Surface sediments are closely related to lake black blooms. The dissolved oxygen （DO） distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elemen...Surface sediments are closely related to lake black blooms. The dissolved oxygen （DO） distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elements such as Fe and S at the sediment-water interface are important factors that could influence the formation of the black bloom. In this study, dredged and undredged sediment cores with different surface properties were used to simulate black blooms in the laboratory. The Micro Profiling System was employed to explore features of the DO and ∑H2S distribution at the sediment-water interface. Physical and chemical characteristics in sediments and pore waters were also analyzed. The results showed that sediment dredging effectively suppressed the black blooms. In the undredged treatment, DO penetration depth was only 50 μm. Fe^2＋ concentrations, ∑H2S concentrations, and ∑H2S production rates were remarkably higher in surface sediments and pore waters compared to control and dredged treatments. Furthermore, depletion of DO and accumulation of Fe^2＋ and ∑H2S in surface sediments and pore waters provided favorable redox environments and necessary material sources for the blooms. The study results proved that physical and chemical characteristics in surface sediments are important factors in the formation of the black bloom, and could provide scientific guidance for emergency treatment and long-term pre-control of black blooms.展开更多
After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, d...After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, dimethyl trisulfide （DMTS） and dimethyl tetrasulfide （DMTeS）. Even in the untreated control without a methionine addition, methionine and its catabolites （VOSCs, mainly DMDS） were found in considerable amounts that were high enough to account for the water＇s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine＋glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.展开更多
Organic matter-induced black blooms （hypoxia and an offensive odor） are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate bl...Organic matter-induced black blooms （hypoxia and an offensive odor） are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate black blooms that were induced by Potamogeton crispus in Lake Taihu, China. The main physical and chemical characteristics, including color- and odor-related substances, of the black blooms were analyzed. The black blooms were characterized by low dissolved oxygen concentration （close to 0 mg/L）, low oxidation-reduction potential, and relatively low pH of overlying water. Notably higher Fe^2＋ and ∑S2- were found in the black-bloom waters than in waters not affected by black blooms. The black color of the water may be attributable to the high concentration of these elements, as black FeS was considered to be the main substance causing the black color of blooms in freshwater lakes. Volatile organic sulfur compounds, including dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, were very abundant in the black-bloom waters. The massive anoxic degradation of dead Potamogeton crispus plants released dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, which were the main odor-causing compounds in the black blooms. The black blooms also induced an increase in ammonium nitrogen and soluble reactive phosphorus levels in the overlying waters. This extreme phenomenon not only heavily influenced the original lake ecosystem but also greatly changed the cycling of Fe, S, and nutrients in the water column.展开更多
Algae-caused black bloom （also known as black water agglomerate） has recently become a critical problem in some Chinese lakes.It has been suggested that the occurrence of algae-caused black bloom was caused by the c...Algae-caused black bloom （also known as black water agglomerate） has recently become a critical problem in some Chinese lakes.It has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae,and sludge dredging was adopted to control black bloom in some lakes of China.In this article,based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions,both un-dredged and dredged sites in three areas of Taihu Lake,China were studied to estimate the effects of dredging on the prevention and control of black bloom.During the experiment,drained algae were added to all six sites as an additional organic load;subsequently,the dissolved oxygen decreased rapidly,dropping to 0 mg/L at the sediment-water interface.Black bloom did not occur in the dredged sites of Moon Bay and Nan Quan,whereas all three un-dredged sites at Fudu Port,Moon Bay and Nan Quan experienced black bloom.Black bloom also occurred at the dredged site of Fudu Port one day later than at the other sites,and the odor and color were lighter than at the other locations.The color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide,among other chemicals,under reductive conditions.The color and odor of the water,together with the high concentrations of nutrients,were mainly caused by the decomposition of the algae and the presence of nutrient-rich sediment.Overall,the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.展开更多
Black cumin (Nigella sativa L.;Family-Ranunculaceae) is an important spice crop. Mature seeds are consumed for edible and medical purposes and also used as a food additive and flavour. Seed of black cumin has great po...Black cumin (Nigella sativa L.;Family-Ranunculaceae) is an important spice crop. Mature seeds are consumed for edible and medical purposes and also used as a food additive and flavour. Seed of black cumin has great potentiality as spice crop due to nutritive and medicinal values. The experiments were carried out at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during 2011 to 2012 to determine optimum planting time for seed production of black cumin. The experiment was two factorials. Factor A: 4 genotypes were V1: Exotic, Iran;V2: BARI kalozira-1;V3: Local, Faridpur and V4: Local, Natore. Factor B: sowing date: D1: 16 October;D2: 1 November;D3: 16 November and D4: 1 December. Therefore, treatment combinations were 16 in total. So, in 3 replications total plot was 48. Result revealed that significantly the highest 2.37 t/ha in V1, followed by V2 (1.96 t/ha). V2 and V3 (1.97 t/ha) were statistically similar and maximum yield was obtained from D2 (2.65 t/ha). In combined effect, maximum yield 3.00 t/ha was obtained in V1D2.. Investigation on time of sowing revealed that performance of black cumin was better in earlier sowings (16 October, 1 November) than later ones. The highest yield (4g plant-1;2.65 tha-1) was obtained when the crop was sown on 1 November. Among the genotypes, the exotic one with sowing in 1 November gave the highest seed yield (4.54 g·plant-1;3.00 t·ha-1).展开更多
基金supported by the Major National Science and Technology Programs on Water Pollution Control and Treatment(No.2012X0713-005)the Natural Science Foundation of Jiangsu Province(No.BK20118790)+2 种基金the 135 Project of Nanjing Institute of Geography and Lim-nologyChinese Academy of Sciences(No.Y213518090)the Industry-University-Research Prosepective Joint Research Projects of Jiangsu Province(No.BY2011165)
文摘Surface sediments are closely related to lake black blooms. The dissolved oxygen （DO） distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elements such as Fe and S at the sediment-water interface are important factors that could influence the formation of the black bloom. In this study, dredged and undredged sediment cores with different surface properties were used to simulate black blooms in the laboratory. The Micro Profiling System was employed to explore features of the DO and ∑H2S distribution at the sediment-water interface. Physical and chemical characteristics in sediments and pore waters were also analyzed. The results showed that sediment dredging effectively suppressed the black blooms. In the undredged treatment, DO penetration depth was only 50 μm. Fe^2＋ concentrations, ∑H2S concentrations, and ∑H2S production rates were remarkably higher in surface sediments and pore waters compared to control and dredged treatments. Furthermore, depletion of DO and accumulation of Fe^2＋ and ∑H2S in surface sediments and pore waters provided favorable redox environments and necessary material sources for the blooms. The study results proved that physical and chemical characteristics in surface sediments are important factors in the formation of the black bloom, and could provide scientific guidance for emergency treatment and long-term pre-control of black blooms.
基金supported by the National Natural Science Foundation of China (No. 50979102, 40730528,40901252, 20907057)
文摘After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, dimethyl trisulfide （DMTS） and dimethyl tetrasulfide （DMTeS）. Even in the untreated control without a methionine addition, methionine and its catabolites （VOSCs, mainly DMDS） were found in considerable amounts that were high enough to account for the water＇s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine＋glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.
基金supported by the Major National Science and Technology Programs on Water Pollution Control and Treatment (No. 2012X0713-005)the Innovation Program of the Chinese Academy of Sciences (No. KZCX2-EW-314)+2 种基金the 135 Project of Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences (No. NIGLAS2012135008)the National Natural ScienceFoundation of China (No. 41103033)the IndustryUniversity-Research Prospective Joint Research Projects of Jiangsu Province (No. BY2011165)
文摘Organic matter-induced black blooms （hypoxia and an offensive odor） are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate black blooms that were induced by Potamogeton crispus in Lake Taihu, China. The main physical and chemical characteristics, including color- and odor-related substances, of the black blooms were analyzed. The black blooms were characterized by low dissolved oxygen concentration （close to 0 mg/L）, low oxidation-reduction potential, and relatively low pH of overlying water. Notably higher Fe^2＋ and ∑S2- were found in the black-bloom waters than in waters not affected by black blooms. The black color of the water may be attributable to the high concentration of these elements, as black FeS was considered to be the main substance causing the black color of blooms in freshwater lakes. Volatile organic sulfur compounds, including dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, were very abundant in the black-bloom waters. The massive anoxic degradation of dead Potamogeton crispus plants released dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, which were the main odor-causing compounds in the black blooms. The black blooms also induced an increase in ammonium nitrogen and soluble reactive phosphorus levels in the overlying waters. This extreme phenomenon not only heavily influenced the original lake ecosystem but also greatly changed the cycling of Fe, S, and nutrients in the water column.
基金supported by the Industry-Academia Cooperation Innovation Fund Project of Jiangsu Province(No.BY2011165)the Innovation Program of the Chinese Academy of Sciences(No.KZCX2-EW-314)+1 种基金the Key Project of"One Three Five"Strategic Developing Plan(No.NIGLAS2012135008)the National Water Pollution Control and Management Technology Major Project(No.2012ZX07103-005,2012ZX07101-010)
文摘Algae-caused black bloom （also known as black water agglomerate） has recently become a critical problem in some Chinese lakes.It has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae,and sludge dredging was adopted to control black bloom in some lakes of China.In this article,based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions,both un-dredged and dredged sites in three areas of Taihu Lake,China were studied to estimate the effects of dredging on the prevention and control of black bloom.During the experiment,drained algae were added to all six sites as an additional organic load;subsequently,the dissolved oxygen decreased rapidly,dropping to 0 mg/L at the sediment-water interface.Black bloom did not occur in the dredged sites of Moon Bay and Nan Quan,whereas all three un-dredged sites at Fudu Port,Moon Bay and Nan Quan experienced black bloom.Black bloom also occurred at the dredged site of Fudu Port one day later than at the other sites,and the odor and color were lighter than at the other locations.The color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide,among other chemicals,under reductive conditions.The color and odor of the water,together with the high concentrations of nutrients,were mainly caused by the decomposition of the algae and the presence of nutrient-rich sediment.Overall,the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.
文摘Black cumin (Nigella sativa L.;Family-Ranunculaceae) is an important spice crop. Mature seeds are consumed for edible and medical purposes and also used as a food additive and flavour. Seed of black cumin has great potentiality as spice crop due to nutritive and medicinal values. The experiments were carried out at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during 2011 to 2012 to determine optimum planting time for seed production of black cumin. The experiment was two factorials. Factor A: 4 genotypes were V1: Exotic, Iran;V2: BARI kalozira-1;V3: Local, Faridpur and V4: Local, Natore. Factor B: sowing date: D1: 16 October;D2: 1 November;D3: 16 November and D4: 1 December. Therefore, treatment combinations were 16 in total. So, in 3 replications total plot was 48. Result revealed that significantly the highest 2.37 t/ha in V1, followed by V2 (1.96 t/ha). V2 and V3 (1.97 t/ha) were statistically similar and maximum yield was obtained from D2 (2.65 t/ha). In combined effect, maximum yield 3.00 t/ha was obtained in V1D2.. Investigation on time of sowing revealed that performance of black cumin was better in earlier sowings (16 October, 1 November) than later ones. The highest yield (4g plant-1;2.65 tha-1) was obtained when the crop was sown on 1 November. Among the genotypes, the exotic one with sowing in 1 November gave the highest seed yield (4.54 g·plant-1;3.00 t·ha-1).
