Carbon sink capacity of public parks and carbon sequestration efficiency improvements in a dense urban landscape.

In Bangkok, the crowded capital of Thailand, the capacity of 25 public parks as carbon (C) sinks was determined from the aboveground C sequestration (Cseq, tons (t)-C) and carbon dioxide absorption (CO2abs, t-CO2) of the trees in these parks. The results revealed that the estimated Cseq and CO2abs of these parks were 11,112.2 t-C and 41,219.4 t-CO2, respectively. Of these values, 10,166.8 t-C and 37,753.1 t-CO2 were obtained for the group 1 trees (all observed species except palms), and 945.5 t-C and 3,466.3 t-CO2 were obtained for the group 2 trees (palms). The CO2abs of the 25 parks was 83.6% of the estimated greenhouse gases (i.e., 49,279 t-CO2 equivalent) absorbed by all green areas in Bangkok, but this amount was trivial and approximately 0.1% of the greenhouse gases emitted by the city (i.e., 46.44 million t-CO2 equivalent). To enhance the capacity of C sinks in dense urban landscapes, both tree Cseq potential and park Cseq efficiency should be simultaneously considered. The results of the linear mixed model and Kendall correlation analysis identified the variables influencing tree Cseq potential, i.e., tree group, species diversity, tree density, and tree diameter at breast height. Based on the preliminary baseline proposed in this study, identifying appropriate specifications for tree planting and park management planning could improve park Cseq efficiency. In each park, the diverse tree subgroup species should be planted, and proportions of green area and tree density should be managed to meet relevant baseline values.

BOD load analysis and management improvement for the Chao Phraya River Basin, Thailand.

The loads of biochemical oxygen demand (BOD) in the Chao Phraya River Basin (CPRB), Thailand were analyzed in terms of how they were generated (BODgen), stocked in the environment (BODen-stock), and discharged into the Chao Phraya River (BODCPR) using material flow analysis. BODgen from the industrial sector was the highest; however, BODen-stock and BODCPR from this point source were not significantly higher than those from the domestic sector. BODgen, BODen-stock, and BODCPR from swine farming and aquaculture across the river basin were lower than those from the domestic and industrial sectors. Of the total 251,884 tons per year (t/year) BODCPR, 49,614 t/year were in the upper river section, 35,976 t/year in the middle river section, and 166,294 t/year in the lower river section. These amounts were more than the carrying capacities of the relevant river sections (i.e., 7230 t/year, 18,380 t/year, and 37,851 t/year of the BOD loads for the upper, middle, and lower river sections, respectively). The first priority in BOD reduction in the CPRB should emphasize domestic wastewater by increasing wastewater treatment efficiency and onsite installations of wastewater treatment systems, while the second should be on paddy fields and other nonpoint sources. Specific best management practices may be considered, e.g., creating constructed wetlands or preserving riverbank vegetation as natural swales to alleviate BOD discharge from agricultural activities into water sources.

Water budget analysis and management for Bangkok Metropolis, Thailand.

The water budget of the Bangkok Metropolis system was analyzed using a material flow analysis model. Total imported flows into the system were 80,080 million m3 per year (Mm3 y-1) including inflows from the Chao Phraya and Mae Klong rivers and rainwater. Total exported flows out of the system were 78,528 Mm3 y-1 including outflow into the lower Chao Phraya River and tap water (TW) distributed to suburbs. Total rates of stock exchange (1,552 Mm3 y-1) were found in the processes of water recycling, TW distribution, domestic use, swine farming, aquaculture, and paddy fields. Only 21% of the total amount of wastewater (1,255 Mm3 y-1) was collected, with insufficient treatment capacity of about 415 Mm3 y-1. Domestic and business (industrial and commercial sectors) areas were major point sources, whereas paddy fields were a major non-point source of wastewater. To manage Bangkok's water budget, critical measures have to be considered. Wastewater treatment capacity and efficiency of wastewater collection should be improved. On-site wastewater treatment plants for residential areas should be installed. Urban planning and land use zoning are suggested to control land use activities. Green technology should be supported to reduce wastewater from farming.

Evaluating urban park ecosystem services and modeling improvement scenarios.

Three ecosystem services of the 25 public parks in Bangkok, including carbon sequestration, avoided runoff, four air pollutant removals (CO, NO2, PM10, and PM2.5), and the relevant monetary values, were determined using i-Tree Eco software. Two modeling scenarios (MS) including MS1 (no greening improvement) and MS2 (improvement by increasing either green area or tree planting, or both in the parks) with tree annual mortality rates (AMR) of 1 and 3% were developed to forecast the parks' ecosystem services for 50 years after 2020 (2021-2071). The results revealed the synergistic interactions of the different tree planting specifications (MS1 and MS2) and tree mortality rates on the parks' ecosystem services. For MC2 with the assigned 1% AMR, the parks' optimal ecosystem services were obtained and the average annual monetary value (0.55 million USD) of the total ecosystem services of the 25 parks over the 50-year forecast was 150% higher than that (0.22 million USD) in 2020. Based on MS1 and MS2, tree rotations should be conducted in the parks after 2057 and 2065, respectively, for the low tree AMR (≤1%) but not later than 2041 and 2043, respectively, for the higher tree AMR.

Abundance exchange models of fish assemblages along the Hudson River Estuary Gradient, New York.

The spatially explicit abundance exchange model (AEM) was built for four fish species: winter flounder (Pseudopleuronectes americanus), Atlantic silverside (Menidia menidia), eastern silvery minnow (Hybognathus regius), and striped bass (Morone saxatilis) along the Hudson River estuary gradient, New York. The fish and habitat data during 1974-1997 were used to develop and calibrate the AEM; and the fish data during 1998-2001 was used to validate the model. Preference indexes of fish species for dissolved oxygen, salinity, water temperature, and bottom substrates along the gradient were estimated; and these were used to compute habitat preference (HP) of the associated fish species. The species HP was a key variable in the AEM to quantify abundance and distribution patterns of the associated species along the gradient. The AEM could efficiently predict abundance and distribution patterns of all modeled species except striped bass. The model ability for predicting a local distribution range of a fish species with broad tolerance on changing environment like striped bass should be improved.

Contingency plan improvement for managing oil spills in the coastal waters of Thailand.

The estimated risks of being impacted by oil spills in the coastal waters were used to improve the oil spill contingency plan of Thailand. Functional roles of local agencies are integrated into the plan. Intensive measures are suggested for the coastal provinces located in high-very high risk zones, whereas light and moderate measures are suggested for the coastal provinces located in low and moderate risk zones, respectively. The estimated percentage risks due to simulated oil slicks hitting the coast and/or important resources (PRoilspill) were used to guide the year-round water activities that should be carefully handled at a certain radius with a low-moderate PRoilspill, whereas they should be avoided at a certain radius with a high-very high PRoilspill. Important measures before, during, and post periods of an oil spill incident are suggested to prevent and monitor oil spill incidents and mitigate their impacts on the environment.

Classifying risk zones by the impacts of oil spills in the coastal waters of Thailand.

Risk zones that could be subject to the impacts of oil spills were identified at a national scale across the 23 coastal provinces of Thailand based on the average percentage risk of critical variables, including frequency of oil spill incidents, number of ports, number of local boats, number of foreign boats, and presence of important resources (i.e., protection area, conservation area, marine park, mangrove, aquaculture, coral reef, seagrass, seagull, seabird, sea turtle, dugong, dolphin, whale, guitar fish, and shark). Risks at the local scale were determined based on the frequency of simulated oil slicks hitting the coast and/or important resources. Four zones with varied risk magnitudes (low, moderate, high, and very high) were mapped to guide the preparation of effective plans to minimize oil spill incidents and impacts in coastal waters. Risk maps with sufficient information could be used to improve regulations related to shipping and vessel navigation in local and regional seas.

Integrated ecosystem assessment: Lake Ontario water management.

BACKGROUND: Ecosystem management requires organizing, synthesizing, and projecting information at a large scale while simultaneously addressing public interests, dynamic ecological properties, and a continuum of physicochemical conditions. We compared the impacts of seven water level management plans for Lake Ontario on a set of environmental attributes of public relevance. METHODOLOGY AND FINDINGS: Our assessment method was developed with a set of established impact assessment tools (checklists, classifications, matrices, simulations, representative taxa, and performance relations) and the concept of archetypal geomorphic shoreline classes. We considered each environmental attribute and shoreline class in its typical and essential form and predicted how water level change would interact with defining properties. The analysis indicated that about half the shoreline of Lake Ontario is potentially sensitive to water level change with a small portion being highly sensitive. The current water management plan may be best for maintaining the environmental resources. In contrast, a natural water regime plan designed for greatest environmental benefits most often had adverse impacts, impacted most shoreline classes, and the largest portion of the lake coast. Plans that balanced multiple objectives and avoided hydrologic extremes were found to be similar relative to the environment, low on adverse impacts, and had many minor impacts across many shoreline classes. SIGNIFICANCE: The Lake Ontario ecosystem assessment provided information that can inform decisions about water management and the environment. No approach and set of methods will perfectly and unarguably accomplish integrated ecosystem assessment. For managing water levels in Lake Ontario, we found that there are no uniformly good and bad options for environmental conservation. The scientific challenge was selecting a set of tools and practices to present broad, relevant, unbiased, and accessible information to guide decision-making on a set of management options.

Effects of changing environments of mangrove creeks on fish communities at Trat Bay, Thailand.

Effects of changing environments of riverside mangroves, coastal land uses, and water quality on fish communities were studied in Bangphra and Thaprik creeks, Trat Bay, Thailand. Regression analysis revealed that fish species richness in the wet season had a negative relationship with water transparency, nitrate, and phosphate and a positive relationship with zooplankton. In the dry season, species richness had a negative relationship with nitrate and phosphate and a positive relationship with salinity, pH, and zooplankton. Abundances and species richness of fish declined over distance from downstream to upstream in both creeks. Riparian mangroves and water quality also declined with distance upstream in both creeks. Results from one-way analysis of variance and Tukey's HSD test revealed that the highest zooplankton volume with the lowest amounts of nitrate and phosphate were observed at the downstream station in both creeks in each season. Low zooplankton volume with high amounts of nitrate and phosphate were found at the midstream and upstream stations of the creeks. The midstream and upstream stations of Bangphra Creek had low to moderate abundance of mangroves along the riversides, whereas shrimp farms were mainly found along the riversides at the midstream and upstream stations of Thaprik Creek. Correlation analysis results of land-use types and the significant habitat factors were discussed. This study found that mangrove degradation, shrimp farming, and residential and agricultural areas altered water quality and the health of fish habitats, causing the decreases in fish abundance and species richness.