Nitrogen interception in floodwater of rice field in Taihu region of China

A field experiment located in Taihu Lake Basin of China was conducted, by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen （N） export in a typical rice field through ＂zero-drainage water management＂ combined with sound irrigation, rainfall forecasting and field drying. N concentrations in floodwater rapidly declined before the first event of field drying after three split fertilizations, and subsequently tended to rearm to the background level. Before the first field drying, total particulate nitrogen （TPN） was the predominant N form in floodwater of plots with no N input, dissolved inorganic nitrogen （DIN） on plots that received urea only, and dissolved organic nitrogen （DON） on plots treated with the mixture of urea and manure. Thereafter TPN became the major form. No N export was found from the rice field, but total nitrogen （TN） of 15.8 kg/hm^2 was remained, mainly due to soil N sorption. The results recommended the zero-drainage water management for full-scale areas for minimizing N export.

Representation of Regional Culture, Spirit of Place and Landscape——Landscape Design of International Conference Center of Taihu Forum,Suzhou

Regional culture and spirit of place is the key and soul of landscape design, without which the landscape design would lose its vitality. Landscape design of Taihu Forum is focused on the discussion upon regional culture and spirit of place.

Beta-Glucosidase Activity in Paddy Soils of the Taihu Lake Region, China

The profile distribution of β-gulcosidase activity in twelve typical paddy soil profiles with high productivity in the Taihu Lake region of China were investigated. Activities of β-gulcosidase in the plow layers were in the range of 52.68- 137.02μg PNP g^-1 soil h^-1 with a mean of 89.22μg PNP g^-1 soil h^-1. However, most plow layers ranged from 70 to 110 μg PNP g^-1 soil h^-1. The profile distribution of β-gulcosidase activity in the 12 soil profiles decreased rapidly with soil depth, with activity at the 60 cm depth only about 10% of that in the surface layers （0-15 cm or 0-20 cm）. In these soil profiles, β-gulcosidase activity was significantly positively correlated with soll organic carbon and arylsulphatase activity. Meanwhile, a significantly negative correlation was shown between β-gulcosidase activity and soil pH.

Residual Levels and New Inputs of Chlorinated POPs in Agricultural Soils from Taihu Lake Region

Selected persistent organochlorine pesticides (OCPs), including 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its principal metabolites 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and 1,1-dichloro-2,2-bis(p-chlorophenyl)e- thane (DDD), hexachlorocyclohexane (HCH) and its isomers (α-,β-, γ-, and δ-HCH), hexachlorobenzene (HCB), endo- sulfan, dieldrin, and endrin were quantified to determine current levels of organochlorine pesticides, to assess the eco- toxicological potential, and to distin…

Assessment of Nitrogen Pollutant Sources in Surface Waters of Taihu Lake Region

The nitrogen （N） pollution status of the 12 most important rivers in Changshu, Taihu Lake region was investigated. Water samples were collected from depths of 0.5-1.0 m with the aid of the global positioning system （GPS）. The seasonal variations in the concentrations of different N components in the rivers were measured. Using tension-free monolith lysimeters and ^15N-labeled fertilizer, field experiments were carried out in this region to determine variations of iSN abundance of NO3^- in the leachate during the rice and wheat growing seasons, respectively. Results showed that the main source of N pollution of surface waters in the Taihu Lake region was not the N fertilizer applied in the farmland but the urban domestic sewage and rural human and animal excreta directly discharged into the water bodies without treatment. Atmospheric dry and wet N deposition was another evident source of N pollutant of the surface waters. In conclusion, it would not be correct to attribute the N applied to farmlands as the source of N pollution of the surface waters in this region.

Research Progresses on Diversity of Quality Traits of Rice Landraces in Taihu Lake Region

It has a long history of rice cultivating in Taihu Lake region, with abounds rice landraces resources. The research on the genetic diversity of rice landraces resources can provide some reference for the protection and utilization of high-quality germplasm resources and breeding of new varieties. In this study, we reviewed the concepts of genetic diversity, research methods, genetic diversity of quality traits of rice landraces in Taihu Lake region and summarized the relevant utilization value of the rice landraces from Taihu Lake region.

Estimate of Methane Emission from Rice Paddy Fieldsin Taihn Region, China

Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closedchamber method in 1992 and 1993 and CH_4 emission from this region (total area of paddy soils was about1.88 million hectares, of which 0.63 million hectares are distributed in the south of Jiangsu Province) wasestimated on the basis of the mean CH_4 fluxes observed. The results showed that the mean CH_4 flaxes fromlate rice and single cropping rice field were quite similar under the prevailing cultivation practices in theregion, being around 5 mg CH_4/m￣2/h (4.31-5.31 mg CH_4/m￣2/h for various cultivars of the late rice and3.20-6.22 mg CH_4/m￣2/h for various treatments of the single cropping rice). Total CH_4 emission from paddysoils in the region was estimated to be 0.185-0.359 Tg CH_4 per year. Continuously flooding the soil witha water layer till ripening caused higher mean CH_4 flux; and addition of nitrification inhibitor (thiourea)stimulated CH_4 emission. There was no simple relationship between CH_4 flux and either soil temperature orsoil Eh.

环太湖地区文化景观的时空层积与特征解译研究——以常州为例

太湖地区以太湖为中心,形成碟形洼地,位于长江三角洲的南部。常州作为太湖平原西北部的区域中心,是早期有人类开发历史记载的重要地区,自古即为运河沿线重要的交通枢纽。通过系统梳理文化景观特征与时空演变,为现代文化景观的保护传承与发展提供理论基础。以地域文化景观这一视角重新审视常州地区,将其理解为融合了自然系统与人文系统的层状体系复合系统,借助文化景观的研究思路,以朝代更迭为时间线索,从历时性、共时性两个维度逐层揭开常州地域文化景观体系中各要素的发展情况,探索古代人地关系的动态演变,并从时空层积、空间特征、关联性内因三个方面进行分析解译。在大运河文化带战略框架下和在快速城镇化进程中,为沿运城市的文化复兴和高质量城乡营建提供一定借鉴意义。

施氮量对太湖流域再生稻产量和温室气体排放的影响

为探索氮肥施用量对再生稻产量及温室气体排放(CH4和N2O)的影响以及太湖流域再生稻种植的最佳施氮量,本研究于2022年4-10月在江苏宜兴采用静态箱-气相色谱法观测CH4和N2O排放通量,试验设置3种再生季施氮量[FL1:75 kg(N)·hm^(-2);FL2:125 kg(N)·hm^(-2);FL3:175 kg(N)·hm^(-2)],头季均施240 kg(N)·hm^(-2),同时设置不施肥处理(FL0)作为对照,并在水稻收获时测定产量及其构成因子。试验结果显示,促芽肥造成的N2O排放峰值最大,且随施肥量的增加呈线性增加趋势,总量占整个生育期的10.0%~50.7%;两个稻季(头季+再生季)的N2O排放总量为1.30~8.69 kg(N)·hm^(-2),再生季排放量占6.94%-22.7%,再生季N2O排放系数为0.38%~1.71%。两季CH4排放总量为58.1~78.7 kg·hm^(-2),再生季占13.3%-23.8%,CH4排放总量随施氮量增加影响较小。两季水稻总产量为8.33~11.6 t·hm^(-2),再生季占34.0%~46.1%,FL2和FL3的再生季产量分别较FL1增加32.3%和17.4%,这与有效穗数分别增加27.2%和13.5%有关。两季温室气体排放强度为0.26~0.54 t(CO_(2)-eq)·t^(-1),FL3和FL2较FL1分别增加38.5%和10.3%。综上,再生季施氮量为125 kg·hm^(-2)时能获得高产且温室气体排放强度相对较低,是太湖流域蓄留再生稻值得推荐的氮肥施用量。

环太湖地区高质量发展时空收敛特征分析

运用综合评价方法测度环太湖地区高质量发展水平,使用σ收敛、β收敛模型回归分析环太湖地区之间在时间上的纵向收敛趋势和内在影响机制,发现2005年至2021年期间,环太湖地区高质量发展呈现逐渐增长趋势;环太湖五市之间的高质量发展指数的差距逐年缩减,存在σ收敛;环太湖五市之间高质量发展指数发生显著的β收敛,经济发展水平较低的城市,如湖州、嘉兴,正以较快的速度追赶苏州、无锡、常州,并以超过15%的速度趋同;低碳绿色发展是促进环太湖地区高质量发展收敛的重要因素。

太湖设防水位变化对区域防洪的影响研究

太湖位于太湖流域中心位置,是流域的洪水集散地,其设防水位是评判流域防洪形势的重要特征水位之一,也是部署流域防汛工作的重要依据之一。近年来的流域性洪水中,太湖水位多次突破原设防水位,对区域防洪产生了较大影响。本文采用太湖流域河网一维水量水质模型,分析研究太湖设防水位的变化对区域防洪的影响。结果表明,太湖设防水位与上游区域洪水位呈正相关,与下游区域洪水位呈负相关。太湖设防水位的升高,使得上游区域超特征水位的幅度和历时逐渐增大,特别是对湖西区和长兴平原的影响更为明显。

稻季施用不同尿素品种的氮素径流和淋溶损失

在太湖地区乌栅土上,利用大型原状土柱研究不同尿素品种、施肥量处理在稻季氮素径流和淋溶损失.结果表明,包膜尿素在基施情况下,田面水总氮浓度始终接近对照水平,通过径流损失的可能性很小.尿素处理施肥后2d内田面水氮浓度达最高值,随后急剧下降,施肥与径流产生时间的间隔是决定径流氮排放大小的关键因素,施肥5d后的降雨不易造成大的径流排放,氮径流损失与尿素施用量呈显著正相关.各处理间的氮素淋溶排放无显著差异,在2.66～3.25kg N/hm2之间;淋溶液中NO3--N浓度最高为0.83mgN/L,在正常施肥情况下,此类土壤氮的淋溶不会造成地下水NO3--N的严重污染.

太湖地区高产水稻生命周期评价

以太湖地区高产水稻典型管理措施为例,应用生命周期评价方法,以生产1t水稻为评价的功能单元,把水稻生命周期划分为原料阶段、农资阶段和种植阶段进行清单分析与影响评价,考虑了能源消耗、水资源消耗、温室效应、环境酸化和富营养化5种环境影响类型。结果表明,太湖地区高产水稻生命周期环境影响潜力大小依次是水资源消耗、富营养化、温室效应、环境酸化和能源消耗,环境影响指数分别为1.45、0.54、0.52、0.32和0.05,环境影响综合指数为0.54。降低稻田水肥投入,提高水分和养分生产效率是控制太湖地区水稻生产体系生命周期环境影响的关键,它在直接减少种植环节资源消耗与污染排放的同时,也间接减轻了上游生产环节的环境影响,从而减缓生命周期的环境影响。

太湖地区蠡河流域不同用地类型面源污染特征

以太湖上游蠡河流域为研究区,通过对面源污染为主子流域和城镇地表径流进行监测,结合GIS空间分析方法,分析了流域林地、耕地及城镇用地等土地利用类型的面源污染流失特征.结果表明,林地产出径流面源COD、TN和TP浓度分别为2.987±1.582,1.690±0.349,0.019±0.009mg/L;耕地的产出径流面源COD、TN和TP浓度分别为9.874±5.146,2.534±2.459,0.185±0.149mg/L;小城镇的产出径流面源COD、TN和TP浓度分别为7.729,1.790,0.117mg/L.蠡河流域的面源污染COD、TN和TP负荷量分别为919.9,306.0,13.5t/a.

太湖上游典型城镇地表径流面源污染特征

选择太湖上游典型城镇,在不同临前降雨条件下,对城镇地表径流系统地进行空间采样,分析采样样本的统计分布特征。结果显示,受城镇复杂人类活动的影响,城镇地表径流面源污染输出具有较大的空间差异,针对典型城镇整体的空间采样样本符合对数正态分布,基于样本频率分布特征,统计城镇地表径流的面源污染浓度,其中COD为7.729(7.299,8.184)mg.L-1,TN和TP分别为1.790(1.752,1.829)mg.L-1和0.117(0.107,0.129)mg.L-1。对不同临前降雨条件下、不同用地类型的样本分别进行统计,获得不同临前降雨条件、不同城镇用地类型的地表径流面源污染浓度统计特征,证实了临前降雨条件、城镇用地类型对城镇地表径流面源污染输出有较大影响。

富营养化河水灌溉对稻田土壤氮磷养分贡献的影响——以太湖地区黄泥土为例

以太湖地区主要稻田土壤类型黄泥土为对象,利用当地富营养化河水对回填土柱和植稻原状土渗漏池进行模拟稻田灌溉试验,系统研究了灌溉水对稻田土壤氮磷营养的贡献。在回填土柱灌溉试验中,在试验初期,不同形态的氮素均有较高的淋失量,以后逐渐降低,表明初期淋失的氮素主要来自土壤,而不是灌溉河水。在整个水稻生长季,均观测到有可溶性有机氮淋失,表明富营养化河水灌溉条件下可溶性有机氮是稻田土壤主要的氮素淋失形态。在本试验中,磷素的淋失动态与氮素的淋失动态截然相反,淹水后很长一段时间内均没有土壤磷素淋失,但在淹水灌溉后期有大量的土壤磷素淋失损失,这可能是淹水后期土壤对磷的吸持已达到饱和状态,不能继续固持土壤中多余的磷所致。与回填土柱模拟灌溉淋洗试验相比,在当前供肥条件下,原状土渗漏池试验氮磷淋失量远低于回填土柱试验,而灌溉水对土壤氮磷养分的贡献远高于回填土柱。通过富营养化河水灌溉带入当季稻田的N量达到每公顷56.3 kg,其中有55.8 kg N可被土壤吸持和作物吸收,表明太湖地区稻田土壤对氮磷养分来说是一个环境友好的生态系统。在利用当地富营养化河水进行稻田土壤灌溉时可适量减少肥料施用量、优化氮磷肥料管理。

太湖地区氮素湿沉降动态及生态学意义:以常熟生态站为例

在常熟生态站 2 0 0 1年 6月至 2 0 0 3年 5月连续两年定位收集湿沉降 ,对太湖地区氮素湿沉降动态进行研究 .结果表明 ,湿沉降氮输入量季节变化显著 ,夏、春季高 ,秋、冬季低 .在湿沉降输入氮中NH+ 4 N、NO-3 N和DON的比例分别为 4 7 6 %、35 1%和 17 4 % .湿沉降中NH+ 4 N主要来自当地农田的氨挥发 ,湿沉降NH+ 4 N月输入量随月降雨量增加而增加 (R2 =0 3178 ) .该地区空气中NO-3 N浓度相对比较稳定 ,湿沉降中NO-3 N浓度与降雨量呈负相关 (R2 =0 4 2 0 5 ) .湿沉降NO-3 N月输入量与月降雨次数呈直线正相关 (R2 =0 6 75 7 ) ,而与月降雨量相关性较差 (R2 =0 1985 ) .湿沉降TN年输入量为2 7 0kg·hm-2 ,并在所有降雨中 ,氮浓度均超过水体富营养化阈值 (0 2mg·L-1) .

基于土地利用动态变化的太湖地区景观生态风险评价

在GIS和RS技术支持下,以遥感数据和土地利用数据为基础,以行政区划为评价单元,定量分析太湖地区1990-2008年土地利用变化及其转化关系;从土地利用变化和景观结构角度构建景观生态风险评价模型,定量评价了研究区内景观生态风险的时空动态变化特征.结果表明:太湖地区景观生态风险分布与区内土地利用方式和强度具有较高关联.景观生态风险整体呈上升趋势,高生态风险区范围不断扩大;受自然特征和社会经济发展影响,景观生态风险空间分异显著,较低风险区主要分布于以苕溪为主的山地丘陵区,中等风险区主要分布于农业发达的平原区,较高风险区及高风险区主要集中于沿湖经济发达区.不同区域景观生态风险来源存在一定差异,各用地类型对生态风险的贡献率亦不尽相同,就全区而言,景观生态风险主要来源于耕地和建设用地,但随着社会经济不断发展,来自水域和林地的生态风险比例越来越大.

长期不同施肥对太湖地区典型土壤酸化的影响

以太湖地区典型土壤黄泥土上26年的长期肥料定位试验为例,研究不同施肥处理对研究区耕作层土壤(0～15 cm)酸化特征及酸化速率的影响。试验采用裂区设计,主区为不施有机肥处理(C)和施有机肥处理(M),副区为不同无机肥及秸秆施用处理。研究结果显示,不同施肥处理对土壤pH和土壤酸碱缓冲容量有显著影响,增施有机肥的主区处理pH显著低于不施有机肥处理,但对应的土壤酸碱缓冲容量略有上升;副区单施尿素处理和尿素增施水稻秸秆处理pH较不施尿素对照分别下降了0.45、0.66个单位,酸碱缓冲容量分别下降1.52、0.95 mmol kg-1;各试验处理的酸化速率为H+0.61～1.74 kmol hm-2a-1,单施尿素处理高于不施尿素处理,而尿素增施有机肥或水稻秸秆的大于单施尿素处理,以尿素配施有机肥和水稻秸秆处理最高。相关分析表明,各处理土壤pH与外源氮输入量、土壤全氮及速效氮存在显著的依变关系。尿素对土壤的酸化影响与有机肥及水稻秸秆存在差异,前者在降低土壤pH的同时还导致土壤酸碱缓冲容量的降低,而增施有机肥及水稻秸秆处理土壤缓冲容量保持稳定甚至提升,但其各自对土壤酸化的具体贡献率等还需进一步研究。