TP Concentrations Research Articles

What drives the dominance and distribution of Cyanobacteria and Dinoflagellata in reservoirs of Sri Lanka?

Frequent records and health concerns in recent times have directed more attention on freshwater cyanobacterial and dinoflagellate blooms in Sri Lanka. Physico-chemical factors influencing phytoplankton growth are still under debate. This necessitates understanding environmental trends governing the dominance and distribution of algal blooms. Hence this study aimed to assess the dominance of Cyanobacteria and Dinoflagellata in reservoirs of Sri Lanka covering the three major climatic regions of the country, the Wet, Intermediate and Dry Zones. Plankton samples were collected using open type 20 µm plankton net and identified using standard phytoplankton keys. Ninety-one species belonging to three phyla of phytoplankton were identified. Phylum Chlorophyta represented the highest species number followed by Bacillariophyta and Cyanophyta. Fourteen genera of Cyanobacteria were recorded and eleven of them were potentially toxigenic. The widest distribution was shown by Chroococcus and Merismopedia. Cylindrospermopsis raciborskii with the highest mean relative abundance was recorded in Intermediate and Dry Zone reservoirs. Peridinium aciculiferum was the only dinoflagellate species recorded during the study with the highest abundance in the Isinbessagala rocky pond. Except sixteen reservoirs which were mesoeutrophic, all the other studied reservoirs were found to be either eutrophic or hypereutrophic. Iranamadu tank recorded the highest TP concentration (236 µg L-1) value. NO3-:TP ratio revealed the phosphate limited conditions in Wet and Dry Zone reservoirs whereas N was a limited factor in Intermediate Zone. Canonical Correspondence Analysis (CCA) results revealed that Secchi depth and area of water spread are important in determining both site and species variations in reservoirs of Sri Lanka.

Distribution Characteristics of Carbon, Nitrogen, and Phosphorus Bearing Pollutants in the Ancient Town Rivers of Suzhou

Suzhou is a water-deficient city with water quality issues. Despite water conservation measures, emission reductions, source control, and pollution interception, water quality remains poor. To understand the total mass and distribution characteristics of carbon, nitrogen, and phosphorus bearing pollutants and inform decisions regarding river dredging, sediment and water samples were collected from 20 representative sections in the town's rivers during the spring of 2019. The depths of the sediments were measured along with the concentrations of carbon, nitrogen, and phosphorus bearing pollutants in the sediments and water, and the pollution degree was evaluated. Variations in various parameters were predicted for change water, diversion water, rainfall, and dredging. The results show that the sediment depths ranged between 22 and 1025 mm (average=266 mm), and the total mass of sediment was approximately 5.2×105 t in the ancient town rivers of Suzhou. The average proportions and concentrations of TOC, TN, NH4+-N, TP, and AP in the sediments were 3.4%, 2074 mg·kg-1, 140.2 mg·kg-1, 1765 mg·kg-1, and 57.2 mg·kg-1, respectively, indicating a moderate level of pollution. The concentration of TP in the sediments at 90% of the sampling points exceeds the national standard. Huancheng River was found to have the highest concentration of TP, suggesting that dredging shuld be targeted here first. In the water samples, the average concentrations of TOC, BOD5, COD, TN, NH4+-N, Kjeldahl nitrogen, TP, and PO43--P were 7.8, 0.6, 13.1, 2.5, 0.643, 1.3, 0.18, and 0.09 mg·L-1, respectively, indicating a severe level of pollution. Overall, water quality in these rivers falls below Class V surface water, and the concentration of TN seriously exceeds the national standard. Based on the patterns of total carbon mass and nitrogen and phosphorus bearing pollutants, the recommended order of dredging in Suzhou is the Huancheng River, the northern rivers of the ancient town, Ganjiang River, and the southern rivers of the ancient town. Under the rainfall scenario, the initial concentrations of pollutants in runoff were high, which leads to a decline in water quality. The total mass of TN in the water was reduced by 0.2 t under the change water and diversion water scenarios, and was further reduced by 4.58 t and 2.19 t, respectively, after dredging. Phosphorus bearing pollutants in the sediment were mainly imported from other sources, meaning that the total mass of TP in the water may increase following dredging activities.

Assessing Impacts of Changes in External Nutrient Loadings on a Temperate Chinese Drinking Water Reservoir

The safety of drinking water is constantly being evaluated. In the last few decades, however, many drinking waters sources in the world, including in China, have undergone serious eutrophication and consequently water quality deterioration due to anthropogenic induced stressors such as elevated external nutrient inputs. In this study, we used the state-of-the-art complex, dynamic, mechanistic model GOTM-FABM-PCLake (a coupled one-dimensional hydrodynamic-lake ecosystem model) to quantitatively assess the impacts of external nutrient loading on the temperate Jihongtan reservoir in Shandong Province, China. Simulated values of all variables targeted in calibration (water temperature, dissolved oxygen, total nitrogen, total phosphorus, and chlorophyll a) agreed well with observations throughout the entire calibration and validation period and generally mimicked seasonal dynamics and inter-annual variations as found in the monitoring data. A series of scenarios, representing changed external nutrient loadings (both increasing and decreasing compared to the current nutrient load), were set up to quantify the effects on the reservoir water quality. Changes relative to the current external nutrient load had a significant effect on the simulated TN and TP concentrations in the reservoir. Our impact assessment indicate that TN will meet the Chinese water quality requirements of the water source (Class III) when the external nitrogen load is reduced by 70%, whereas TP will meet the requirements even if the external phosphorus load is increased by 100% relative to current loads. The model predicts progressively higher summer and autumn phytoplankton biomasses in the scenarios with increasing external phosphorus loading and potential toxic cyanobacteria will become more dominant at the expense of diatoms and other algae. Strict control of the external nutrient loading is therefore needed to maintain good drinking water quality in the reservoir.

Novel approaches to investigating spatial variability in channel bank total phosphorus at the catchment scale

Phosphorus (P) is often a limiting nutrient that leads to the eutrophication of aquatic systems. While dissolved P forms are the most bioavailable, the form, mobility, transport and fate of P are directly related to its association with fine-grained riverine sediment. Therefore, to implement successful P catchment management strategies it is important to understand the relative contribution of different sediment sources to P loads across the river continuum. While agricultural topsoil and, to a lesser extent, riverbed sediment are important sources of sediment-associated P, channel banks have been shown to be an important sediment source in some catchments. However, comparatively little is known about the P concentration and corresponding spatial variability in channel bank sediment and the associated implications for catchment management. The present study examines the spatial variability of P associated with channel bank profiles within a series of three nested catchments using both non-spatial and spatial statistical methods, where for the latter, a novel spatial approach was used to estimate the spatial averages and variances of P in channel bank sediment along the stream network. Channel bank P concentrations were compared to factors such as catchment scale, stream order, land use, bank exposure and location along the stream network. Concentrations of TP ranged between 129.6 and 1206.9 mg P kg−1 of which the water extractable P (WEP) content ranged from 0.01 to 0.12%. Stream order was found to influence TP concentrations, while land use and catchment scale provided only a moderate influence. This suggested that focussing channel bank sampling strategies at the largest catchment scale would capture key drivers of TP variability provided stream order is sufficiently represented. Whether the bank was had limited vegetation and was exposed and potentially eroding had a slight influence on TP variability in second-order stream banks in the larger of the two nested catchments. However, the slightly lower TP concentrations measured at these sites indicated that banks that are actually eroding may be contributing less TP than the total channel bank TP values measured across the catchments as a whole. The results of an explicitly spatial analysis demonstrated that local channel bank TP averages and TP variances vary along the stream network. Specifically, the most accurate spatial predictor of TP was local TP means with the use of ‘crow flies’ rather than stream network distances. Local TP variances were used to provide optimal designs for future channel bank TP sampling campaigns, given available resources. Throughout, both standard and outlier-resistant statistical analyses were applied to improve interpretation of the study findings.

Growth of Zostera japonica in different sediment habitats of the Yellow River estuary in China.

The estuarine delta of the Yellow River is a region of strong land-ocean-human interactions that undergoes a unique evolutionary process. The delta is formed by deposition of large quantities of sediments carried by the Yellow River, especially during the annual water and sediment regulation period; more than one-third of the total annual sediments is deposited to the estuary area. The seagrass Zostera japonica is located at the forefront of the Yellow River delta. To study the impact of the different sediment environments on the Z. japonica growth, its growth and water quality and sediment parameters were measured on the northern and southern sides of the estuary from April to October in 2019. The action of wind and tides have re-suspended and dispersed sediments over time, producing shores on the southern delta characterized by nutrient-enriched clays and shores on the northern delta characterized by coarser sands and silts with poor nutrients. During the monitoring period, the concentrations of TC, TN, and TP in the root-zone sediments at the southern site were 1.56%, 0.04%, and 0.06%, respectively, whereas they were 0.69%, 0.007%, and 0.06%, respectively, at the northern site. Sufficient nutrients supported the growth of Z. japonica at the southern site, while poor nutrition limited the continuous growth of Z. japonica at the northern site. In July, the plant height, biomass, and shoot density of Z. japonica at the southern site reached the maximum values of 23.6 cm, 0.14 g/shoot, and 3245 shoots/m2, respectively, whereas they were 16.4 cm, 0.06 g/shoot, and 2740 shoots/m2, respectively, at the northern site. The sediment grain size and their nutrients contributed to different growth patterns of Z. japonica at the southern and northern sites. Our research could provide important implication for the conservation of Z. japonica habitats in the Yellow River estuary in China.

A novel pilot-scale IFAS-MBR system with low aeration for municipal wastewater treatment: Linkages between nutrient removal and core functional microbiota

In this study, we proposed a novel IFAS-MBR with low aeration for the treatment of real municipal wastewater. With biocarriers packed in the anoxic tank, the pilot-scale IFAS-MBR operated with average dissolved oxygen concentrations of 0.56 mg/L in the oxic tank. Over 110 days of operation, highly efficient nutrient removal was achieved with the total nitrogen (TN) and phosphorus (TP) removal efficiencies of 78.1 ± 7.2% and 93.7 ± 5.8%, respectively. The average effluent concentrations of TN and TP reached 5.4 and 0.26 mg/L, respectively. Meanwhile, the removal efficiency of COD reached 95.3 ± 1.3% in the system, and the concentrations of COD decreased from 31.9 ± 3.7 (sludge supernatant) to 12.7 ± 1.6 mg/L (permeate) after membrane filtration. Microbial community analysis showed that Nitrosomonas (0.32%) and Nitrospira (1.85%) in activated sludge were the main drivers of the nitrification process, while various denitrifying bacteria in activated sludge and biofilms were responsible for nitrate reduction in the anoxic tank. Candidatus Accumulibacter (0.34%) and Dechloromonas (1.31%) primarily contributed to denitrifying phosphorus uptake in the anoxic tank. Furthermore, these organisms (i.e., core functional microbiota) exhibited stable levels over the entire operation. The highly enriched hydrolytic fermentation bacteria drove community succession, and the remarkable functional robustness of microbial communities in activated sludge and biofilms favored nutrient removal. Overall, the novel IFAS-MBR system provides an energy-efficient MBR alternative owing to its highly efficient performance and low operating costs enabled by low aeration rates and the absence of an external carbon source.

Dynamics of fluvial hydro-sedimentological, nutrient, particulate organic matter and effective particle size responses during the U.K. extreme wet winter of 2019–2020

The floc size distribution of suspended sediment is a critical driver for in-channel sedimentation and sediment-associated contaminant and nutrient transfer and fate in river catchments. Real-time, in situ, floc size characterisation is possible using available technology but, to date, limited high resolution floc data have been published for fluvial systems draining upland extensive grassland catchments. To that end, suspended sediment floc size distribution and turbidity were characterised at 15-minute intervals using Laser In-Situ Scattering and Transmissometry (LISST) diffraction and a YSI turbidity sonde for six storm events in the upper River Taw (15 km2) catchment in SW England. Maximum event discharges (Q) ranged between 4.3 and 20.0 m3 s−1, with clockwise hysteretic responses (HI = 0.18–0.48) of total suspended solid concentrations (TSS) and Q. The sediment flushing index was highest in the early autumn (0.93) and storm event TSS fluxes varied from 0.04 to 2.9 t km−2. This suggests a change in sources or composition of sediment during higher Q and highly variable patterns of sediment flux from event-to-event. The proportion of particulate organic matter (POM) to TSS was highly variable (5–89%) and did not increase with Q, indicating POM source limitation. The fine-grained tail (D10 and D16) of the floc size distributions decreased during hydrograph rising limbs, with the finest floc sizes associated with the highest TN and TP concentrations at peak Q. The results suggest that dynamic interactions between wet ground and extreme rainfall events can flush significant amounts of sediment from the relatively undisturbed extensive grassland upland catchment. We strongly encourage a sensors-based approach to reveal the spatio-temporal complexity of floc size and associated pollutant export during high Q generated by extreme rainfall since this can help to elucidate processes and mechanisms and generate high-resolution data for water quality modelling without significant user intervention.

Application of in-situ restoration combination technique for eutrophic water in Bailuwan Ecological Wetland Park

Bailuwan Ecological Wetland Park with an area of 200 hm2, has been the first “National Urban Wetland Park” in Chengdu which is divided into A and B two zones. In zone A, as a window and image representative of the city, 50% recharge water in Daxuanhu Lake comes from Xiaoxuanhu Lake. The water eutrophication was serious with water blooms appeared in Xiaoxuanhu Lake in 2017. In order to repair the eutrophic water body, in-situ ecological restoration combination technology was applied. Thirteen kinds of plants, including submerged water, emergent water and floating leaf together with man-made wetland, submerged macrophyte, ecological floating bed and floating leaf plant were selected to construct as restoration system for Xiaoxuanhu Lake. The results showed that Xiaoxuanhu Lake water quality had improved significantly after restoration. The main physical and chemical indexes were up to the standard of III class of surface water from inferior V in one year’s operation. The annual average concentration of CODMn, TP, TN and NH3-N compared with influent decreased 10.4%, 67.7%, 25.1% and 25.6% respectively. The high quality water supply for Daxuanhu Lake was guaranteed in this way. The technique can be used in situ restoration of eutrophic water body in the ecological wetland park and ecological restoration of eutrophic water body in urban rivers and lakes.

Development of a double-layer EPS-ASM2d model to illustrate the effect on mainstream biological phosphorus system in side-stream phosphorus recovery process

In order to deeply investigate the influences of side-stream phosphorus (P) recovery operation on mainstream biological P removal system, an improved activated sludge model no. 2 (ASM2d) was established to illuminate the metabolic processes of P in a side-stream P recovery reactor. The improved ASM2d (named D-EPS-ASM2d) was established by extending of the P metabolic processes of double-layer extracellular polymeric substances (EPS) into conventional ASM2d model. The predicted effluent concentrations of COD, NH4, and TP by the D-EPS-ASM2d had good fits with measured values in the side-stream P recovery process. Comparing with conventional ASM2d, the likelihood values of D-EPS-ASM2d related to COD, NH4, and TP effluents were increased from 0.694, 0.837 and 0.762 to 0.868, 0.904 and 0.920, respectively, implying the simulation performances of D-EPS-ASM2d on nutrient removal processes were significantly improved. Besides, the calibrated values of fPP,TEPS was 0.09, 0.102 and 0.123 as side-stream volume (SSV) increasing from 0.3 to 0.9, implying the fraction of P removal by tightly-bound EPS was enhanced with the increase of SSV.

Evaluating the spatial distribution and source of phthalate esters in the surface water of Xingkai Lake, China during summer

Increasing production and usage of phthalate esters (PAEs) has made them ubiquitous in the environment. In this study, the distribution and source of PAEs in the surface water of Xingkai Lake, China were analyzed. The concentration of ΣPAEs in the water of Xingkai Lake ranged from 0.26 to 3.83 μg/L with a median of 1.28 μg/L. It was observed that the difference in the concentration of ƩPAEs between the small and large Xingkai Lakes is not significant (p > 0.05). Agriculturally dominated land use types in the Xingkai Lake watershed may be mainly responsible for the occurrence of PAEs in this Lake. The distribution of butyl benzyl phthalate (BBP) in small and large Xingkai Lakes showed a significant difference (p < 0.05) which may be related to anthropogenic activities. ƩPAEs in the water of Xingkai Lake demonstrated significant positive correlations with the ratio of total nitrogen (TN) to concentration of TP (rp = 0.697, p < 0.01) and the concentration of suspended particulate organic matter (SPOM) (rp = 0.345, p < 0.05). These results further indicate that the concentration of nutrients from agricultural activity had an impact on the concentrations of PAE in the lakes. Furthermore, the more SPOM would lead to more suspension of PAEs in the water phase. The source analysis of PAEs showed that high molecular weight PAEs were dominant in the Xingkai Lake which may be arising from the combustion of plastics or from building materials and household furnishing.

Integrated empirical models to assess nutrient concentration in water resources: case study of a small basin in southeastern Brazil.

A significant contributor to water pollution is increased nutrient concentration that results in eutrophication. Modeling approaches are crucial to understanding the dynamics of nutrients in river basins. This study integrates empirical models into Geographic Information Systems to quantify total nitrogen and phosphorus (TN and TP) load and concentration in watercourses of Brazil's Lobo Stream Hydrographic Basin (LSHB). Land use, topographic, demographic, and hydrological data were used to simulate the load and concentration of nutrients generated by point and nonpoint pollution sources. The results indicate that the simulated TN and TP load is primarily generated by nonpoint sources, 81% and 76%, respectively. The Itaqueri River subbasin is the most critical, yielding more than half of the basin's TN and TP load. About 90% of annual LSHB point pollution load is generated in the Itaqueri River subbasin, principally from the Água Branca Stream. The linear regression between simulated and observed concentration indicates significant relationships (TN, r2 = 0.73 (p < 0.05), TP, r2 = 0.78 (p < 0.05)). The method used was able to simulate TN and TP concentration in watercourses, but was inconsistent for point pollution, indicating it represents the dynamics of nutrients in rural basins more effectively than in urban ones. The study shows that its methodology, despite limitations, enables scientists and managers to understand and predict spatial distribution of nutrient concentration in LSHB watercourses.

Mechanism of contaminant removal by algae-bacteria symbiosis in a PBR system during the treatment of anaerobic digestion effluents

Large volumes of anaerobic digestion effluents (ADEs) are generated by intense livestock and poultry farm activities. If untreated, these effluents represent a threat to the environment. Previous data have indicated that microalgae are able to grow in photobioreactors (PBR) where high concentrations of inorganic salts are present. In the present research, algae-assisted sequencing batch photo-bio-reactor (A-SBPBR) with single micro-algae systems and single activated sludge systems were developed. We studied the effects of the treatments on different parameters including COD, TN, AN, and TP. We analyzed changes in bacterial community diversity using the high-throughput sequencing analysis. The degradation mechanism of the ADEs was studied by means of algal-bacterial symbiosis. Experimental results indicated that contaminants were efficiently removed from the ADEs when using the A-SBPBR. After treatment, the degradation rates of COD, TN, AN, and TP were 73.78%, 80.67%, 89.74%, and 95.39%, respectively. The outlet concentrations of COD, TN, AN, and TP were 355.09 ± 17.90, 83.97 ± 9.37, 35.42 ± 2.65 and 0.87 ± 29 mg/L, respectively. In the initial stage of the process (day 1), the most abundant bacteria present in the ABS (algal-bacterial symbiosis system) included proteobacteria, bacteroidetes, actinobacteria, acidobacteria and chloroflexi. Among these, those with the highest abundance values were proteobacteria and bacteroidetes. Abundance values were 24.33% and 19.97%, respectively. A-SBPBR contained various microorganisms including aerobic bacteria, fungus, and chlorella. In a reciprocal interaction, bacteria and microalgae were able to use each other´s metabolites. Under intermittent aeration conditions, organic C, N, and P present in the macromolecules were converted to smaller species. C was transformed to CO2 and organic C. In addition, N and P stayed as part of small molecules that were used by aerobic bacteria and fungus. When ABS operation reached stability, hydrolytic acidifying bacteria, which belonged to acidobacteria, were able to degrade different organic compounds including saccharides.

EFFECTS OF ORAL ADMINISTRATION OF Lepidium sativum, Moringa oleifera OILS AND AQUEOUS EXTRACT OF Vitex agnnus castus ON REPRODUCTIVE PERFORMANCE AND BLOOD BIOCHEMICAL OF DOE RABBITS

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Исследование потенциала препаратов на основе экстрактов лекарственных растений в отношении подавления репликации SARS-CoV-2: пилотное исследование*

Relevance. Medicinal products of plant origin have long been successfully used in the treatment of various diseases, including those of viral etiology. Nevertheless, their effect on the replication of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has not been studied so far. Objective. To evaluate the potential of drugs based on validated plant extracts – RE (Bronchipret, Bronchipret TP, Tonsilgon N, Sinupret extract, Tonsipret) with respect to their ability to suppress SARS-CoV-2 replication in vitro. Materials and methods. Vero cells (Vero) incubated with RE of different concentrations were infected with SARS-CoV-2 virus. After 48 h the virus replication (the number of viral RNA copies in cell culture supernatant) was determined by quantitative polymerase chain reaction. Results. SARS-CoV-2 RNA copy number under the action of non-cytotoxic concentrations of Bronchipret TP decreased by 1000 times and by 10 times under the action of drugs Tonsilgon N and Tonsipret. Conclusion. Some of the studied REs in vitro demonstrated promising antiviral activity. It is advisable to conduct further, including clinical, studies of their activity against SARS-CoV-2 in the treatment of coronavirus infection (COronaVirus Disease 2019 – COVID-19).

Influence of 8 Km Training On Cardiac Biomarkers Alongside Haematobiochemical Profiles In Race Camels

This study was designed to investigate the effect of 8 km training on the serum concentrations of the cardiac biomarkers troponin I (cTnl) and creatine kinase myocardial band (CK-MB) in 23 healthy racing camels (Camelus dromedarius). From each camel, 2 blood samples were collected; before training (T0) and within 2 h after training (T1). Serum concentrations of cTnI and CK-MB, and hematobiochemical profiles were estimated. Compared to a value of 7.21+1.9 X109/L pre-training, neutrophils decreased significantly to 6.2±2.2 x 109/L post-training (P=0.05). Similarly, haemoglobin concentration decreased from 11.1+1.1 g/dL before training to 10.3+2.0 g/dL after training (P=0.0002). The MCV showed a similar pattern where it decreased from 26.0±1.3 (fl) pre-training to 24.0±3.6 (fl) post-training (P=0.01). Other haematological variables did not show any significant changes before and after training (P>0.05). The serum activity of AST increased from 85.5+12.8 U/L before training to 91.5+8.6 U/L after training (P=0.0001). Serum concentration of TP increased also from 54.2+8.7 g/L pre-training to 59.0+3.8 g/L post-training (P=0.04). On the contrary, the serum concentration of lactic acid decreased from 3.9+0.8 (mmol/L) before training to 3.3+0.4 (mmol/L) after training (P=0.004). Other biochemical variables did not show any significant changes before and after training (P>0.05). Before training the serum concentration of cTnI was 0.03±0.03 ng/mL; a value that did not differ significantly when compared to the value of 0.04±0.02 (ng/mL) after training (P=0.60). The CK-MB value differed significantly before and after training (0.47±0.1 ng/mL before training vs 0.48±0.8 ng/mL after training; P=0.004). In conclusion, the cardiac biomarker cTnI did not change significantly after training compared to baseline levels, a result that disagrees with values in camels after race. However, the CK-MB increased significantly after training compared to pre-training serum concentrations.

Major Watershed Characteristics Influencing Spatial Variability of Stream TP Concentration in the Nakdong River Basin

Major Watershed Characteristics Influencing Spatial Variability of Stream TP Concentration in the Nakdong River Basin

Chemical speciation of phosphorus in surface sediments from a geological phosphorus-rich watershed, South China

In order to clarify the distribution characteristics and potentially environmental effect of phosphorus (P) chemical speciation in river sediments from a typical geological P-rich (GPR) watershed, South China. Forty-eight sediment samples collected from the Huangbai River watershed, Yichang city, Hubei province. The levels of TP in Huangbai River wathershed were remarkably higher than those in most Chinese lakes, reservoirs, and river. The Ca-P and Res-P were the two dominant species that accounted for 78.7% and 13.3% of TP, respectively. Based on the sediment quality guideline (SQGs) and background values of Chinese soil and sediment, the majority of the mean TP concentrations in surface sediments were higher than their background values. The unique distribution pattern of P species in the Huangbai River watershed depends on local environment conditions and P sources. These findings improve our understanding of the eutrophication and P cycle in the GPR watershed.

Identifying Nonpoint Sources of Phosphorus and Nitrogen: A Case Study of Pollution That Enters a Freshwater Wetland (Laguna Cartagena, Puerto Rico)

Point and nonpoint sources of phosphorus (P) and nitrogen (N) can cause reductions in water quality, including eutrophication. Nonpoint pollution represents a special challenge because of dispersed not easily identifiable sources such as the runoff from soil, nutrients, and other chemicals from agricultural fields and residential areas. Laguna Cartagena is a tropical freshwater wetland, situated in southwestern Puerto Rico. It is a eutrophic ecosystem, and its eutrophication is caused by both external nutrient loading and internal, mainly by phosphorus. This wetland has been affected by phosphorus loading from inorganic agricultural fertilizer in this historically oligotrophic wetland system until the end of subsidized fertilizer use and sugar cane cultivation in the late 1990s. This study identifies: 1) nonpoint sources of phosphorus (SRP, Soluble Reactive Phosphorus and TP, Total Phosphorus) and nitrogen (nitrate, nitrite, and ammonia) that enter Laguna Cartagena; and 2) the role of precipitation events on the contributions of phosphorus and nitrogen loading to ecosystems. Herein we assess water samples from five channelized external sources of P and N that enter Laguna Cartagena at two-week intervals from October 2013 through November 2014. Rainfall data were obtained weekly from a rain gauge. Standard methods were used for all chemical analyses. Results showed that the channelized waterways that carry water to the lagoon can be classified as hypereutrophic (>100 μg/L) for TP concentrations and oligotrophic (<200 μg/L) for nitrogen concentrations. Currently agriculture (rice and cattle) is the predominant land use at the nearby University of Puerto Rico (UPR) Lajas Agricultural Experiment Substation, the predominant nonpoint source of nutrient pollution (SRP, TP and ammonia) in the principal channelized water sources to the lagoon. Current nutrient loads are likely derived from fertilizers applied to the Substation’s rice fields, and a high density livestock. The second important cause of external surface water degradation (SRP, TP and ammonia) is the discharge from rural households in the drainage basin that discharge greywater directly to the environment, as indicated by the results from Cerro Alto hills immediately to the north of the lagoon. Precipitation also was associated with SRP, TP and ammonia loads.

The Distribution Pattern of Mollusks Has Economic Value Concerning Substrate Characteristics in Lake Maninjau

Lake Maninjau is one of the tectovulcanic type lakes in West Sumatra Province which is used as a food source in the presence of fauna groups such as mollusks. The main purpose of this study is to determine the distribution of mollusks concerning the substrate in Lake Maninjau. This research was conducted three times from March-September 2015 at seven points of the river estuary around Lake Maninjau. The result of the study shows that Corbicula moltkiana was mostly found at Pandan station, while Melanoides tuberculata and Anodonta woodiana were mostly found at Muko-Muko station. The distribution pattern of Corbicula moltkiana and Melanoides tuberculata shows a tendency to live in groups. The waters of the estuary around Lake Maninjau are dominated by sand with TN and TP concentrations ranged from 0.093 - 0.610 mg kg-1 and 0.427 - 2.137 mg kg-1, respectively.

Quantifying the contributions of structural factors on runoff water quality from green roofs and optimizing assembled combinations using Taguchi method

Runoff water quality of green roofs often comes under debate, and the mechanism of runoff pollution retention is still unclear. How to quantify the influencing contributions of structural factors to runoff pollution of green roofs and optimize the assembled combinations for improving water quality are ambiguous. In this study, runoff plots of extensive green roofs with Taguchi designed structural factors and levels were constructed and simulated rainfall experiments were conducted. Influences of structural factors on outflow water quality of green roofs were statistically assessed and quantified. Runoff water quality of green roofs with assembled combinations at specific levels were optimized and predicted by using the Taguchi method. Results showed that except for the pH and NO3– concentrations, the extensive green roofs acted as a source of the tested pollutants in stormwater runoff. Contributions of substrate materials on pH, EC, ESP (exchangeable sodium percentage), F−, NO3– and NO2-N concentrations were the highest among the structural factors, and contribution percentages ranged from 33.38% to 64.47%. The vegetation types had important contributions on Cl−, SO42− and TP concentrations, and the contribution percentage was 74.72%, 71.23% and 45.16% respectively. Influences of substrate depths and slope gradients on outflow water quality were small. Most of the determination coefficients (R2) of regression analysis between the measured and predicted water quality parameters under Taguchi design were ranged from 0.843 to 0.997. Except the pH and NO3– parameters, the Taguchi predicted water quality under the optimum conditions were improved by 10.2–77.6%. These results will aid understanding of the retention mechanism of green roofs on runoff pollutants and improving runoff water quality through the optimization of green roof design.