ministers of the Environment (CCME) Water Quality Index (CCMEWQI) to obtain a tool in classification of surface waters according to quality defined by the European Legislation—75/440/EEC. Three categories were proposed, and the category ranges of CCMEWQI have been modified depending on the objective chosen. The application of the CCMEWQI with modified categorization scheme was demonstrated to assess overall water quality by integrating observed water quality determinants in the Kucuk Menderes Basin, Turkey. In this scope, the samples analyzed for pH, total dissolved solids (TDS), chlorides (Cl), nitrate–nitrogen (NO₃–N), dissolved oxygen (DO), biochemical oxygen demand (BOD₅), sulfate (SO₄), and boron (B), variables taken monthly over 2 years from the five monitoring sites, were processed. Results revealed that the overall surface water mainly fell within the A2 water class. The CCMEWQI with modified categorization scheme is believed to assist water managers to integrate and interpret the picture of overall water quality based on the European legislation concerning the quality required of surface water intended for the abstraction of drinking water in the Member States (75/440/EEC).     

Assessing the ecological condition of streams in a southeastern Brazilian basin using a probabilistic monitoring design

Prompt assessment and management actions are required if we are to reduce the current rapid loss of habitat and biodiversity worldwide. Statistically valid quantification of the biota and habitat condition in water bodies are prerequisites for rigorous assessment of aquatic biodiversity and habitat. We assessed the ecological condition of streams in a southeastern Brazilian basin. We quantified the percentage of stream length in good, fair, and poor ecological condition according to benthic macroinvertebrate assemblage. We assessed the risk of finding degraded ecological condition associated with degraded aquatic riparian physical habitat condition, watershed condition, and water quality. We describe field sampling and implementation issues encountered in our survey and discuss design options to remedy them. Survey sample sites were selected using a spatially balanced, stratified random design, which enabled us to put confidence bounds on the ecological condition estimates derived from the stream survey. The benthic condition index indicated that 62 % of stream length in the basin was in poor ecological condition, and 13 % of stream length was in fair condition. The risk of finding degraded biological condition when the riparian vegetation and forests in upstream catchments were degraded was 2.5 and 4 times higher, compared to streams rated as good for the same stressors. We demonstrated that the GRTS statistical sampling method can be used routinely in Brazilian rain forests and other South American regions with similar conditions. This survey establishes an initial baseline for monitoring the condition and trends of streams in the region.