High anthropogenic N loads and abundant bacteria are characteristic of highly contaminated urban rivers.To better understand the dispersal and accumulation of bacteria, we determined contents and isotopic compositions...High anthropogenic N loads and abundant bacteria are characteristic of highly contaminated urban rivers.To better understand the dispersal and accumulation of bacteria, we determined contents and isotopic compositions of suspended particulate organic matter(SPOM) and bacteria in a highly contaminated urban river(the Nanming)and effluents in winter and summer of 2013. Relative to SPOM, bacterial biomass in the river was depleted in ^(13)C and ^(15)N and its C/N ratio was lower(δ^(13)C:-33.2% ± 3.1%; δ^(15)N:-1.5% ± 1.2%; C/N:4.8 ± 0.6), while effluents showed higher ^(13)C and ^(15)N contents and C/N ratios(δ^(13)C:-25% ± 2.1%; δ ^(15)N:-8.5% ± 1.1%; C/N: 8.1 ± 1.2). Source recognition of SPOM was based on carbon isotopes because they are conservative and distinct between end-members(effluent detritus and bacterial biomass). Using a mixing model,bacterial biomass in the river was calculated to account for <20% and <56% of bulk suspended particulate organic nitrogen in winter and summer, respectively. An N budget showed that bacterial N was a small proportion of total nitrogen(<7.4%) in the riverwater.展开更多
We compared chemical and biological properties of soils in organically and conventionally fertilized apple orchards in Nagano Prefecture (one of the major apple producing regions in Japan). Five apple orchards with di...We compared chemical and biological properties of soils in organically and conventionally fertilized apple orchards in Nagano Prefecture (one of the major apple producing regions in Japan). Five apple orchards with different fertilizer management systems were used for this study. The total carbon and total nitrogen contents were higher in the organically fertilized orchard, while the total phosphorus and total potassium were at similar levels in both organically and conventionally fertilized orchards. The bacterial biomass did not differ between the two orchards, but the N circulation activity was clearly higher in the organically fertilized orchard from April to December. Total carbon from 50,000 to 60,000 mg/kg, total nitrogen at about 3000 to 4000 mg/kg, and a C/N ratio of 15 - 20 were suggested to be suitable conditions for a high level of apple production under an organic fertilizer management system.展开更多
The effective utilization of steel slag, a byproduct produced in large quantities from the steel refining process, is an important issue. Because steel slag contains abundant mineral components, the effects of steel s...The effective utilization of steel slag, a byproduct produced in large quantities from the steel refining process, is an important issue. Because steel slag contains abundant mineral components, the effects of steel slag on soil bacterial biomass and plant mineral uptake were analyzed in this study. The soil pH increased in proportion to the amount of steel slag added. A lower concentration (0.2% to 1%) of steel slag addition did not change the bacterial biomass. However, a higher concentration of steel slag (above 1%) had a negative effect on bacterial biomass. A lower amount of steel slag (0.2% to 1%) addition in soil leads to increased mineral (Ca, Mg, and Fe) uptake and plant growth in Brassica rapa var. periviridis and Spinacia oleracea L. However, mineral uptake by the plants decreased when a large amount of steel slag (above 1%) was added to the soil. Low concentrations of steel slag (0.2% to 1%) in soil had positive effects on plant growth, mineral uptake of plants, and bacterial biomass.展开更多
Soil samples from 139 agricultural orchard fields (apple, grape, tea, and others) w</span><span style="font-family:Verdana;">ere</span><span style="font-family:Verdana;"> an...Soil samples from 139 agricultural orchard fields (apple, grape, tea, and others) w</span><span style="font-family:Verdana;">ere</span><span style="font-family:Verdana;"> analyzed using the soil fertility index. From these samples, an orchard field database was constructed and the soil properties between orchard, upland, and paddy fields </span><span style="font-family:Verdana;">were </span><span style="font-family:""><span style="font-family:Verdana;">compared. The average value of bacterial biomass in the orchard fields was 7.4 × 10</span><sup><span style="font-family:Verdana;">8</span></sup><span style="font-family:Verdana;"> cells/g-soil, ranging from not detected (lower than 6.6 × 10</span><sup><span style="font-family:Verdana;">6</span></sup><span style="font-family:Verdana;"> cells/g-soil) to 7.7 × 10</span><sup><span style="font-family:Verdana;">9</span></sup><span style="font-family:Verdana;"> cells/g-soil. The average values of total carbon (TC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK), were 24,000 mg/kg (2670 to 128,100 mg/kg), 1460 mg/kg (133 to 6400 mg/kg), 1030 mg/kg (142 to 5362 mg/kg), and 5370 mg/kg (1214 to 18,155 mg/kg), respectively. The C/N and C/P ratios were 19 (3 to 85) and 27 (2 to 101), respectively. Soil properties of the orchard fields were compared with those of the upland and the paddy fields. The average value of bacterial biomass in the orchard fields was almost the same as that in the upland fields (8.0 × 10</span><sup><span style="font-family:Verdana;">8</span></sup><span style="font-family:Verdana;"> cells/g-soil), but the number was lower than that in the paddy fields (12.9 × 10</span><sup><span style="font-family:Verdana;">8</span></sup><span style="font-family:Verdana;"> cells/g-soil). The average values of TC and TN in the orchard fields fell between those in the upland fields (TC: 33,120 mg/kg, TN: 2010 mg/kg) and the paddy fields (TC: 15,420 mg/kg, TN: 1080</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">mg/kg). The relationship between the bacterial biomass and TC in the orchard fields resembled that in the upland fields. A suitable soil condition for the orchard fields was determined as TC: ≥25,000 mg/kg, TN: ≥1500 mg/kg, TP: ≥900 mg/kg and TK: 2500 - 10,000 mg/kg.</span><span style="font-family:""> </span><span style="font-family:Verdana;">These recommended values will be effective for the improvement of the soil quality in the orchard fields by enhancing the number and activities of microorganisms.展开更多
基金kindly supported by the National Key Research and Development Program of China through Grant 2016YFA0601000the National Natural Science Foundation of China through Grant 41425014
文摘High anthropogenic N loads and abundant bacteria are characteristic of highly contaminated urban rivers.To better understand the dispersal and accumulation of bacteria, we determined contents and isotopic compositions of suspended particulate organic matter(SPOM) and bacteria in a highly contaminated urban river(the Nanming)and effluents in winter and summer of 2013. Relative to SPOM, bacterial biomass in the river was depleted in ^(13)C and ^(15)N and its C/N ratio was lower(δ^(13)C:-33.2% ± 3.1%; δ^(15)N:-1.5% ± 1.2%; C/N:4.8 ± 0.6), while effluents showed higher ^(13)C and ^(15)N contents and C/N ratios(δ^(13)C:-25% ± 2.1%; δ ^(15)N:-8.5% ± 1.1%; C/N: 8.1 ± 1.2). Source recognition of SPOM was based on carbon isotopes because they are conservative and distinct between end-members(effluent detritus and bacterial biomass). Using a mixing model,bacterial biomass in the river was calculated to account for <20% and <56% of bulk suspended particulate organic nitrogen in winter and summer, respectively. An N budget showed that bacterial N was a small proportion of total nitrogen(<7.4%) in the riverwater.
文摘We compared chemical and biological properties of soils in organically and conventionally fertilized apple orchards in Nagano Prefecture (one of the major apple producing regions in Japan). Five apple orchards with different fertilizer management systems were used for this study. The total carbon and total nitrogen contents were higher in the organically fertilized orchard, while the total phosphorus and total potassium were at similar levels in both organically and conventionally fertilized orchards. The bacterial biomass did not differ between the two orchards, but the N circulation activity was clearly higher in the organically fertilized orchard from April to December. Total carbon from 50,000 to 60,000 mg/kg, total nitrogen at about 3000 to 4000 mg/kg, and a C/N ratio of 15 - 20 were suggested to be suitable conditions for a high level of apple production under an organic fertilizer management system.
文摘The effective utilization of steel slag, a byproduct produced in large quantities from the steel refining process, is an important issue. Because steel slag contains abundant mineral components, the effects of steel slag on soil bacterial biomass and plant mineral uptake were analyzed in this study. The soil pH increased in proportion to the amount of steel slag added. A lower concentration (0.2% to 1%) of steel slag addition did not change the bacterial biomass. However, a higher concentration of steel slag (above 1%) had a negative effect on bacterial biomass. A lower amount of steel slag (0.2% to 1%) addition in soil leads to increased mineral (Ca, Mg, and Fe) uptake and plant growth in Brassica rapa var. periviridis and Spinacia oleracea L. However, mineral uptake by the plants decreased when a large amount of steel slag (above 1%) was added to the soil. Low concentrations of steel slag (0.2% to 1%) in soil had positive effects on plant growth, mineral uptake of plants, and bacterial biomass.
文摘Soil samples from 139 agricultural orchard fields (apple, grape, tea, and others) w</span><span style="font-family:Verdana;">ere</span><span style="font-family:Verdana;"> analyzed using the soil fertility index. From these samples, an orchard field database was constructed and the soil properties between orchard, upland, and paddy fields </span><span style="font-family:Verdana;">were </span><span style="font-family:""><span style="font-family:Verdana;">compared. The average value of bacterial biomass in the orchard fields was 7.4 × 10</span><sup><span style="font-family:Verdana;">8</span></sup><span style="font-family:Verdana;"> cells/g-soil, ranging from not detected (lower than 6.6 × 10</span><sup><span style="font-family:Verdana;">6</span></sup><span style="font-family:Verdana;"> cells/g-soil) to 7.7 × 10</span><sup><span style="font-family:Verdana;">9</span></sup><span style="font-family:Verdana;"> cells/g-soil. The average values of total carbon (TC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK), were 24,000 mg/kg (2670 to 128,100 mg/kg), 1460 mg/kg (133 to 6400 mg/kg), 1030 mg/kg (142 to 5362 mg/kg), and 5370 mg/kg (1214 to 18,155 mg/kg), respectively. The C/N and C/P ratios were 19 (3 to 85) and 27 (2 to 101), respectively. Soil properties of the orchard fields were compared with those of the upland and the paddy fields. The average value of bacterial biomass in the orchard fields was almost the same as that in the upland fields (8.0 × 10</span><sup><span style="font-family:Verdana;">8</span></sup><span style="font-family:Verdana;"> cells/g-soil), but the number was lower than that in the paddy fields (12.9 × 10</span><sup><span style="font-family:Verdana;">8</span></sup><span style="font-family:Verdana;"> cells/g-soil). The average values of TC and TN in the orchard fields fell between those in the upland fields (TC: 33,120 mg/kg, TN: 2010 mg/kg) and the paddy fields (TC: 15,420 mg/kg, TN: 1080</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">mg/kg). The relationship between the bacterial biomass and TC in the orchard fields resembled that in the upland fields. A suitable soil condition for the orchard fields was determined as TC: ≥25,000 mg/kg, TN: ≥1500 mg/kg, TP: ≥900 mg/kg and TK: 2500 - 10,000 mg/kg.</span><span style="font-family:""> </span><span style="font-family:Verdana;">These recommended values will be effective for the improvement of the soil quality in the orchard fields by enhancing the number and activities of microorganisms.