Agricultural area is one of the major non-point sources of phosphorus pollutants in Japan, as in many countries. In this study the runoff loading of phosphorus from agricultural lands located in the Mikawa Bay watershed in central Japan was evaluated to clarify its impact on coastal areas. Water quality and the discharge of rivers in the area were investigated in 2002. Phosphorus was mainly discharged as dissolved form in dry periods while particulate phosphorus (PP) was discharged in great quantities in storm periods in the areas. The runoff characteristics of phosphorus were the washout type, which means that the concentrations increase with the increase of discharge. There was a positive correlation between the runoff characteristics of PP and the proportion of agricultural land use. Results of experimental desorption tests with soil of the agricultural fields suggested that desorption of phosphorus from the soil can quickly occur in coastal areas, depending on the pH and salinity of the water body. It was estimated that about 10% of the loading of phosphorus from the areas could be quickly changed from particulate form to dissolved form in seawater.

View full abstract

In Japan, Nitrate nitrogen pollution of the ground water by overuse of fertilizer in the upland field had become a serious issue. In order to purify it, the nitrogen removal method using the Topographical chain system was examined. Spring water from upland field was installed to test fields and the experiment was conducted over a long period. The result showed no significant difference for the three kinds of vegetation. In the irrigation period, organic matter supplied by the generation of algae sustained the nitrogen removal. In order to explore the mechanism of the nitrogen removal, experiments were conducted by sampling soil in thin layers. In the rice plot, rice stubbles were put back into the soil did not show significant differences among the layers. In the non-vegetation test plot, the surface and the lower layer had large nitrogen removal. In the shield plot there are no differences in the two upper layers but the lower layers have large value because organic matter below 2 cm layer had not been used for denitrification. Therefore it is thought that denitrification in the paddy fields (wetlands) had happened at around the upper 2cm layer of soil surface

View full abstract

Yakushima, facing at 800 km east of Shanghai in the East China Sea, is a tall cone-shaped island with seven exceeding 1800 m peaks. The prevailing winds of westrelie on the island blow mostly fromnorthwest and west. It has been exposed to acid rain of pH 4.7 and precipitation 8000 mm in the central highland. More than sixty mountainous streams were observed at downstream points seasonally for past twelve years. The alkalinity of streamwaters in the southwestern part was lower than others. The concentrations of SO₄^2- in the northwestern part were higher than others. The high concentrations of SO₄^2-, dissolved SiO₂ and other ions in the southwestern part with high canopy density of evergreen broadleaved forest were caused by higher air temperature, less rainfall and higher evapotranspiration than other parts. The alkalinity, pH and EC in the catchment of north stream in the upstream branch of the R. Anboh became lower than those in the catchment of south stream. The height of catchment boundaries, the direction of the main axis of a catchment and the prevailing winds govern the influence of acid deposition on water quality of branch streams.

View full abstract

Small-scale mining occurs on a sizeable scale in many developing countries throughout the world. Active measures are undertaken by governments to promote the development of this mining sector for the promotion of the economy. The development of this sector does not bode well for the environment, as this sector is largely internationally unregulated.

The challenge is to manage small-scale mining in an environmentally acceptable manner, and by so doing, develop appropriate implementation and environmental management strategies. These strategies must be relevant, understandable, affordable, be aimed at maintaining a balance between encouraging economic developments and preserving high standards of environmental management. Various strategies for managing the water-related impacts caused by small-scale mining have been developed in South Africa. These government initiatives have focused on two levels namely, the small-scale miners themselves as well the regulators.

Through on going consultation between the regulators and small-scale miners and a continued education programme with documentation produced in South Africa, these initiatives will assist in the reduction of diffuse pollution impacts of current and future small-scale mining practises in developing countries.

View full abstract

Not only to estimate the impact of storm water on receiving waters but also to deduce the origin of the pollutants, it is important to analyze the runoff characteristics of pollutants during storm events. We conducted seven surveys during storm events to clarify the runoff characteristics of various pollutants and relationships between pollutant loads and runoff patterns. In addition, origins of various ions were deduced by examining the temporal variations of ion composition. Typical first flush effects in VSS and T-BOD concentrations were observed, and it was estimated that river sediments deposited in fine days strongly affect the runoff of VSS during a storm event. NO₃^--N concentration decreased by the early runoff, but kept up higher level at the recession stage, while ion concentrations decreased during the rising stage and increased again at the recession stage, indicating that ions were diluted by the major runoff. Relationships between pollutant loads and runoff were examined by the empirical equation “L/A = a (Q/A)ⁿ”. Judging from the n values, ash, SS, VSS, NH₄⁺-N and TP were easily flushed out during storm events, while TN, DN, NO₃^--N, K⁺ and DOC kept almost constant concentration during a storm event. Most ions seemed to be diluted by storm water. It was indicated that NO₃^-, SO₄^2- and K⁺ were mainly originated from diffuse sources during storm events in the surveyed watershed, while Mg²⁺ and Na⁺ was from the same source as Cl^-. Most of the nitrate and sulfate loads seemed to be drained out from the surface soil layer of river basins and carried by subsurface runoff.

View full abstract

Urban stormwater runoff has been identified as the major source of many pollutants. Estimating stormwater mass emissions is inherently difficult due to the large area, many emission points, and the difficulty associated with sampling episodic storm events. Modeling urban stormwater runoff often requires land use information to estimate emissions.

Conventional collection of land use information, i.e. ground surveys, is time-consuming and expensive. Alternatively, land use data can be estimated from satellite imagery, and pollutants can be correlated using previously developed relationships. An alternate but less often used approach is to estimate stormwater pollutant loadings directly from satellite imagery, which is the objective of this research.

We conducted Bayesian network classification with Landsat TM image of Marina del Rey area in Santa Monica Bay Watershed. The results suggest an improved classification system for stormwater modeling, using open land use as low pollutant loading areas and transportation land use as high pollutant loading areas. Commercial and industrial land uses were medium and high loading areas, depending on the pollutant type. This indicates that management strategies should generally address transportation areas first. Classification systems should be developed for each water quality parameter. These results are useful in developing management practices for stormwater runoff.

View full abstract

Many people in the world still cannot access to the appropriate sanitation. To halve this population is the global target. In Bauniabad, which is one of the poor settlements in Dhaka, Bangladesh, small-scale biogas plants connected to the latrines of about 100 households have been installed as a sanitation option. The purpose of this study is to clarify the background of how the local people came to use the biogas plant for sanitation purpose, and to examine the performance of the biogas plant for the reduction of the pollution load to the surrounding water bodies. The questionnaire to the local people about their behaviors regarding sanitation was conducted to know the change of their attitudes and the situation of their living environment before and after the installation of the sanitation options. The water quality analysis was conducted to review the performance of the biogas plant. From the questionnaire, it was revealed that the hygiene condition of the latrines was improved after the connection to the biogas plants. On the other hand, from the water quality analysis, it was revealed that the anaerobic digestion of the biogas plants did not work sufficiently good due to lack of maintenance.

View full abstract

The Root Zone Water Quality Model (RZWQM) was used to simulate the movement of atrazine after entry into switchgrass (Panicum virgatum L.) Riparian Buffer Strips (RBS). A multi-species RBS located along Bear Creek, Iowa, was used as the basis for model inputs and simulation. Atrazine entered the RBS at rates representing atrazine loss in runoff of 1, 3, and 5% of a 1.5-kg ha^-1 application to an adjacent cornfield. Water equivalent to runoff depths of 0.125, 0.25 and 0.5-cm from the adjacent cornfield was added to the natural rainfall to allow the model to simulate surface water entering the RBS. RBS retained about 79-94% of atrazine in runoff from the adjacent cornfield. The RZWQM predicted very low atrazine concentrations in seepage (< 3-μ g L^-1). Atrazine loss in runoff leaving the RBS was most sensitive to macropore size and plant residue, but less sensitive to soil organic matter content. At macropore sizes larger than 0.01-cm there was no atrazine in runoff leaving the RBS. Plant residue mass was directly proportional to atrazine loss in runoff, but organic matter content was inversely proportional to atrazine loss in runoff. The RZWQM needed more improvement in pesticide leaching transport, and pesticide loss in runoff components.

View full abstract

Wastewater reclamation is an effective countermeasure to water shortage. However, there is a concern that wastewater reclamation causes health risks of infection by pathogens and cancer by disinfection by-products such as trihalomethanes (THMs). To discuss these risks, the Disability-Adjusted Life Years (DALY) has been employed and integrated with the unit of lost lifetime. Health risks such as infection and cancer in Fukushima city with population of 0.3 millions were evaluated using the DALY in the wastewater reclamation as a drinking water source. The damage [%·day] from the shortage of water was quantified using the product of the percentage deficiency to water supply demand [%] and the period of deficiency [days]. In the current situation of water utilization without reclamation, the DALY for total population was about 11 years. Reclamation of secondary effluent without disinfection brought no increase of DALY when the damage between 0 and 300 %·day was reduced. On the other hand, the DALY drastically increased when the reduction of the damage was over 300 %·days. If the secondary effluent was disinfected with chlorine, the maximum damage of 1200 %·day could be reduced by its reclamation without any increase of DALY.

View full abstract

A distributed water quality tank model was developed to evaluate nitrogen load reduction by artificial wetlands in the A10 area, located in the Lake Kasumigaura watershed in Japan. In order to collect data for model calibration and verification, a year-long field investigation was conducted. The study area was divided into a 50 m × 50 m grid, and attributes and the model are added to each cell. The model simulates the runoff and the total nitrogen (TN) concentration with average relative errors of 10% and 2%, respectively, except for no-rain periods. Scenario analyses were conducted considering artificial wetlands at different locations. The three scenarios are as follows: no artificial wetland, cell located at the head of the valley and cell located on a flow path through animal waste cell. Compared with case 1, the annual TN concentration was lower by 4% and 11% in cases 2 and 3, respectively. The results suggest that artificial wetlands on water flow paths with a large nitrogen load effectively reduce these loads and that the model quantitatively evaluates the difference in the nitrogen concentration across locations.

View full abstract

In a tributary watershed of the Kuji River of Japan, the hydrological components of runoff associated with a precipitation event were investigated using isotope tracers of hydrogen (²H) and oxygen (¹⁸O) in precipitations and stream water. The runoff was separated into “old water” (pre-existing in the ground before the precipitation event) and “new water”(from the precipitation). It was found that the discharge of several hazardous trace elements (Sb, Cu, Cr) was largely (24-54%) attributable to that of the new water in spite of its small contribution to the total water discharge. These investigations suggest that the new water may play an important role in the migration of atmospherically derived, hazardous trace elements to streams during precipitation events. The present findings will contribute to current necessity of assessment of a risk of long-term exposure to pollutants at low concentrations by providing information on their transport among different environmental media.

View full abstract

Spatial planning is a valuable tool to support sustainable development by basing the plans, measures and interventions on key sustainability principles. The development of a spatial plan runs through three main processes; baseline data analysis of the existing situation and problems and potentials; formulation of objectives and strategies; and integration across sectors and synthesis of all aspects into a coherent balanced spatial framework. The technical part of planning was based on development of a comprehensive Geographic Information System (GIS) and database system and also included mathematical models to predict outcomes of certain measures. The planning maps of the relevant issues are constructed in order to plan for watershed management. As an example, the initial analysis determined that reforestation was a high priority issue for many reasons, both related to preservation and enhancement of nature and environment and people′s living conditions. GIS was applied to define potential zones for reforestation and mathematical models calculated the result in terms of runoff, sedimentation and water quality. The potential zones for reforestation were then used as a framework for integrated planning. This paper will demonstrate the planning maps used for integrated water shed management on the basis of spatial planning concept.

View full abstract

Penetration experiments were carried out for a period of over two years at an experimental field located in Kusatsu City. The field was divided into two tanks and each tank filled with different types of soil. Polluted water discharged from the road surface was supplied to the field during storm events. The effluent from the field was composed of Surface and Infiltrated flow. The flow was gauged at three points and water sampled for quality analysis. In order to analyze measures against clogging, soil in one tank was replaced to investigate the recovery of soil contents, penetration efficiency, and purification efficiency. The other tank was researched continuously for 26 months to analyze the change of purification efficiency with precipitation characteristics and the continuous use the facility. Sustainability was analyzed by modeling long-term mass balance in the facilities using water quality data (COD, N, P and SS) and comparing the results with actual measured data of the change of pollutants in the soil. The facility achieved high pollutant removal efficiencies of between 50% - 90% during the survey. Simulation results using water quality data compared well with actual measured data of change of pollutants in soil.

View full abstract

An inexpensive tool for indicating microbial quality in watersheds is presented that utilizes the conventional total coliform test, comparing the relative concentrations of different colonies that form on a membrane filter fed by m-Endo media. These bacterial colonies can be classified into 3 types; typical (TC), atypical (AC), and background. The ratio of the concentrations of AC colonies to those of TC is related to water quality, fecal loadings, and fecal age. The AC/TC ratio relies upon shifts in populations between indigenous and introduced bacteria, with the indigenous bacteria providing a baseline against which the concentrations of the introduced are evaluated. When the AC/TC ratio is low (<5), fresh fecal material is in the water and pathogen risk can be expected to be higher. As time passes, the AC/TC ratio increases (>20) and can be related to healthier water quality conditions. Different types of runoff have different AC/TC values with human sewage at the lowest end of the spectrum with a value of 1.5 under normal conditions.

View full abstract

Due to stormwater runoff along Pohang Bay at typhoon Rusa and Maemi in 2002 and 2003, P steel Company requires a counter measure for all future typhoons. P steel Company will have the challenge of both determining the benefits of their existing treatment facility and deciding what additional practices they will need to achieve the goal. In order to reduce the nonpoint source pollution during rainfalls, P steel Company is considering the installation of stormwater pits and the construction of a stormwater treatment plant. This study analyzed the reduction effect of nonpoint source pollution achieved through such measures using the Storm Water Management Model (SWMM). As a result, we found that the installation of stormwater pits (storage capacity 60mm/day) and stormwater treatment plant have reduced the pollution load (SS) by 38 to 87% compared to the existing state, and the concentration of SS in outflow also satisfied 20mg/L or lower.

View full abstract

The present study was conducted to obtain a bioflocculant from activated sludge by a simple procedure. An extracellular polymer mainly composed of protein was extracted by sonication from an activated sludge suspension. The polymer exhibited flocculating activity for kaolin clay, activated charcoal, and muddy water (when cations were present), and stimulated reflocculation of deflocculated sludge. Flocculating activity for kaolin clay was related to a concentration of the polymer below 10 ppm. The activity was significantly affected by pH since in basic buffer the activity was inhibited completely while in acidic buffer it was increased. When the polymer was digested with pronase, flocculating activity significantly decreased, although the activity was not affected by heat treatment at 100°C for 5 min. These results suggest that flocculating activity is mainly due to the portion of heat stable protein in the polymer. The results obtained in the present study suggest that the isolation of new biodegradable and economical flocculants from activated sludge is feasible.

View full abstract