Bay Water Quality Research Articles

Thermal stratification and its relationship with water quality in the typical tributary bay of the Three Gorges Reservoir

AbstractThe effect of thermal stratification and its relationship with water quality was researched by field observation in this study. Through assessing the degree of thermal stratification by calculating the dimensionless parameter of thermal resistance to mixing (RTRM) indices from 2008 to 2010, it indicated that the water body of Xiangxi River was stratified strongly in the summer months. The analysis of the degree of thermal stratification with both the meteorological and hydrodynamic factors showed thermal stratification intensity was more sensitive to meteorological factors in Xiangxi River. Through the analysis of the relationship between thermal stratification and water quality, the results indicated that the concentration of Chlorophyll a was higher in the epilimnion affected by the thermal stratification, which could cause algal bloom. The results may further help to evaluate the thermal stratification role in eutrophication process and algal bloom formation in Xiangxi River.

Predicting Lake Eutrophication Responses to Multiple Scenarios of Lake Restoration: A Three-Dimensional Modeling Approach

To improve the water quality and alleviate the eutrophication of Lake Yangchenghu, the third largest freshwater body within the Lake Taihu basin in China and an important source of drinking water, nutrient reduction strategies should be urgently addressed by decision makers, since virtually no improvement of water quality has taken place since the mid-1990s. Due to the lack of sufficient observation data and simulation results, a vertically compressed three-dimensional numerical model, the EcoTaihu model, was used to study the impact of three restoration measures on the water quality—namely, total nitrogen (TN), total phosphorus (TP) and biomass of phytoplankton (BP)—of Lake Yangchenghu: (i) total nutrient reduction, (ii) intensification of flushing by water transfer, and (iii) spatial adjustment of inflow channels. In particular, the spatial effects of the three restoration measures on the water quality were investigated. The results showed that the EcoTaihu model is applicable to other shallow lakes in China. The water quality responses to the different restoration scenarios showed significant spatio-temporal differences. The reduction of nutrient loads from inflows appeared to be the most effective measure for controlling the eutrophication and algal blooms in Lake Yangchenghu. The effectiveness of water transfer on the improvement of water quality for TN and TP was more influenced by the differences of nutrient concentrations between the transferred water and lake water, rather than flow rate, since no proportionate increase of improvement was observable in the case of larger transferred rates (60 m3 s−1). The spatial narrowing of inflowing rivers in the southwestern lake could preferentially improve the water quality in the southern bay of the western lake, but would also result in a deterioration trend of water quality in the total lake and drinking water abstraction areas.

Monitoring and modeling land-based marine pollution

An integrated numerical coastal water quality model was developed to simulate the effects of land-based pollutants. The model was applied to Izmir Inner Bay, Turkey. Water temperature, salinity, conductivity, pH, turbidity, dissolved oxygen, total dissolved solids, ammonium, nitrite, nitrate, total dissolved and inorganic phosphorus, and total dissolved and organic carbon were measured monthly, for one year. Land-based pollutant loadings were estimated using the USEPA’s Storm Water Management Model (SWMM, v5.1). The study considered the loads washed off from the surrounding basin of the Izmir Inner Bay, namely, total suspended solids, biological and chemical oxygen demand, inorganic phosphorus, ammonia, nitrite, and nitrate concentrations, from urban and as well as industrial effluents. The coastal circulations and changes in the water quality parameters were simulated by HYDROTAM-3D, a three-dimensional coastal hydrodynamics, transport, and water quality model. The concentrations of water quality parameters, namely, total dissolved phosphorus, ammonia, nitrite, nitrate nitrogen, and dissolved oxygen for Izmir Inner Bay were estimated for the year 2015 and compared with the monthly field measurements conducted at six monitoring stations located near discharge points in the bay. The model successfully simulated the effects of land use on coastal water quality parameters. The results indicated that Izmir Inner Bay coastal waters were hypertrophic in 2015. Best management practices in remediation, street cleaning, good agricultural practices, and increased proportions of wastewater treatment before discharge were considered in the model to reduce the land-based pollution in projections for 2040. The results showed that remediation will reduce the point and distributed source loadings on the sub-basins, and Izmir Inner Bay water quality is expected to improve significantly.

연안오염총량관리제도 도입에 따른 마산만 해양환경 변화

연안오염총량관리제도 도입에 따른 마산만 해양환경 변화

Chesapeake Bay's water quality condition has been recovering: Insights from a multimetric indicator assessment of thirty years of tidal monitoring data

To protect the aquatic living resources of Chesapeake Bay, the Chesapeake Bay Program partnership has developed guidance for state water quality standards, which include ambient water quality criteria to protect designated uses (DUs), and associated assessment procedures for dissolved oxygen (DO), water clarity/underwater bay grasses, and chlorophyll-a. For measuring progress toward meeting the respective states' water quality standards, a multimetric attainment indicator approach was developed to estimate combined standards attainment. We applied this approach to three decades of monitoring data of DO, water clarity/underwater bay grasses, and chlorophyll-a data on annually updated moving 3-year periods to track the progress in all 92 management segments of tidal waters in Chesapeake Bay. In 2014–2016, 40% of tidal water segment-DU-criterion combinations in the Bay (n = 291) are estimated to meet thresholds for attainment of their water quality criteria. This index score marks the best 3-year status in the entire record. Since 1985–1987, the indicator has followed a nonlinear trajectory, consistent with impacts from extreme weather events and subsequent recoveries. Over the period of record (1985–2016), the indicator exhibited a positive and statistically significant trend (p < 0.05), indicating that the Bay has been recovering since 1985. Patterns of attainment of individual DUs are variable, but improvements in open water DO, deep channel DO, and water clarity/submerged aquatic vegetation have combined to drive the improvement in the Baywide indicator in 2014–2016 relative to its long-term median. Finally, the improvement in estimated Baywide attainment was statistically linked to the decline of total nitrogen, indicating responsiveness of attainment status to the reduction of nutrient load through various management actions since at least the 1980s.

Keragaman dan Kelimpahan Plankton Sebagai Bioindikator Kualitas Lingkungan di Perairan Pantai Jayapura

The aims of this research were to know the water environmental quality and to determine the diversity and abundance of plankton in Youtefa and Yos Sudarso Bay. The Sampling was conducted from October 2012 to January 2013 at two observation stations of Youtefa Bay and four observation stations of Yos Sudarso Bay during the dry and rainy seasons. The Sampling of plankton in each observation stations were made horizontally using a plankton net size number of 25. Biological data are determined using diversity index, uniformity index, dominance index and abundance calculations. Physico-chemical parameters were analyzed descriptively by comparing the result data of research with waters quality standards for marine’s biota based on decree of Environment Minister No. 51 year 2004. The results of water quality showed that in general, the quality of aquatic environment in Youtefa and Yos Sudarso Bay did not comply with water quality standards for marine’s biota issued by The Minister of Environment of Republic of Indonesia. While based on the diversity index analysis, water quality in Youtefa and Yos Sudarso Bay was categorized as a half polluted-heavily polluted. Diversity of plankton in Youtefa and Yos Sudarso Bay during the dry and rainy seasons was categorized as low-medium. Abundance of plankton in Youtefa and Yos Sudarso Bay was in low category. Key words: Abundance, diversity, plankton, Youtefa Bay, Yos Sudarso Bay.

Rating Water Quality in Sevastopol Bay by the Fluxes of Pollutant Deposition in Bottom Sediments

Sevastopol Bay is used as an example for the development of criteria for rating anthropogenic impact by elimination fluxes from the water area of post-Chernobyl (90Sr, 137Cs, 239,240Pu) and natural (210Pо) radionuclides, as well as mercury and organochlorine compounds. The differentiation of the bay water area into zones with different biogeochemical conditions and the balance approach to interpreting field observation data were used to assess the conditioning capacity of Sevastopol Bay ecosystem for conservative radioactive and chemical substances by elimination fluxes of pollutants into aqueous depot, which is the open part of the Black Sea and into the geological depot, i.e., its bottom sediment stratum.

Chesapeake Bay Dissolved Oxygen Criterion Attainment Deficit: Three Decades of Temporal and Spatial Patterns.

Low dissolved oxygen (DO) conditions are a recurring issue in waters of Chesapeake Bay, with detrimental effects on aquatic living resources. The Chesapeake Bay Program partnership has developed criteria guidance supporting the definition of state water quality standards and associated assessment procedures for DO and other parameters, which provides a binary classification of attainment or impairment. Evaluating time series of these two outcomes alone, however, provides limited information on water quality change over time or space. Here we introduce an extension of the existing Chesapeake Bay water quality criterion assessment framework to quantify the amount of impairment shown by space-time exceedance of DO criterion (“attainment deficit”) for a specific tidal management unit (i.e., segment). We demonstrate the usefulness of this extended framework by applying it to Bay segments for each 3-year assessment period between 1985 and 2016. In general, the attainment deficit for the most recent period assessed (i.e., 2014–2016) is considerably worse for deep channel (DC; n = 10) segments than open water (OW; n = 92) and deep water (DW; n = 18) segments. Most subgroups - classified by designated uses, salinity zones, or tidal systems - show better (or similar) attainment status in 2014–2016 than their initial status (1985–1987). Some significant temporal trends (p < 0.1) were detected, presenting evidence on the recovery for portions of Chesapeake Bay with respect to DO criterion attainment. Significant, improving trends were observed in seven OW segments, four DW segments, and one DC segment over the 30 3-year assessment periods (1985–2016). Likewise, significant, improving trends were observed in 15 OW, five DW, and four DC segments over the recent 15 assessment periods (2000–2016). Subgroups showed mixed trends, with the Patuxent, Nanticoke, and Choptank Rivers experiencing significant, improving short-term (2000–2016) trends while Elizabeth experiencing a significant, degrading short-term trend. The general lack of significantly improving trends across the Bay suggests that further actions will be necessary to achieve full attainment of DO criterion. Insights revealed in this work are critical for understanding the dynamics of the Bay ecosystem and for further assessing the effectiveness of management initiatives aimed toward Bay restoration.

Revised Method and Outcomes for Estimating Soil Phosphorus Losses from Agricultural Land in the Chesapeake Bay Watershed Model.

Current restoration efforts for the Chesapeake Bay watershed mandate a timeline for reducing the load of nutrients and sediment into receiving waters. The Chesapeake Bay watershed model (WSM) has been used for two decades to simulate hydrology and nutrient and sediment transport; however, spatial limitations of the WSM preclude edge-of-field scale representation of phosphorus (P) losses. Rather, the WSM relies on literature-derived, county-scale rates of P loss (targets) for simulated land uses. An independent field-scale modeling tool, Annual Phosphorus Loss Estimator (APLE), was used as an alternative to the current WSM approach. Identical assumptions of county-level acreage, soil properties, nutrient management practices, and transport factors from the WSM were used as inputs to APLE. Incorporation of APLE P-loss estimates resulted in greater estimated total P loss and a revised spatial pattern of P loss compared with the WSM's original targets. Subsequently, APLE's revised estimates for P loss were substituted into the WSM and resulted in improved WSM calibration performance at up to 79% of tributary monitoring stations. The incorporation of APLE into the WSM will improve its ability to assess P loss and the impact of field management on Chesapeake Bay water quality.

Marsh persistence under sea-level rise is controlled by multiple, geologically variable stressors

ABSTRACTIntroduction: Marshes contribute to habitat and water quality in estuaries and coastal bays. Their importance to continued ecosystem functioning has led to concerns about their persistence.Outcomes: Concurrent with sea-level rise, marshes are eroding and appear to be disappearing through ponding in their interior; in addition, in many places, they are being replaced with shoreline stabilization structures. We examined the changes in marsh extent over the past 40 years within a subestuary of Chesapeake Bay, the largest estuary in the United States, to better understand the effects of sea-level rise and human pressure on marsh coverage.Discussion: Approximately 30 years ago, an inventory of York River estuary marshes documented the historic extent of marshes. Marshes were resurveyed in 2010 to examine shifts in tidal marsh extent and distribution. Marsh change varied spatially along the estuary, with watershed changes between a 32% loss and an 11% gain in marsh area. Loss of marsh was apparent in high energy sections of the estuary while there was marsh gain in the upper/riverine section of the estuary and where forested hummocks on marsh islands have become inundated. Marshes showed little change in the small tributary creeks, except in the creeks dominated by fringing marshes and high shoreline development.Conclusions: Differential resilience to sea-level rise and spatial variations in erosion, sediment supply, and human development have resulted in spatially variable changes in specific marsh extents and are predicted to lead to a redistribution of marshes along the estuarine gradient, with consequences for their unique communities.

Phytoplankton Index of Biotic Integrity and Reference Communities for Barnegat Bay–Little Egg Harbor, New Jersey: A Pilot Study

ABSTRACT Ren, L.; Belton, T.J.; Schuster, R., and Enache, M., 2017. Phytoplankton index of biotic integrity and reference communities for Barnegat Bay–Little Egg Harbor, New Jersey: A pilot study. In: Buchanan, G.A.; Belton, T.J., and Paudel, B. (eds.), A Comprehensive Assessment of Barnegat Bay–Little Egg Harbor, New Jersey. A pilot study was carried out to quantify season-salinity-specific phytoplankton reference communities and to develop a phytoplankton index of biotic integrity (P-IBI) for Barnegat Bay–Little Egg Harbor (BB-LEH) estuary, using approaches similar to those for the Chesapeake Bay. Synchronized phytoplankton and water-quality data collected between August 2011 and August 2013 from the Barnegat Bay Water Quality Monitoring Program were used as calibration data set. The results showed that one-fifth of samples were from the least-impaired habitat condition, with low turbidity and low concentrations of dissolved inorganic nitrogen and orthophosphate (PO4). Nearly 60% of samples were from un...

Effects of Local Watershed Land Use on Water Quality in Mid-Atlantic Coastal Bays and Subestuaries of the Chesapeake Bay

Nutrient inputs have degraded estuaries worldwide. We investigated the sources and effects of nutrient inputs by comparing water quality at shallow (< 2m deep) nearshore (within 200 m) locations in a total of 49 Chesapeake subestuaries and Mid-Atlantic coastal bays with differing local watershed land use. During July–October, concentrations of total nitrogen (TN), dissolved ammonium, dissolved inorganic N (DIN), and chlorophyll a were positively correlated with the percentages of cropland and developed land in the local watersheds. TN, DIN, and nitrate were positively correlated with the ratio of watershed area to subestuary area. Total phosphorus (TP) and dissolved phosphate increased with cropland but were not affected by developed land. The relationships among N, P, chlorophyll a, and land use suggest N limitation of chlorophyll a production from July–October. We compared our measurements inside the subestuaries to measurements by the Chesapeake Bay Program in adjacent estuarine waters outside the subestuaries. TP and dissolved inorganic P concentrations inside the subestuaries correlated with concentrations outside the subestuaries. However, water quality inside the subestuaries generally differed from that in adjacent estuarine waters. The concentration of nitrate was lower inside the subestuaries, while the concentrations of other forms of N, TP, and chlorophyll a were higher. This suggests that shallow nearshore waters inside the subestuaries import nitrate while exporting other forms of N as well as TP and chlorophyll a. The importance of local land use and the distinct biogeochemistry of shallow waters should be considered in managing coastal systems.

A Retrospective Analysis of Water Quality in an Open Bay on the Mexican Pacific

ABSTRACT de la Lanza-Espino, G.; Silva, R.; Hernandez-Pulido, S.; Marino-Tapia, I., and Enriquez, C., 2017. A retrospective analysis of water quality in an open bay on the Mexican Pacific. In: Martinez, M.L.; Taramelli, A., and Silva, R. (eds.), Coastal Resilience: Exploring the Many Challenges from Different Viewpoints. Journal of Coastal Research, Special Issue, No. 77, pp. 39–50. Coconut Creek (Florida), ISSN 0749-0208. Lack of knowledge about the complex interactions between the dynamics of natural systems (physical, chemical and biological) and the need for the resources found in coastal environments has led to the unplanned and disorganized development of several anthropogenic activities in the study area. It is important to revert this tendency and promote medium term studies that can help to foresee the unwanted effects, sometimes irreversible, of human activities on the environment. This paper includes results from hydrodynamic and water quality studies carried out in Petacalco Bay, Guerrero (Mex...

Physical and Chemical Conditions of Bayur Bay Waters On the East and West Season

Physical construction of Bayur bay coastal area as a port was followed by a variety of environmental issues, both physical degradation of the natural environment, biology reduction and an increase in social problems, directly affect to water quality decreasing in the coastal Bayur Bay. This study aims to determine the concentration distribution of physical and chemical parameters and their influence to water conditions on the east and west season. The method used is descriptive method (data taken by in situ and laboratory analysis), determining the location of sampling points based on purposive sampling method and tide prediction by NAOtide software. The results of field survey and laboratory measurements analysed using statistical method. The speed of sea currents on the east season ranged from 3,48 to 24,9 cm.s-1, while in the West season flow rate ranged from 1,4 to 57,7 cm.s-1. Rainfall in East Season ranged from 0-45 mm and The intensity of rainfall in West Season ranged from 0-30 mm. Sea-surface temperatures in the Eastern season range between 26,2- 31.5 °C, while in the west season SST range from 24,3 to 30,5°C. Dissolve oxygen concentration in the east season range from 4,3 to 6,1 mg.L-1, while the west monsoon conditions range from 4,1 to 6,4 mg.L-1. The pH values ranged from 7,4 to 8,1 in the Eastern season and ranged from 7,12 to 8,27 in the West season. Bayur Bay water quality conditions is not much different from its value range on the west and east season and influencing each other. Keywords: Bayur Bay, Seasons, SST, Statistical method

Long-term variations of water quality in the Inner Murchison Bay, Lake Victoria.

The water quality in the Inner Murchison Bay (IMB) located in Uganda on the northern shores of Lake Victoria is affected by a complex mixture of processes and driving factors including pollution, river inflows, lake water levels, wetland management and flora and fauna populations. This study attempts to explain long-term variations of the IMB water quality and to provide a plausible water quality model. Because intermittent monitoring around the Bay hinders accurate determination of pollution, concentrations at the extreme northern shores (hotspots) are considered indicative of the pollutant loading into the bay. Delft3D-Flow was applied to study the Bay hydrodynamics and coupled with the Delwaq module to investigate water quality processes related to oxygen: organic and nutrient components i.e. dissolved oxygen (DO), biological oxygen demand (BOD) and ammonium (NH4+). It is found that the IMB water quality deteriorated exponentially in the period 2001-2014 due to increased pollution and the high residence time of water. The worst water quality was in 2010 when diffuse pollution intensified due to the lining of more drainage channels within Kampala City in addition to the declining wetland effect. The water quality towards the Outer Murchison Bay (OMB) deteriorated over time with dilution accounting for 40-60% of pollutant reduction. Although the effect of lake level variations is negligible compared to pollution into the IMB, increased lake levels after 2011 improved DO levels and mixing and hence BOD levels in the IMB.

Impact of Reservoir Sediment Scour on Water Quality in a Downstream Estuary.

The Conowingo Reservoir is situated at the lower terminus of the Susquehanna ---River watershed, immediately above Chesapeake Bay. Since construction, the reservoir has been filling with sediment to the point where storage capacity is nearly exhausted. The potential for release of accumulated sediments, organic matter, and nutrients, especially through the action of storm scour, causes concern for water quality in Chesapeake Bay. We used hydrodynamic and eutrophication models to examine the effects of watershed loads and scour loads on bay water quality under total maximum daily load conditions. Results indicate that increased suspended solids loads are not a threat to bay water quality. For most conditions, solids scoured from the reservoir settle out before the season during which light attenuation is critical. The organic matter and nutrients associated with the solids are, however, detrimental. This material settles to the estuary bottom and is mineralized in bed sediments. Carbon diagenesis spurs oxygen consumption in bottom sediments and in the water column via release of chemical oxygen demand. The nutrients are recycled to the water column and stimulate algal production. As a result of a scour event, bottom-water dissolved oxygen declines up to 0.2 g m, although the decline is 0.1 g m or less when averaged over the summer season. Surface chlorophyll increases 0.1 to 0.3 mg m during the summer growing season.

Conowingo Reservoir Sedimentation and Chesapeake Bay: State of the Science.

The Conowingo Reservoir is situated on the Susquehanna River, immediately upstream of Chesapeake Bay, the largest estuary in the United States. Sedimentation in the reservoir provides an unintended benefit to the bay by preventing sediments, organic matter, and nutrients from entering the bay. The sediment storage capacity of the reservoir is nearly exhausted, however, and the resulting increase in loading of sediments and associated materials is a potential threat to Chesapeake Bay water quality. In response to this threat, the Lower Susquehanna River Watershed Assessment was conducted. The assessment indicates the reservoir is in a state of "dynamic equilibrium" in which sediment loads from the upstream watershed to the reservoir are balanced by sediments leaving the reservoir. Increased sediment loads are not a threat to bay water quality. Increased loads of associated organic matter and nutrients are, however, detrimental. Bottom-water dissolved oxygen declines of 0.1 to 0.2 g m are projected as a result of organic matter oxidation and enhanced eutrophication. The decline is small relative to normal variations but results in violations of standards enforced in a recently enacted total maximum daily load. Enhanced reductions in nutrient loads from the watershed are recommended to offset the decline in water quality caused by diminished retention in the reservoir. The assessment exposed several knowledge gaps that require additional investigation, including the potential for increased loading at flows below the threshold for reservoir scour and the nature and reactivity of organic matter and nutrients scoured from the reservoir bottom.

Spotlight on Sediments: How is the Chesapeake Bay affected by storm flows from the Conowingo Reservoir?

Spotlight on Sediments: How is the Chesapeake Bay affected by storm flows from the Conowingo Reservoir?

Chesapeake Bay recovery and factors affecting trends: Long-term monitoring, indicators, and insights

Monitoring the outcome of restoration efforts is the only way to identify the status of a recovery and the most effective management strategies. In this paper, we discuss Chesapeake Bay and watershed recovery and factors influencing water quality trends. For over 30 years, the Chesapeake Bay Program Partnership’s long-term tidal and watershed water quality monitoring networks have measured physical, chemical and biological parameters throughout the bay and its surrounding watershed underpinning an adaptive management process to drive ecosystem recovery. There are many natural and anthropogenic factors operating and interacting to affect the watershed and bay water quality recovery responses to management actions. Across habitats and indicators, the bay and its watershed continue to express a diverse spatial and temporal fabric of multiscale conditions, stressors and trends that show a range of health conditions and impairments, as well as evidence of progress and degradation. Recurrent independent reviews of the monitoring program have driven a culture of continued adaptation of the monitoring networks to reflect ever evolving management information needs. The adherence to bay and watershed-wide consistent monitoring protocols provides monitoring data supporting analyses and development of scientific syntheses that underpin indicator and model development, regulatory assessments, targeting of management actions, evaluation of management effectiveness, and directing of priorities and policies.

In Brief

The recent Sponge City Development (SCD) policy enacted in China has attracted tremendous investment, although its role in tackling water pollution remains vague. This study investigated the impact of SCD in Shenzhen, a national pilot city for SCD, on water quality in the transjurisdictional bay between Shenzhen and Hong Kong. A system modeling approach that coupled watershed nutrient load calculations with three-dimension bay water quality simulations was adopted. The main study findings include the following. While the planned SCD approach may result in much higher load reductions in total phosphorus and biochemical oxygen demand (BOD) and a comparable reduction in total nitrogen compared with those obtained by upgrading wastewater treatment plants, the contribution from green infrastructure (23.2%, 21.1% and 17.4% for total nitrogen, total phosphorus and BOD, respectively), which is a definitive component of SCD, is much smaller than that of pipeline construction (i.e., a gray infrastructure component of SCD). The overall cost-effectiveness ranking is green infrastructure > pipeline > upgrading wastewater treatment plants. On average, SCD in Shenzhen could reduce the total nitrogen and total phosphorus concentrations in the bay by 2.4% and 20.2%, respectively, but increase the chlorophyll a concentration by 5.5% due to improved light conditions. This study represents one of the few attempts to quantitatively assess the water quality impact of the SCD policy at a regional scale. The study findings suggest that SCD emphasizing green infrastructure should be preferably adopted by small-to medium-sized cities, and SCD for an individual city may only have a local impact on water quality and needs to be harmonized with other policies within the regional context.