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.

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 52.68-137.02 μg PNP g-1 soil h-1 with a mean of 89.22 μg 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 soil 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 distinguish previous and current inputs in agricultural soils from the Taihu Lake region. Gas chromatography equipped with a 63Ni electron-capture detector (GC-ECD) system was employed. Thirteen OCPs were detectable in all soil samples, with DDTs being the main residues, and HCHs had the second highest level of OCP residues. Although OCP residual levels were lower than those in 1990s, the residual levels for most of the DDTs and some of HCHs were still higher than the national environmental standards for agricultural soils. The ratios of DDT/DDE and γ-/α-HCH in twelve soils indicated that new inputs could be present in the soils. Thus, efforts should be made to completely ban the production of OCPs and their use in agriculture so as to reduce the threat of OCPs to food quality and human health.

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 15N 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.

The non-point output of different agriculture landuse types in Zhexi hydraulic region of Taihu Basin

This paper takes Zhexi hydraulic region in Taihu Basin as a study area. On the basis of hydraulic analysis function of Arcgis8.3, the drainages were delineated by selecting the monitoring points and discharge stations as outlets. The landuse map were finished by denoting the TM/ETM image. The precipitation map was finished by spatial interpolation according to the rainfall monitoring records. Overlaying the drainage boundary, landuse map and precipitation map, the rainfall, different landuse type area, and runoff pollution concentration and runoff were calculated. Based on these data in different sub-watersheds, by Origin7.0 regression tool, an equation is established to predict runoff using the relationships between runoff, precipitation depth and land use patterns in each of the sub-watersheds. Selecting the sub-watershed which is mainly composed of forest landuse type, the mean runoff concentration (MRC) from sub-watershed has been estimated. The mean runoff concentration of farmland has been estimated by the same methods after the contribution of forest landuse type was removed. The results are: for the forest landuse type, the mean runoff concentrations of COD, BOD, Total N and Total P are 2.95 mg/l, 1.080 mg/l, 0.715 mg/l, and 0.039 mg/l, respectively; for the farmland, the mean runoff concentrations of COD, BOD, Total N and Total P are 5.721 mg/l, 3.097 mg/l, 2.092 mg/l, and 0.166 mg/l, respectively. By using these results, the agriculture non-point pollution loads have been assessed. The loads of COD, BOD, Total N and Total P in Zhexi region are 14,631.69 t/a, 6401.93 t/a, 4281.753 t/a and 287.67 t/a, respectively.

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.

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。

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。

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

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多尺度分级河网模型在江苏省太湖地区的应用研究

江苏省太湖地区地处长江三角洲地区,河网密布,城镇化率高,水利工程众多且调度复杂,流域、区域、圩区等特点明显,区域防洪、城市防洪排涝、圩区排涝等问题比较突出。由于平原河网水动力模拟模型有其内在的复杂性,大型平原河网的水文—水动力联合模拟通常难以满足模型数据动态更新和多尺度分级模拟要求。利用多尺度智能模型构建思路,针对江苏省太湖地区洪涝问题开展多尺度智能分级模型的构建与模拟,结果表明,多尺度模型能够快速模拟江苏省太湖地区洪涝情况,为江苏省太湖地区洪涝精准调度提供有力支撑。

环太湖地区综合交通发展特征和体系构建研究

环太湖地区是长三角一体化下的重要协同区域,构建一体化的交通体系对于加强地区间人员往来与经济交流,携手共同发展具有重要意义。首先,对环太湖地区人口、经济、空间等方面进行分析;其次,利用手机信令数据从对外联系、地区内部交往、旅游交通等方面深入剖析环太湖地区的交通发展特征,发现环太湖地区呈现明显的圈层化特征,各圈层在空间布局和出行需求上存在较大差异;最后,结合国际先进湖区的发展经验,提出在环太湖地区构建多圈层联动交通体系的总体框架,系统阐述区域高速交通圈、城镇一体交通圈、滨湖文旅交通圈的功能定位与构建要点,并通过多级枢纽体系实现各个圈层间的高效联动。本研究通过构建高效便捷、品质生态的交通体系,服务不同圈层的差异化出行需求,支撑环太湖地区的协同一体发展,并为类似环湖地区的交通发展提供参考。

江苏省太湖地区沿江潮位特征要素变化分析

感潮地区外江潮位变化对区域洪涝体系的有效发挥非常重要。目前江苏省太湖地区现状防洪规划并未将外江潮位变化纳入区域防洪标准的制定进行考虑。根据江苏省太湖地区沿江3个潮位代表站长系列潮位资料,对沿江潮位变化特征进行分析研究。结果表明,代表站年内最高潮位与汛期排涝设计潮位均表现出整体升高的趋势,其中以镇江(二)站变化最为显著。进入21世纪,沿江潮位特征值均出现由降低转为升高的突变现象,也反映出外部排江环境在变差,在后续地区防洪规划修编时,要增加考虑潮位变化可能产生的影响,特别是在流域上游的湖西地区。

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。

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) .

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。

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.