Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 12.208
Filtrar
1.
Sci Total Environ ; 750: 141188, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182162

RESUMO

Scientists have correlated land application of animal wastes as fertilizer with the feminization of fish. Two questions were asked. 1) Under a worst case scenario when animal waste (layer and roaster litter, or farrowing swine slurry) is applied and tilled in 24 h prior to a surface-runoff producing rainfall, will estrogenic equivalents exceed the Lowest Observable Effect Concentration (LOEC) for fish (10 ng/L)? 2) Can calcium concentrations in runoff, measured using a rapid meter-based method, be used as a sentinel of elevated estrogenic activity? In a 3-yr study wastes were surface-applied and incorporated and 24 h later, 1.5 by 3 m plots were subjected to simulated rainfall and again 1 wk. and 3 wk. later. Nutrients in runoff were also measured, and in year 1 total coliforms and E. coli. were assessed. Except for an initial preliminary test run, runoff from all plots and years never exceeded 10 ng/L E2Eq equivalent. Calcium concentrations in runoff were not related to estrogenicity, negating its use as a sentinel marker. Specific estrogens in animal waste and runoff were identified by mass spectrometry with concentrations in runoff dependant on manure source and timing of rainfall. As expected, total coliform and E. coli concentrations in runoff were increased by the application of layer litter. Concentrations of nutrients in runoff would not be expected to result in surface water concentrations higher than guidelines for protection of aquatic species. Animal wastes applied in quantities appropriate for crop nutrient requirements, tilled into the soil surface, in observance of regulations avoiding application within 24 h of a predicted rain event, should not result in estrogen levels of environmental concern.


Assuntos
Escherichia coli , Esterco , Agricultura , Animais , Fertilizantes , Fósforo , Chuva , Suínos , Movimentos da Água
2.
Sci Total Environ ; 748: 141375, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33113681

RESUMO

Storm runoff is important for maintaining surface water resources, while this function is significantly affected by land use and land cover changes, e.g., afforestation and reforestation. The Chinese Loess Plateau (CLP) has undergone large-scale vegetation rehabilitation, especially afforestation over the past 20 years. We hypothesize that afforestation has profoundly changed the amounts and mechanisms of storm runoff generation in headwater catchments on the CLP. To test this hypothesis, rainfall, soil moisture, and streamflow were monitored in a grass catchment and an adjacent forest catchment for two consecutive years. The objective of this study was to elucidate the varied mechanisms of storm runoff generation in these two contrasting revegetated catchments. Results showed that (1) average runoff coefficient in the grassland catchment (0.042) was approximately ten times higher than that in the forestland catchment (0.004), confirming the impact of catchment afforestation on the suppression of storm runoff generation. (2) Peak rainfall intensity was the first-order control of the runoff coefficient in the grassland catchment, but not in the forestland catchment. (3) Threshold values for antecedent soil moisture (~18%) and the sum of antecedent soil moisture index and event precipitation (~210 mm) were identified in the grassland catchment, above which storm runoff significantly increased. (4) Two extraordinary high runoff coefficient events were observed in the grassland catchment, one due to high peak rainfall intensity and strong surface runoff and the other due to high rainfall amount and high antecedent soil moisture. We conclude that long-term afforestation has changed the mechanisms and patterns of storm runoff generation, and different conditions of rainfall intensity, rainfall amount and antecedent soil moisture determined the hydrological connectivity between the upper hillslope and downhill gully in the catchment. This study deepens our understanding of the mechanisms and thresholds of storm runoff generation in headwater catchments on the CLP.


Assuntos
Chuva , Movimentos da Água , Hidrologia , Poaceae , Solo
3.
Water Sci Technol ; 82(8): 1603-1613, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33107854

RESUMO

The baffle-drop shaft structure is usually applied in deep tunnel drainage systems to transfer shallow storm water to underground tunnels. At present, the definition of the maximum operational capacity of baffle-drop shafts is lack of scientific and reasonable analysis, and the researches on hydraulic and energy dissipation characteristics have been insufficient. In this paper, a 1:25 scale hydraulic model test was conducted to observe the flow phenomena during the discharge process, analyze the relationship between the maximum inflow discharge and the baffle parameters, and calculate the energy dissipation rate of the shaft under different flow conditions. The results demonstrated that three kinds of flow regimes were presented in the discharge process: wall-impact confined flow, critical flow, and free-drop flow. The impact wave majorly brought about the energy dissipation of water on the baffle. The impingement and breakup of the inflow at the bottom of the drop shaft, as well as the reverse flow, resulted in the final energy loss. The time-averaged pressure value of the upper baffle was 1.5-3 times that of the central and lower baffles. The baffle with a design angle could effectively reduce the time-averaged pressure of the water flow acting on the baffle. The energy dissipation rate of the drop shaft decreased with the increase in the inflow discharge, and the energy dissipation rate was found to range from about 63.14% to 96.40%. The optimal size of the baffle-drop shaft with the maximum energy dissipation rate was d/B = 0.485 and θ = 10° (d, B, and θ are the baffle spacing, width, and angle, respectively).


Assuntos
Movimentos da Água , Água
4.
Water Sci Technol ; 82(7): 1312-1326, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079712

RESUMO

The Municipality of Asker (Norway) is at risk of not meeting the water quality targets set by the European Union Water Framework Directive within the stipulated timeframe. While there are multiple factors negatively impacting water quality in the municipality, wastewater is likely to be a major contributor. Infiltration and inflow water (I/I-water) leads to a number of unwanted consequences, of which direct discharge of untreated wastewater through overflow points is particularly important. In Aker municipality the portion of I/I-water is about 63%, while the goal is to achieve a level of about 30%. This study utilises a socio-economic cost-effectiveness analysis of measures to prevent sewer overflows into waterbodies. The most effective alternative identified in the analysis is a complete renovation of old pipes in combination with troubleshooting for faulty stormwater connections, when compared to alternatives considering upsizing/retention. I/I-water cost the municipality of Asker NOK34 million in 2017, when using a price of NOK16,434 for each kg of total phosphorus (Tot-P) let into the recipient water bodies. If the phosphorus cost is equal to or less than NOK17,806/kg Tot-P, then it will not be socio-economically justified to reduce I/I-water.


Assuntos
Movimentos da Água , Água , Cidades , Análise Custo-Benefício , Noruega
5.
J Environ Qual ; 49(1): 85-96, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016357

RESUMO

Phosphorus (P) runoff from pastures can cause accelerated eutrophication of surface waters. However, few long-term studies have been conducted on the effects of best management practices, such as rotational grazing and/or buffer strips on P losses from pastures. The objective of this study was to evaluate the long-term effects of grazing management and buffer strips on P runoff from pastures receiving annual (5.6 Mg ha-1 ) poultry litter applications. A 14-yr study was conducted on 15 small watersheds (0.14 ha) with five treatments: hayed (H), continuously grazed (CG), rotationally grazed (R), rotationally grazed with an unfertilized buffer strip (RB), and rotationally grazed with an unfertilized fenced riparian buffer (RBR). Runoff samples were collected using automatic samplers during runoff events. Average annual runoff volumes from H (40 mm yr-1 ) and RBR (48 mm yr-1 ) were lower than CG and RB, which were both 65 mm yr-1 , and from R (67 mm yr-1 ). Rotational grazing alone did not reduce P loads compared with continuous grazing (1.88 and 1.71 kg P ha-1 for R and CG, respectively). However, compared with CG, total P losses from RB pastures were reduced 36% with unfertilized buffer strips (1.21 kg P ha-1 ), 60% in RBR watersheds with unfertilized fenced riparian buffer strips (0.74 kg P ha-1 ), and 49% by converting pastures to hayfields (0.97 kg P ha-1 ). Hence, the use of unfertilized buffer strips, unfertilized fenced riparian buffer strips, or converting pastures to hayfields are effective best management practices for reducing P runoff in U.S. pasture systems.


Assuntos
Fósforo , Aves Domésticas , Animais , Esterco , Movimentos da Água
6.
J Environ Qual ; 49(3): 675-687, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016383

RESUMO

Legacy phosphorus (P) in agricultural soils can be transported to surface waters via runoff and tile drainage, where it contributes to the development of harmful and nuisance algal blooms and hypoxia. However, a limited understanding of legacy P loss dynamics impedes the identification of mitigation strategies. Edge-of-field data from 41 agricultural fields in northwestern Ohio, USA, were used to develop regressions between legacy P concentrations (C) and discharge (Q) for two P fractions: total P (TP) and dissolved reactive P (DRP). Tile drainage TP concentration (CTP ) and DRP concentration (CDRP ) both increased as Q increased, and CTP tended to increase at a greater rate than CDRP . Surface runoff showed greater variation in C-Q regressions, indicating that the response of TP and DRP to elevated Q was field specific. The relative variability of C and Q was explored using a ratio of CVs (CVC /CVQ ), which indicated that tile drainage TP and DRP losses were chemodynamic, whereas losses via surface runoff demonstrated both chemodynamic and chemostatic behavior. The chemodynamic behavior indicated that legacy P losses were strongly influenced by variation in P source availability and transport pathways. In addition, legacy P source size influenced C, as demonstrated by a positive relationship between soil-test P and the CTP and CDRP in both tile drainage and surface runoff. Progress towards legacy P mitigation will require further characterization of the drivers of variability in CTP and CDRP , including weather-, soil-, and management-related factors.


Assuntos
Fósforo/análise , Movimentos da Água , Agricultura , Ohio , Solo
7.
J Environ Qual ; 49(3): 663-674, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016402

RESUMO

The impacts of low-disturbance manure application (LDMA) on runoff water quality in hay crop forages are not well known. Our objective in this study was to determine surface runoff losses of total nitrogen (TN), ammonium N (NH4 -N), nitrate N (NO3 -N), total phosphorus (TP), dissolved reactive P (DRP), and suspended sediment from alfalfa (Medicago sativa L.)-grass plots in central Wisconsin after surface broadcasting manure and LDMA compared with no application. Treatments were (a) surface banding (BAND), (b) surface banding with aeration (A/B), (c) shallow disk injection (INJECT), (d) surface broadcast (BCAST), and (e) a no-manure control (CONT). Runoff events were generated (n = 7) from replicated plots following a standardized rainfall simulation protocol. Although runoff was variable across plots and within treatments, mean runoff concentrations of TN (P = .03), NH4 -N (P = .03), TP (P = .001), and DRP (P < .0001) were lower for incorporated (INJECT and A/B) vs. unincorporated (BCAST and BAND) treatments. INJECT had lower mean DRP concentration (P = .02) than A/B and was similar to CONT and had lower cumulative TN (P = .05), TP (P = .07), and DRP (P = .01) loads than A/B. Additionally, TP, TN, DRP, and NH4 -N loads and concentrations were strongly related with soil surface manure coverage extent (R2 = 0.50-0.84; P < .0001), suggesting that manure was a main source of N and P losses. Although INJECT appeared to be the most effective in mitigating nutrient loss in surface runoff, more research is needed to determine LDMA impacts on farm economics, soil properties, and runoff water quality.


Assuntos
Esterco , Qualidade da Água , Agricultura , Medicago sativa , Chuva , Movimentos da Água , Wisconsin
8.
J Environ Qual ; 49(5): 1273-1285, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016436

RESUMO

Artificial subsurface (tile) drainage systems can convey phosphorus (P) from agricultural fields to surface waters; however, controls of subsurface dissolved reactive P (DRP) losses at the sub-field scale are not fully understood. We characterized subsurface DRP loads and flow-weighted mean concentration (FWMC) from January 2015 through September 2017 to determine seasonal (growing vs. non-growing) patterns from 36 individually monitored plots across a farm under a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation in east-central Illinois. Using linear mixed models, we investigated the effects of soil test P (STP), depression depth, and their interaction with precipitation and P fertilization on subsurface DRP losses. Dissolved reactive P loads in drainage tiles increased with precipitation and were greatest during the non-growing season (NGS) in 2016 and 2017. Annual subsurface DRP loads were positively related to STP, and during the NGS, there was a positive relationship between depression depth quantified at the plot-scale and subsurface DRP loads and FWMC. Along a depression-depth gradient, piecewise regression displayed a threshold at a depth of 0.38 m at which STP increased, indicating soil P accumulation in deeper closed depressions. Our study highlights the need to identify areas with the greatest risk of subsurface P losses to implement sub-field scale nutrient management practices.


Assuntos
Fósforo/análise , Solo , Agricultura , Depressão , Illinois , Movimentos da Água
9.
J Environ Qual ; 49(5): 1370-1383, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016447

RESUMO

Recent research on tile-drainage has placed emphasis on dissolved reactive phosphorus (DRP) delivery and transport pathways but less emphasis on particulate P (PP), resulting in its exclusion from agricultural water management models. In this study, we quantified the fluxes, mechanisms, and factors driving PP delivery into tiles through statistical analysis of a long-term hydrologic and water quality dataset. The dataset includes 5 yr of surface and tile discharge, total P (TP), DRP, total nitrogen (TN), and dissolved inorganic N concentrations from two edge-of-field study sites with contrasting soil and management practices. Hydrograph recession techniques were coupled with multiple linear regression for understanding hydrologic flow pathways, and empirical mode decomposition (EMD) time-series analysis was used to determine the significance of PP seasonality processes and the effect of management practices. The analysis of hydrologic flow pathways demonstrated that quickflow contributed 66 and 36% of subsurface discharge in the clay and loam sites, respectively. Phosphorus loading analysis showed that macropore flow plays a significant role in PP delivery to subsurface P loading and that PP significantly contributed to TP and DRP delivery; however, greater PP loadings were observed at the clay site despite greater subsurface discharge and soil test P levels at the loam site. Furthermore, PP delivery was significantly affected by environmental conditions and management practices. We highlight the efficacy of hydrograph recession analysis for identifying macropore and diffuse drainage, of P/N ratios to characterize sediment delivery mechanisms in tiles, and of EMD to detect management impacts on TP and DRP at the field scale.


Assuntos
Fósforo/análise , Movimentos da Água , Agricultura , Hidrologia , Solo
10.
Science ; 370(6514): 294-295, 2020 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-33060350
11.
Huan Jing Ke Xue ; 41(9): 4105-4112, 2020 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124292

RESUMO

A field-scale dry grass swale with impermeable bottom and shallow substrate layer was built in Shanghai, where the groundwater table is very high, to avoid groundwater pollution caused by runoff infiltration. The underdrain pipe of the facility was up bended to avoid outside water flowing backward because local ground elevation is very low. Performance of the facility under the actual precipitation conditions was evaluated in the rainy season of 2019. The average runoff volume reduction is 39.4%, and the peak flow is reduced effectively when rain intensity is lower than 8.0 mm ·h-1. Influent mass load reduction of TSS, COD, TP, and TN are 95.4%, 83.1%, 90.0%, and 57.7%, respectively. Wood chips in the substrate layer and the saturated zone are effective for denitrification during the wet and dry periods, respectively. Hydraulic loading rate and antecedent drying period are the main factors affecting denitrification. Improved influent quality combined with the storage volume supplied by the local urban river network could meet the goal of annual runoff volume reduction and annual pollution load removal in districts with high groundwater levels.


Assuntos
Poaceae , Poluentes Químicos da Água , China , Nitrogênio/análise , Chuva , Movimentos da Água , Poluentes Químicos da Água/análise
12.
Huan Jing Ke Xue ; 41(9): 4113-4123, 2020 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124293

RESUMO

Most sponge city constructions in China are carried out in urban parcel-based catchments, and the quality and quantity of surface runoff can be controlled by several low impact development (LID) facilities. However, there are few reports on the generation and control of urban diffuse pollution. In this study, two areas with different hardening rates were compared to analyze the load conditions during the accumulation-wash-off-transport process of particulate pollutants. The results showed that the road surface in the catchment was the main underlying surface that the particulate pollutants contributed to. The road dust accumulation in the medium hardening rate (61.1%) and high hardening rate (73.6%) plots accounted for 88.4% (2.22-12.51 g ·m-2) and 90.1% (4.99-33.43 g ·m-2) of the catchment area unit, respectively. The contribution to the suspended solids (SS) load of runoff was 91.7% (0.97-7.34 g ·m-2) and 90.5% (0.92-18.77 g ·m-2), respectively. The SS load of road runoff accounted for approximately 95.2% and 83.1%, respectively. The pollution load (SS) after treatment by the LID facilities was approximately 24.0% and 40.2% of the surface runoff, respectively. The particle size distribution of road dust during the accumulation and wash-off processes was>150 µm, while that in surface and output runoff was <50 µm. With the increase in the impervious area, the distribution of finer particles (<105 µm) in the process of accumulation and wash-off increased (24.4%, 106.4%), while the distribution of particles <50 µm in road runoff decreased (12.4%). The particle size distribution of the accumulated, washed dust, and the rain runoff on the roof were roughly similar to those on the road. However, compared to the particle size distribution of road dust, in the accumulation and wash-off processes, the coarser particles (>1000 µm) of the medium hardening rate plot and the particles of size 250-450 µm and <45 µm of the high hardening rate plot increased significantly (>1000 µm: 58.1%, 108.5%; 250-450 µm: 72.9%, 41.8%; <45 µm: 59.2%, 64.8%). The results revealed the entire distribution process (accumulation-wash-off-transport) of particulate pollutants and the effect of LID facilities on the total SS pollution load of the catchment, which can provide an important reference for the scientific assessment of the project performance of LID installation in urban parcel-based catchments.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , China , Cidades , Poeira , Monitoramento Ambiental , Chuva , Movimentos da Água , Poluentes Químicos da Água/análise
13.
Huan Jing Ke Xue ; 41(8): 3646-3656, 2020 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124338

RESUMO

To comprehend the runoff load of nitrogen (N) and phosphorus (P) and the impact on the receiving river in an agricultural area with an intensive orchard plantation and a longitudinal ridge and furrow morphology in the Three Gorges Reservoir Area, the runoff and N and P concentrations were dynamically monitored in a typical citrus orchard catchment in Wanzhou Country, Chongqing, China. The results showed that the nutrient concentration in runoff water from the intensive citrus planting catchment was very high. The average annual event mean concentrations (EMC) were 9.31 mg·L-1 for total nitrogen (TN), 8.11 mg·L-1 for dissolved nitrogen (DN), 5.66 mg·L-1 for nitrate nitrogen (NN), 0.51 mg·L-1 for ammonium nitrogen (AN), 0.87 mg·L-1 for total phosphorus, 0.56 mg·L-1 for solved phosphorus (DP), and 0.32 mg·L-1 for particulate phosphorus (DP). In addition, the annual loss loads were 13.43, 12.20, 8.77, 0.75, 1.26, 0.84, and 0.42 kg·(hm2·a)-1 for TN, DN, NN, AN, TP, DP, and PP, respectively. The annual average concentrations of TN and TP were 8.49 mg·L-1 and 0.87 mg·L-1, respectively, which exceeded the category V values of the surface water quality standards (GB3838-2002) by 4.25 times and 2.2 times, respectively, and also exceeded the internationally recognized thresholds for the eutrophication of waterbodies. The TN and TP loss load from storm runoff was one of the main reasons for the degradation of the river water quality, thus suggesting the need to treat surface runoff and control runoff nutrient losses, especially during the first storm events after fertilization. During two typical long-duration springtime rainfall events after fertilization, the loads of nitrate nitrogen (NN) and dissolved phosphorus (DP) were 4.94 kg·hm-2 and 0.28 kg·hm-2, respectively, which accounted for 92.90% and 64.69% of the total annual TN and TP loss loads, respectively. The loads of NN and DP in a short-duration high-intensity rainfall event were 0.52 and 0.05 kg·hm-2 respectively, which accounted for 65.92% and 74.88% of the total annual TN and TP loss loads, respectively. The DN and DP were the main forms of nitrogen and phosphorus losses from the intensive citrus orchard with a longitudinal ridge and furrow morphology. Meanwhile, the catchment showed a significant first-flush phenomenon during a typical rainfall event, with a total of 58.0%, 57.0%, 58.5%, 79.0%, 62.0%, 63.5%, and 60.0% of the mass of TN, DN, NN, AN, TP, DP, and PP in the initial 20% of the runoff, respectively. Hence, controlling the surface runoff at the early runoff stage plays an important role in reducing nutrient losses.


Assuntos
Fósforo , Poluentes Químicos da Água , China , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise , Chuva , Movimentos da Água , Poluentes Químicos da Água/análise
14.
Huan Jing Ke Xue ; 41(8): 3657-3664, 2020 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124339

RESUMO

The Taihu Lake plain is a highly urbanized region in China with many water-related environmental problems. Although point-source pollution has been effectively controlled by government legislation, urban surface runoff pollution is still a major issue. Different types of urban communities were selected for rainfall runoff experiments. According to the monitoring data of rainfall events, multiple methods were used to analyze the characteristics of surface runoff pollution and estimate the pollution load for different types of communities. The results indicated that surface runoff from urban communities reduced the river water quality. Certain degrees of the 'first flush' effect occurred in different types of urban communities. The surface runoff pollution in the commercial residential community was weaker than that in commercial and private residential communities; however, the first flush occurred more frequently in the commercial residential community. Holding back 30% of the surface runoff could effectively improve the runoff water quality in commercial and private residential communities as well as the commercial residential community with restaurants. In the commercial residential community, 25% of surface runoff should be held to improve runoff water quality effectively. The loads of pollutants, especially nitrogen and phosphorus, in urban communities in the Taihu Lake basin were higher than those in other regions in China. This research can assist with the reduction of surface runoff pollution in highly urbanized communities.


Assuntos
Movimentos da Água , Poluentes Químicos da Água , China , Monitoramento Ambiental , Fósforo/análise , Chuva , Poluentes Químicos da Água/análise
15.
Huan Jing Ke Xue ; 41(10): 4599-4606, 2020 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-33124392

RESUMO

Determining the influence of pervious/impervious underlying surface pattern (composition, position, proportion, etc.) on the generation capacity of surface runoff and pollution in the urban parcel-based catchment could aid in alleviating the urban waterlogging and control non-point source pollution significantly. Landscape metrics were used to analyze the relationship between the characteristics of pervious/impervious underlying surface pattern and total runoff (Q) and the cumulative load of dissolved pollutants (Ld) and particulate pollutants (Lp). The results showed that: ① For the metrics of fragmentation, the patch density (PD) was positively correlated with Q and Ld. and largest patch index (LPI) was negatively correlated with them. Especially, the PD exhibited a significantly positive correlation with Ld(r=0.59, P<0.05, calculated in COD). However, the LPI exhibited a significantly negative correlation with Ld (r=-0.60, P<0.05, calculated in COD). ② For the metrics of complexity, landscape shape index (LSI) was positively correlated with Q and Lp, and mean shape index (MSI) was negatively correlated with them. Especially, the LSI exhibited a significantly positive correlation with Lp (r=0.61, P<0.05, calculated in TP) significantly. However, the MSI exhibited a significantly negative correlation with Lp (r=-0.62, P<0.01, calculated in TP) significantly. ③ For the metrics of vergence, the split index (SPLIT) was positively correlated with Q and Ld, and the cohesion index (COHESION) was negatively correlated with them. The COHESION exhibited a significantly negative correlation with Ld(r=-0.59, P<0.05, calculated in COD), whereas the SPLIT exhibited a significantly positive correlation with Ld (r=0.6, P<0.05, calculated in COD). ④ In the planning on the distribution and pattern of pervious surface under small-scale catchment, it is suggested that the scattered small-regular patches should be transformed to large-irregular patches or patch group. The relationship of the fragmentation, complexity, and vergence of pervious/impervious surface, with the runoff generation, and pollution output in parcel-based catchment was analyzed, which provided a new method for rainfall runoff and pollution control by considering rational allocation of LID facilities in terms of its pattern characteristics (area, distance, shape, etc.).


Assuntos
Movimentos da Água , Poluentes Químicos da Água , China , Cidades , Poeira , Monitoramento Ambiental , Poluição Ambiental , Chuva , Poluentes Químicos da Água/análise
16.
Nature ; 586(7827): 29-30, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32999477
17.
Water Sci Technol ; 82(5): 918-926, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031070

RESUMO

The appearance of extreme weather causes frequent airport flooding, which has a serious impact on the normal operation of an airport. In this study, three simulation scenarios are set in order to study the effect of low impact development (LID) facilities (green roof and vegetative swale) on the water depth of overflow junctions and total inflow to the study area outlet in an airport at different rainfall return periods (2 a, 5 a, 20 a and 50 a). Vegetative swale has better reduction effect on water depth of overflow junctions than has green roof. The reduction rate of vegetative swale is about 25-52% at different rainfall return periods, but the effect of green roof is not obvious. For the double peak rainstorm, the reduction effect on the water depth of overflow junctions after setting vegetative swale for the first rain peak is better than that for the second rain peak. Under the condition of 2 a, 5 a, and 20 a, the total inflow reduction rates of study area outlet after applied green roof and vegetative swale are 16.85%, 20% and 22.17% respectively, and the effect is poor (only 2.26%) at low-frequency return period (50 a). This study can provide theoretical guidance for the design of LID facilities of a sponge airport.


Assuntos
Aeroportos , Chuva , Inundações , Água , Movimentos da Água
18.
J Environ Manage ; 276: 111248, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32891029

RESUMO

The discharge of excess nutrients to surface waters causes eutrophication, resulting in algal blooms, hypoxia, degraded water quality, reduced and contaminated fisheries, threats to potable water supplies, and decreases in tourism, cultural activities, and coastal economies. An understanding of the contribution of urban runoff to eutrophication is needed to inform management strategies. More broadly, the seasonality in nutrient concentrations and loads in urban runoff needs further analysis since algal blooms and hypoxia are seasonal in nature. This study quantifies the variation of nutrients and sediment in stormwater runoff across seasons from four urban residential sewersheds located in Columbus, Ohio, USA. An average of 62 runoff events at each sewershed were sampled using automated samplers during stormflow and analyzed for nutrients and total suspended solids (TSS). Spring total nitrogen concentrations had a significantly (p < 0.05) higher median concentration (2.19 mg/L) than fall (1.55 mg/L) and summer (1.50 mg/L). Total phosphorus concentrations were significantly higher in spring (0.22 mg/L) and fall (0.23 mg/L) than summer (0.15 mg/L). TSS concentrations were significantly higher in the spring (74.5 mg/L) and summer (56.5 mg/L) than the fall (34.0 mg/L). In contrast, seasonal loading differences for nutrients or sediment were rare because runoff volume varied in such a way as to offset significant concentration differences and significant seasonality in rainfall intensity. Annual pollutant loadings were similar in magnitude to other residential and even some agricultural runoff studies. Although nutrient loads are the key indicator for determining algal biomass, nutrient concentrations are important for real-time algal growth. Future research efforts should be focused not only on understanding how seasonal urban concentrations and loads impact coastal eutrophication, but also developing improved watershed management focused on critical periods. Improved designs for stormwater control measures need to account for seasonality in pollutant discharge.


Assuntos
Chuva , Poluentes Químicos da Água , Monitoramento Ambiental , Nitrogênio/análise , Nutrientes , Ohio , Fósforo/análise , Movimentos da Água , Poluentes Químicos da Água/análise
19.
Mar Environ Res ; 160: 105025, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32907735

RESUMO

Disturbance is a key factor in most natural environments and, globally, disturbance regimes are changing, driven by increased anthropogenic influences, including climate change. There is, however, still a lack of understanding about how disturbance interacts with species dispersal capacity to shape marine assemblage structure. We examined the impact of ice scour disturbance history (2009-2016) on the nearshore seafloor in a highly disturbed region of the Western Antarctic Peninsula by contrasting the response of two groups with different dispersal capacities: one consisting of high-dispersal species (mobile with pelagic larvae) and one of low-dispersal species (sessile with benthic larvae). Piecewise Structural Equation Models were constructed to test multi-factorial predictions of the underlying mechanisms, based on hypothesised responses to disturbance for the two groups. At least two or three disturbance factors, acting at different spatial scales, drove assemblage composition. A comparison between both high- and low-dispersal models demonstrated that these mechanisms are dispersal dependent. Disturbance should not be treated as a single metric, but should incorporate remote and direct disturbance events with consideration of taxa-dispersal and disturbance legacy. These modelling approaches can provide insights into how disturbance shapes assemblages in other disturbance regimes, such as fire-prone forests and trawl fisheries.


Assuntos
Mudança Climática , Meio Ambiente , Larva , Animais , Regiões Antárticas , Oceanos e Mares , Movimentos da Água
20.
Environ Monit Assess ; 192(10): 643, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32935220

RESUMO

Hydrological models apply different methods to estimate runoff and route flows. Suitability of these methods is not unique, but varies with catchment conditions. This study aims to find the suitable overland runoff and flow routing methods for a catchment in Hyderabad, India, using customised Storm Water Management Model (SWMM-C). Currently, SWMM adapts only non-linear reservoir (NLR) method to estimate overland runoff. Linear reservoir (LR) and kinematic wave overland flow (KWO) have been incorporated as additional overland runoff methods. For flow routing, SWMM currently has kinematic wave (KW) and dynamic wave (DW) methods. Muskingum, Muskingum Cunge (MC) and lag methods have been included as additional methods in this customised version. SWMM-C was calibrated with four event rainfalls and tested with six event rainfalls using all possible combinations of overland runoff and flow routing methods. Efficiency of SWMM-C in simulating runoff was evaluated using performance indices. Results showed that for low magnitude event rainfalls, NLR, LR and KWO simulated runoff with a maximum deviation of 50%, 60% and 40% from observed runoff, respectively. In high magnitude event rainfalls, NLR, LR and KWO simulated runoff with maximum deviations of 20%, 40% and 20%, respectively, from the observed runoff. It was inferred from model outputs that NLR method could simulate runoff reasonably well for rainfalls that have duration greater than the time of concentration of catchment. LR method could simulate peak runoff better. KWO method was found to be suitable for chosen catchment for all rainfall durations. Flow routing methods KW, DW and MC are found to have minor influences on the runoff.


Assuntos
Chuva , Movimentos da Água , Monitoramento Ambiental , Índia , Modelos Teóricos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA