Heavy metal pollution in China: Origin, pattern and control

Goal, Scope and Background. Heavy metal is among one of the pollutants, which cause severe threats to humans and the environment in China. The aim of the present review is to make information on the source of heavy metal pollution, distribution of heavy metals in the environment, and measures of pollution control accessible internationally, which are mostly published in Chinese. Methods. Information from scientific journals, university journals and governmental releases are compiled focusing mainly on Cd, Cu, Pb and Zn. Partly Al, As, Cr, Fe, Hg, Mn and Ni are included also in part as well. Results and Discussion. In soil, the average contents of Cd, Cu, Pb and Zn are 0.097, 22.6, 26.0 and 74.2 mg/kg, respectively. In the water of. the Yangtze River Basin, the concentrations of Cd, Cu, Pb and Zn are 0.080, 7.91, 15.7 and 18.7 pg/L, respectively. In reference to human activities, the heavy metal pollution comes from three sources: industrial emission, wastewater and solid waste. The environment such as soil, water and air were polluted by heavy metals in some cases. The contents of Cd, Cu, Pb and Zn even reach 3.16, 99.3, 84.1 and 147 mg/kg, respectively, in the soils of a wastewater irrigation zone. These contaminants pollute drinking water and food, and threaten human health. Some diseases resulting from pollution of geological and environmental origin, were observed with long-term and non-reversible effects. Conclusions. In China, the geological background level of heavy metal is low, but with the activity of humans, soil, water, air, and plants are polluted by heavy metals in some cases and even affect human health through the food chain. Recommendations and Outlook. To remediate and improve environmental quality is a long strategy for the polluted area to keep humans and animals healthy. Phytoremediation would be an effective technique to remediate the heavy metal pollutions.

Revision of the cyprinid genus Placocheilus Wu, 1977 in China, with description of a new species from Yunnan

Placocheilus is re-diagnosed on the basis of oromandibular structures compared to those of closely related groups. It is represented in China by three species restricted to Yunnan, namely P. caudofasciatus from the Tengtiaohe River (Nam Na), P. cryptonemus from the Nujiang Rive ( upper Salween River basin), and P. robustus, herein described as a new species from the Yuanjiang River ( Red River basin). P. robustus n. sp. is differentiated from its congeners in having a stout caudal peduncle ( depth 72.4-82.5% of its length) and the medium-sized scaleless midventral region of belly extended slightly beyond halfway from the pectoral- to pelvic-fin origin. It is further distinguished from P. caudofasciatus in having a coarsely crenulated rostral fold with 18-23 indentations on its distal margin and a smaller mental adhesive disc ( length 66.7-71.4% of its width and 37.0-43.1% of the head length).

Four new terrestrial species of Marionina (Clitellata, Enchytraeidae) from China and re-examination of M. hoVbaueri Moller

Enchytraeid surveys were made in China, mainly along the Changjiang (Yangtze) River Basin, during the period 1991-1999. Among the findings, four terrestrial species of Marionina are new to science and well illustrate the taxonomic complexity of the genus as currently defined. Marionina sinica sp. n. is characterized by a specific chaetal distribution, the marionine pattern of the dorsal blood vessel, and elongate, fusiform, spermathecal ectal ducts. Marionina sacculata sp. n. is distinguished by the possession of a pair of pouch-like oesophageal appendages in IV, the lack of lateral chaetae in VII-XI, a marionine pattern of the dorsal blood vessel, and short spermathecal ectal ducts gradually expanding into spherical ampullae. Both M. sinica and M. sacculata have minute bodies (2-3 mm long in vivo) and lack spermathecal accessory glands. The former species shows its closest aYnities with the European M. brendae Rota, 1995, whereas the latter is closest to the German M. hoVbaueri Moller, 1971, for which an amended diagnosis is provided. Marionina seminuda sp. n. has only ventral chaetal bundles, distributed from III onwards and bisetose. It is similar to the Holarctic M. subterranea (Knollner, 1935) in lacking entirely the lateral chaetae and in having the brain incised posteriorly, the dorsal vessel bifurcating behind the pharynx, and coelomocytes containing opaque granules, but diVers from it in having the longest chaetae in preclitellar segments and gland cells distributed all over the spermathecal ectal ducts. Marionina righiana sp. n. is diagnosed by the location of the head pore on the prostomium, the absence of lateral chaetae from VIII ( VII or IX) onwards, the possession of free spermathecae extending backwards through one to four segments, the brain deeply incised posteriorly, the lumbricilline pattern of the dorsal blood vessel, and the opacity of coelomocytes in vivo. Prior to this study, members of the genus so atypical as M. righiana with respect to the position of the head pore and the structure of the spermathecae were known only from South American soils. Until the taxonomy of Marionina has been more thoroughly assessed and revised, the assignment of the four species to this large assemblage should be regarded as tentative.

辽河流域降雨侵蚀力的时空变化分析

降雨侵蚀力是反映流域降雨侵蚀能力的综合指标之一。根据辽河流域10个气象站的日降雨量资料,利用日降雨侵蚀力模型估算辽河流域的降雨侵蚀力。结果表明:辽河流域降雨侵蚀力的空间变异与降雨量的空间分布趋势基本一致,由东南向西北递减,变化于1 000~3 800 MJ.mm/(hm2.h.a)之间;降雨侵蚀力年内集中度高,6—8月3个月约占全年的80%;降雨侵蚀力年际变化大,年际变率Cv在0.367~0.649之间,采用时序系列的Mann-Kendall检验表明,降雨侵蚀力并无显著变化趋势;特别是在流域水土流失严重的西辽河地区,年降雨侵蚀力较小,但年内集中程度大,年际变化更突出。

松花江流域河流泥沙及其对人类活动的响应特征

对松花江流域主要水文站输沙量变化的分析表明:51年来,嫩江除1998年发生洪水外其余年份输沙量变化不大,第二松花江输沙量表现为明显的下降趋势,松花江干流输沙量也表现为下降趋势,而松花江整个流域在1979年之前为下降趋势,1979年之后为上升趋势。松花江干流区域和第二松花江为主要的泥沙来源区,分别占整个松花江流域输沙量的72.1%和16.2%。通过对单位降雨侵蚀力输沙量的分析,松花江流域输沙量负荷的变化与流域内重大历史事件、国家政策等人为活动的变化密切相关。"大跃进"时期嫩江流域输沙量负荷显著增大,三年自然灾害时期各区段输沙量负荷都出现峰值,"文革"时期各区段输沙量负荷起伏变化比较大,改革开放特别是家庭联产承包责任制实施以后,各区段输沙量负荷都呈现显著增长的趋势,90年代自然灾害频发使输沙量负荷持续出现峰值,直至1999年退耕还林后输沙量负荷才有所下降,但此后输沙量负荷又有不同程度的增长趋势。

土壤稳定入渗速率空间插值不确定性研究

以黄土丘陵沟壑第三副区的藉河流域为研究区,根据65个实测点数据,采用普通克里格法、反距离权重法、样条函数法等插值方法,分析了测点数量变化、栅格像元尺寸变化及插值方法的差异对土壤稳定入渗速率空间插值结果的影响,剖析了空间插值中的不确定性。结果表明:(1)参与插值站点越多,所得插值结果不确定性越小;(2)像元尺寸在25~800 m间变化对土壤稳定入渗速率的插值结果影响微弱;(3)不同插值方法对插值结果的精度影响较大,说明插值方法的差异对插值结果的不确定性有较大影响。

黄土高原水土保持政策演变

水土保持政策是指导和促进水土保持开展的主要社会驱动力之一。新中国成立以来,黄土高原水土保持经过探索治理、重点治理、全民治理、小流域综合治理和预防为主、依法防治等5个阶段。在不同阶段,水土保持目标和任务、治理主体、政策的针对性和治理主导措施侧重等均有变化。在分析政策演变的基础上,提出了针对新时期水土保持特点的政策建议。

地理环境要素与渭河流域水沙关系的定量研究

定量评价影响渭河流域产水、产沙的地理环境要素因子,为渭河流域产水、产沙格局划分及流域生态环境建设提供理论依据。【方法】分析渭河流域主要支流产水、产沙对年降雨量(P)、植被净初级生产力(NPP)、泥沙中数直径(D50)等地带性因子之间的响应机制。【结果】流域产水、产沙模数与以上3种因子之间均存在明显的非线性关系。采用回归分析得到了流域产水、产沙与地带性因子之间的多元回归模型。【结论】建立了渭河流域产水、产沙与地理环境要素之间的多项式回归模型。

延河流域种子植物区系特征与物种空间分布

以延河流域为例,采用环境梯度分层采样技术,对该流域种子植被的区系成分进行调查分析。结果表明,延河流域主要的种子植物区系共涉及57个科、148属、211种,其中裸子植物3科3属3种,被子植54科145属208种。从植物区系科属的分布型看,热带亚热带成分占31.57%,温带成分占28.07%;从属的分布型看,热带亚热带成分占11.72%,温带成分占60.54%。温带成分构成了本区系的主体,本区种子植物区系属温带性质。虽然数量上较整个黄土高原的植物区系成分较少,但这些物种却是该流域种子植物群落的主要构成种,对该区的生态恢复具有更重要的意义。在此基础上,进一步借助物种空间分布与环境要素响应图,分析211个物种分布的环境梯度空间,结果表明,它们可直接满足生态恢复重建的物种选择等需求,具有较好的应用价值。

辽宁太子河流域枯季水资源实时预报研究

太子河流域位于辽河中下游，区内分布有我国重要的钢铁、石化和粮食生产基地，是辽宁社会和经济发达地区。当前，太子河流域水资源短缺、水污染和地下水超采问题突出，水资源已成为制约当地社会经济持续、健康、稳定发展的重要因素。针对当前太子河流域严峻的水资源开发利用态势，论文提出了水资源实时评价的内容和方法，根据水资源实时监控管理的实际需要，将水资源实时评价分为汛末水资源实时评价和汛前水资源实时评价两部分。其中汛末评价主要是为计划用水和节约用水服务，而汛前评价主要是为抗旱减灾服务。在实时评价基础上，将水资源实时预报分为面向实时管理的水资源实时预报和面向实时调度的水资源实时预报两部分。建立了基于人工神经网络的地表径流实时预报模型和基于数值模拟技术的地下水可开采量（可供水量）实时预报模型，并进行了模型的率定、识别和验证。此外，借助由水资源实时预报模型和水资源实时管理模型构成的水资源实时预报管理祸合计算模式及计算流程，经模型祸合迭代计算，得出了太子河流域枯水期（2001～2002年度）水资源实时管理方案。上述研究成果，可以为辽宁太子河流域实现“计划用水和节约用水”提供决策依据，并可为北方干旱、半干旱地区流域水资源的“统一管理、动态管理和科学管理”提供可借鉴模式。

杂谷脑流域景观格局优化配置研究

景观格局优化理论、方法和技术的研究是景观生态学的一个热点问题，同时也是一个难点。本文以眠江上游典型研究区-杂谷脑流域为研究对象，利用遥感和GIS技术分析该流域从1974年到2000年景观格局的时空变化，并分析了对该流域生态安全存在威胁的主要因素；以空间模拟技术和线性规划为基础建模，从理论和方法上探讨景观格局优化配置问题，以期为该区域的农林复合景观系统的生态安全和可持续发展找出切实可行的格局优化模式；并提出生态敏感度概念，为景观管理优先级提供依据。本文的主要结论如下：（l）杂谷脑流域作为长江上游重要的森林资源输出地，从1974年到2000年景观变化得出，有林地面积减少13％；灌木林地面积增加37％；相应的水源涵养能力下降，土壤侵蚀量增加7.8％；（2）杂谷脑流域陡坡耕作严重，分布在20°-45°坡度上的耕地占耕地总面积的78．2％；干旱河谷分布范围扩大，面积从1974年的217.99km2增加到2000年的237．38kmZ对生态安全造成威胁；（3）产业结构以资源密集型产业和重污染工业为主，结构不合理，第一产业比例大，农民人均纯收入远低于同期全国平均水平，教育水平比较低，这些问题会对杂谷脑流域生态安全产生负向影响；（4）以减少土壤侵蚀为依据，通过空间建模和线性规划方法优化设计杂谷脑流域景观格局，优化结果显示土壤侵蚀量比2000年减少2.35*106吨／年，土壤保持能力与1974年相近，水源涵养能力增强；（5）景观管理对于区域安全必不可少，针对该流域现存问题，建议以提高科学技术水平，调整产业结构和资源利用方式，提高教育水平为突破口。

基于GIS的区域水土流失生态风险评价

为了给区域尺度的水土流失治理、规划及评价提供科学的依据,将"风险评价"的概念引入水土保持学科之中,定义了区域水土流失生态风险评价的概念,提出了评价的方法与步骤,构建了区域水土流失生态风险评价模型框架,并以延河流域为例进行了应用。结果表明:延河中游及安塞县和宝塔区为优先治理区;证明区域水土流失生态风险评价可以为政府水土保持管理决策提供参考。

延河流域退耕前后土壤侵蚀强度的变化

根据修正通用土壤流失方程,在ArcGIS软件平台下,以黄土高原延河流域为例,在合理选用和计算修正通用土壤流失方程中各因子参数的基础上,计算并分析陕北黄土高原延河流域退耕前后土壤侵蚀量的变化及其动态分布。结果表明:1)延河流域退耕后,土壤侵蚀明显减少,与1986—1997年相比,退耕后至2000年土壤侵蚀量平均减少34%;2)坡耕地对土壤侵蚀影响明显,尤其是陡坡耕地退耕至关重要;3)在修正通用土壤流失方程各因子中,短期内影响土壤侵蚀动态变化的主控因子是植被覆盖管理因子,所以调整土地利用结构是减少土壤侵蚀的有效方法。

中国水土流失的概况及其综合治理

本文以翔实的数据说明了我国水土流失严重的现状 ,并从良化生态环境 ,坚持综合整治、搞好小流域治理、提高防洪综合能力、加大执法力度、增强保水保土意识等方面 ,提出了防治我国水土流失的具体途径。

Drivers of soil net nitrogen mineralization in the temperate grasslands in Inner Mongolia, China

Soil net nitrogen mineralization (NNM) of four grasslands across the elevation and precipitation gradients was studied in situ in the upper 0-10 cm soil layer using the resin-core technique in Xilin River basin, Inner Mongolia, China during the growing season of 2006. The primary objectives were to examine variations of NNM among grassland types and the main influencing factors. These grasslands included Stipa baicalensis (SB), Aneulolepidum Chinense (AC), Stipa grandis (SG), and Stipa krylovii (SK) grassland. The results showed that the seasonal variation patterns of NNM were similar among the four grasslands, the rates of NNM and nitrification were highest from June to August, and lowest in September and October during the growing season. The rates of NNM and nitrification were affected significantly by the incubation time, and they were positively correlated with soil organic carbon content, total soil nitrogen (TN) content, soil temperature, and soil water content, but the rates of NNM and nitrification were negatively correlated with available N, and weakly correlated with soil pH and C:N ratio. The sequences of the daily mean rates of NNM and nitrification in the four grasslands during the growing season were AC > SG > SB > SK, and TN content maybe the main affecting factors which can be attributed to the land use type.