Water Quality In Coastal Areas Research Articles

Application Of Remote Sensing Technologies On Industrial Outfalls

Industrial effluents are a byproduct of various industries. They may contain harmful and toxic substances of organic or inorganic origin, such as pesticides, pharmaceuticals, hydrocarbons, detergents, and oils. In addition, industrial effluent can also come from thermal power plants in the coastal area, which use seawater for cooling, which they return to the environment after the process. Hence, the zone near the outlet has increased temperature, affecting the mortality and reduction of certain types of fish and algae, variations in the number of phytoplankton, and other ecological problems (Zhao et al., 2015). Nowadays, an increasing amount of industrial wastewater from desalination processes is brine, which is considered a minor risk to public health but has a more significant impact on the environment (Lattemann and Amy, 2013). Due to the increase in population, the demand for drinking water has increased, especially on the islands and coastal areas. With the desalination process, drinking water is produced from sea or brackish water by removing suspended matter and dissolved minerals, mainly salt, and the effluent, i.e., brine, is discharged back into the coastal area. An increased amount of salt can potentially negatively affect the marine ecosystem, leading to the dehydration of cells and possible death of organisms (Missimer and Maliva, 2018). In addition, the brine may have a higher temperature than the environment and contain heavy metals and residues of hazardous chemicals applied in the process, such as anti-scale agents, flocculation agents, and coagulants (Panagopoulos and Haralambous, 2020.). The increasing hydrogen generation from renewable sources requires more freshwater. Consequently, a significant increase in this type of effluent is expected in the future. Therefore, analysis and monitoring of the operation of industrial outfalls is essential to preserve the marine environment and public health. Previous research (Law and Tang 2016) proposes long-term monitoring after the outfall has been commissioned to study environmental effects. Historically, monitoring of wastewater outfalls was mainly obtained by in situ sampling methods to ensure water quality in coastal areas (Gierach et al., 2017). Such practices have temporal and spatial limitations with high costs; hence, they are impractical for analyzing a larger coastal area. Therefore, in this research, we propose using remote sensing technologies for monitoring industrial outfalls.

Estimating the Chlorophyll-a in the Nha Trang Bay using Landsat-8 OLI data

The pigment chlorophyll-a (Chl-a) is used to evaluate aquatic ecological health. Using remote sensing techniques to estimate this pigment and spatially mapping its distribution becomes essential for measuring and assessing water quality in coastal areas. Nha Trang Bay is famous not only for its scenery but also for its biodiversity values, especially the existence of coral reefs. In this study, Landsat-8 OLI was taken on June 3, 2015, and field measurements of Chl-a at 13 survey sites from June 6-8, 2015, were used to build a local algorithm to monitor the spatio-temporal distribution of Chl-a content in Nha Trang Bay. The ACOLITE processor was employed for the atmospheric modification of Landsat-8 OLI images to obtain atmospherically corrected surface reflectance products. Four types of simple regression models, including linear, exponential, logarithmic, and power models, were used to describe the relationship between the in-situ measurement of Chl-a and remote sensing reflectance of Landsat-8 OLI data. The results of correlation analysis have shown a statistically significant relationship between field measurement of Chl-a concentration and the remote sensing reflectance ratio of Landsat-8 band 3 versus band 2 using an exponential model with a coefficient of determination of 0.88 (p < 0.001) and root mean square error (RMSE) of 0.40 mg/m3. This empirical relationship was applied to map the spatial distribution of Chl-a concentration from 27 cloudless Landsat-8 OLI images from 2013 to 2021. The spatio-temporal distribution of Chl-a indicated that the Chl-a concentration in the Bay has a low value (less than 1 mg/m3). However, this concentration becomes high in the coastal areas (greater than 1 mg/m3) and the Cai and Tac rivers (greater than 2 mg/m3). It is also noted that the content of Chl-a in the rainy season is fairly higher than in the dry season, by an average of 0.68 mg/m3 and 0.53 mg/m3, respectively. This research highlights that Landsat-8 OLI data can be an effective and valuable tool in monitoring Chl-a for coastal areas.

Rancang Bangun Smart System Pendeteksi Air Layak Minum Pada Sumur di Daerah Pesisir Pantai Berbasis Internet Of Things (IoT)

Water is an important natural resource for human life, but in some coastal areas, the availability of clean water is often a serious problem. One source of water used by communities in these areas is wells, which often do not meet health standards for consumption. Manual methods for detecting well water quality still require long, expensive, and inefficient processes. Therefore, the development of a system that can detect water quality in real-time and provide fast and accurate information to the community is needed. The Internet of Things (IoT) technology, which allows objects to be connected to the internet, provides a solution that can be utilized. In this study, a Smart System was designed using salinity and manganese sensors to monitor the real-time quality of well water in coastal areas. Data from these sensors are sent to a server through the internet and analyzed to provide information to users via the Blynk application on their smartphones. With this system, communities can directly monitor the quality of well water, take appropriate actions, and safeguard the health of local residents. Additionally, this system can also assist relevant government or institutions in monitoring and taking quick actions in response to changes in well water quality in coastal areas

Spatial and temporal analysis and quantification of pollution sources of the surface water quality in a coastal province in Vietnam.

The surface water quality in coastal areas may be highly vulnerable to degradation due to various pollution sources such as seawater intrusion and anthropogenic activities. The current study sought to spatially and temporally analyze and quantify pollution sources of the surface water system in the coastal province of Tra Vinh, Vietnam. A total of 600 surface water samples were taken from 30 monitoring sites distributed over 4 spatial zones. Water samples were collected in four campaigns each year during the dry and rainy seasons from 2016 to 2020 and analyzed for 10 physiochemical and biological parameters. The analyzed data were calculated for the water quality index (WQI). Two-way analysis of variance, principal component analysis/factor analysis (PCA/FA), and multivariable regression analysis (MRA) were conducted over the whole dataset. The results showed that the WQI decreased from the inland zone to the coastal area, was greater in the river zone than in the canal zone, and was higher in the dry season than in the rainy season. The PCA/FA revealed that surface water quality was affected by at least 4 main pollution sources, including agricultural production, seawater intrusion, residential activities, and mixed sources. MRA revealed that these pollution sources explained 68.3%, 12.8%, 7.0%, and 2.7% of the total variance of the WQI, respectively. In summary, the surface water quality in the study area significantly changed spatially and temporally, depending on four pollution sources, which need to be managed properly for a better environment and sustainable development.

Spatiotemporal assessments of nutrients and water quality in coastal areas using remote sensing and a spatiotemporal deep learning model

Revealing the spatiotemporal variations of nutrients in coastal waters is crucial to the understanding and evaluation of coastal environment, thereby providing efficient guidance for the aquatic environmental treatment. This study proposed a spatiotemporal-incorporated deep learning model, which is easily applicable to establish the quantitative relationships between measured environmental factors and large-scale satellite maps, and can reduce estimation errors by more than 40% compared with non-spatiotemporal-incorporated deep learning model. The spatiotemporal distributions of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphate (DIP) over 44400 km2 of the East China Sea on 8-day scale from 2010 to 2018 were obtained. Based on the spatiotemporal variations, the water quality patterns were depicted, and the fluctuation variations of the two essential nutrients were found in the harbors with complex anthropogenic influences, in the typical estuaries with multiple river inputs, and in the open seas with important fisheries. Although the concentration of DIN and DIP decreased by 24% and 19% in 9 years, respectively, the water quality level in the inshore sea has not been significantly improved, especially in autumn and winter. Further, we quantitatively analyzed the main factors of deteriorated water and provided scientific suggestions for targeted monitoring and regional cooperative governances.

Evidence of improvements in the water quality of coastal areas around China

Coastal areas are huge carbon stores and hotspots for marine carbon fixation. Changes in the water quality of coastal areas are closely linked to their carbon fixation function. In this study, monitoring data were analyzed to identify how the water quality in China's coastal areas changed from 2001 to 2020. The results showed that the water quality in the coastal areas had improved gradually since 2001. The proportion of water quality in Class II and above gradually increased from 41.4% in 2001 to 77.4% in 2020, meanwhile, the proportion of water quality less than Class II, decreased from 58.6% to 22.6%, respectively. Of the four sea areas, the water quality was best in the Yellow Sea, and was poor in the East China Sea. The water quality varied between the different coastal provinces and cities and was good in coastal areas of Hainan, Guangxi, Shandong, and other provinces and cities, but was poor in Shanghai, Zhejiang, and Tianjin. Terrestrial anthropogenic pollutants were the main influence on the water quality in the coastal areas. As a hotspot for fixing blue carbon, the continuous improvement of the water quality of coastal areas laid a foundation for the health of the blue carbon ecosystems.

Acid sulfate soils decrease surface water quality in coastal area of West Malaysia: Quo Vadis?

To satiate the surging world food demand, agricultural activities have been attempted on marginal land such as acid sulfate soils (ASS) which are distinguished by their low pH and presence of oxidized sulfidic material. However, the spatial distribution of chemical characteristics in ASS areas has received little attention; thus, this study was carried out with the goal of investigating an actual ASS area from a geochemical perspective and its effects on the quality of a nearby waterbody. ASS samples were collected from Kampung Sungai Raya, an agricultural area located at the west coast of Peninsular Malaysia. The study site is mostly covered with silty soil with a pH of 3.6 ± 0.9 throughout the 1-m soil profile. Soil content of aluminum, iron and soluble sulfate were found to be significantly different between the sampling locations (p < 0.05). Iron hydroxysulfate jarosite was identified at most of the sampling points, confirming the presence of oxidative dissolution processes of iron sulfide. The Sungai Raya river that flows in the vicinity of the ASS study area displayed comparable results with respect to low pH as well as soluble sulfate, aluminum, and iron concentrations. There is a possibility of intensification of sulfate and aluminum concentration as the river water flows downstream. Study on this site indicates that sustainable amelioration of the ASS area for growing crops requires an appropriate soil amendment practice. Alternatively, restoration of the land to its natural ecology and practicing silviculture or agroforestry could be a solution for ASS, both at this site and potentially at other active ASS sites all over the world.

Impact of Precipitation and Flow Rate Changes on the Water Quality of a Coastal River

This paper aims to investigate the effects of natural variables, including precipitation and flow rate, on the quality of the Zarjoub River in Guilan province, Iran. The new hydrological insight in this study is a lack of national research focused on the dual effects of rainfall and flow rate on river water quality in coastal areas along the Anzali Wetland. To investigate the effect of precipitation and flow rate on river water quality, nine water quality variables were monitored during the 10-year period. In this article, (a) the existence of trends and the best fitted models of water quality parameters and the discharge and precipitation were analysed using statistical techniques and (b) the relationships between concentration of constituents with the discharge and precipitation on the up-stream and middle station were also examined. Box plots, for explaining the distribution of a data collection, were used. The results showed the existence of trend of water quality parameters with river flow and rainfall. As presented in Section 3, with increasing precipitation and flow rate, concentration of all constituents, except pH and SO₄2, decreased. On the contrary, the maximum amount of water quality elements was observed in low precipitations; therefore, the maximum concentration occurred in less than 15 mm precipitation. Simple regression was used to evaluate the discharge concentration and precipitation concentration. According to the correlation coefficient (r), the relationship between concentration and precipitation is weaker than (0.238) discharge concentration (0.699). The results further showed climate change and river water quality to be related.

Review: Saltwater intrusion in fractured crystalline bedrock

During the past few years, the number of regional and national assessments of groundwater quality in regard to saltwater intrusion in coastal aquifers has increased steadily. However, most of the international literature on saltwater intrusion is focused on coastal plains with aquifers in unconsolidated material. Case studies, modelling approaches and parameter studies dealing with saltwater intrusion in those systems are abundant. While the hydrogeology of fractured rock has been intensively studied with both modelling approaches and parameter studies—mainly in relation to deep-laying fractured crystalline bedrock as potential waste repositories—case studies on saltwater intrusion in shallow fractured rocks are still an exception. This review summarizes the actual knowledge on saltwater intrusion in fractured crystalline rock. In combination with short overviews of the processes of saltwater intrusion, flow in fractured systems and the genesis of these systems, the review highlights the importance of the fracture systems and its specific characteristics. Fracture properties are a direct consequence of the geological history as well as the current situation of the coastal area. A holistic assessment of water quality in coastal areas hosting fractured crystalline bedrock therefore requires the combination of different approaches in order to investigate the impact of saltwater intrusion through the fractured system.

Trace Metal Element Analysis in Some Seafood in the Coastal Zone of the Red River (Ba Lat Estuary, Vietnam) by Green Sample Preparation and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).

Fisheries and aquaculture production in the coastal zone of Vietnam contribute significantly to the national economy. However, seafood quality and safety, especially in terms of metal contents, are of increasing concern, for both domestic and international markets. This paper presents the results of an investigation in some trace metal elements (iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), arsenic (As), cadmium (Cd), and mercury (Hg)) concentrations in some fishes, crustaceans, and molluscs in the coastal zone of the Red River (in the Ba Lat estuary in Thai Binh and Nam Dinh provinces) during four sampling campaigns in 2020. All samples were treated by a green sample preparation using microwave digestion and then analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed that the trace metal element concentrations in fish, crustacean, and mollusc samples decreased in the following order: Fe > Zn > Mn > Cu > As > Cd ∼ Hg. In more details, the ranges of trace metal elements in seafood samples were 13.13–202.73; 7.63–82.71; 0.48–22.73; 0.72–15.58; 0.18–5.12; 0.001–1.114; and 0.001–0.923 mg·kg−1 for Fe, Zn, Mn, Cu, As, Cd, and Hg, respectively. The research results contribute to the dataset of the seafood (both fishery and aquacultural seafood) quality in the Red River coastal zone. Although the mean values of different trace metal elements observed in this study were lower than the allowed values of Vietnam's or European's threshold for food safety, some high concentrations were detected. The survey results suggest the need to expand the monitoring scope (frequency of monitoring, number of samples, and observed variables) for obtaining a fully comprehensive assessment of seafood quality in this region. Our results also indicate that it is necessary to manage water quality in coastal areas, especially where aquaculture activities are carried out.

Effects of ecological water diversion in coastal plain river network considering different control plans

The water environment in coastal plain river network becomes serious due to its dense population and low flow rate, the ecological water diversion is widely accepted as an effective method to improve the water quality in coastal areas. As a typical coastal city in China, Pinghu city has suffered from the serious water quality problem for years especially in the downtown area. Therefore, the local water diversion project has been constructed since 2010 for the purpose of providing an efficient way to improve the river network water quality. However, a systematic research of the control plan of water diversion is still necessary. In this study, a numerical model is introduced to predict the improvement of river network water quality considering different control plans. The simulation results comparison among different water diversion control plans show than the pre-drainage plan obtains the best water quality in this coastal plain river network, and it becomes a good choice for the local government to further improve the regional water environment.

Assessment of Marine Water Quality in Quang Binh and Quang Ngai Provinces for Tourism Development Activities

This article assessing status of water quality in coastal areas of Quang Binh and Quang Ngai provinces for the purpose of tourism development. The results of research showed that water quality at monitoring sites at the beaches in Quang Binh and Quang Ngai provinces met requirements of QCVN 10-MT:2015/BTNMT for beach and underwater sport. Particularly with parameters such as: turbidity (NTU) at LS2, LS7 and LS14 sites exceed standards of ASEAN and chemical oxygen demand (COD) was increased. However, COD is not regulations in QCVN 10-MT: 2015 / BTNMT, ASEAN and Australia but when compared with QCVN 01: 2009 / BYT are more than two times. This can influence for health when exposed to coastal water in tourist areas.

A GIS methodology to support sea water quality assessment in coastal areas

The development of methodologies for assessing water quality in coastal areas including mapping of eutrophication levels is a research area of high interest. A wide range of methodological approaches can be found in the literature, including multivariate techniques, since marine eutrophication is a multi-parametric phenomenon. In this context, statistical analysis and in particular Principal Component Analysis (PCA) have been widely applied. However, no attempt has been presented so far for mapping eutrophication levels based on information acquired from PCA results in integration with spatial analysis methods. The rapid development of Geographical Information Systems provides the appropriate framework for the development and application of methodologies integrating statistical analysis, spatial analysis methods and mapping techniques. This paper proposes such a methodological approach for assessing sea water quality in coastal areas. The methodology is clearly described and the Strait of Mytilene at the east of the Island of Lesvos in the NE Aegean Sea, Greece is used as a case study.

Applying linear discriminant analysis to predict groundwater redox conditions conducive to denitrification

Diffuse nitrate losses from agricultural land pollute groundwater resources worldwide, but can be attenuated under reducing subsurface conditions. In New Zealand, the ability to predict where groundwater denitrification occurs is important for understanding the linkage between land use and discharges of nitrate-bearing groundwater to streams. This study assesses the application of linear discriminant analysis (LDA) for predicting groundwater redox status for Southland, a major dairy farming region in New Zealand. Data cases were developed by assigning a redox status to samples derived from a regional groundwater quality database. Pre-existing regional-scale geospatial databases were used as training variables for the discriminant functions. The predictive accuracy of the discriminant functions was slightly improved by optimising the thresholds between sample depth classes. The models predict 23% of the region as being reducing at shallow depths (<15 m), and 37% at medium depths (15–75 m). Predictions were made at a sub-regional level to determine whether improvements could be made with discriminant functions trained by local data. The results indicated that any gains in predictive success were offset by loss of confidence in the predictions due to the reduction in the number of samples used.The regional scale model predictions indicate that subsurface reducing conditions predominate at low elevations on the coastal plains where poorly drained soils are widespread. Additional indicators for subsurface denitrification are a high carbon content of the soil, a shallow water table, and low-permeability clastic sediments. The coastal plains are an area of widespread groundwater discharge, and the soil and hydrology characteristics require the land to be artificially drained to render the land suitable for farming. For the improvement of water quality in coastal areas, it is therefore important that land and water management efforts focus on understanding hydrological bypassing that may occur via artificial drainage systems.

MOLLUSCA' BIODIVERSITY (GASTROPODA AND BIVALVIA) AS A BIO INDICATOR OF QUALITY OF WATER IN THE COASTAL ISLAND OF TUNDA ISLAND, BANTEN

The research has been done on Juli 2017 in the coastal region of Tunda Island. This study aims to determine the Biodiversity of Mollusca (Gastropoda and Bivalvia) As Bioindicator of Water Quality In Coastal Area of Tunda Island, Banten. Sampling consists of 2 observation stations, namely the mangrove coastal area (3 transects) and the seagrass coastal area (2 transects) determined by purposive sampling. The observation of each station is done by using the quadratic transect method with 100 m transect line distance, and in each transect line there are 5 observation plots measuring 1m2 x 1m2. The data analysis includes density, biodiversity, bio-indicators of water quality based on diversity index. Result of research on 5 transect found 45 type Mollusca which represent 2 class, that is Gastropoda class of 29 species Gastropoda joined in 14 Family. As for Bivalvia class found 16 species incorporated in 9 families. The total density of Mollusca is 541.2 ind / m2 which consists of 392.4 ind / m2 for Gastropoda class and 148.8 ind / m2 for Bivalvia class. Mollusca diversity was calculated using the diversity index of Shannon-Wienner (H '). The results of diversity index ranged from 3.1356 - 3.3314 with high category. Bioindicator of aquatic quality using diversity index indicates that the coastal area of Tunda Island belongs to a very mildly polluted category.

ALGORITHM DEVELOPMENT OF SATELLITE IMAGE PROCESSING TO DETECT THE CONCENTRATION OF SUSPENDED PARTICULATE MATTER IN COASTAL WATERS OF RED RIVER DELTA

In this research, a set of optical data measured in the coastal waters of Red River Delta is used to develop the empirical algorithm for detecting the concentration of suspended particulate matter (SPM). The result of the study shows that the relationship between water-leaving reflectance and the concentration of SPM follows polynomial function with correlative coefficient (R2) &gt; 0.9. Landsat-8 OLI and VNREDSAT-1 satellite images were used to apply this algorithm for detecting the concentration of SPM in the coastal waters of Red River Delta. The concentrations of SPM from image processing and numerical model are much close to each other. The study result will be a valuable reference for studying on water quality in coastal area from remote sensing.

Bioconcentration Factor of Copper (Cu), Lead (Pb), and Zinc (Zn) in Anadara indica Related to the Water Quality in Coastal Areas

The Garapan river mouth forms part of the Tanjung Pasir coastal area. This region receives materials n ot only from coastal waters but also from domestic sewage and in dustrial wastewater that contains heavy metals such as Cu, Pb, and Zn. On the contrary, the Cibungur river mouth in th e different coastal area, receives relatively lower amounts of domestic sewage and industrial wastewater. The objective of this study was to determine the Cu, Pb, an d Zn content in the coastal sediment as well as the levels of A.indica and their relationship with water quality paramete rs. Samples were collected from four stations located in the Garapan and Cibungur river mouths and were analyzed for metal content using atomic absorption spectrometry Shimadzu 6300. Samples of A. indica found in the field are categorized into three diferent size classes. It is because size related t o heavy metal accumulation. Results showed that bio concentration factor (BCF) values were Zn>Cu>Pb in both locations. Small size A. indica tends to have higher values of BCF for Cu and Zn compared to medium and larger sized samples. Furthermore, the BCF values of Cu, Pb, and Zn in A. indica were higher when the sediment had a lower concentration of orga nic matter.

Impact of Shrimp Farm Effluent on Water Quality in Coastal Areas of the World Heritage-Listed Ha Long Bay

Problem statement: Shrimp farming has rapidly developed in coastal areas of the World Heritage-listed Ha Long Bay since the last decade. Effluent discharged from shrimp farms with high levels of nutrient waste may cause eutrophication in receiving waterways. Therefore, assessing water quality at tidal creeks receiving shrimp farm effluent in coastal areas of Ha Long Bay supports environmental protection and decision making for sustainable development of the region. Approach: Water samples were collected at 3 different locations for spatial assessment: inside sections of creeks directly receiving farm effluent (IEC), from main creeks adjacent to points of effluent discharge outside concentrated shrimp farms (OEC) and a few kilometers away from shrimp farm (ASF). Samples were taken on 3 occasions for temporal assessment. Parameters related to nutrient waste from shrimp farms, including: Total Ammonia Nitrogen (TAN), Nitrite-Nitrogen (NO2-N), Nitrate-Nitrogen (NO3-N), Total Phosphorus (TP), Dissolved Orthophosphate (PO4-P), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Chlorophyll-a (Chl-a), Temperature, Salinity, pH and Dissolved Oxygen (DO) were determined using standard methods. Results: There were statistically significant differences in the concentrations of TAN, NO2-N, NO3-N, TP, PO4-P, BOD, COD and Chl-a among IEC, OEC, ASF and the levels of these parameters increased after shrimp crops, especially after the main shrimp crop of the season in North Vietnam. The concentrations of TAN, NO3-N, TP, BOD, COD, Chl-a, TSS at IEC sites were higher than recommended for protecting aquatic ecosystems. Principal Component Analysis (PCA) efficiently summarized patterns of co-variation in water quality parameters among locations and study times. Conclusion/Recommendations: The findings of this study indicate that greater awareness of the environmental impacts of shrimp farms is required if this industry is to be sustainable and if the highly valued marine ecosystem of Ha Long Bay is to be protected for the future.

THE USE OF SOIL MOISTURE PROBES FOR IMPROVED UNIFORMITY AND IRRIGATION CONTROL IN GREENHOUSES

There is wide variety of soil moisture sensors available for use in greenhouse production and research applications. Such sensors can play a valuable role in improving uniformity of substrate water content in greenhouses, as well as in automating irrigation based on plant water use. Quantification of spatial variability can be used to improve the design of irrigation systems to better match plant water use. The use of soil moisture sensors for irrigation control is promising, because it can greatly reduce temporal variability in substrate water content by watering based on actual crop water use. This not only results in better temporal uniformity, but can also greatly reduce water use. Understanding the spatial distribution of substrate water content and root water uptake within a container is important in determining the optimal sensor location within a container. At the same time, the properties of different sensors need to be considered when choosing the optimal sensor for a particular application. In small containers, it may be possible to measure most of the substrate with a single sensor, while in larger containers sensors ideally would be placed in that part of the substrate where most of the water uptake occurs. INTRODUCTION High quality irrigation water is becoming increasingly scarce in many areas of the world. Population growth, increased urbanization, and drought conditions can result in a decrease in the quantity of water available for irrigation, while salt water infiltration into fresh water aquifers can affect water quality in coastal areas. Efficient irrigation practices for agricultural production, including greenhouse production, will become increasingly important. Not only is greenhouse irrigation directly affected by the quality of the available irrigation water, greenhouse irrigation practices also can affect water quality. Soilless substrates generally have a low anion exchange capacity, and greenhouse growers typically use water-soluble fertilizers. This combination can result in leaching of water and dissolved nutrients, especially nitrate and phosphate. If this leachate is not collected and recycled, runoff from greenhouses can result in significant non-point source pollution (Lea-Cox et al., 2001). Increasingly strict environmental regulations put pressure on greenhouse growers to irrigate more efficiently in order to conserve water and reduce the risk of negative environmental impacts of their facilities. To improve irrigation practices, a detailed understanding of the spatial and temporal dynamics of the water in the root zone is required. Many commercial greenhouses use timers to turn irrigation on and off. Timers do not take into account that crop water use changes on a day-to-day basis, based on environmental conditions such as solar radiation, temperature, humidity, and air circulation. For example, daily water use of vinca (Catharanthus roseus) throughout a 40day period is shown in Figure 1, along with the daily light integral (DLI, total daily a mvanier@uga.edu b sburnett@maine.edu Proc. IS on High Technology for Greenhouse Systems GreenSys2009

Study of Sediment Quality at Dredged Hollow Places in Port of Han-nan, Osaka Bay

Laboratory experiments in sediment quality at the hollow places are carried out in the presenting paper. They are designed to have the correct information of sediment in hollow area and to clarify the influence of the sediment on water quality in coastal areas. The sediment qualities in the hollows are much worse than those outside of the hollows, so that the rate of oxygen consumption by the bottom sediment in the hollows is as 2-10 times as that outside of the hollows.The formation rate of inorganic phosphorus and nitrogen in the sea mud and the diffusion rate of inorganic phosphorus and nitrogen to seawater in the hollows are much higher than those outside of hollows. These rates are different between sediments in two hollow places because of sulfide form.