鄱阳湖流域泥沙流失及吸附态氮磷输出负荷评估

水土流失是吸附态氮磷输出负荷的主要方式,也是非点源污染评估的重要环节。鄱阳湖流域水土流失及其所带来的泥沙和吸附态氮磷等营养盐将直接影响到鄱阳湖的生态功能,进而影响着长江中下游水环境安全。科学估算鄱阳湖赣江、抚河、信江、饶河、修河等五大流域的土壤侵蚀量和吸附态氮、磷的输出负荷,将为鄱阳湖流域农业非点源污染控制及鄱阳湖生态建设和环境保护提供理论依据。以2007年全国第一次农业污染源普查数据和2007年江西省土壤质量调查数据为基础,利用RUSLE方程和GIS的空间统计功能,对江西省境内鄱阳湖流域的土壤侵蚀量和吸附态氮、吸附态磷的输出负荷进行估算。结果表明：基于RUSLE得到的2007年鄱阳湖五大流域输沙模数比较可信,鄱阳湖流域内泥沙、吸附态氮、吸附态磷的年输出负荷分别为1245183t、3383t和73t,其中赣江流域吸附态氮磷的年输出负荷最大,占鄱阳湖全流域的58.1%,抚河、饶河、信江、修河等分别占11.2%、7.2%、11.3%和12.2%。与流域内农业污染源总氮、总磷排放量相比较,尽管流域尺度内泥沙的输出负荷相对较大,但吸附态氮、磷的输出负荷较小,应该不是鄱阳湖水污染中总氮和总磷等营养盐的主要来源。     

太湖一级保护区非点源磷污染的定量化研究

采用田间实验与实地调查相结合的方法,研究了太湖一级保护区武进市雪堰镇水稻季节各种类型非点源磷污染的负荷分配情况。结果表明,雪堰镇各种类型农业非点源污染中,农田磷排放总量为1313kg,占排放总量的56．2％;农村居民磷排放总量为442kg,占排放总量的18．9％;城镇居民磷排放总量为518kg．占排放总量的22．2％;养殖业磷排放总量为62kg,占排放总量的2．7％．在当前的非点源磷污染治理中,除采取有力措施控制农田养分外,对于城镇和农村居民生活污水和人粪尿的排放也应引起重视。     

Seasonal and storm event nutrient removal by a created wetland in an agricultural watershed

This study examines the effectiveness of a 1.2-ha created/restored emergent marsh at reducing nutrients from a 17.0 ha agricultural and forested watershed in the Ohio River Basin in west central Ohio, USA, during base flow and storm flow conditions. The primary source of water to the wetland was surface inflow, estimated in water year 2000 (October 1999–September 2000) to be 646 cm/year. The wetland also received a significant amount of groundwater discharge at multiple locations within the site that was almost the same in quantity as the surface flow. The surface inflow had 2-year averages concentrations of 0.79, 0.033, and 0.16 mg L⁻¹ for nitrate + nitrite (as N), soluble reactive phosphorus (SRP), and total phosphorus (TP), respectively. Concentrations of nitrate–nitrite, SRP, and TP were 40, 56, and 59% lower, respectively, at the outflow than at the inflow to the wetland over the 2 years of the study. Concentrations of SRP and TP exported from the wetland increased significantly (α = 0.05) during precipitation events in 2000 compared to dry weather flows, but concentrations of nitrate–nitrite did not increase significantly. During these precipitation events the wetland retained 41% of the nitrate–nitrite, 74% of the SRP, and 28% of the TP (by mass). The wetland received an average of 50 g N m⁻² per year of nitrate–nitrite and 7.1 g m⁻² per year of TP in 2000. Retention rates for the wetland were 39 g N m⁻² per year of nitrates and 6.2 g P m⁻² per year. These are close to rates suggested in the literature for sustainable non-point source retention by wetlands. The design of this wetland appears to be suitable as it retained a significant portion of the influent nutrient load and did not lose much of its retention capacity during heavy precipitation events. Some suggestions are given for further design improvements.     

减少农业对水体污染的对策与措施

水体富营养化是一个全球关注的问题。逐渐增加的化肥施用量和畜禽养殖业产生的粪便进一步引起营养流失,进而产生了N、P营养物质的不平衡。因此农业面源污染已被视为水体富营养化的主要污染源。本文简要地概述了农业面源污染对造成水体富营养化的危害,同时介绍了国内外防治农业面源污染的主要措施,包括面源控制措施和转移转化措施。指出了建立稳定、和谐与良性循环的农业生态系统是治理农业面源污染的长久之计。     

太湖水体溶解性氨基酸的空间分布特征

为探索氨基酸(DAAs)组分特征对生物可利用性溶解有机质(DOM)的示踪及定量表征可能性, 对太湖3个湖区(北太湖: 藻型湖区,东太湖: 草型湖区, 南太湖: 农业污染湖区)水体DAAs浓度、组分特征及其空间变化进行了调查研究,并对控制其量、质空间分布的因素加以讨论。结果表明夏季太湖水体DAAs的浓度范围为0.27-3.95 μmol/L,平均值为(1.38±1.17)μmol/L,与湖泊、海洋中研究中报道结果相近。北太湖、南太湖、东太湖3个湖区的DAAs浓度平均值分别为(2.59±0.71)μmol/L,(0.48±0.14)μmol/L,(0.48±0.16)μmol/L,北太湖DAAs浓度及对有机碳氮的贡献都明显高于其他湖区,DAAs组分中以苯丙氨酸和赖氨酸为主,而在南太湖和东太湖,赖氨酸都是最主要的DAAs组分。表明水体的DAAs组分特征能对湖泊营养状态及生态类型的变化做出响应,可以作为指示湖泊营养状态的生物标记物。DAAs也可以作为DOM 生物降解性的评价参数,反映湖泊水体中与生物活性相关的DOM 动态变化。根据氨基酸对有机碳的贡献估算出北太湖的活性溶解性有机碳相对含量为(17.65±17.84)%,显著高于南太湖和东太湖。但由于太湖高度的空间异质性,还需要在今后的研究工作中进行相关的室内实验,建立适用于太湖的经验公式。     

Simultaneous Monitoring of Phosphine and of Phosphorus Species in Taihu Lake Sediments and Phosphine Emission from Lake Sediments

Phosphine (PH₃) was monitored in the Taihu Lake in China by a GC/NPD method, coupled with cryo-trapping enrichment technology. Results showed that PH₃ was universally detected in sediments, lake water and atmosphere of the Taihu Lake area. Total phosphorus (TP_s) and fractions of different phosphorus species in lake sediments were separately measured as dissolved phosphate (DP), phosphorus bound to aluminum (Al-P), iron (Fe-P) and calcium (Ca-P), occluded phosphorus (OP), and organic phosphorus (Org-P) by sequential chemical extraction. High PH₃ levels were correlated with high TP_s values in sediments and with eutrophication at different sites. In addition, a positive linear correlation equation was obtained between the concentrations of PH₃ in lake sediments and of the phosphorus fractions. The resulting multiple linear regression equation is PH₃ = −165 + 63.3 DP + 0.736 Al-P + 2.33 Ca-P + 2.29 Org-P. The flux of PH₃ across the sediment–water interface was estimated from sediment core incubation in May and October 2002. The annual average sediment–water flux of PH₃ was estimated at ca. 0.0138±0.005 pg dm⁻² h⁻¹, the average yearly emission value of PH₃ from Taihu Lake sediments to water was calculated to be 28.3±10.2 g year⁻¹, which causes a water PH₃ concentration of up to 0.178±0.064 pmol dm⁻³. The real importance of PH₃ could be higher, because PH₃ could be consumed in the oxic sediment–water boundary layer and in the water column. Spatial and temporal distributions of total phosphorus (TP_w) and chlorophyll a (Chl-a) in the water column of Taihu Lake were measured over the study period. Higher water PH₃ has also been found where the TP_w content was high. Similarly, high Chl-a was consistent with higher water PH₃. Positive relationships between PH₃ and TP_w (average R² = 0.47±0.26) and Chl-a (average R² = 0.23±0.31) were observed in Taihu Lake water.     

Effects of hydrodynamics on phosphorus concentrations in water of Lake Taihu,a large,shallow, eutrophic lake of China

To understand the effect of hydrodynamical process on water phosphorus concentration, wind, wave, and several water quality indices were observed in Meiliang Bay, a shallow and eutrophic bay locates in north of Lake Taihu. During the 7 day observation period, wind speed and significant wave height were recorded more than 3 h per day, and water samples were collected in five water-depth layers once a day. Hydrodynamical disturbance had no significant correlationship with the water quality at the top layer when the significant wave height was smaller than 30 cm, but it significantly increased suspended solids (SS) concentration of the bottom water layer. Concentrations of nutrients showed no positive correlationship with SS concentration in the water body. Intensive sediment resuspension may not have occurred when the hydrodynamic stress on sediment was only a little higher than the critical stress for sediment resuspension. A new method for confirming the critical stress for intensive sediment resuspension and nutrient release still needs to be developed. The range of the water quality indices was quite high during the seven days of observation. High variation seems to be a common character of large shallow lakes like Taihu.     

植物篱的生态效益研究进展

植物篱/植被隔离带指沿坡地等高线,或在农田、河岸、沟道等水体边缘营建的,由草本或木本植物单一或组合形成的植物条带.植物篱可以改善土壤结构,对土壤质地、孔隙度、容重等物理性质有显著影响,其机械阻挡作用可以拦截径流、增加入渗、减少土壤流失、影响侵蚀过程,还能减缓坡度、促进坡耕地梯化.本文通过梳理和总结国内外学者在不同生态系统类型区和自然地理单元上开展的相关研究,综述了植物篱对改良土壤理化属性、调节降雨入渗和水蚀过程、植被恢复、生物多样性保护、优化景观及生态服务等多个方面的影响.同时,提出了当前植物篱研究中的两大主要问题：在工程技术与应用上,需要对植物篱种植模式、结构选择、管理办法系统化;在科学研究层面上,要深入探究影响植被恢复与生态演替的机理.     

Total inputs of phosphorus and nitrogen by wet deposition into Lake Taihu, China

Lake Taihu suffers from eutrophication caused by riverine nutrient inputs and air deposition. To characterize wet deposition of phosphorus (P) and nitrogen (N) to the lake, precipitation collection and measurements of total phosphorus (TP) and total nitrogen (TN) and other components at five cities around Lake Taihu were made from July 2002 to June 2003. TP and TN concentrations and deposition rates exhibited strong spatial variation in the whole catchment. An inverse correlation between station-averaged TP and TN concentrations and precipitation amount was found. Maximal TP concentration in rainfall was found in Suzhou, and maximal TN in Wuxi. However, highest wet deposition rates of TP and TN were found in Suzhou, which suggests that atmospheric nutrients are mostly from the east and northwest area of Lake Taihu. Mean TP and TN deposition rates were 0.03 and 2.0 t km⁻² year⁻¹ respectively in Lake Taihu, which are greater than reported values in other areas by comparision. Total N and P contributed to the lake by wet deposition were 75 and 4720 t per year, respectively, which represent about 7.3% and 16.5% of total annual N and P inputs via inflow rivers. Wet deposition, especially N, could have significant effects on eutrophication in the lake, which shows that air deposition should be taken into account while reducing the external nutrients in the lake.     

太湖岸带湿地土壤动物群落结构与多样性

土壤动物是湿地生态系统物质循环和能量流动的关键环节,也是湿地生态系统演化的重要驱动因子。2010年4月—2011年2月研究了太湖岸带湿地4种生境类型(A酸模岸带、B乔灌岸带、C农作物岸带、D天然芦苇岸带)中的土壤动物群落结构和多样性。4次调查共分离到土壤动物3575只,隶属4门12纲,共有105类,土壤动物群落密度达到2794.49—67766.39个/m2。在大类群中,节肢动物门(Arthropoda)为优势类群,占总个体数的55.75%,其次为线虫动物门(Nematoda),占总个体数的36.27%;节肢动物门和线虫动物门构成了该区土壤动物的主体,对土壤动物群落特征起着决定性作用。土壤动物群落各多样性指数的季节变化动态不同,Pielou均匀度的方差分析表明:2010年4月份类型A与类型C之间存在显著性差异(P0.05);而Shannon多样性方差分析表明:2011年2月份类型A与C、D存在显著性差异(P0.05)。土壤动物的整体数量表现为2010年4月2010年11月2010年8月2011年2月。Sorensen和Morisita-Horn相似性分析说明不同生境类型对土壤动物物种丰度产生了不同的影响。太湖岸带湿地土壤动物个体数量在垂直分布上均有一定的表聚性,但不同季节表聚性程度不同。研究结果可为太湖岸带湿地的健康评价及科学管理提供理论依据。     

污染足迹及其在区域水污染压力评估中的应用——以太湖流域上游湖州市为例

传统生态足迹理论虽然在可持续发展评价等方面得到了广泛的应用,但却仍然无法全面衡量人类活动对生态系统造成的各种影响。其无法全面评估人类活动的根源在于,土地功能排他性假设限制了其对利用生态系统非生物生产性产品和服务的人类活动的衡量。为了摆脱传统生态足迹理论的局限性,建议承认土地功能多样性的客观事实,将生态足迹构建于多种生态系统服务功能之上。针对传统生态足迹对定义中废弃物吸纳的考虑不足,提出了基于污染物吸纳功能的生态足迹,即污染足迹。污染足迹不是对传统生态足迹中能源足迹的简单置换,而是能够囊括人类活动产生的大部分污染物,并可以根据不同的污染物类别或类型进一步细化的足迹类型。构建了太湖流域有机物、氮和磷污染足迹模型,并利用该模型对流域上游湖州市的水污染压力进行了综合评估。结果表明:(1)2007年湖州市污染足迹为39948.73 hm²,东部平原地区污染足迹较大,西部丘陵地区污染足迹相对较小;(2)湖州市人类活动排放的氮磷污染物对水域空间的生态占用已经远远超过了有机污染物;(3)2007年湖州市污染承载力为20896.00 hm²,污染赤字为19052.73 hm²,人类排污活动俨然超出了当地水域的承载能力;(4)2007年湖州市污染压力指数为1.91,当地水环境总体上处于轻度接近中度污染压力;(5)湖州市水污染压力较大的地区,区域内人类活动的维持建立在区域水环境质量恶化或污染物向下游输移的基础之上。     

湘江流域工业污染源对农田生态系统土壤动物群落影响的研究

对湘江流域工业污染区的土壤动物群落研究表明,接近污染源和污染物质富集的农田,土壤动物的种类和数量减少;工业污染区土壤的污染主要是重金属有毒物质的过量累积。调查共获得29类土壤动物,隶属于4门10纲,动物的种类与数量随着重金属污染程度的增加而递减,土壤动物密度与重金属元素Hg、Cd,zn、Cu、As、Pb的浓度密切相关,这在污染模拟实验中也得到证明。     

Spatial and temporal variability of internal and external phosphorus loads in Mona Lake,Michigan

A study was conducted in Mona Lake, a small eutrophic lake located in western Michigan (USA) to address the temporal and spatial variability of external and internal phosphorus loading. External P load varied among subbasins, which was mostly related to discharge, but also to land use. Black Creek, which drains lands with natural cover and agriculture, accounted for the majority of flow, and total phosphorus (TP) and soluble reactive phosphorus (SRP) load, to Mona Lake. However, the relative contribution of SRP load was greater in Little Black Creek, which flows through a mostly urbanized subbasin, than in Black Creek. The relative importance of internal loading was strongly related to season, as internal TP loads contributed only ∼9% of the overall P load in April 2005, but ∼68–82% of the overall P load in the summer and early fall seasons. Internal TP and SRP loading was greater under anaerobic than aerobic conditions. Mean anaerobic TP release rates ranged from 0.80 to 15.56 mg P m⁻² d⁻¹, varying with site and season. Spatial variability in both internal phosphorus loading and sediment P concentration was also evident. By taking into account the spatial and temporal variability of different loading sources, management practices can be targeted to optimize nutrient source control strategies.     

Phosphorus release from cyanobacterial blooms in Meiliang Bay of Lake Taihu, China

To investigate the relationship between cyanobacterial density and phosphorus release into a lake aquatic environment, in situ experiments with 2.5 L microcosms were conducted in Meiliang Bay, located in the northern part of Lake Taihu, China. The effects of different environmental factors on phosphorus release and the ways changes of water quality indexes are involved in phosphorus release were further examined. It was found that total dissolved phosphorus (TDP) concentration kept to low levels (around 0.488 mg L⁻¹) in the microcosm with the low cyanobacterial density (8.85 × 10⁷ cell L⁻¹) throughout the experimental period, whereas first-order kinetics of TDP release was observed in microcosms with intermediate (7.60 × 10⁸ cell L⁻¹) and high cyanobacterial density (3.65 × 10⁹ cell L⁻¹). Accordingly their TDP release rate constants were both approximately 0.8930 d⁻¹ in the latter two treatments. The dissolved inorganic phosphorus (DIP) concentrations also increased with the increase of cyanobacterial density in 4 days. However, the DIP decreased from 35.52 mg L⁻¹ on day 4 to 6.72 mg L⁻¹ on day 6 in microcosm with the high cyanobacterial density during the experiments. Temperature could remarkably improve phosphorus release, while disturbance and illumination had negative effects on it. In addition, both TDP and DIP concentrations were positively correlated with electronic conductivity, salinity and total dissolved solid, but negatively correlated to chlorophyll-a and cyanobacterial density when cyanobacterial density was more than 7.60 × 108 cell L⁻¹. Thus, more phosphorus can be released from cyanobacterial blooms at higher cyanobacterial densities in Meiliang Bay, which is also determined by high temperature. Higher dissolved phosphorus concentration in cyanobacteria-dominated lakes (regions) is mainly due to the decomposition of cyanobacteria during the outbreak of cyanobacterial bloom in Lake Taihu, especially in Meiliang Bay.     

太湖地区土壤环境中SAS的分布和降解特点

采集了江苏省吴县市不同利用、不同乡镇和环境影响类型下的土壤样品 ,采用比色法分析其SAS含量 ,并以LAS为标物研究了SAS在土壤环境中的降解行为 .结果表明 ,供试土壤环境中SAS达 2～ 10mg·kg-1,并在土壤全剖面检测到 .土壤环境中SAS含量与土壤性质及其环境影响特点有关 .LAS在供试土壤环境中的降解符合土壤有机质分解的一级反应动力学方程 ,其半衰期为 10～ 16d ,因土壤种类而异 ,说明SAS作为特殊的有机污染物在土壤环境中的滞留性及其可能的环境危害 .     

免耕对农牧交错带农田休闲期土壤风蚀及其相关土壤理化性状的影响

以北方农牧交错带为研究对象,分析了免耕对农田土壤风蚀的影响,评价了不同耕作方式下与土壤风蚀相关的土壤物理、化学和生物学特性的差异。研究结果表明:翻耕农田土壤风蚀量是免耕地的3~8倍,翻耕地和免耕地的地表粗糙度分别为0.032和0.417;与翻耕地相比,免耕地表层0~10cm土壤粘粒和粉粒含量较多;免耕地土层0~5cm和5~10cm的土壤容重、坚实度和土壤水分都大于翻耕地,其中0~5cm、5~10cm和10~20cm土层土壤坚实度分别是翻耕地的4.7、2.8倍和3.8倍。经过3年的免耕,0~5cm土层土壤全氮、有机质、有效磷和有效钾含量均高于翻耕土壤,有效钾含量比翻耕地增加了77%。所有测定土层的土壤有机质含量免耕地均高于翻耕地,在0~5cm和5~10cm土层达到5%显著水平。免耕地表层0~10cm土壤微生物量碳是翻耕地的2.1倍。     

太湖流域丘陵区两种土地利用类型土壤水分分布控制因素

为探究太湖流域丘陵区典型土地利用类型(如竹林地和茶园)土壤水分的控制因素,在不同深度土壤水分定期观测的基础上,根据前7d降雨量将研究时段划分为干旱状态和湿润状态,利用分类与回归树(CART)方法得出不同干湿状态下土壤水分分布的主控因子,并借助典范对应分析(CCA)定量分析不同土地利用类型、不同土壤深度土壤水分格局与环境因子关系。结果表明:(1)高程、土地利用类型和土层厚度对土壤水分分布的相对贡献率最大,但在不同干湿状态下其影响程度存在差异;(2)干旱状态时土壤水分主要受高程、坡度、地形湿度指数(TWI)和剖面曲率等地形因素的作用,而土层厚度和粘粒也分别为0—20 cm和20—40 cm深度土壤水分的主控因子;(3)在湿润状态下,茶园0—20 cm土壤水分的主控因素为地形因子,在20—40 cm则以土壤性质为主,竹林地两个深度的土壤水分受地形和土壤性质的作用都很强,其中20—40 cm深度土壤水分与环境因子的关系较0—20 cm深度更为复杂。     

太湖流域生态风险评价

随着城镇的急剧扩张和经济的快速增长,流域生态环境遭到极大冲击和破坏,致使生态系统出现资源退化、环境恶化与灾害风险加剧的趋势,生态环境面临前所未有的挑战.从复合生态系统入手,深入分析流域内各生态系统要素之间的相互作用与影响机制,综合考虑多风险源、多风险受体和生态终点共存情况下的风险大小,从风险源危险度、生境脆弱度及受体损失度三方面构建了流域生态风险评价技术体系,并选取太湖流域为实证区域,对太湖流域2000年、2008年两个时期生态风险的时空演化特征进行评价与分析.结果表明:太湖流域生态风险指数介于0.015-0.253之间,以中等和较低生态风险为主.至2008年,高、较高生态风险所占面积逐渐扩大,已由2000年的5.66％、13.42％增加至6.05％、18.42％,主要集中在流域北部的常州市区、江阴市大部分地区以及无锡市区.